{"gene":"HECTD1","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":2007,"finding":"HECTD1 (identified via the ENU-induced 'open mind' mutation) is a ubiquitously expressed HECT-domain E3 ubiquitin ligase required for cranial neural tube closure; loss-of-function causes exencephaly associated with abnormal head mesenchyme development and dorsal-lateral hinge point formation. Two different Hectd1 alleles cause neural tube defects in heterozygotes, indicating a critical threshold requirement.","method":"ENU mutagenesis screen, genetic complementation, homozygous mutant embryo analysis, molecular marker expression","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function with defined developmental phenotype, two independent alleles replicated across the same study, clear molecular mechanism (E3 ligase identity established)","pmids":["17442300"],"is_preprint":false},{"year":2012,"finding":"HECTD1 is a functional E3 ubiquitin ligase that ubiquitinates HSP90, promoting its intracellular retention and suppressing its secretion. Loss of HECTD1 in cranial mesenchyme leads to enhanced extracellular HSP90 secretion, which drives increased cell emigration and underlies the neural tube defect (exencephaly) in Hectd1 mutant mice.","method":"In vitro ubiquitin ligase assay (demonstrating ubiquitination of HSP90), cranial mesenchyme explant emigration assays, rescue experiments with HSP90 neutralization, mutant mouse analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro ubiquitin ligase activity demonstrated, substrate (HSP90) identified, functional rescue experiment performed, mechanistic link to neural tube defect established","pmids":["22431752"],"is_preprint":false},{"year":2012,"finding":"HECTD1 (HectD1) modifies APC with Lys-63-linked polyubiquitin chains. This modification promotes the APC-Axin interaction within the destruction complex, thereby negatively regulating Wnt signaling. Knockdown of HectD1 diminishes APC ubiquitylation, disrupts the APC-Axin interaction, and augments Wnt3a-induced β-catenin stabilization and signaling.","method":"Co-immunoprecipitation, siRNA knockdown, ubiquitin linkage-specific assays, β-catenin signaling reporter assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, specific ubiquitin linkage type identified (K63), functional epistasis with Wnt pathway readout, multiple orthogonal methods in one study","pmids":["23277359"],"is_preprint":false},{"year":2013,"finding":"HECTD1 ubiquitinates PIPKIγ90 (phosphatidylinositol 4-phosphate 5-kinase type I γ) at lysine 97, leading to its proteasomal degradation. This cycling of PIPKIγ90 removes it from the PIPKIγ90-talin complex after on-site PIP2 production, providing a regulatory mechanism for focal adhesion assembly/disassembly and cell migration. The PIPKIγ90(K97R) ubiquitination-resistant mutant enhanced PIP2/PIP3 production and inhibited FA dynamics and cancer cell migration/invasion/metastasis.","method":"In vitro ubiquitination assay, site-directed mutagenesis (K97R), Co-IP, cell migration/invasion assays, FA dynamics analysis, metastasis mouse model","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro ubiquitination assay, specific ubiquitination site identified by mutagenesis, functional consequences validated in multiple cell-based assays and in vivo metastasis model","pmids":["23572508"],"is_preprint":false},{"year":2014,"finding":"The N-terminal domain of HectD1 adopts a novel 5-helix bundle fold termed the Basic Tilted Helix Bundle (BTHB) domain, structurally related to FKBP25. A positively charged surface patch centered on the tilted helix H4 is conserved in both proteins, suggesting a conserved functional role, possibly in nucleic acid binding.","method":"NMR structure determination, comparative structural analysis","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — NMR structure solved for the domain, but functional role of the BTHB domain in HECTD1 specifically was not experimentally validated (only inferred from structural conservation)","pmids":["24667607"],"is_preprint":false},{"year":2014,"finding":"Hectd1 is required for development of multiple trophoblast cell subtypes in the mouse placenta junctional zone, including trophoblast giant cells (TGCs), spongiotrophoblasts, and glycogen trophoblasts. Loss of Hectd1 results in mid-gestation lethality and intrauterine growth restriction, with differential changes in proliferation and apoptosis across placental layers.","method":"Homozygous mutant mouse analysis, immunohistochemistry, in situ hybridization with cell-type-specific markers, proliferation and apoptosis assays","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockout with defined developmental phenotype, multiple cell-type markers examined, replicated across multiple litters with littermate controls","pmids":["24855001"],"is_preprint":false},{"year":2017,"finding":"HECTD1 interacts with IQGAP1 and regulates its degradation through ubiquitination, thereby controlling focal complex (FX) dynamics and directionality of cell migration. Loss of Hectd1 in MEF cells causes accelerated spreading and migration but impaired directionality, mislocalization of paxillin and zyxin, and increased focal complexes. Overexpression of IQGAP1 phenocopies Hectd1 loss; siRNA-mediated knockdown of IQGAP1 rescues migration defects of Hectd1 mutant cells.","method":"Hectd1 mutant MEF cell line, Co-IP, ubiquitination assay, siRNA rescue, IQGAP1 overexpression phenocopy, live cell imaging of migration and adhesion dynamics","journal":"Cell communication and signaling : CCS","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal genetic epistasis (rescue and phenocopy), Co-IP, ubiquitination assay, multiple orthogonal functional readouts in one study","pmids":["28073378"],"is_preprint":false},{"year":2017,"finding":"USP15 deubiquitinates and stabilizes HECTD1 in glioblastoma cells. Depletion of USP15 leads to decreased HECTD1 protein levels. USP15 expression attenuates Wnt pathway activity in a HECTD1-dependent manner; modulation of HECTD1 expression phenocopies USP15 effects on the Wnt pathway.","method":"Mass spectrometry protein interaction screen, Co-IP, siRNA knockdown, Wnt reporter assays, protein stability assays","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and MS identification of interaction, functional epistasis via phenocopy experiments, single lab study","pmids":["29299163"],"is_preprint":false},{"year":2018,"finding":"HectD1 ubiquitinates and promotes proteasome-mediated degradation of the microtubule plus-end tracking protein ACF7. Depletion of HectD1 stabilizes ACF7, which enhances the EMT program and cell migration. Decreased HectD1 expression increased metastases in mouse models.","method":"shRNA screens, Co-IP, ubiquitination assays, ACF7 protein stability assays, EMT marker analysis, in vivo metastasis mouse models","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — ubiquitination assay, protein stability assay, multiple functional readouts (EMT markers, migration, in vivo metastasis), consistent across cell lines and animal models","pmids":["29386124"],"is_preprint":false},{"year":2019,"finding":"HECTD1 binds to and influences ubiquitination of the retinoic acid receptor alpha (RARA). Loss of HECTD1 reduces activation of a retinoic acid response element (RARE) reporter in mutant cells and embryos. Genetic interaction between Hectd1 and Raldh2 (retinoic acid synthesis enzyme) in double-heterozygous embryos causes 4th pharyngeal arch artery hypoplasia, establishing HECTD1 as a novel modulator of retinoic acid signaling during aortic arch development.","method":"Co-IP (HECTD1-RARA interaction), RARE reporter assays in cells and embryos, genetic epistasis (double heterozygous mouse crosses), embryo phenotype analysis","journal":"Disease models & mechanisms","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP, functional reporter assay, and genetic epistasis in vivo all support the same conclusion, multiple orthogonal methods","pmids":["30578278"],"is_preprint":false},{"year":2020,"finding":"HECTD1 interacts with SNAIL and regulates its stability through ubiquitination; knockdown of HECTD1 increases SNAIL expression levels. HECTD1 shuttles between cytoplasm and nucleus via nuclear localization and export signals, regulated by EGF. Nuclear retention of HECTD1 (by leptomycin B) is associated with loss of SNAIL expression. Under hypoxia, HECTD1 expression is decreased by miR-210.","method":"Co-IP, ubiquitination assay, siRNA knockdown, nuclear/cytoplasmic fractionation, leptomycin B treatment, miR-210 overexpression, cell migration assay","journal":"International journal of oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ubiquitination assay for SNAIL substrate, localization assay with functional consequence, single lab with multiple orthogonal methods","pmids":["32319576"],"is_preprint":false},{"year":2020,"finding":"HECTD1 promotes base excision repair (BER) in chromatin by ubiquitylating histones, which stimulates AP endonuclease 1 (APE1) incision of abasic sites (THF) when the DNA damage is facing the histone core. A recombinant truncated form of HECTD1 directly stimulates THF incision by APE1 in reconstituted mononucleosome assays. siRNA depletion of HECTD1 leads to deficiencies in DNA damage repair and decreased cell survival following x-ray irradiation.","method":"Reconstituted mononucleosome BER assay with site-specific synthetic abasic sites, purification of HECTD1 activity from HeLa extracts, recombinant protein in vitro assay, siRNA knockdown, x-ray irradiation cell survival assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted in vitro assay with purified recombinant HECTD1 and mononucleosomes, biochemical purification from cell extracts, complementary cell-based functional assay","pmids":["31799632"],"is_preprint":false},{"year":2020,"finding":"Latexin (LXN) forms a functional complex with HECTD1 and ribosomal protein subunit 3 (Rps3). IκBα is a substrate of HECTD1. LXN knockdown enhances the HECTD1-Rps3 interaction, contributing to ubiquitination-mediated degradation of IκBα and subsequent NF-κB activation, promoting colitis