{"gene":"HELQ","run_date":"2026-04-28T18:06:53","timeline":{"discoveries":[{"year":2013,"finding":"HELQ directly interacts with the RAD51 paralogue complex BCDX2 and functions in parallel to the Fanconi anaemia pathway to promote efficient homologous recombination at damaged replication forks. Helq helicase-deficient mice exhibit subfertility, germ cell attrition, ICL sensitivity and tumour predisposition.","method":"Co-IP, mouse knockout model with defined phenotypic readouts (subfertility, ICL sensitivity, tumour predisposition), genetic epistasis with FA pathway","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 — reciprocal interaction, KO mouse with multiple orthogonal phenotypes, epistasis with FA pathway, independently confirmed by Takata et al. same year","pmids":["24005329"],"is_preprint":false},{"year":2013,"finding":"Human HELQ is associated with the RAD51 paralogs RAD51B/C/D and XRCC2, and with the DNA damage-responsive kinase ATR. HELQ-knockout cells show reduced CHK1 phosphorylation after MMC treatment and reduced G2/M accumulation, placing HELQ in an ATR-CHK1 signaling arm during ICL repair.","method":"Proteomic/mass spectrometry interaction analysis, HELQ knockout cells, phosphorylation assay, cell cycle analysis after MMC treatment","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — MS-defined interactome, functional KO with defined signaling phenotype, corroborated by parallel Nature paper","pmids":["24005565"],"is_preprint":false},{"year":2021,"finding":"HELQ possesses both DNA unwinding and DNA strand annealing activities that are differentially regulated: RAD51 forms a complex with HELQ and strongly stimulates translocation/unwinding, whereas RPA inhibits DNA unwinding but strongly stimulates DNA strand annealing. HELQ can capture RPA-bound DNA strands and displace RPA to facilitate annealing of complementary sequences. HELQ deficiency compromises single-strand annealing (SSA) and microhomology-mediated end-joining (MMEJ) pathways and biases towards long-tract gene conversion during HR.","method":"Biochemical reconstitution in vitro, single-molecule imaging, HELQ-deficient cell lines with SSA/MMEJ/HR reporter assays, direct protein-protein interaction","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution, single-molecule imaging, mutagenesis, multiple orthogonal cellular assays in one study","pmids":["34937945"],"is_preprint":false},{"year":2021,"finding":"The non-catalytic N-terminal region of HelQ contains a PWI-like domain that mediates interaction with RPA, orchestrating loading of the helicase domains onto ssDNA. Once loaded, ATP-Mg2+ binding activates the helicase core, and HelQ translocates along ssDNA as a dimer.","method":"Domain characterization, in vitro binding assays, ATPase/helicase assays with mutant HelQ proteins, biochemical reconstitution","journal":"NAR cancer","confidence":"High","confidence_rationale":"Tier 1 — domain mutagenesis combined with biochemical reconstitution of loading and translocation","pmids":["34316696"],"is_preprint":false},{"year":2011,"finding":"Human HEL308 localizes to damaged replication forks (colocalizing with RAD51 and FANCD2) upon camptothecin treatment, requires a 3' ssDNA overhang for loading, preferentially unwinds the lagging strand of stalled replication fork substrates, and its unwinding is stimulated by human RPA.","method":"GFP-fusion live cell imaging/colocalization, purified protein helicase assays with fork-model substrates, RPA stimulation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — direct localization experiment linked to functional consequence, multiple in vitro assays with defined substrates","pmids":["21398521"],"is_preprint":false},{"year":2008,"finding":"C. elegans HEL-308 (HELQ ortholog) functions in ICL repair through a Fanconi anemia-dependent pathway, genetically distinct from the polq-1/BRCA1-dependent pathway, as established by epistasis analysis.","method":"Genetic epistasis analysis in C. elegans, survival assays, checkpoint/apoptosis readouts after ICL treatment","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 2 — clean genetic epistasis in model organism with defined phenotypic readouts","pmids":["18472307"],"is_preprint":false},{"year":2013,"finding":"Mouse HELQ is non-epistatic with FANCC: Helq/Fancc double-mutant