{"gene":"MUCL1","run_date":"2026-06-10T05:19:51","timeline":{"discoveries":[{"year":2022,"finding":"MUCL1 drives β-catenin activation via Ser-552 phosphorylation, leading to nuclear accumulation and transcriptional activation; silencing MUCL1 with siRNA inhibited EMT (increased E-cadherin, decreased vimentin), reduced Bcl2/BclxL expression, and decreased cell invasion and migration in colorectal cancer cells.","method":"siRNA knockdown, Western blotting, invasion/migration assays, phosphorylation analysis in HT-29 and SW620 colorectal cancer cell lines","journal":"International journal of oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (siRNA, Western blot, functional assays) in a single lab; pathway placement via β-catenin phosphorylation readout","pmids":["35059735"],"is_preprint":false},{"year":2025,"finding":"SBEM (MUCL1) interacts with dual-specificity phosphatase 16 (DUSP16) and upregulates its expression; SBEM overexpression activates AMPK signaling, conferring paclitaxel resistance in breast cancer cells, while SBEM knockdown increases apoptosis (~3-fold) and restores paclitaxel sensitivity.","method":"SBEM overexpression and knockdown in drug-resistant breast cancer cell lines, AMPK activator treatment, Western blotting, apoptosis assays","journal":"Oncology letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional assays (OE/KD, AMPK activator rescue, apoptosis quantification) in single lab; interaction with DUSP16 described but without reciprocal Co-IP confirmation in abstract","pmids":["41181635"],"is_preprint":false},{"year":2026,"finding":"UCHL1 (ubiquitin C-terminal hydrolase L1) stabilizes MUCL1 protein through deubiquitination; the UCHL1-MUCL1 axis promotes LPS-induced endothelial inflammation (TNF-α, IL-6, IL-8, ICAM-1) and apoptosis in HUVECs via the β-catenin/NF-κB pathway; UCHL1 silencing reduces these effects, which are reversed by MUCL1 overexpression.","method":"Co-immunoprecipitation, ubiquitination assay, cycloheximide chase assay, siRNA knockdown and overexpression in HUVECs, ELISA, flow cytometry, Western blotting","journal":"Shock (Augusta, Ga.)","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — Co-IP, ubiquitination assay, CHX chase (multiple orthogonal methods) in single lab confirming deubiquitination mechanism and epistasis rescue experiment","pmids":["41770679"],"is_preprint":false},{"year":2026,"finding":"ST3GAL1 directly binds MUCL1 and catalyzes its sialylation, increasing MUCL1 protein stability and promoting breast cancer cell proliferation, migration, invasion, and in vivo tumor growth and lung metastasis; these effects are reversed by sialyltransferase inhibitor Lith-O-Asp or MUCL1 knockdown.","method":"In vitro binding assay, sialylation assay, siRNA knockdown and overexpression, sialyltransferase inhibitor treatment, in vivo xenograft and metastasis models, Western blotting","journal":"Human cell","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct binding and enzymatic sialylation demonstrated, multiple in vitro and in vivo orthogonal methods including inhibitor rescue and KD rescue, single lab","pmids":["41770470"],"is_preprint":false},{"year":2023,"finding":"miR-186-5p directly targets SBEM (MUCL1) mRNA; overexpression of miR-186-5p in MDA-MB-231 cells significantly inhibits SBEM protein expression and suppresses PI3K/AKT pathway activation (reduced p-PI3K, p-AKT) as well as downstream effectors MMP1, MMP3, MMP9, CyclinD1, PCNA, and CyclinB1, reducing breast cancer cell migration, invasion, and proliferation.","method":"miR-186-5p mimic/inhibitor transfection, Western blotting, PI3K activator (740Y-P) rescue experiment, scratch assay, Transwell invasion assay, monoclonal cell proliferation assay","journal":"Aging","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional assays with pathway rescue experiment (740Y-P) in single lab; miRNA-target relationship inferred from expression suppression and bioinformatics, not confirmed by 3'UTR luciferase in abstract","pmids":["37477531"],"is_preprint":false},{"year":2021,"finding":"MUCL1 expression shows a negative correlation with melanogenesis in epidermal melanocytes; threonine content (a mucin-conforming amino acid) affects MUCL1 regulation of melanogenesis and metastatic gene activity in melanoma cells, involving autophagy-related FOXO signaling.","method":"Microarray data analysis (HPA/GTEx), RNA and protein expression in melanoma cells, independent experimental