severity.","method":"Proteomics/Co-IP (LXN-HECTD1-Rps3 complex), ubiquitination assay of IκBα, siRNA knockdown, ectopic expression, DSS-induced colitis mouse model","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP complex identification, ubiquitination assay of IκBα substrate, functional in vivo colitis model, single lab","pmids":["32555320"],"is_preprint":false},{"year":2021,"finding":"HectD1 ubiquitinates and degrades ZNF622, an assembly factor for the ribosomal 60S subunit. Loss of HectD1 causes accumulation of ZNF622 and the anti-association factor eIF6 on 60S, resulting in 60S/40S ribosomal subunit joining defects, reduced protein synthesis, and impaired hematopoietic stem cell (HSC) function under stress. Znf622 depletion in Hectd1-deficient HSCs restored ribosomal subunit joining, protein synthesis, and HSC reconstitution capacity.","method":"Conditional knockout mice, genetic epistasis (Hectd1 KO + Znf622 knockdown double mutant rescue), ubiquitination assay, ribosome profiling/polysome analysis, protein synthesis measurement, HSC transplantation assays","journal":"Cell stem cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — ubiquitination assay for ZNF622 substrate, genetic rescue (epistasis) by Znf622 depletion, ribosome assembly functional readout, protein synthesis measurement, in vivo HSC reconstitution","pmids":["33711283"],"is_preprint":false},{"year":2021,"finding":"The deubiquitinase TRABID stabilizes HECTD1 by removing ubiquitin chains. HECTD1 preferentially assembles K29- and K48-linked ubiquitin chains and requires branching at K29/K48 for full ligase activity. TRABID depletion leads to rapid HECTD1 degradation, establishing TRABID-HECTD1 as a DUB/E3 pair.","method":"TRABID catalytic-dead construct interactome (trapping assay), UbiCREST assay, Ub-AQUA proteomics, in vitro autoubiquitination assay with ubiquitin mutants, siRNA knockdown and genetic knockout of TRABID, protein stability assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro autoubiquitination with ubiquitin mutants defining chain type, UbiCREST and mass spectrometry for chain linkage, trapping assay for DUB substrate identification, multiple orthogonal methods in one study","pmids":["33853758"],"is_preprint":false},{"year":2021,"finding":"HECTD1 is upregulated in astrocytes following LPS treatment. Its expression is transcriptionally controlled by the σ-1R-JNK/p38-FOXJ2 signaling axis: LPS activates σ-1R, which activates JNK/p38, which promotes nuclear translocation of the transcription factor FOXJ2 to drive HECTD1 expression. Knockdown of HECTD1 suppresses LPS-induced astrocyte activation; overexpression facilitates it.","method":"siRNA knockdown, overexpression, pharmacological inhibition (σ-1R antagonist, JNK inhibitor, p38 inhibitor), nuclear translocation assays, in vivo astrocyte-specific knockdown","journal":"Cell & bioscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockdown and overexpression with functional readouts, epistasis via pharmacological inhibitors, in vivo validation, single lab","pmids":["33781347"],"is_preprint":false},{"year":2021,"finding":"BIRC6 protein stability is regulated by HECTD1: EGF-JNK signaling prevents HECTD1-mediated ubiquitination and proteasomal degradation of BIRC6. Activation of JNK by EGF blocks HECTD1 from ubiquitinating BIRC6, leading to BIRC6 accumulation in TNBC cells.","method":"Co-IP, ubiquitination assay, JNK inhibitor treatment, EGF stimulation, siRNA knockdown, protein stability/half-life assay","journal":"Molecular therapy. Nucleic acids","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ubiquitination assay for BIRC6 substrate, pharmacological epistasis with JNK inhibitor, single lab with multiple orthogonal methods","pmids":["34729249"],"is_preprint":false},{"year":2022,"finding":"HECTD1 depletion in HEK293T and HeLa cells decreases cell number by slowing mitotic progression. HECTD1 depletion increases the proportion of cells in prometaphase/metaphase and prolongs NEBD-to-anaphase onset time. HECTD1 depletion reduces Spindle Assembly Checkpoint activity, and BUB3 (a component of the Mitosis Checkpoint Complex) is identified as a novel HECTD1 interactor.","method":"siRNA knockdown and genetic knockout, flow cytometry (pH3-Ser28 mitotic marker), time-lapse microscopy, Co-IP (BUB3 interaction), cell counting assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO and transient KD with functional readout (time-lapse mitotic timing), Co-IP for BUB3 interaction, single lab","pmids":["35915203"],"is_preprint":false},{"year":2022,"finding":"HECTD1 ubiquitinates and targets DLC1 (a RhoGAP tumor suppressor) for proteasomal degradation. siRNA-mediated knockdown of HECTD1 increases DLC1 protein levels and impairs its degradation. HECTD1 modulation alters DLC1 abundance at focal adhesions. USP7 deubiquitinates and stabilizes DLC1, acting oppositely to HECTD1.","method":"Mass spectrometry identification of DLC1-HECTD1 interaction, siRNA knockdown, protein stability assay, immunofluorescence microscopy of focal adhesion localization","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS interaction identification, siRNA knockdown with DLC1 stability readout, localization assay, single lab","pmids":["35322810"],"is_preprint":false},{"year":2022,"finding":"HECTD1 ubiquitinates GLT-1 (glutamate transporter 1) in astrocytes, promoting its degradation. Knockdown of HECTD1 restores GLT-1 expression impaired by MPP+ treatment. Vitamin C reduces HECTD1 expression, thereby reducing GLT-1 ubiquitination and restoring its expression. Overexpression of HECTD1 abolishes the protective effect of vitamin C on GLT-1.","method":"siRNA knockdown, overexpression, ubiquitination assay, transcriptome sequencing, western blot, in vivo murine PD model","journal":"ACS chemical neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic gain and loss of function with ubiquitination readout, epistasis via HECTD1 overexpression blocking vitamin C effect, single lab","pmids":["35148069"],"is_preprint":false},{"year":2023,"finding":"HECTD1 ubiquitinates Rubicon at lysine residue 534, targeting it for proteasomal degradation. HECTD1-mediated Rubicon degradation activates chondrocyte autophagy, mitigating stress-induced chondrocyte death and OA progression. Overexpression of HECTD1 in mouse joints alleviated OA, while cartilage-specific Hectd1 knockout aggravated OA in surgery- and aging-induced models.","method":"Co-IP, ubiquitination assay with site-specific mutagenesis (K534), conditional knockout mice, adeno-associated virus overexpression in joints, autophagy flux assays, OA histology scoring","journal":"Arthritis & rheumatology (Hoboken, N.J.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — specific ubiquitination site identified by mutagenesis, Co-IP, conditional KO in vivo, rescue by HECTD1 overexpression, autophagy functional assay, multiple orthogonal methods","pmids":["36121967"],"is_preprint":false},{"year":2023,"finding":"HectD1 co-localizes with centriolin at the centrosome during mitosis, and binds to centriolin in a cell-cycle-dependent manner. HectD1 expression fluctuates through the cell cycle, with highest levels during mitosis coinciding with a marked reduction in centriolin expression, suggesting HectD1-mediated degradation of centriolin.","method":"Co-IP (HectD1-centriolin interaction), immunofluorescence co-localization, cell-cycle-staged protein expression analysis","journal":"BMC research notes","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP and co-localization, no direct ubiquitination assay for centriolin substrate, speculative degradation claim","pmids":["38115153"],"is_preprint":false},{"year":2023,"finding":"HECTD1 contributes to ubiquitination and proteasomal degradation of NUP93 (Nucleoporin 93) in esophageal squamous cell carcinoma cells. HECTD1 acts as an upstream regulator of NUP93 and functions as a tumor suppressor in ESCC.","method":"Co-IP, ubiquitination assay, siRNA knockdown and overexpression, cell proliferation/migration/invasion assays","journal":"Human cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ubiquitination assay demonstrating HECTD1-NUP93 interaction and ubiquitination, functional cell-based assays, single lab","pmids":["37993750"],"is_preprint":false},{"year":2024,"finding":"Five rare HECTD1 missense variants identified in human NTD cases reduce HECTD1's ability to suppress extracellular HSP90 secretion in HEK293T cells. One variant (A1084T) also shows reduced protein expression. These functional data support the role of HECTD1-mediated control of eHSP90 secretion in human NTD etiology.","method":"Targeted next-generation sequencing, HEK293T functional assays for eHSP90 secretion, protein expression analysis of missense variants","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional variant analysis with defined molecular readout (eHSP90 secretion suppression), multiple variants tested with benign control, single lab","pmids":["38451291"],"is_preprint":false},{"year":2024,"finding":"HECTD1 ubiquitinates HSP90, and this ubiquitination is regulated by miR-16-5p delivered via DRG-derived exosomes: miR-16-5p targets HECTD1 mRNA, reducing HECTD1 levels and consequently altering ubiquitination of HSP90 in microglia, thereby promoting microglial activation and neuropathic pain.","method":"Co-IP, western blot for HSP90 ubiquitination, RNA pull-down and dual-luciferase reporter (miR-16-5p/HECTD1 interaction), miR-16-5p knockdown in DRG-exosomes, behavioral NP assays in SNL mice, immunofluorescence","journal":"Biological research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ubiquitination assay, miR-16-5p/HECTD1 interaction validated by multiple assays, in vivo rescue experiments, single lab","pmids":["38750549"],"is_preprint":false},{"year":2025,"finding":"HECTD1 ubiquitinates AURKA, promoting its proteasomal degradation. Inflammatory conditions (IL-1β) cause DNMT1-mediated methylation-driven downregulation of HECTD1, which releases AURKA from ubiquitination-mediated degradation. Elevated AURKA then phosphorylates eIF4E, enhancing cap-dependent mRNA translation of ADAMTS12, resulting in extracellular matrix degradation