mice display significantly worse phenotypes than either single mutant (chromosome instability, micronuclei, 53BP1 nuclear bodies), establishing that HELQ operates in a pathway distinct from the FA core complex for suppression of spontaneous replication-associated genome instability.","method":"Double-mutant mouse model, epistasis analysis, cytogenetic assays (micronuclei, 53BP1 bodies), FANCD2 ubiquitination assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis in vivo with multiple orthogonal readouts; FANCD2 monoubiquitination intact in Helq mutant confirms distinct pathway","pmids":["24005041"],"is_preprint":false},{"year":2007,"finding":"Crystal structure of archaeal Hel308 (HELQ homolog) reveals a five-domain architecture with a central pore lined with DNA-binding residues. Domain 5 acts as an autoinhibitory 'molecular brake' clamping ssDNA extruded through the pore to limit processivity. Hel308 can displace streptavidin from biotinylated DNA and partially displaces RPA/Alba1 but not RadA.","method":"X-ray crystallography, protein-streptavidin displacement assay, DNA unwinding assays with RPA/Alba1/RadA","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — high-resolution crystal structure with functional domain validation by mutagenesis and biochemical assay","pmids":["18056710"],"is_preprint":false},{"year":2010,"finding":"Archaeal Hel308 physically interacts with RPA via a conserved C-terminal amino acid motif; this interaction does not require SSB and is proposed to recruit Hel308 to aberrant ssDNA at blocked replication forks rather than directly stimulating helicase activity.","method":"Pulldown/interaction assay, motif mutagenesis, helicase stimulation assay","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 3 — single pulldown with motif mutation; archaeal system consistent with mammalian HELQ-RPA interaction","pmids":["21195035"],"is_preprint":false},{"year":2007,"finding":"Domain V (C-terminal) of archaeal Hel308 couples DNA binding to ATP hydrolysis and positions ssDNA relative to the helicase ratchet domain IV; mutagenesis of three arginine residues in domain V impairs DNA binding, unwinding, and ATPase activities.","method":"Site-directed mutagenesis, ATPase assay, helicase assay, DNA binding assay","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 1 — in vitro mutagenesis with multiple biochemical assays, single lab","pmids":["17991488"],"is_preprint":false},{"year":2005,"finding":"Archaeal Hel308 acts at stalled replication forks in vivo (synthetic lethality with E. coli dnaE stalled-fork strains) and in vitro specifically displaces lagging strands and the invading strand of D-loops.","method":"In vivo complementation/synthetic lethality assay, in vitro helicase assay with fork and D-loop substrates","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 1/2 — in vitro biochemistry plus in vivo genetics, archaeal ortholog","pmids":["15994460"],"is_preprint":false},{"year":2023,"finding":"Human HelQ halts DNA synthesis by Pol δ and by the Pol δ-PCNA-RPA holoenzyme; this inhibition maps to a 70-amino-acid intrinsically disordered region (IDR) of HelQ and is independent of HelQ DNA binding. The Pol δ subunit POLD3 physically interacts with HelQ via this IDR and strongly stimulates HelQ DNA strand annealing activity.","method":"In vitro DNA synthesis inhibition assay, HelQ mutant proteins, Co-IP/pulldown of POLD3-HelQ interaction, strand annealing assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with mutant analysis, interaction mapping to specific domain, multiple orthogonal assays","pmids":["36718939"],"is_preprint":false},{"year":2023,"finding":"HELQ helicase activity is required for EXO1-mediated DSB end resection, while HELQ's ssDNA-binding capacity is required for its recruitment to stalled replication forks where it protects nascent DNA from degradation and prevents chromosome aberrations. HELQ synergizes with CtIP (but not BRCA1/BRCA2) in fork protection.","method":"HELQ-deficient human cells, resection assays, fork protection assay (nascent DNA degradation), epistasis with CtIP/BRCA1/BRCA2, genetic complementation with helicase-dead and ssDNA-binding mutants","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 — KO cells with structure-function mutants, multiple orthogonal readouts, epistasis