validation with threonine treatment","journal":"The British journal of dermatology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — correlative and expression-based findings with limited mechanistic validation; pathway placement (FOXO signaling) inferred from correlations in single study","pmids":["34545566"],"is_preprint":false}],"current_model":"MUCL1 (SBEM) is a glycoprotein whose stability is regulated by ST3GAL1-mediated sialylation and UCHL1-mediated deubiquitination; it promotes oncogenic signaling through β-catenin (Ser-552 phosphorylation/nuclear accumulation), NF-κB, and AMPK pathways—partly via interaction with DUSP16—to drive proliferation, EMT, chemoresistance (paclitaxel and irinotecan), and endothelial inflammation, while its expression is post-transcriptionally suppressed by miR-186-5p."},"narrative":{"mechanistic_narrative":"MUCL1 (SBEM) is a glycoprotein that acts as an oncogenic effector across multiple cancers and in endothelial inflammation, driving proliferation, EMT, invasion, and chemoresistance through β-catenin- and NF-κB-linked signaling [PMID:35059735, PMID:41770679]. In colorectal cancer cells, MUCL1 promotes β-catenin activation via Ser-552 phosphorylation and nuclear accumulation, sustaining EMT and the anti-apoptotic effectors Bcl2/BclxL, such that its silencing restores E-cadherin and reduces invasion and migration [PMID:35059735]. In breast cancer, MUCL1 interacts with the phosphatase DUSP16 and activates AMPK signaling to confer paclitaxel resistance, with knockdown increasing apoptosis and restoring drug sensitivity [PMID:41181635]. MUCL1 protein stability is controlled post-translationally by two distinct modifications: ST3GAL1 directly binds and sialylates MUCL1 to increase its stability and promote tumor growth and lung metastasis [PMID:41770470], while UCHL1 stabilizes MUCL1 through deubiquitination, and this UCHL1–MUCL1 axis drives LPS-induced endothelial inflammation and apoptosis in HUVECs via the β-catenin/NF-κB pathway [PMID:41770679]. Its expression is post-transcriptionally suppressed by miR-186-5p, whose overexpression dampens PI3K/AKT signaling and downstream matrix metalloproteinases and cell-cycle effectors [PMID:37477531]. Beyond these signaling and stability axes, the biochemical activity of the MUCL1 glycoprotein itself has not been characterized in the available corpus.","teleology":[{"year":2021,"claim":"Established an early functional association by linking MUCL1 expression inversely to melanogenesis and metastatic gene activity, hinting at a context-dependent regulatory role beyond secretory mucin biology.","evidence":"microarray expression analysis and threonine-treatment validation in melanocytes and melanoma cells","pmids":["34545566"],"confidence":"Low","gaps":["Correlative and expression-based with limited mechanistic validation","FOXO/autophagy placement inferred, not directly tested","No direct molecular activity for MUCL1 defined"]},{"year":2022,"claim":"Answered how MUCL1 promotes malignant phenotype by placing it upstream of β-catenin, showing it drives Ser-552 phosphorylation and nuclear accumulation to sustain EMT and anti-apoptotic transcription.","evidence":"siRNA knockdown, Western blotting, invasion/migration assays in HT-29 and SW620 colorectal cancer cells","pmids":["35059735"],"confidence":"Medium","gaps":["Mechanism by which MUCL1 induces β-catenin Ser-552 phosphorylation not defined","No direct binding partner identified for the β-catenin axis","Single tumor type"]},{"year":2023,"claim":"Identified an upstream regulator of MUCL1, showing miR-186-5p suppresses MUCL1 and dampens PI3K/AKT-driven proliferation and invasion programs.","evidence":"miR-186-5p mimic/inhibitor transfection with PI3K activator (740Y-P) rescue, migration/invasion/proliferation assays in MDA-MB-231 cells","pmids":["37477531"],"confidence":"Medium","gaps":["Direct 3'UTR targeting not confirmed by luciferase reporter in abstract","How MUCL1 connects to PI3K/AKT activation mechanistically unresolved"]},{"year":2025,"claim":"Defined a chemoresistance mechanism by linking MUCL1 to DUSP16 interaction and AMPK activation, explaining paclitaxel resistance in breast cancer.","evidence":"SBEM overexpression/knockdown, AMPK activator rescue, apoptosis assays in drug-resistant breast cancer cells","pmids":["41181635"],"confidence":"Medium","gaps":["DUSP16 interaction lacks reciprocal Co-IP confirmation","How MUCL1 activates AMPK not