in OA chondrocytes.","method":"Co-IP, GST pull-down (HECTD1-AURKA interaction), ubiquitination assay, DNMT1 methylation analysis, cap-dependent translation reporter assay, OA mouse model (ACL-T), siRNA knockdown/overexpression","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and GST pull-down for substrate identification, ubiquitination assay, pathway epistasis with functional OA readout, single lab","pmids":["40838484"],"is_preprint":false},{"year":2025,"finding":"HECTD1 ubiquitinates VDAC3, promoting its degradation. Hypothermia upregulates HECTD1 and increases VDAC3 ubiquitination in a rat cardiac arrest/CPR model. Hectd1 knockdown reduces VDAC3 ubiquitination, abolishes hypothermia-induced neuroprotection, and worsens neurological outcomes.","method":"Co-immunoprecipitation (HECTD1-VDAC3 interaction), immunofluorescence co-localization, siRNA knockdown (adeno-associated viral vector), western blot for ubiquitination, neurological deficit scoring, rat cardiac arrest model","journal":"International journal of medical sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ubiquitination assay for VDAC3 substrate, in vivo rescue with functional neurological readout, single lab","pmids":["42158826"],"is_preprint":false},{"year":2018,"finding":"In SiO2-exposed macrophages, HECTD1 protein expression is increased concomitantly with decreased circHECTD1. HECTD1 is involved in ZC3H12A-dependent ubiquitination during macrophage activation, contributing to SiO2-induced inflammatory responses. HECTD1 upregulation in macrophages promotes fibroblast proliferation and migration.","method":"siRNA knockdown, western blot, Co-IP, cell functional assays (proliferation, migration), in vivo silicosis tissue validation","journal":"Theranostics","confidence":"Low","confidence_rationale":"Tier 3 / Weak — mechanistic detail of HECTD1's specific substrates in this context not fully characterized; ZC3H12A ubiquitination inferred but not directly demonstrated with purified components","pmids":["29290828"],"is_preprint":false},{"year":2025,"finding":"Conditional knockout of Hectd1 in the neural lineage in mice results in microcephaly, severe hippocampal malformations, and complete agenesis of the corpus callosum, supporting a role for Hectd1 in embryonic brain development. Functional studies of select HECTD1 variants in C. elegans revealed dominant effects including change-of-function or loss-of-function/haploinsufficient mechanisms.","method":"Neural lineage-specific conditional knockout mice, brain morphology analysis, C. elegans functional variant assays, clinical cohort sequencing (GeneMatcher)","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean conditional KO with defined brain developmental phenotype, functional variant analysis in C. elegans model organism, replication across 14 unrelated human cases","pmids":["39879987"],"is_preprint":false}],"current_model":"HECTD1 is a HECT-domain E3 ubiquitin ligase that assembles preferentially K29/K48-branched ubiquitin chains and targets a diverse set of substrates—including HSP90, PIPKIγ90, APC, ACF7, IQGAP1, SNAIL, ZNF622, Rubicon, DLC1, RARA, BIRC6, GLT-1, NUP93, AURKA, and VDAC3—for proteasomal degradation or functional modification, thereby regulating focal adhesion dynamics and cell migration, Wnt and retinoic acid signaling, ribosome assembly and protein synthesis in hematopoietic stem cells, autophagy in chondrocytes, base excision repair in chromatin, mitotic progression, EMT and metastasis, and neural tube and aortic arch development; its own stability is controlled by the deubiquitinase TRABID, and it is subject to transcriptional regulation via the σ-1R-JNK/p38-FOXJ2 axis and miRNA-mediated post-transcriptional control."},"narrative":{"mechanistic_narrative":"HECTD1 is a HECT-domain E3 ubiquitin ligase that controls developmental morphogenesis, cell migration, and signaling by ubiquitinating a broad set of substrates and thereby directing their degradation, localization, or function [PMID:17442300, PMID:22431752, PMID:33853758]. Biochemically it preferentially assembles K29/K48-branched ubiquitin chains and depends on this branching for full ligase activity, while its own abundance is set by the deubiquitinase TRABID, defining a DUB/E3 pair [PMID:33853758]. Through substrate ubiquitination HECTD1 restrains intracellular-to-extracellular HSP90 secretion to permit cranial neural tube closure—a function disrupted by rare human NTD-associated missense variants [PMID:22431752, PMID:38451291]—and degrades focal-adhesion and cytoskeletal regulators including PIPKIγ90, IQGAP1, ACF7, and DLC1 to govern adhesion dynamics, directional migration, EMT, and metastasis [PMID:23572508, PMID:28073378, PMID:29386124, PMID:35322810]. It modulates Wnt signaling by K63-ubiquitinating APC to stabilize the APC-Axin destruction complex [PMID:23277359] and tunes retinoic acid signaling via RARA during aortic arch development [PMID:30578278]. Additional substrates link HECTD1 to ribosomal 60S subunit assembly and protein synthesis in hematopoietic stem cells (ZNF622) [PMID:33711283], chondrocyte autophagy and osteoarthritis (Rubicon, AURKA) [PMID:36121967, PMID:40838484], histone-dependent base excision repair (stimulating APE1 incision) [PMID:31799632], and mitotic progression and spindle-assembly-checkpoint signaling (BUB3 interactor) [PMID:35915203]. HECTD1 is essential for placental, neural, and brain development, with neural-lineage loss causing microcephaly, hippocampal malformation, and corpus callosum agenesis, and human variants producing dominant or haploinsufficient effects [PMID:17442300, PMID:24855001, PMID:39879987].","teleology":[{"year":2007,"claim":"Established HECTD1's biological identity and necessity by showing an ENU-induced mutation in this HECT E3 ligase causes cranial neural tube defects, defining a dose-sensitive developmental requirement.","evidence":"ENU mutagenesis screen with two alleles and homozygous mutant embryo analysis in mouse","pmids":["17442300"],"confidence":"High","gaps":["No substrate or enzymatic mechanism identified at this stage","Cell-type-specific requirement not resolved"]},{"year":2012,"claim":"Connected HECTD1 enzymatic activity to its developmental phenotype by identifying HSP90 ubiquitination as the mechanism restraining cranial mesenchyme cell emigration.","evidence":"In vitro ubiquitin ligase assay, explant emigration assays with HSP90 neutralization rescue in mouse","pmids":["22431752"],"confidence":"High","gaps":["Ubiquitin chain linkage on HSP90 not defined","How ubiquitination suppresses secretion mechanistically unclear"]},{"year":2012,"claim":"Showed HECTD1 negatively regulates Wnt signaling by K63-ubiquitinating APC to promote the APC-Axin destruction complex, extending its role into signaling pathway control.","evidence":"Reciprocal Co-IP, siRNA knockdown, linkage-specific ubiquitin assays, β-catenin reporter assays","pmids":["23277359"],"confidence":"High","gaps":["Whether APC modification is direct in cells not fully resolved","Link to a developmental Wnt phenotype not established here"]},{"year":2013,"claim":"Defined a focal-adhesion regulatory role by mapping HECTD1 ubiquitination of PIPKIγ90 at K97, coupling lipid kinase turnover to adhesion dynamics and metastasis.","evidence":"In vitro ubiquitination, K97R mutagenesis, FA dynamics and migration/invasion assays, metastasis mouse model","pmids":["23572508"],"confidence":"High","gaps":["Chain type on PIPKIγ90 not specified","Upstream signals triggering degradation unclear"]},{"year":2014,"claim":"Provided structural insight by solving the N-terminal BTHB domain fold and proposing a conserved nucleic-acid-binding surface.","evidence":"NMR structure determination and comparative structural analysis","pmids":["24667607"],"confidence":"Medium","gaps":["Functional role of BTHB domain in HECTD1 not experimentally tested","No demonstrated nucleic acid binding"]},{"year":2014,"claim":"Extended the developmental requirement to extraembryonic tissue, showing Hectd1 is needed for multiple trophoblast subtypes and placental viability.","evidence":"Homozygous mutant mouse analysis with cell-type markers, proliferation/apoptosis assays","pmids":["24855001"],"confidence":"High","gaps":["Substrate driving placental defects not identified","Cell-autonomy vs. systemic effect unresolved"]},{"year":2017,"claim":"Identified additional cytoskeletal/migration control via IQGAP1 ubiquitination governing focal complex dynamics and migration directionality.","evidence":"Hectd1 mutant MEFs, Co-IP, ubiquitination assay, IQGAP1 phenocopy and siRNA rescue, live imaging","pmids":["28073378"],"confidence":"High","gaps":["Chain type and direct in vitro ubiquitination of IQGAP1 not shown","Relationship to PIPKIγ90 pathway unclear"]},{"year":2017,"claim":"Showed HECTD1 stability is post-translationally controlled, with USP15 deubiquitinating and stabilizing it to modulate Wnt activity in glioblastoma.","evidence":"MS interaction screen, Co-IP, siRNA knockdown, Wnt reporter and stability assays","pmids":["29299163"],"confidence":"Medium","gaps":["Direct deubiquitination not reconstituted","Single-lab study"]},{"year":2018,"claim":"Linked HECTD1 to EMT and metastasis suppression through ACF7 ubiquitination and degradation.","evidence":"shRNA screens, Co-IP, ubiquitination and stability assays, EMT markers, in vivo metastasis models","pmids":["29386124"],"confidence":"High","gaps":["Chain linkage on ACF7 not defined","Interplay with other migration substrates not integrated"]},{"year":2019,"claim":"Established HECTD1 as a modulator of retinoic acid signaling via RARA, with a genetic interaction with Raldh2 controlling aortic arch artery development.","evidence":"Co-IP, RARE reporter assays in cells and embryos, double-heterozygous mouse crosses","pmids":["30578278"],"confidence":"High","gaps":["Whether RARA is a degradation substrate vs. modulated unclear","Direct in vitro ubiquitination not shown"]},{"year":2020,"claim":"Defined a chromatin/DNA-repair function showing HECTD1 ubiquitylates histones to stimulate APE1 incision during base excision repair.","evidence":"Reconstituted mononucleosome