analysis","pmids":["37897354"],"is_preprint":false},{"year":2023,"finding":"In archaeal Hel308, motif IVa (F/YHHAGL) in the RecA2 domain acts as a catalytic switch that modulates both DNA helicase and strand annealing activities; a single substitution in motif IVa generates hyper-active helicase/annealase and causes 160,000-fold increased recombination (gene conversion only) in archaeal cells, revealing that Hel308 suppresses recombination in vivo.","method":"Site-directed mutagenesis, in vitro helicase/annealing assays, all-atom MD simulation, in vivo recombination assay in archaea","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with mutagenesis, structural simulation, in vivo genetic assay, multiple orthogonal methods","pmids":["37409572"],"is_preprint":false},{"year":2023,"finding":"FANCD2-driven mitotic DNA synthesis (MiDAS) in untransformed human cells requires HELQ at an early step, with a prerequisite of FANCD2 mono-ubiquitination by FA proteins, and functions to preserve common fragile site (CFS) stability.","method":"HELQ-deficient cells, MiDAS assay, CFS stability assay, epistasis with FA pathway components","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 — KO cells with defined cellular phenotype, epistasis with FA proteins, single lab","pmids":["37777152"],"is_preprint":false},{"year":2022,"finding":"In Drosophila, HELQ (MUS301 ortholog) promotes formation of recombination intermediates during synthesis-dependent strand annealing (SDSA), acting early in the process; double mutants of helq with blm or fancm show more severe SDSA defects than single mutants, indicating non-redundant roles.","method":"Double-strand gap repair assay in Drosophila, genetic epistasis (single and double mutants of helq, blm, fancm)","journal":"Genes","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with defined SDSA repair assay in Drosophila ortholog","pmids":["35328029"],"is_preprint":false},{"year":2025,"finding":"Human HELQ is recruited to R-loops via RPA interaction through its N-terminal disordered domain; HELQ resolves R-loops in an ATPase/helicase-dependent manner and functionally interacts with the nuclear 5'→3' exoribonuclease XRN2 to coordinate R-loop unwinding with RNA degradation.","method":"In-cell R-loop resolution assay, in vitro R-loop unwinding, Co-IP of HELQ-XRN2 interaction, catalytic mutant HELQ","journal":"Open biology","confidence":"Medium","confidence_rationale":"Tier 2 — in cellulo and in vitro with catalytic mutant, interaction confirmed by Co-IP, single lab","pmids":["39965657"],"is_preprint":false},{"year":2024,"finding":"HELQ specifically suppresses cisplatin sensitivity in PRIMPOL-overexpressing cells by reducing ssDNA gap accumulation; RAD52 acts as a mediator that promotes ssDNA gap accumulation through a BRCA-dependent mechanism, defining a HELQ-RAD52-BRCA axis in ssDNA gap repair.","method":"CRISPR genome-wide KO screen, HELQ-KO cell lines, ssDNA gap accumulation assay, epistasis with RAD52 and BRCA","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 — genome-wide screen followed by mechanistic validation with KO cells and epistasis, single lab","pmids":["39530221"],"is_preprint":false},{"year":2017,"finding":"The winged helix domain (WHD) of archaeal Hel308 directly binds duplex DNA (but not ssDNA); mutations in a solvent-exposed α-helix reduce DNA binding and unwinding. The interface between WHD and a RecA-like domain is essential for ATPase and helicase activities. The isolated WHD of human HelQ also binds duplex DNA, indicating conservation.","method":"In vitro mutagenesis, DNA binding assays (isolated WHD vs. full-length), ATPase assay, helicase assay, interface disruption mutants","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 1 — mutagenesis with multiple biochemical assays, functional validation in both archaeal and human HelQ","pmids":["28738244"],"is_preprint":false},{"year":2025,"finding":"HELQ interacts with the H3K9me3 demethylase KDM4B in primordial germ cells; absence of HELQ increases KDM4B protein levels, reduces H3K9me3 at LINE-1 retrotransposon loci, triggers LINE-1 expression and DNA damage accumulation, causing PGC proliferation defects reversible by retrotransposition inhibition.","method":"Co-IP of HELQ-KDM4B interaction, H3K9me3 ChIP, LINE-1 expression assay, retrotransposition