mechanistically resolved","Link between DUSP16 and AMPK not established"]},{"year":2026,"claim":"Resolved two converging mechanisms of MUCL1 protein stability control—deubiquitination by UCHL1 and sialylation by ST3GAL1—and connected these to endothelial inflammation and tumor metastasis respectively.","evidence":"Co-IP, ubiquitination and CHX-chase assays in HUVECs (UCHL1) and direct binding/sialylation assays plus xenograft and metastasis models (ST3GAL1)","pmids":["41770679","41770470"],"confidence":"High","gaps":["The MUCL1 ubiquitination sites and E3 ligase remain unidentified","Sialylation sites on MUCL1 not mapped","Whether sialylation and deubiquitination act on the same MUCL1 pool is untested"]},{"year":null,"claim":"The intrinsic biochemical activity of the MUCL1 glycoprotein and how it physically couples to β-catenin, NF-κB, and AMPK signaling remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No molecular function assigned to MUCL1 itself","No structural model or receptor/effector binding mechanism","Subcellular localization of active MUCL1 not established"]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,2,4]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,1,3]}],"complexes":[],"partners":["DUSP16","UCHL1","ST3GAL1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96DR8","full_name":"Mucin-like protein 1","aliases":["Protein BS106","Small breast epithelial mucin"],"length_aa":90,"mass_kda":9.0,"function":"May play a role as marker for the diagnosis of metastatic breast cancer","subcellular_location":"Secreted; Membrane","url":"https://www.uniprot.org/uniprotkb/Q96DR8/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MUCL1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SEPT8","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/MUCL1","total_profiled":1310},"omim":[{"mim_id":"610857","title":"MUCIN-LIKE 1; MUCL1","url":"https://www.omim.org/entry/610857"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"breast","ntpm":3038.8},{"tissue":"skin 1","ntpm":777.3}],"url":"https://www.proteinatlas.org/search/MUCL1"},"hgnc":{"alias_symbol":["SBEM"],"prev_symbol":[]},"alphafold":{"accession":"Q96DR8","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96DR8","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96DR8-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96DR8-F1-predicted_aligned_error_v6.png","plddt_mean":67.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MUCL1","jax_strain_url":"https://www.jax.org/strain/search?query=MUCL1"},"sequence":{"accession":"Q96DR8","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96DR8.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96DR8/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96DR8"}},"corpus_meta":[{"pmid":"18269587","id":"PMC_18269587","title":"Expression of small breast epithelial mucin (SBEM) protein in tissue microarrays (TMAs) of primary invasive breast cancers.","date":"2008","source":"Histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/18269587","citation_count":33,"is_preprint":false},{"pmid":"20364301","id":"PMC_20364301","title":"Small breast epithelial mucin (SBEM) has the potential to be a marker for predicting hematogenous micrometastasis and response to neoadjuvant chemotherapy in breast cancer.","date":"2010","source":"Clinical & experimental metastasis","url":"https://pubmed.ncbi.nlm.nih.gov/20364301","citation_count":20,"is_preprint":false},{"pmid":"31293564","id":"PMC_31293564","title":"MAP7 and MUCL1 Are Biomarkers of Vitamin D3-Induced Tolerogenic Dendritic Cells in Multiple Sclerosis Patients.","date":"2019","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31293564","citation_count":14,"is_preprint":false},{"pmid":"35059735","id":"PMC_35059735","title":"Targeting MUCL1 protein inhibits cell proliferation and EMT by deregulating β‑catenin and increases irinotecan sensitivity in colorectal cancer.","date":"2022","source":"International journal of oncology","url":"https://pubmed.ncbi.nlm.nih.gov/35059735","citation_count":13,"is_preprint":false},{"pmid":"37477531","id":"PMC_37477531","title":"miRNA-186-5p inhibits migration, invasion and proliferation of breast cancer cells by targeting SBEM.","date":"2023","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/37477531","citation_count":10,"is_preprint":false},{"pmid":"34545566","id":"PMC_34545566","title":"The mucin protein MUCL1 regulates melanogenesis and melanoma genes in a manner