BER assay, purified recombinant HECTD1, siRNA and irradiation survival assay","pmids":["31799632"],"confidence":"High","gaps":["Specific histone residues ubiquitylated not fully mapped","How HECTD1 is recruited to damaged chromatin unknown"]},{"year":2020,"claim":"Implicated HECTD1 in NF-κB signaling and colitis through an LXN-HECTD1-Rps3 complex driving IκBα degradation.","evidence":"Co-IP/proteomics, IκBα ubiquitination assay, siRNA, DSS colitis mouse model","pmids":["32555320"],"confidence":"Medium","gaps":["Direct vs. complex-dependent ubiquitination of IκBα unresolved","Single-lab study"]},{"year":2020,"claim":"Showed HECTD1 controls SNAIL stability and shuttles between nucleus and cytoplasm under EGF control, with miR-210 reducing its expression under hypoxia.","evidence":"Co-IP, ubiquitination assay, fractionation, leptomycin B, miR-210 overexpression, migration assays","pmids":["32319576"],"confidence":"Medium","gaps":["NLS/NES sequences not mapped","Direct ubiquitination of SNAIL not reconstituted"]},{"year":2021,"claim":"Revealed a translational/stem-cell role by showing HECTD1 degrades the 60S assembly factor ZNF622 to enable ribosomal subunit joining and HSC function under stress.","evidence":"Conditional KO mice, Znf622-depletion epistasis rescue, ubiquitination assay, polysome/protein synthesis and HSC transplantation","pmids":["33711283"],"confidence":"High","gaps":["Whether ZNF622 ubiquitination is direct in vivo across tissues unclear","Role outside hematopoietic stress not defined"]},{"year":2021,"claim":"Defined HECTD1's intrinsic enzymology and stability control: it builds K29/K48-branched chains requiring branching for activity, and TRABID is its stabilizing deubiquitinase.","evidence":"In vitro autoubiquitination with ubiquitin mutants, UbiCREST, Ub-AQUA MS, TRABID trapping and knockout/stability assays","pmids":["33853758"],"confidence":"High","gaps":["Whether substrate chains are also K29/K48-branched not established for each substrate","Structural basis of branch specificity unknown"]},{"year":2021,"claim":"Identified transcriptional control of HECTD1 via the σ-1R-JNK/p38-FOXJ2 axis driving its expression during LPS-induced astrocyte activation.","evidence":"siRNA/overexpression, pharmacological inhibitors, nuclear translocation assays, in vivo astrocyte knockdown","pmids":["33781347"],"confidence":"Medium","gaps":["Direct FOXJ2 binding to HECTD1 promoter not mapped","Substrates in astrocyte activation not defined"]},{"year":2021,"claim":"Showed EGF-JNK signaling protects BIRC6 from HECTD1-mediated ubiquitination, linking HECTD1 to apoptosis regulation in TNBC.","evidence":"Co-IP, ubiquitination assay, JNK inhibitor and EGF stimulation, stability assays","pmids":["34729249"],"confidence":"Medium","gaps":["Mechanism by which JNK blocks ubiquitination unclear","Single-lab study"]},{"year":2022,"claim":"Implicated HECTD1 in mitotic progression and spindle-assembly-checkpoint function, identifying BUB3 as a new interactor.","evidence":"siRNA/KO, flow cytometry, time-lapse microscopy, Co-IP in HEK293T/HeLa","pmids":["35915203"],"confidence":"Medium","gaps":["No mitotic ubiquitination substrate established","Whether BUB3 is a substrate vs. binding partner unclear"]},{"year":2022,"claim":"Showed HECTD1 degrades the RhoGAP tumor suppressor DLC1, opposed by USP7, linking it to focal-adhesion-localized DLC1 abundance.","evidence":"MS interaction, siRNA knockdown, stability and immunofluorescence assays","pmids":["35322810"],"confidence":"Medium","gaps":["Direct ubiquitination not reconstituted","Single-lab study"]},{"year":2022,"claim":"Extended HECTD1 substrate range to the glutamate transporter GLT-1 in astrocytes, with vitamin C lowering HECTD1 to preserve GLT-1.","evidence":"siRNA/overexpression, ubiquitination assay, transcriptome sequencing, in vivo PD model","pmids":["35148069"],"confidence":"Medium","gaps":["Direct ubiquitination site not mapped","Mechanism of vitamin C effect on HECTD1 unclear"]},{"year":2023,"claim":"Defined a cartilage-protective role through K534 ubiquitination and degradation of Rubicon, activating chondrocyte autophagy and limiting osteoarthritis.","evidence":"Co-IP, K534 mutagenesis, conditional KO and AAV overexpression, autophagy flux and OA histology","pmids":["36121967"],"confidence":"High","gaps":["Upstream regulation of HECTD1 in chondrocytes only partly defined","Chain linkage on Rubicon not specified"]},{"year":2023,"claim":"Suggested a centrosomal mitotic substrate by showing cell-cycle-dependent HectD1-centriolin co-localization and inverse expression.","evidence":"Co-IP, immunofluorescence co-localization, cell-cycle-staged expression","pmids":["38115153"],"confidence":"Low","gaps":["No direct ubiquitination assay for centriolin — degradation claim is inferential","Single Co-IP without functional validation"]},{"year":2023,"claim":"Identified HECTD1 as a tumor suppressor in esophageal squamous cell carcinoma acting through ubiquitination and degradation of NUP93.","evidence":"Co-IP, ubiquitination assay, siRNA/overexpression, proliferation/migration/invasion assays","pmids":["37993750"],"confidence":"Medium","gaps":["Direct ubiquitination site not mapped","Single-lab study"]},{"year":2024,"claim":"Provided human genetic support for the HSP90 mechanism, showing rare NTD-associated HECTD1 missense variants impair suppression of extracellular HSP90 secretion.","evidence":"Targeted NGS and HEK293T eHSP90 secretion functional assays","pmids":["38451291"],"confidence":"Medium","gaps":["Causality in patients not proven beyond functional assay","Variant effects on catalytic activity only partly characterized"]},{"year":2024,"claim":"Showed exosomal miR-16-5p targets HECTD1 mRNA to alter HSP90 ubiquitination in microglia, linking HECTD1 to neuropathic pain.","evidence":"Co-IP, ubiquitination western blot, RNA pull-down/luciferase, in vivo SNL behavioral assays","pmids":["38750549"],"confidence":"Medium","gaps":["Direct microglial HSP90 ubiquitination consequence not fully resolved","Single-lab study"]},{"year":2025,"claim":"Connected HECTD1 to chondrocyte ECM degradation, with DNMT1-driven methylation downregulating HECTD1 to release AURKA, which phosphorylates eIF4E to enhance ADAMTS12 translation.","evidence":"Co-IP/GST pull-down, ubiquitination assay, methylation analysis, cap-dependent translation reporter, OA mouse model","pmids":["40838484"],"confidence":"Medium","gaps":["Direct AURKA ubiquitination site not mapped","Single-lab study"]},{"year":2025,"claim":"Showed hypothermia-induced HECTD1 ubiquitinates VDAC3 to mediate neuroprotection after cardiac arrest.","evidence":"Co-IP, immunofluorescence, AAV siRNA knockdown, ubiquitination western blot, rat cardiac arrest model","pmids":["42158826"],"confidence":"Medium","gaps":["Direct ubiquitination site not defined","Single-lab study"]},{"year":2025,"claim":"Established HECTD1 as a human neurodevelopmental disease gene, with neural-lineage knockout causing brain malformations and patient variants showing dominant or haploinsufficient mechanisms.","evidence":"Neural-lineage conditional KO mouse brain morphology, C. elegans variant assays, clinical cohort sequencing","pmids":["39879987"],"confidence":"Medium","gaps":["Substrate driving brain phenotype not identified","Genotype-phenotype correlation across variants incomplete"]},{"year":null,"claim":"How HECTD1's K29/K48-branched chain specificity is structurally achieved and which substrate-specific chain architectures and recruitment mechanisms direct its many context-dependent functions remains unresolved.","evidence":"No discovery in the timeline reconstitutes substrate-specific branched-chain assembly or maps substrate recruitment determinants","pmids":[],"confidence":"Low","gaps":["No full-length structure with substrate","Substrate selection rules across tissues unknown","Whether branched chains apply to all substrates undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a 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pulmonary fibrosis by targeting EMT and subsequent fibroblasts activation.","date":"2026","source":"Toxicology letters","url":"https://pubmed.ncbi.nlm.nih.gov/42167616","citation_count":0,"is_preprint":false},{"pmid":"41311373","id":"PMC_41311373","title":"HECTD1-mediated SFTPB overexpression in fibrotic lung induced by silica.","date":"2025","source":"Biochemistry and biophysics reports","url":"https://pubmed.ncbi.nlm.nih.gov/41311373","citation_count":0,"is_preprint":false},{"pmid":"42158826","id":"PMC_42158826","title":"Therapeutic Hypothermia Ameliorates Apoptosis and Cerebral Injury by Upregulating HECTD1-mediated Ubiquitination and VDAC3 Degradation in a Rat CPR Model.","date":"2026","source":"International journal of medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/42158826","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":28644,"output_tokens":8169,"usd":0.104234,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":17739,"output_tokens":7206,"usd":0.134423,"stage2_stop_reason":"end_turn"},"total_usd":0.238657,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"HECTD1 (identified via the ENU-induced 'open mind' mutation) is a ubiquitously expressed HECT-domain E3 ubiquitin ligase required for cranial neural tube closure; loss-of-function causes exencephaly associated with abnormal head mesenchyme development and dorsal-lateral hinge point formation. Two different Hectd1 alleles cause neural tube defects in heterozygotes, indicating a critical threshold requirement.\",\n      \"method\": \"ENU mutagenesis screen, genetic complementation, homozygous mutant embryo analysis, molecular marker expression\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function with defined developmental phenotype, two independent alleles replicated across the same study, clear molecular mechanism (E3 ligase identity established)\",\n      \"pmids\": [\"17442300\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HECTD1 is a functional E3 ubiquitin ligase that ubiquitinates HSP90, promoting its intracellular retention and suppressing its secretion. Loss of HECTD1 in cranial mesenchyme leads to enhanced extracellular HSP90 secretion, which drives increased cell emigration and underlies the neural tube defect (exencephaly) in Hectd1 mutant mice.