inhibitor rescue, mouse embryo HELQ-KO","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP interaction, ChIP, rescue experiment, KO model with defined molecular mechanism, single lab","pmids":["40542648"],"is_preprint":false},{"year":2025,"finding":"In C. elegans, HELQ (hel-308) contributes to ICL-induced deletion formation via end-joining, acting in parallel to POLQ-mediated end joining, as a mutagenic ICL repair mechanism distinct from translesion synthesis.","method":"C. elegans genetic knockout, whole-genome mutation spectrum analysis after psoralen ICL treatment","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — KO with defined mutational spectrum readout; C. elegans ortholog","pmids":["40082407"],"is_preprint":false}],"current_model":"HELQ is a conserved 3'→5' superfamily 2 DNA helicase that also possesses intrinsic DNA strand annealing activity; it is recruited to stalled replication forks and DNA double-strand breaks via its N-terminal PWI-like domain interaction with RPA, whereupon RAD51 (via the BCDX2 paralogue complex) stimulates its translocation/unwinding activity while RPA suppresses unwinding but promotes annealing, enabling HELQ to function in multiple DSB repair sub-pathways (homologous recombination, SSA, MMEJ, SDSA) as well as ICL repair in parallel to the Fanconi anaemia pathway, EXO1-dependent end resection, R-loop resolution in concert with XRN2, and suppression of ssDNA gap accumulation through a RAD52-BRCA axis, with its DNA-synthesis-inhibitory interaction with POLD3 providing an additional regulatory node that restrains Pol δ activity and promotes strand annealing during repair."},"narrative":{"teleology":[{"year":2005,"claim":"Establishing that the Hel308 family acts at stalled replication forks — archaeal Hel308 was shown to specifically displace lagging strands and D-loop invading strands, defining the substrate specificity of this helicase family for replication-associated structures.","evidence":"In vitro helicase assays with fork/D-loop substrates and in vivo synthetic lethality in E. coli stalled-fork strains","pmids":["15994460"],"confidence":"Medium","gaps":["Archaeal system; relevance to mammalian HELQ not yet tested","No protein interaction partners identified","No structural information available"]},{"year":2007,"claim":"Determining the structural basis for Hel308 unwinding — the crystal structure revealed a five-domain architecture with domain V acting as an autoinhibitory 'molecular brake' that clamps extruded ssDNA, explaining how processivity is regulated.","evidence":"X-ray crystallography of archaeal Hel308, mutagenesis, streptavidin displacement and DNA unwinding assays","pmids":["18056710","17991488"],"confidence":"High","gaps":["Structure solved for archaeal ortholog only","Mechanism of autoinhibition relief unknown","No co-crystal with DNA fork substrate"]},{"year":2010,"claim":"Identifying RPA as a physical partner that recruits Hel308 to ssDNA — archaeal Hel308 was found to bind RPA through a conserved C-terminal motif, suggesting a recruitment rather than direct stimulation mechanism.","evidence":"Pulldown assay, motif mutagenesis, helicase stimulation assay in archaeal system","pmids":["21195035"],"confidence":"Medium","gaps":["Single pulldown without reciprocal validation","Interaction mapped in archaea, not yet confirmed for human HELQ","Functional consequence of recruitment not demonstrated in cells"]},{"year":2011,"claim":"Demonstrating that human HELQ localizes to damaged replication forks and preferentially unwinds lagging-strand DNA — this placed HELQ at the site of replication stress alongside RAD51 and FANCD2 in human cells.","evidence":"GFP-fusion live-cell imaging after camptothecin, helicase assays with fork-model substrates, RPA stimulation assay","pmids":["21398521"],"confidence":"High","gaps":["Functional requirement at forks not tested by depletion","Mechanism of substrate strand selection unknown"]},{"year":2013,"claim":"Placing HELQ in a DNA repair pathway parallel to Fanconi anaemia — mouse knockouts and epistasis analyses revealed that HELQ interacts with the BCDX2 RAD51 paralogue complex, operates non-epistatically with FANCC, and contributes to ATR-CHK1 signaling during ICL repair, with Helq-deficient mice showing subfertility, germ cell loss, and tumour