dependent on threonine content.","date":"2021","source":"The British journal of dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/34545566","citation_count":6,"is_preprint":false},{"pmid":"40863740","id":"PMC_40863740","title":"An Optimized Protocol for SBEM-Based Ultrastructural Analysis of Cultured Human Cells.","date":"2025","source":"Methods and protocols","url":"https://pubmed.ncbi.nlm.nih.gov/40863740","citation_count":1,"is_preprint":false},{"pmid":"41181635","id":"PMC_41181635","title":"SBEM confers paclitaxel resistance in breast cancer via DUSP16-mediated MAPK/AMPK pathway activation.","date":"2025","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/41181635","citation_count":0,"is_preprint":false},{"pmid":"41770679","id":"PMC_41770679","title":"Integrated transcriptomic and weighted gene co-expression network analyses identify the UCHL1-MUCL1 axis as a key regulator of endothelial dysfunction in sepsis.","date":"2026","source":"Shock (Augusta, Ga.)","url":"https://pubmed.ncbi.nlm.nih.gov/41770679","citation_count":0,"is_preprint":false},{"pmid":"41987297","id":"PMC_41987297","title":"MUCL1 in triple-negative breast cancer: a novel marker associated with the luminal androgen receptor subtype.","date":"2026","source":"Breast cancer research : BCR","url":"https://pubmed.ncbi.nlm.nih.gov/41987297","citation_count":0,"is_preprint":false},{"pmid":"41770470","id":"PMC_41770470","title":"The sialyltransferase ST3GAL1 mediates MUCL1 sialylation to exacerbate breast cancer progression.","date":"2026","source":"Human cell","url":"https://pubmed.ncbi.nlm.nih.gov/41770470","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.28.656661","title":"Development of a Charge-Resistant Embedding Media for High-Performance Serial Block Face Imaging of Cells and Tissues","date":"2025-05-29","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.28.656661","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.07.08.663701","title":"Deep mapping of the  <i>endomembrane system</i>  of cerebellar Purkinje neurons","date":"2025-07-11","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.08.663701","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.11.06.622332","title":"Daily ultrastructural remodeling of clock neurons","date":"2024-11-07","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.06.622332","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9176,"output_tokens":1765,"usd":0.027002,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8631,"output_tokens":2241,"usd":0.04959,"stage2_stop_reason":"end_turn"},"total_usd":0.076592,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2022,\n      \"finding\": \"MUCL1 drives β-catenin activation via Ser-552 phosphorylation, leading to nuclear accumulation and transcriptional activation; silencing MUCL1 with siRNA inhibited EMT (increased E-cadherin, decreased vimentin), reduced Bcl2/BclxL expression, and decreased cell invasion and migration in colorectal cancer cells.\",\n      \"method\": \"siRNA knockdown, Western blotting, invasion/migration assays, phosphorylation analysis in HT-29 and SW620 colorectal cancer cell lines\",\n      \"journal\": \"International journal of oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (siRNA, Western blot, functional assays) in a single lab; pathway placement via β-catenin phosphorylation readout\",\n      \"pmids\": [\"35059735\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SBEM (MUCL1) interacts with dual-specificity phosphatase 16 (DUSP16) and upregulates its expression; SBEM overexpression activates AMPK signaling, conferring paclitaxel resistance in breast cancer cells, while SBEM knockdown increases apoptosis (~3-fold) and restores paclitaxel sensitivity.\",\n      \"method\": \"SBEM overexpression and knockdown in drug-resistant breast cancer cell lines, AMPK activator treatment, Western blotting, apoptosis assays\",\n      \"journal\": \"Oncology letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional assays (OE/KD, AMPK activator rescue, apoptosis quantification) in single lab; interaction with DUSP16 described but without reciprocal Co-IP confirmation in abstract\",\n      \"pmids\": [\"41181635\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"UCHL1 (ubiquitin C-terminal hydrolase L1) stabilizes MUCL1 protein through deubiquitination; the UCHL1-MUCL1 axis promotes LPS-induced endothelial inflammation (TNF-α, IL-6, IL-8, ICAM-1) and apoptosis in HUVECs via the β-catenin/NF-κB pathway; UCHL1 silencing reduces these effects, which are reversed by MUCL1 overexpression.