\",\n      \"method\": \"In vitro ubiquitin ligase assay (demonstrating ubiquitination of HSP90), cranial mesenchyme explant emigration assays, rescue experiments with HSP90 neutralization, mutant mouse analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro ubiquitin ligase activity demonstrated, substrate (HSP90) identified, functional rescue experiment performed, mechanistic link to neural tube defect established\",\n      \"pmids\": [\"22431752\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HECTD1 (HectD1) modifies APC with Lys-63-linked polyubiquitin chains. This modification promotes the APC-Axin interaction within the destruction complex, thereby negatively regulating Wnt signaling. Knockdown of HectD1 diminishes APC ubiquitylation, disrupts the APC-Axin interaction, and augments Wnt3a-induced β-catenin stabilization and signaling.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, ubiquitin linkage-specific assays, β-catenin signaling reporter assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, specific ubiquitin linkage type identified (K63), functional epistasis with Wnt pathway readout, multiple orthogonal methods in one study\",\n      \"pmids\": [\"23277359\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"HECTD1 ubiquitinates PIPKIγ90 (phosphatidylinositol 4-phosphate 5-kinase type I γ) at lysine 97, leading to its proteasomal degradation. This cycling of PIPKIγ90 removes it from the PIPKIγ90-talin complex after on-site PIP2 production, providing a regulatory mechanism for focal adhesion assembly/disassembly and cell migration. The PIPKIγ90(K97R) ubiquitination-resistant mutant enhanced PIP2/PIP3 production and inhibited FA dynamics and cancer cell migration/invasion/metastasis.\",\n      \"method\": \"In vitro ubiquitination assay, site-directed mutagenesis (K97R), Co-IP, cell migration/invasion assays, FA dynamics analysis, metastasis mouse model\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro ubiquitination assay, specific ubiquitination site identified by mutagenesis, functional consequences validated in multiple cell-based assays and in vivo metastasis model\",\n      \"pmids\": [\"23572508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The N-terminal domain of HectD1 adopts a novel 5-helix bundle fold termed the Basic Tilted Helix Bundle (BTHB) domain, structurally related to FKBP25. A positively charged surface patch centered on the tilted helix H4 is conserved in both proteins, suggesting a conserved functional role, possibly in nucleic acid binding.\",\n      \"method\": \"NMR structure determination, comparative structural analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — NMR structure solved for the domain, but functional role of the BTHB domain in HECTD1 specifically was not experimentally validated (only inferred from structural conservation)\",\n      \"pmids\": [\"24667607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Hectd1 is required for development of multiple trophoblast cell subtypes in the mouse placenta junctional zone, including trophoblast giant cells (TGCs), spongiotrophoblasts, and glycogen trophoblasts. Loss of Hectd1 results in mid-gestation lethality and intrauterine growth restriction, with differential changes in proliferation and apoptosis across placental layers.\",\n      \"method\": \"Homozygous mutant mouse analysis, immunohistochemistry, in situ hybridization with cell-type-specific markers, proliferation and apoptosis assays\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockout with defined developmental phenotype, multiple cell-type markers examined, replicated across multiple litters with littermate controls\",\n      \"pmids\": [\"24855001\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HECTD1 interacts with IQGAP1 and regulates its degradation through ubiquitination, thereby controlling focal complex (FX) dynamics and directionality of cell migration. Loss of Hectd1 in MEF cells causes accelerated spreading and migration but impaired directionality, mislocalization of paxillin and zyxin, and increased focal complexes. Overexpression of IQGAP1 phenocopies Hectd1 loss; siRNA-mediated knockdown of IQGAP1 rescues migration defects of Hectd1 mutant cells.\",\n      \"method\": \"Hectd1 mutant MEF cell line, Co-IP, ubiquitination assay, siRNA rescue, IQGAP1 overexpression phenocopy, live cell imaging of migration and adhesion dynamics\",\n      \"journal\": \"Cell communication and signaling : CCS\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal genetic epistasis (rescue and phenocopy), Co-IP, ubiquitination assay, multiple orthogonal functional readouts in one study\",\n      \"pmids\": [\"28073378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"USP15 deubiquitinates and stabilizes HECTD1 in glioblastoma cells. Depletion of USP15 leads to decreased HECTD1 protein levels. USP15 expression attenuates Wnt pathway activity in a HECTD1-dependent manner; modulation of HECTD1 expression phenocopies USP15 effects on the Wnt pathway.\",\n      \"method\": \"Mass spectrometry protein interaction screen, Co-IP, siRNA knockdown, Wnt reporter assays, protein stability assays\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and MS identification of interaction, functional epistasis via phenocopy experiments, single lab study\",\n      \"pmids\": [\"29299163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"HectD1 ubiquitinates and promotes proteasome-mediated degradation of the microtubule plus-end tracking protein ACF7. Depletion of HectD1 stabilizes ACF7, which enhances the EMT program and cell migration. Decreased HectD1 expression increased metastases in mouse models.\",\n      \"method\": \"shRNA screens, Co-IP, ubiquitination assays, ACF7 protein stability assays, EMT marker analysis, in vivo metastasis mouse models\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ubiquitination assay, protein stability assay, multiple functional readouts (EMT markers, migration, in vivo metastasis), consistent across cell lines and animal models\",\n      \"pmids\": [\"29386124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HECTD1 binds to and influences ubiquitination of the retinoic acid receptor alpha (RARA). Loss of HECTD1 reduces activation of a retinoic acid response element (RARE) reporter in mutant cells and embryos. Genetic interaction between Hectd1 and Raldh2 (retinoic acid synthesis enzyme) in double-heterozygous embryos causes 4th pharyngeal arch artery hypoplasia, establishing HECTD1 as a novel modulator of retinoic acid signaling during aortic arch development.\",\n      \"method\": \"Co-IP (HECTD1-RARA interaction), RARE reporter assays in cells and embryos, genetic epistasis (double heterozygous mouse crosses), embryo phenotype analysis\",\n      \"journal\": \"Disease models & mechanisms\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP, functional reporter assay, and genetic epistasis in vivo all support the same conclusion, multiple orthogonal methods\",\n      \"pmids\": [\"30578278\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HECTD1 interacts with SNAIL and regulates its stability through ubiquitination; knockdown of HECTD1 increases SNAIL expression levels. HECTD1 shuttles between cytoplasm and nucleus via nuclear localization and export signals, regulated by EGF. Nuclear retention of HECTD1 (by leptomycin B) is associated with loss of SNAIL expression. Under hypoxia, HECTD1 expression is decreased by miR-210.\",\n      \"method\": \"Co-IP, ubiquitination assay, siRNA knockdown, nuclear/cytoplasmic fractionation, leptomycin B treatment, miR-210 overexpression, cell migration assay\",\n      \"journal\": \"International journal of oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ubiquitination assay for SNAIL substrate, localization assay with functional consequence, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"32319576\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HECTD1 promotes base excision repair (BER) in chromatin by ubiquitylating histones, which stimulates AP endonuclease 1 (APE1) incision of abasic sites (THF) when the DNA damage is facing the histone core. A recombinant truncated form of HECTD1 directly stimulates THF incision by APE1 in reconstituted mononucleosome assays. siRNA depletion of HECTD1 leads to deficiencies in DNA damage repair and decreased cell survival following x-ray irradiation.\",\n      \"method\": \"Reconstituted mononucleosome BER assay with site-specific synthetic abasic sites, purification of HECTD1 activity from HeLa extracts, recombinant protein in vitro assay, siRNA knockdown, x-ray irradiation cell survival assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted in vitro assay with purified recombinant HECTD1 and mononucleosomes, biochemical purification from cell extracts, complementary cell-based functional assay\",\n      \"pmids\": [\"31799632\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Latexin (LXN) forms a functional complex with HECTD1 and ribosomal protein subunit 3 (Rps3). IκBα is a substrate of HECTD1. LXN knockdown enhances the HECTD1-Rps3 interaction, contributing to ubiquitination-mediated degradation of IκBα and subsequent NF-κB activation, promoting colitis severity.\",\n      \"method\": \"Proteomics/Co-IP (LXN-HECTD1-Rps3 complex), ubiquitination assay of IκBα, siRNA knockdown, ectopic expression, DSS-induced colitis mouse model\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP complex identification, ubiquitination assay of IκBα substrate, functional in vivo colitis model, single lab\",\n      \"pmids\": [\"32555320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HectD1 ubiquitinates and degrades ZNF622, an assembly factor for the ribosomal 60S subunit. Loss of HectD1 causes accumulation of ZNF622 and the anti-association factor eIF6 on 60S, resulting in 60S/40S ribosomal subunit joining defects, reduced protein synthesis, and impaired hematopoietic stem cell (HSC) function under stress. Znf622 depletion in Hectd1-deficient HSCs restored ribosomal subunit joining, protein synthesis, and HSC reconstitution capacity.