predisposition.","evidence":"Co-IP, MS interactome, mouse KO models (single and double mutants with FA genes), ICL sensitivity, phosphorylation assays, cytogenetic readouts","pmids":["24005329","24005565","24005041"],"confidence":"High","gaps":["Direct biochemical mechanism of HELQ in ICL processing not resolved","How BCDX2 regulates HELQ enzymatically unknown","Tumour spectrum and penetrance not fully characterized"]},{"year":2017,"claim":"Defining the winged helix domain as a conserved duplex-DNA-binding module — mutagenesis showed that the WHD binds dsDNA and its interface with the RecA-like domain is essential for ATPase activity, a feature conserved from archaea to human HELQ.","evidence":"Isolated domain DNA binding assays, mutagenesis in archaeal and human HELQ, ATPase and helicase assays","pmids":["28738244"],"confidence":"Medium","gaps":["No full-length human HELQ structure","How WHD-dsDNA binding coordinates with N-terminal RPA-loading domain unclear"]},{"year":2021,"claim":"Revealing HELQ's dual enzymatic nature — reconstitution showed that HELQ possesses intrinsic strand annealing activity alongside unwinding, with RAD51 stimulating unwinding and RPA switching the enzyme toward annealing, explaining HELQ's roles in SSA, MMEJ, and SDSA repair pathways.","evidence":"Biochemical reconstitution, single-molecule imaging, SSA/MMEJ/HR reporter assays in HELQ-deficient cells, PWI-like domain characterization","pmids":["34937945","34316696"],"confidence":"High","gaps":["How the annealing-unwinding switch is structurally controlled unknown","In vivo stoichiometry of RAD51/RPA regulation of HELQ not determined","Contribution of dimerization to pathway choice unclear"]},{"year":2022,"claim":"Establishing HELQ as an early actor in synthesis-dependent strand annealing — Drosophila HELQ ortholog was shown to promote formation of recombination intermediates during SDSA, non-redundantly with BLM and FANCM helicases.","evidence":"Double-strand gap repair assay in Drosophila, genetic epistasis with blm and fancm","pmids":["35328029"],"confidence":"Medium","gaps":["Precise step in SDSA where HELQ acts not biochemically defined","Conservation of this specific SDSA role in mammals not directly tested"]},{"year":2023,"claim":"Discovering that HELQ inhibits Pol δ and is reciprocally stimulated by POLD3 — a 70-amino-acid IDR of HELQ directly binds POLD3, halting DNA synthesis while POLD3 stimulates HELQ's strand annealing, establishing a regulatory handoff between DNA synthesis and annealing during repair.","evidence":"In vitro DNA synthesis inhibition assay, HELQ mutant mapping, Co-IP/pulldown of POLD3-HELQ, strand annealing assay","pmids":["36718939"],"confidence":"High","gaps":["In vivo relevance of Pol δ inhibition not tested","Whether other replisome components modulate this interaction unknown"]},{"year":2023,"claim":"Separating HELQ's helicase and fork-protection functions — helicase activity was shown to be required for EXO1-mediated end resection, while ssDNA binding mediates fork recruitment and nascent DNA protection in synergy with CtIP, revealing separable structure-function contributions.","evidence":"HELQ-KO human cells, resection and fork protection assays, epistasis with CtIP/BRCA1/BRCA2, complementation with separation-of-function mutants","pmids":["37897354"],"confidence":"High","gaps":["Structural basis for separable functions not resolved","How HELQ coordinates with EXO1 biochemically undefined"]},{"year":2023,"claim":"Identifying a catalytic switch controlling recombination — motif IVa in the RecA2 domain toggles between helicase and annealase modes; a single mutation caused 160,000-fold increased gene conversion, demonstrating that HELQ normally suppresses recombination in vivo.","evidence":"Site-directed mutagenesis, in vitro helicase/annealing assays, MD simulation, in vivo recombination assay in archaea","pmids":["37409572"],"confidence":"High","gaps":["Whether motif IVa switch operates identically in human HELQ not tested","Structural basis for the conformational switch at atomic resolution unknown"]},{"year":2023,"claim":"Linking HELQ to mitotic DNA synthesis — HELQ was shown to be required at an early step for FANCD2-driven MiDAS at common fragile sites, placing HELQ downstream of FANCD2 mono-ubiquitination.","evidence":"HELQ-deficient