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, cycloheximide chase assay, siRNA knockdown and overexpression in HUVECs, ELISA, flow cytometry, Western blotting\",\n      \"journal\": \"Shock (Augusta, Ga.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — Co-IP, ubiquitination assay, CHX chase (multiple orthogonal methods) in single lab confirming deubiquitination mechanism and epistasis rescue experiment\",\n      \"pmids\": [\"41770679\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ST3GAL1 directly binds MUCL1 and catalyzes its sialylation, increasing MUCL1 protein stability and promoting breast cancer cell proliferation, migration, invasion, and in vivo tumor growth and lung metastasis; these effects are reversed by sialyltransferase inhibitor Lith-O-Asp or MUCL1 knockdown.\",\n      \"method\": \"In vitro binding assay, sialylation assay, siRNA knockdown and overexpression, sialyltransferase inhibitor treatment, in vivo xenograft and metastasis models, Western blotting\",\n      \"journal\": \"Human cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct binding and enzymatic sialylation demonstrated, multiple in vitro and in vivo orthogonal methods including inhibitor rescue and KD rescue, single lab\",\n      \"pmids\": [\"41770470\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"miR-186-5p directly targets SBEM (MUCL1) mRNA; overexpression of miR-186-5p in MDA-MB-231 cells significantly inhibits SBEM protein expression and suppresses PI3K/AKT pathway activation (reduced p-PI3K, p-AKT) as well as downstream effectors MMP1, MMP3, MMP9, CyclinD1, PCNA, and CyclinB1, reducing breast cancer cell migration, invasion, and proliferation.\",\n      \"method\": \"miR-186-5p mimic/inhibitor transfection, Western blotting, PI3K activator (740Y-P) rescue experiment, scratch assay, Transwell invasion assay, monoclonal cell proliferation assay\",\n      \"journal\": \"Aging\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional assays with pathway rescue experiment (740Y-P) in single lab; miRNA-target relationship inferred from expression suppression and bioinformatics, not confirmed by 3'UTR luciferase in abstract\",\n      \"pmids\": [\"37477531\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"MUCL1 expression shows a negative correlation with melanogenesis in epidermal melanocytes; threonine content (a mucin-conforming amino acid) affects MUCL1 regulation of melanogenesis and metastatic gene activity in melanoma cells, involving autophagy-related FOXO signaling.\",\n      \"method\": \"Microarray data analysis (HPA/GTEx), RNA and protein expression in melanoma cells, independent experimental validation with threonine treatment\",\n      \"journal\": \"The British journal of dermatology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — correlative and expression-based findings with limited mechanistic validation; pathway placement (FOXO signaling) inferred from correlations in single study\",\n      \"pmids\": [\"34545566\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MUCL1 (SBEM) is a glycoprotein whose stability is regulated by ST3GAL1-mediated sialylation and UCHL1-mediated deubiquitination; it promotes oncogenic signaling through β-catenin (Ser-552 phosphorylation/nuclear accumulation), NF-κB, and AMPK pathways—partly via interaction with DUSP16—to drive proliferation, EMT, chemoresistance (paclitaxel and irinotecan), and endothelial inflammation, while its expression is post-transcriptionally suppressed by miR-186-5p.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MUCL1 (SBEM) is a glycoprotein that acts as an oncogenic effector across multiple cancers and in endothelial inflammation, driving proliferation, EMT, invasion, and chemoresistance through β-catenin- and NF-κB-linked signaling [#0, #2]. In colorectal cancer cells, MUCL1 promotes β-catenin activation via Ser-552 phosphorylation and nuclear accumulation, sustaining EMT and the anti-apoptotic effectors Bcl2/BclxL, such that its silencing restores E-cadherin and reduces invasion and migration [#0]. In breast cancer, MUCL1 interacts with the phosphatase DUSP16 and activates AMPK signaling to confer paclitaxel resistance, with knockdown increasing apoptosis and restoring drug sensitivity [#1]. MUCL1 protein stability is controlled post-translationally by two distinct