\",\n      \"method\": \"Conditional knockout mice, genetic epistasis (Hectd1 KO + Znf622 knockdown double mutant rescue), ubiquitination assay, ribosome profiling/polysome analysis, protein synthesis measurement, HSC transplantation assays\",\n      \"journal\": \"Cell stem cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — ubiquitination assay for ZNF622 substrate, genetic rescue (epistasis) by Znf622 depletion, ribosome assembly functional readout, protein synthesis measurement, in vivo HSC reconstitution\",\n      \"pmids\": [\"33711283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The deubiquitinase TRABID stabilizes HECTD1 by removing ubiquitin chains. HECTD1 preferentially assembles K29- and K48-linked ubiquitin chains and requires branching at K29/K48 for full ligase activity. TRABID depletion leads to rapid HECTD1 degradation, establishing TRABID-HECTD1 as a DUB/E3 pair.\",\n      \"method\": \"TRABID catalytic-dead construct interactome (trapping assay), UbiCREST assay, Ub-AQUA proteomics, in vitro autoubiquitination assay with ubiquitin mutants, siRNA knockdown and genetic knockout of TRABID, protein stability assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro autoubiquitination with ubiquitin mutants defining chain type, UbiCREST and mass spectrometry for chain linkage, trapping assay for DUB substrate identification, multiple orthogonal methods in one study\",\n      \"pmids\": [\"33853758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HECTD1 is upregulated in astrocytes following LPS treatment. Its expression is transcriptionally controlled by the σ-1R-JNK/p38-FOXJ2 signaling axis: LPS activates σ-1R, which activates JNK/p38, which promotes nuclear translocation of the transcription factor FOXJ2 to drive HECTD1 expression. Knockdown of HECTD1 suppresses LPS-induced astrocyte activation; overexpression facilitates it.\",\n      \"method\": \"siRNA knockdown, overexpression, pharmacological inhibition (σ-1R antagonist, JNK inhibitor, p38 inhibitor), nuclear translocation assays, in vivo astrocyte-specific knockdown\",\n      \"journal\": \"Cell & bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockdown and overexpression with functional readouts, epistasis via pharmacological inhibitors, in vivo validation, single lab\",\n      \"pmids\": [\"33781347\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"BIRC6 protein stability is regulated by HECTD1: EGF-JNK signaling prevents HECTD1-mediated ubiquitination and proteasomal degradation of BIRC6. Activation of JNK by EGF blocks HECTD1 from ubiquitinating BIRC6, leading to BIRC6 accumulation in TNBC cells.\",\n      \"method\": \"Co-IP, ubiquitination assay, JNK inhibitor treatment, EGF stimulation, siRNA knockdown, protein stability/half-life assay\",\n      \"journal\": \"Molecular therapy. Nucleic acids\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ubiquitination assay for BIRC6 substrate, pharmacological epistasis with JNK inhibitor, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"34729249\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HECTD1 depletion in HEK293T and HeLa cells decreases cell number by slowing mitotic progression. HECTD1 depletion increases the proportion of cells in prometaphase/metaphase and prolongs NEBD-to-anaphase onset time. HECTD1 depletion reduces Spindle Assembly Checkpoint activity, and BUB3 (a component of the Mitosis Checkpoint Complex) is identified as a novel HECTD1 interactor.\",\n      \"method\": \"siRNA knockdown and genetic knockout, flow cytometry (pH3-Ser28 mitotic marker), time-lapse microscopy, Co-IP (BUB3 interaction), cell counting assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO and transient KD with functional readout (time-lapse mitotic timing), Co-IP for BUB3 interaction, single lab\",\n      \"pmids\": [\"35915203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HECTD1 ubiquitinates and targets DLC1 (a RhoGAP tumor suppressor) for proteasomal degradation. siRNA-mediated knockdown of HECTD1 increases DLC1 protein levels and impairs its degradation. HECTD1 modulation alters DLC1 abundance at focal adhesions. USP7 deubiquitinates and stabilizes DLC1, acting oppositely to HECTD1.\",\n      \"method\": \"Mass spectrometry identification of DLC1-HECTD1 interaction, siRNA knockdown, protein stability assay, immunofluorescence microscopy of focal adhesion localization\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS interaction identification, siRNA knockdown with DLC1 stability readout, localization assay, single lab\",\n      \"pmids\": [\"35322810\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"HECTD1 ubiquitinates GLT-1 (glutamate transporter 1) in astrocytes, promoting its degradation. Knockdown of HECTD1 restores GLT-1 expression impaired by MPP+ treatment. Vitamin C reduces HECTD1 expression, thereby reducing GLT-1 ubiquitination and restoring its expression. Overexpression of HECTD1 abolishes the protective effect of vitamin C on GLT-1.\",\n      \"method\": \"siRNA knockdown, overexpression, ubiquitination assay, transcriptome sequencing, western blot, in vivo murine PD model\",\n      \"journal\": \"ACS chemical neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic gain and loss of function with ubiquitination readout, epistasis via HECTD1 overexpression blocking vitamin C effect, single lab\",\n      \"pmids\": [\"35148069\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HECTD1 ubiquitinates Rubicon at lysine residue 534, targeting it for proteasomal degradation. HECTD1-mediated Rubicon degradation activates chondrocyte autophagy, mitigating stress-induced chondrocyte death and OA progression. Overexpression of HECTD1 in mouse joints alleviated OA, while cartilage-specific Hectd1 knockout aggravated OA in surgery- and aging-induced models.\",\n      \"method\": \"Co-IP, ubiquitination assay with site-specific mutagenesis (K534), conditional knockout mice, adeno-associated virus overexpression in joints, autophagy flux assays, OA histology scoring\",\n      \"journal\": \"Arthritis & rheumatology (Hoboken, N.J.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — specific ubiquitination site identified by mutagenesis, Co-IP, conditional KO in vivo, rescue by HECTD1 overexpression, autophagy functional assay, multiple orthogonal methods\",\n      \"pmids\": [\"36121967\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HectD1 co-localizes with centriolin at the centrosome during mitosis, and binds to centriolin in a cell-cycle-dependent manner. HectD1 expression fluctuates through the cell cycle, with highest levels during mitosis coinciding with a marked reduction in centriolin expression, suggesting HectD1-mediated degradation of centriolin.\",\n      \"method\": \"Co-IP (HectD1-centriolin interaction), immunofluorescence co-localization, cell-cycle-staged protein expression analysis\",\n      \"journal\": \"BMC research notes\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP and co-localization, no direct ubiquitination assay for centriolin substrate, speculative degradation claim\",\n      \"pmids\": [\"38115153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HECTD1 contributes to ubiquitination and proteasomal degradation of NUP93 (Nucleoporin 93) in esophageal squamous cell carcinoma cells. HECTD1 acts as an upstream regulator of NUP93 and functions as a tumor suppressor in ESCC.\",\n      \"method\": \"Co-IP, ubiquitination assay, siRNA knockdown and overexpression, cell proliferation/migration/invasion assays\",\n      \"journal\": \"Human cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ubiquitination assay demonstrating HECTD1-NUP93 interaction and ubiquitination, functional cell-based assays, single lab\",\n      \"pmids\": [\"37993750\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Five rare HECTD1 missense variants identified in human NTD cases reduce HECTD1's ability to suppress extracellular HSP90 secretion in HEK293T cells. One variant (A1084T) also shows reduced protein expression. These functional data support the role of HECTD1-mediated control of eHSP90 secretion in human NTD etiology.\",\n      \"method\": \"Targeted next-generation sequencing, HEK293T functional assays for eHSP90 secretion, protein expression analysis of missense variants\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional variant analysis with defined molecular readout (eHSP90 secretion suppression), multiple variants tested with benign control, single lab\",\n      \"pmids\": [\"38451291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HECTD1 ubiquitinates HSP90, and this ubiquitination is regulated by miR-16-5p delivered via DRG-derived exosomes: miR-16-5p targets HECTD1 mRNA, reducing HECTD1 levels and consequently altering ubiquitination of HSP90 in microglia, thereby promoting microglial activation and neuropathic pain.\",\n      \"method\": \"Co-IP, western blot for HSP90 ubiquitination, RNA pull-down and dual-luciferase reporter (miR-16-5p/HECTD1 interaction), miR-16-5p knockdown in DRG-exosomes, behavioral NP assays in SNL mice, immunofluorescence\",\n      \"journal\": \"Biological research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ubiquitination assay, miR-16-5p/HECTD1 interaction validated by multiple assays, in vivo rescue experiments, single lab\",\n      \"pmids\": [\"38750549\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HECTD1 ubiquitinates AURKA, promoting its proteasomal degradation. Inflammatory conditions (IL-1β) cause DNMT1-mediated methylation-driven downregulation of HECTD1, which releases AURKA from ubiquitination-mediated degradation. Elevated AURKA then phosphorylates eIF4E, enhancing cap-dependent mRNA translation of ADAMTS12, resulting in extracellular matrix degradation in OA chondrocytes.