cells, MiDAS assay, CFS stability assay, epistasis with FA components","pmids":["37777152"],"confidence":"Medium","gaps":["Biochemical mechanism of HELQ at MiDAS not determined","Whether HELQ acts directly on CFS structures or indirectly through downstream effectors unclear"]},{"year":2024,"claim":"Defining a HELQ–RAD52–BRCA axis in ssDNA gap suppression — HELQ was found to specifically suppress cisplatin sensitivity caused by PRIMPOL overexpression by reducing ssDNA gap accumulation, with RAD52 promoting gaps through a BRCA-dependent mechanism.","evidence":"Genome-wide CRISPR KO screen, HELQ-KO cells, ssDNA gap assay, epistasis with RAD52 and BRCA","pmids":["39530221"],"confidence":"Medium","gaps":["Biochemical mechanism by which HELQ fills or seals gaps unknown","Single-lab finding not independently replicated"]},{"year":2025,"claim":"Extending HELQ's substrate repertoire to R-loops — HELQ was shown to be recruited to R-loops via RPA and to resolve them in an ATPase-dependent manner, coordinating with XRN2 for RNA degradation, revealing a new non-DSB function.","evidence":"In-cell R-loop resolution assay, in vitro R-loop unwinding, Co-IP of HELQ–XRN2, catalytic mutant HELQ","pmids":["39965657"],"confidence":"Medium","gaps":["In vivo significance for transcription-replication conflicts not tested","Single-lab finding, no independent replication"]},{"year":2025,"claim":"Uncovering a chromatin-regulatory role in germ cells — HELQ was found to interact with KDM4B, and its absence leads to derepression of LINE-1 retrotransposons via reduced H3K9me3, causing DNA damage and PGC proliferation failure reversible by retrotransposition inhibition.","evidence":"Co-IP of HELQ–KDM4B, H3K9me3 ChIP, LINE-1 expression assay, retrotransposition inhibitor rescue, mouse embryo HELQ-KO","pmids":["40542648"],"confidence":"Medium","gaps":["Whether HELQ regulates KDM4B degradation or activity not distinguished","Generalizability beyond PGCs unclear","Single-lab Co-IP without reciprocal confirmation"]},{"year":null,"claim":"Key unresolved questions include: (1) the atomic structure of full-length human HELQ, (2) the structural mechanism by which the annealing-unwinding switch is controlled in the mammalian enzyme, (3) the in vivo stoichiometry and regulation of the HELQ–RAD51/BCDX2–RPA tripartite complex, and (4) the biological significance of HELQ's Pol δ inhibition during repair in cells.","evidence":"","pmids":[],"confidence":"Low","gaps":["No full-length mammalian HELQ structure","Annealing-unwinding switch mechanism not structurally resolved","In vivo reconstitution of regulatory complexes lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[2,3,7,9,13]},{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[2,4,10,13]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[3,7,12,18]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[4,12,16]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[4,14]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[0,2,5,6,12,15]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[4,12,14]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,14]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,6]}],"complexes":["HELQ–BCDX2 complex"],"partners":["RAD51B","RAD51C","RAD51D","XRCC2","RPA1","POLD3","XRN2","KDM4B"],"other_free_text":[]},"mechanistic_narrative":"HELQ is a conserved 3′→5′ superfamily 2 DNA helicase that couples DNA unwinding with intrinsic strand annealing activity to maintain genome integrity at stalled replication forks and DNA double-strand breaks [PMID:34937945, PMID:21398521]. Its N-terminal PWI-like domain mediates RPA-dependent recruitment to ssDNA substrates, where RAD51 paralogues (BCDX2 complex) stimulate translocation and unwinding while RPA suppresses unwinding but promotes annealing, enabling HELQ to participate in homologous recombination, single-strand annealing, microhomology-mediated end joining, synthesis-dependent strand annealing, and interstrand crosslink repair in parallel to the Fanconi anaemia pathway [PMID:24005329, PMID:34937945, PMID:34316696, PMID:24005041]. HELQ additionally inhibits Pol δ–mediated DNA synthesis through a direct POLD3-binding intrinsically disordered region, promotes EXO1-dependent end resection, resolves R-loops in concert with XRN2, and suppresses ssDNA gap accumulation through a RAD52–BRCA axis [PMID:36718939, PMID:37897354, PMID:39965657, PMID:39530221]. Helq-deficient mice exhibit subfertility, germ cell attrition, ICL hypersensitivity, and tumour predisposition, with germ cell defects linked to derepression of LINE-1 retrotransposons via dysregulated KDM4B-dependent H3K9me3 maintenance [PMID:24005329, PMID:40542648]."