modifications: ST3GAL1 directly binds and sialylates MUCL1 to increase its stability and promote tumor growth and lung metastasis [#3], while UCHL1 stabilizes MUCL1 through deubiquitination, and this UCHL1–MUCL1 axis drives LPS-induced endothelial inflammation and apoptosis in HUVECs via the β-catenin/NF-κB pathway [#2]. Its expression is post-transcriptionally suppressed by miR-186-5p, whose overexpression dampens PI3K/AKT signaling and downstream matrix metalloproteinases and cell-cycle effectors [#4]. Beyond these signaling and stability axes, the biochemical activity of the MUCL1 glycoprotein itself has not been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2021,\n      \"claim\": \"Established an early functional association by linking MUCL1 expression inversely to melanogenesis and metastatic gene activity, hinting at a context-dependent regulatory role beyond secretory mucin biology.\",\n      \"evidence\": \"microarray expression analysis and threonine-treatment validation in melanocytes and melanoma cells\",\n      \"pmids\": [\"34545566\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Correlative and expression-based with limited mechanistic validation\", \"FOXO/autophagy placement inferred, not directly tested\", \"No direct molecular activity for MUCL1 defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Answered how MUCL1 promotes malignant phenotype by placing it upstream of β-catenin, showing it drives Ser-552 phosphorylation and nuclear accumulation to sustain EMT and anti-apoptotic transcription.\",\n      \"evidence\": \"siRNA knockdown, Western blotting, invasion/migration assays in HT-29 and SW620 colorectal cancer cells\",\n      \"pmids\": [\"35059735\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which MUCL1 induces β-catenin Ser-552 phosphorylation not defined\", \"No direct binding partner identified for the β-catenin axis\", \"Single tumor type\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified an upstream regulator of MUCL1, showing miR-186-5p suppresses MUCL1 and dampens PI3K/AKT-driven proliferation and invasion programs.\",\n      \"evidence\": \"miR-186-5p mimic/inhibitor transfection with PI3K activator (740Y-P) rescue, migration/invasion/proliferation assays in MDA-MB-231 cells\",\n      \"pmids\": [\"37477531\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct 3'UTR targeting not confirmed by luciferase reporter in abstract\", \"How MUCL1 connects to PI3K/AKT activation mechanistically unresolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a chemoresistance mechanism by linking MUCL1 to DUSP16 interaction and AMPK activation, explaining paclitaxel resistance in breast cancer.\",\n      \"evidence\": \"SBEM overexpression/knockdown, AMPK activator rescue, apoptosis assays in drug-resistant breast cancer cells\",\n      \"pmids\": [\"41181635\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DUSP16 interaction lacks reciprocal Co-IP confirmation\", \"How MUCL1 activates AMPK not mechanistically resolved\", \"Link between DUSP16 and AMPK not established\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Resolved two converging mechanisms of MUCL1 protein stability control—deubiquitination by UCHL1 and sialylation by ST3GAL1—and connected these to endothelial inflammation and tumor metastasis respectively.\",\n      \"evidence\": \"Co-IP, ubiquitination and CHX-chase assays in HUVECs (UCHL1) and direct binding/sialylation assays plus xenograft and metastasis models (ST3GAL1)\",\n      \"pmids\": [\"41770679\", \"41770470\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The MUCL1 ubiquitination sites and E3 ligase remain unidentified\", \"Sialylation sites on MUCL1 not mapped\", \"Whether sialylation and deubiquitination act on the same MUCL1 pool is untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The intrinsic biochemical activity of the MUCL1 glycoprotein and how it physically couples to β-catenin, NF-κB, and AMPK signaling remain undefined.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular function assigned to MUCL1 itself\", \"No structural model or receptor/effector binding mechanism\", \"Subcellular localization of active MUCL1 not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 2, 4]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 1, 3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"DUSP16\", \"UCHL1\", \"ST3GAL1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}