\",\n      \"method\": \"Co-IP, GST pull-down (HECTD1-AURKA interaction), ubiquitination assay, DNMT1 methylation analysis, cap-dependent translation reporter assay, OA mouse model (ACL-T), siRNA knockdown/overexpression\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and GST pull-down for substrate identification, ubiquitination assay, pathway epistasis with functional OA readout, single lab\",\n      \"pmids\": [\"40838484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HECTD1 ubiquitinates VDAC3, promoting its degradation. Hypothermia upregulates HECTD1 and increases VDAC3 ubiquitination in a rat cardiac arrest/CPR model. Hectd1 knockdown reduces VDAC3 ubiquitination, abolishes hypothermia-induced neuroprotection, and worsens neurological outcomes.\",\n      \"method\": \"Co-immunoprecipitation (HECTD1-VDAC3 interaction), immunofluorescence co-localization, siRNA knockdown (adeno-associated viral vector), western blot for ubiquitination, neurological deficit scoring, rat cardiac arrest model\",\n      \"journal\": \"International journal of medical sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ubiquitination assay for VDAC3 substrate, in vivo rescue with functional neurological readout, single lab\",\n      \"pmids\": [\"42158826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In SiO2-exposed macrophages, HECTD1 protein expression is increased concomitantly with decreased circHECTD1. HECTD1 is involved in ZC3H12A-dependent ubiquitination during macrophage activation, contributing to SiO2-induced inflammatory responses. HECTD1 upregulation in macrophages promotes fibroblast proliferation and migration.\",\n      \"method\": \"siRNA knockdown, western blot, Co-IP, cell functional assays (proliferation, migration), in vivo silicosis tissue validation\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — mechanistic detail of HECTD1's specific substrates in this context not fully characterized; ZC3H12A ubiquitination inferred but not directly demonstrated with purified components\",\n      \"pmids\": [\"29290828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Conditional knockout of Hectd1 in the neural lineage in mice results in microcephaly, severe hippocampal malformations, and complete agenesis of the corpus callosum, supporting a role for Hectd1 in embryonic brain development. Functional studies of select HECTD1 variants in C. elegans revealed dominant effects including change-of-function or loss-of-function/haploinsufficient mechanisms.\",\n      \"method\": \"Neural lineage-specific conditional knockout mice, brain morphology analysis, C. elegans functional variant assays, clinical cohort sequencing (GeneMatcher)\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean conditional KO with defined brain developmental phenotype, functional variant analysis in C. elegans model organism, replication across 14 unrelated human cases\",\n      \"pmids\": [\"39879987\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HECTD1 is a HECT-domain E3 ubiquitin ligase that assembles preferentially K29/K48-branched ubiquitin chains and targets a diverse set of substrates—including HSP90, PIPKIγ90, APC, ACF7, IQGAP1, SNAIL, ZNF622, Rubicon, DLC1, RARA, BIRC6, GLT-1, NUP93, AURKA, and VDAC3—for proteasomal degradation or functional modification, thereby regulating focal adhesion dynamics and cell migration, Wnt and retinoic acid signaling, ribosome assembly and protein synthesis in hematopoietic stem cells, autophagy in chondrocytes, base excision repair in chromatin, mitotic progression, EMT and metastasis, and neural tube and aortic arch development; its own stability is controlled by the deubiquitinase TRABID, and it is subject to transcriptional regulation via the σ-1R-JNK/p38-FOXJ2 axis and miRNA-mediated post-transcriptional control.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HECTD1 is a HECT-domain E3 ubiquitin ligase that controls developmental morphogenesis, cell migration, and signaling by ubiquitinating a broad set of substrates and thereby directing their degradation, localization, or function [#0, #1, #14]. Biochemically it preferentially assembles K29/K48-branched ubiquitin chains and depends on this branching for full ligase activity, while its own abundance is set by the deubiquitinase TRABID, defining a DUB/E3 pair [#14]. Through substrate ubiquitination HECTD1 restrains intracellular-to-extracellular HSP90 secretion to permit cranial neural tube closure—a function disrupted by rare human NTD-associated missense variants [#1, #23]—and degrades focal-adhesion and cytoskeletal regulators including PIPKI\\u03b390, IQGAP1, ACF7, and DLC1 to govern adhesion dynamics, directional migration, EMT, and metastasis [#3, #6, #8, #18]. It modulates Wnt signaling by K63-ubiquitinating APC to stabilize the APC-Axin destruction complex [#2] and tunes retinoic acid signaling via RARA during aortic arch development [#9]. Additional substrates link HECTD1 to ribosomal 60S subunit assembly and protein synthesis in hematopoietic stem cells (ZNF622) [#13], chondrocyte autophagy and osteoarthritis (Rubicon, AURKA) [#20, #25], histone-dependent base excision repair (stimulating APE1 incision) [#11], and mitotic progression and spindle-assembly-checkpoint signaling (BUB3 interactor) [#17]. HECTD1 is essential for placental, neural, and brain development, with neural-lineage loss causing microcephaly, hippocampal malformation, and corpus callosum agenesis, and human variants producing dominant or haploinsufficient effects [#0, #5, #28].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established HECTD1's biological identity and necessity by showing an ENU-induced mutation in this HECT E3 ligase causes cranial neural tube defects, defining a dose-sensitive developmental requirement.\",\n      \"evidence\": \"ENU mutagenesis screen with two alleles and homozygous mutant embryo analysis in mouse\",\n      \"pmids\": [\"17442300\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No substrate or enzymatic mechanism identified at this stage\", \"Cell-type-specific requirement not resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Connected HECTD1 enzymatic activity to its developmental phenotype by identifying HSP90 ubiquitination as the mechanism restraining cranial mesenchyme cell emigration.\",\n      \"evidence\": \"In vitro ubiquitin ligase assay, explant emigration assays with HSP90 neutralization rescue in mouse\",\n      \"pmids\": [\"22431752\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ubiquitin chain linkage on HSP90 not defined\", \"How ubiquitination suppresses secretion mechanistically unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showed HECTD1 negatively regulates Wnt signaling by K63-ubiquitinating APC to promote the APC-Axin destruction complex, extending its role into signaling pathway control.\",\n      \"evidence\": \"Reciprocal Co-IP, siRNA knockdown, linkage-specific ubiquitin assays, β-catenin reporter assays\",\n      \"pmids\": [\"23277359\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether APC modification is direct in cells not fully resolved\", \"Link to a developmental Wnt phenotype not established here\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined a focal-adhesion regulatory role by mapping HECTD1 ubiquitination of PIPKI\\u03b390 at K97, coupling lipid kinase turnover to adhesion dynamics and metastasis.\",\n      \"evidence\": \"In vitro ubiquitination, K97R mutagenesis, FA dynamics and migration/invasion assays, metastasis mouse model\",\n      \"pmids\": [\"23572508\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Chain type on PIPKI\\u03b390 not specified\", \"Upstream signals triggering degradation unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Provided structural insight by solving the N-terminal BTHB domain fold and proposing a conserved nucleic-acid-binding surface.\",\n      \"evidence\": \"NMR structure determination and comparative structural analysis\",\n      \"pmids\": [\"24667607\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of BTHB domain in HECTD1 not experimentally tested\", \"No demonstrated nucleic acid binding\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Extended the developmental requirement to extraembryonic tissue, showing Hectd1 is needed for multiple trophoblast subtypes and placental viability.\",\n      \"evidence\": \"Homozygous mutant mouse analysis with cell-type markers, proliferation/apoptosis assays\",\n      \"pmids\": [\"24855001\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate driving placental defects not identified\", \"Cell-autonomy vs. systemic effect unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified additional cytoskeletal/migration control via IQGAP1 ubiquitination governing focal complex dynamics and migration directionality.\",\n      \"evidence\": \"Hectd1 mutant MEFs, Co-IP, ubiquitination assay, IQGAP1 phenocopy and siRNA rescue, live imaging\",\n      \"pmids\": [\"28073378\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Chain type and direct in vitro ubiquitination of IQGAP1 not shown\", \"Relationship to PIPKI\\u03b390 pathway unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed HECTD1 stability is post-translationally controlled, with USP15 deubiquitinating and stabilizing it to modulate Wnt activity in glioblastoma.\",\n      \"evidence\": \"MS interaction screen, Co-IP, siRNA knockdown, Wnt reporter and stability assays\",\n      \"pmids\": [\"29299163\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct deubiquitination not reconstituted\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Linked HECTD1 to EMT and metastasis suppression through ACF7 ubiquitination and degradation.\",\n      \"evidence\": \"shRNA screens, Co-IP, ubiquitination and stability assays, EMT markers, in vivo metastasis models\",\n      \"pmids\": [\"29386124\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Chain linkage on ACF7 not defined\", \"Interplay with other migration substrates not integrated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established HECTD1 as a modulator of retinoic acid signaling via RARA, with a genetic interaction with Raldh2 controlling aortic arch artery development.