},"prefetch_data":{"uniprot":{"accession":"Q8TDG4","full_name":"Helicase POLQ-like","aliases":["Mus308-like helicase","POLQ-like helicase"],"length_aa":1101,"mass_kda":124.1,"function":"Single-stranded 3'-5' DNA helicase that plays a key role in homology-driven double-strand break (DSB) repair (PubMed:11751861, PubMed:19995904, PubMed:21398521, PubMed:24005041, PubMed:24005565, PubMed:34316696, PubMed:34937945). Involved in different DSB repair mechanisms that are guided by annealing of extensive stretches of complementary bases at break ends, such as microhomology-mediated end-joining (MMEJ), single-strand annealing (SSA) or synthesis-dependent strand annealing (SDSA) (PubMed:34937945). Possesses both DNA unwinding and annealing activities (PubMed:34937945). Forms a complex with RAD51, stimulating HELQ DNA helicase activity and ability to unwing DNA (PubMed:34937945). Efficiently unwinds substrates containing 3' overhangs or a D-loop (PubMed:21398521, PubMed:34937945). In contrast, interaction with the replication protein A (RPA/RP-A) complex inhibits DNA unwinding by HELQ but strongly stimulates DNA strand annealing (PubMed:34937945). Triggers displacement of RPA from single-stranded DNA to facilitate annealing of complementary sequences (PubMed:34316696, PubMed:34937945)","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/Q8TDG4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HELQ","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/HELQ","total_profiled":1310},"omim":[{"mim_id":"618611","title":"HOMOLOGOUS RECOMBINATION FACTOR WITH OB-FOLD; HROB","url":"https://www.omim.org/entry/618611"},{"mim_id":"606769","title":"HELICASE, POLQ-LIKE; HELQ","url":"https://www.omim.org/entry/606769"},{"mim_id":"602954","title":"RAD51 PARALOG D; RAD51D","url":"https://www.omim.org/entry/602954"},{"mim_id":"602948","title":"RAD51 PARALOG B; RAD51B","url":"https://www.omim.org/entry/602948"},{"mim_id":"602774","title":"RAD51 PARALOG C; RAD51C","url":"https://www.omim.org/entry/602774"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/HELQ"},"hgnc":{"alias_symbol":["Hel308"],"prev_symbol":[]},"alphafold":{"accession":"Q8TDG4","domains":[{"cath_id":"3.40.50.300","chopping":"316-517","consensus_level":"high","plddt":91.8803,"start":316,"end":517},{"cath_id":"3.40.50.300","chopping":"524-737","consensus_level":"high","plddt":90.6893,"start":524,"end":737},{"cath_id":"1.10.10.10","chopping":"753-831","consensus_level":"high","plddt":90.4076,"start":753,"end":831},{"cath_id":"-","chopping":"842-1085","consensus_level":"medium","plddt":91.2048,"start":842,"end":1085}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDG4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDG4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDG4-F1-predicted_aligned_error_v6.png","plddt_mean":73.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HELQ","jax_strain_url":"https://www.jax.org/strain/search?query=HELQ"},"sequence":{"accession":"Q8TDG4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TDG4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TDG4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDG4"}},"corpus_meta":[{"pmid":"18472307","id":"PMC_18472307","title":"Caenorhabditis elegans POLQ-1 and HEL-308 function in two distinct DNA interstrand cross-link repair pathways.","date":"2008","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/18472307","citation_count":86,"is_preprint":false},{"pmid":"24005329","id":"PMC_24005329","title":"HELQ promotes RAD51 paralogue-dependent repair to avert germ cell loss and tumorigenesis.","date":"2013","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/24005329","citation_count":85,"is_preprint":false},{"pmid":"19525970","id":"PMC_19525970","title":"Structural evidence for consecutive Hel308-like modules in the spliceosomal ATPase Brr2.","date":"2009","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19525970","citation_count":82,"is_preprint":false},{"pmid":"18056710","id":"PMC_18056710","title":"Structure of the DNA repair helicase hel308 reveals DNA binding and autoinhibitory domains.