\",\n      \"evidence\": \"Co-IP, RARE reporter assays in cells and embryos, double-heterozygous mouse crosses\",\n      \"pmids\": [\"30578278\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RARA is a degradation substrate vs. modulated unclear\", \"Direct in vitro ubiquitination not shown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined a chromatin/DNA-repair function showing HECTD1 ubiquitylates histones to stimulate APE1 incision during base excision repair.\",\n      \"evidence\": \"Reconstituted mononucleosome BER assay, purified recombinant HECTD1, siRNA and irradiation survival assay\",\n      \"pmids\": [\"31799632\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific histone residues ubiquitylated not fully mapped\", \"How HECTD1 is recruited to damaged chromatin unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Implicated HECTD1 in NF-\\u03baB signaling and colitis through an LXN-HECTD1-Rps3 complex driving I\\u03baB\\u03b1 degradation.\",\n      \"evidence\": \"Co-IP/proteomics, I\\u03baB\\u03b1 ubiquitination assay, siRNA, DSS colitis mouse model\",\n      \"pmids\": [\"32555320\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. complex-dependent ubiquitination of I\\u03baB\\u03b1 unresolved\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed HECTD1 controls SNAIL stability and shuttles between nucleus and cytoplasm under EGF control, with miR-210 reducing its expression under hypoxia.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, fractionation, leptomycin B, miR-210 overexpression, migration assays\",\n      \"pmids\": [\"32319576\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"NLS/NES sequences not mapped\", \"Direct ubiquitination of SNAIL not reconstituted\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealed a translational/stem-cell role by showing HECTD1 degrades the 60S assembly factor ZNF622 to enable ribosomal subunit joining and HSC function under stress.\",\n      \"evidence\": \"Conditional KO mice, Znf622-depletion epistasis rescue, ubiquitination assay, polysome/protein synthesis and HSC transplantation\",\n      \"pmids\": [\"33711283\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether ZNF622 ubiquitination is direct in vivo across tissues unclear\", \"Role outside hematopoietic stress not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defined HECTD1's intrinsic enzymology and stability control: it builds K29/K48-branched chains requiring branching for activity, and TRABID is its stabilizing deubiquitinase.\",\n      \"evidence\": \"In vitro autoubiquitination with ubiquitin mutants, UbiCREST, Ub-AQUA MS, TRABID trapping and knockout/stability assays\",\n      \"pmids\": [\"33853758\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether substrate chains are also K29/K48-branched not established for each substrate\", \"Structural basis of branch specificity unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified transcriptional control of HECTD1 via the \\u03c3-1R-JNK/p38-FOXJ2 axis driving its expression during LPS-induced astrocyte activation.\",\n      \"evidence\": \"siRNA/overexpression, pharmacological inhibitors, nuclear translocation assays, in vivo astrocyte knockdown\",\n      \"pmids\": [\"33781347\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct FOXJ2 binding to HECTD1 promoter not mapped\", \"Substrates in astrocyte activation not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed EGF-JNK signaling protects BIRC6 from HECTD1-mediated ubiquitination, linking HECTD1 to apoptosis regulation in TNBC.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, JNK inhibitor and EGF stimulation, stability assays\",\n      \"pmids\": [\"34729249\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which JNK blocks ubiquitination unclear\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Implicated HECTD1 in mitotic progression and spindle-assembly-checkpoint function, identifying BUB3 as a new interactor.\",\n      \"evidence\": \"siRNA/KO, flow cytometry, time-lapse microscopy, Co-IP in HEK293T/HeLa\",\n      \"pmids\": [\"35915203\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No mitotic ubiquitination substrate established\", \"Whether BUB3 is a substrate vs. binding partner unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed HECTD1 degrades the RhoGAP tumor suppressor DLC1, opposed by USP7, linking it to focal-adhesion-localized DLC1 abundance.\",\n      \"evidence\": \"MS interaction, siRNA knockdown, stability and immunofluorescence assays\",\n      \"pmids\": [\"35322810\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ubiquitination not reconstituted\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Extended HECTD1 substrate range to the glutamate transporter GLT-1 in astrocytes, with vitamin C lowering HECTD1 to preserve GLT-1.\",\n      \"evidence\": \"siRNA/overexpression, ubiquitination assay, transcriptome sequencing, in vivo PD model\",\n      \"pmids\": [\"35148069\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ubiquitination site not mapped\", \"Mechanism of vitamin C effect on HECTD1 unclear\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined a cartilage-protective role through K534 ubiquitination and degradation of Rubicon, activating chondrocyte autophagy and limiting osteoarthritis.\",\n      \"evidence\": \"Co-IP, K534 mutagenesis, conditional KO and AAV overexpression, autophagy flux and OA histology\",\n      \"pmids\": [\"36121967\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream regulation of HECTD1 in chondrocytes only partly defined\", \"Chain linkage on Rubicon not specified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Suggested a centrosomal mitotic substrate by showing cell-cycle-dependent HectD1-centriolin co-localization and inverse expression.\",\n      \"evidence\": \"Co-IP, immunofluorescence co-localization, cell-cycle-staged expression\",\n      \"pmids\": [\"38115153\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct ubiquitination assay for centriolin — degradation claim is inferential\", \"Single Co-IP without functional validation\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified HECTD1 as a tumor suppressor in esophageal squamous cell carcinoma acting through ubiquitination and degradation of NUP93.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, siRNA/overexpression, proliferation/migration/invasion assays\",\n      \"pmids\": [\"37993750\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ubiquitination site not mapped\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Provided human genetic support for the HSP90 mechanism, showing rare NTD-associated HECTD1 missense variants impair suppression of extracellular HSP90 secretion.\",\n      \"evidence\": \"Targeted NGS and HEK293T eHSP90 secretion functional assays\",\n      \"pmids\": [\"38451291\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causality in patients not proven beyond functional assay\", \"Variant effects on catalytic activity only partly characterized\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showed exosomal miR-16-5p targets HECTD1 mRNA to alter HSP90 ubiquitination in microglia, linking HECTD1 to neuropathic pain.\",\n      \"evidence\": \"Co-IP, ubiquitination western blot, RNA pull-down/luciferase, in vivo SNL behavioral assays\",\n      \"pmids\": [\"38750549\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct microglial HSP90 ubiquitination consequence not fully resolved\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Connected HECTD1 to chondrocyte ECM degradation, with DNMT1-driven methylation downregulating HECTD1 to release AURKA, which phosphorylates eIF4E to enhance ADAMTS12 translation.\",\n      \"evidence\": \"Co-IP/GST pull-down, ubiquitination assay, methylation analysis, cap-dependent translation reporter, OA mouse model\",\n      \"pmids\": [\"40838484\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct AURKA ubiquitination site not mapped\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed hypothermia-induced HECTD1 ubiquitinates VDAC3 to mediate neuroprotection after cardiac arrest.\",\n      \"evidence\": \"Co-IP, immunofluorescence, AAV siRNA knockdown, ubiquitination western blot, rat cardiac arrest model\",\n      \"pmids\": [\"42158826\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ubiquitination site not defined\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Established HECTD1 as a human neurodevelopmental disease gene, with neural-lineage knockout causing brain malformations and patient variants showing dominant or haploinsufficient mechanisms.\",\n      \"evidence\": \"Neural-lineage conditional KO mouse brain morphology, C. elegans variant assays, clinical cohort sequencing\",\n      \"pmids\": [\"39879987\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Substrate driving brain phenotype not identified\", \"Genotype-phenotype correlation across variants incomplete\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How HECTD1's K29/K48-branched chain specificity is structurally achieved and which substrate-specific chain architectures and recruitment mechanisms direct its many context-dependent functions remains unresolved.\",\n      \"evidence\": \"No discovery in the timeline reconstitutes substrate-specific branched-chain assembly or maps substrate recruitment determinants\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No full-length structure with substrate\", \"Substrate selection rules across tissues unknown\", \"Whether branched chains apply to all substrates undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 3, 6, 8, 13, 20, 22]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [0, 1, 14]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [10]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [21]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 3, 8, 14]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 9]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 5, 9, 28]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [13]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [17]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"HSP90\", \"PIPKI\\u03b390\", \"APC\", \"IQGAP1\", \"ACF7\", \"RARA\", \"TRABID\", \"BUB3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}