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18056710","citation_count":82,"is_preprint":false},{"pmid":"15994460","id":"PMC_15994460","title":"Archaeal Hel308 helicase targets replication forks in vivo and in vitro and unwinds lagging strands.","date":"2005","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/15994460","citation_count":75,"is_preprint":false},{"pmid":"19716790","id":"PMC_19716790","title":"Common design principles in the spliceosomal RNA helicase Brr2 and in the Hel308 DNA helicase.","date":"2009","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/19716790","citation_count":75,"is_preprint":false},{"pmid":"24005565","id":"PMC_24005565","title":"Human DNA helicase HELQ participates in DNA interstrand crosslink tolerance with ATR and RAD51 paralogs.","date":"2013","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/24005565","citation_count":67,"is_preprint":false},{"pmid":"34937945","id":"PMC_34937945","title":"HELQ is a dual-function DSB repair enzyme modulated by RPA and RAD51.","date":"2021","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/34937945","citation_count":58,"is_preprint":false},{"pmid":"30649515","id":"PMC_30649515","title":"Determining the effects of DNA sequence on Hel308 helicase translocation along single-stranded DNA using nanopore tweezers.","date":"2019","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/30649515","citation_count":34,"is_preprint":false},{"pmid":"21398521","id":"PMC_21398521","title":"Human HEL308 localizes to damaged replication forks and unwinds lagging strand structures.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21398521","citation_count":33,"is_preprint":false},{"pmid":"24005041","id":"PMC_24005041","title":"Helq acts in parallel to Fancc to suppress replication-associated genome instability.","date":"2013","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/24005041","citation_count":33,"is_preprint":false},{"pmid":"21195035","id":"PMC_21195035","title":"Physical interaction between archaeal DNA repair helicase Hel308 and Replication Protein A (RPA).","date":"2010","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/21195035","citation_count":18,"is_preprint":false},{"pmid":"17991488","id":"PMC_17991488","title":"Archaeal Hel308 domain V couples DNA binding to ATP hydrolysis and positions DNA for unwinding over the helicase ratchet.","date":"2007","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17991488","citation_count":18,"is_preprint":false},{"pmid":"34316696","id":"PMC_34316696","title":"The HelQ human DNA repair helicase utilizes a PWI-like domain for DNA loading through interaction with RPA, triggering DNA unwinding by the HelQ helicase core.","date":"2021","source":"NAR cancer","url":"https://pubmed.ncbi.nlm.nih.gov/34316696","citation_count":17,"is_preprint":false},{"pmid":"29572031","id":"PMC_29572031","title":"Helicase POLQ-like (HELQ) as a novel indicator of platinum-based chemoresistance for epithelial ovarian cancer.","date":"2018","source":"Gynecologic oncology","url":"https://pubmed.ncbi.nlm.nih.gov/29572031","citation_count":16,"is_preprint":false},{"pmid":"21265761","id":"PMC_21265761","title":"Winged helix domains with unknown function in Hel308 and related helicases.","date":"2011","source":"Biochemical Society transactions","url":"https://pubmed.ncbi.nlm.nih.gov/21265761","citation_count":14,"is_preprint":false},{"pmid":"28738244","id":"PMC_28738244","title":"DNA binding and unwinding by Hel308 helicase requires dual functions of a winged helix domain.","date":"2017","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/28738244","citation_count":13,"is_preprint":false},{"pmid":"28000895","id":"PMC_28000895","title":"HELQ reverses the malignant phenotype of osteosarcoma cells via CHK1-RAD51 signaling pathway.","date":"2016","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/28000895","citation_count":11,"is_preprint":false},{"pmid":"37921071","id":"PMC_37921071","title":"HELQ as a DNA helicase: Its novel role in normal cell function and tumorigenesis (Review).","date":"2023","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/37921071","citation_count":10,"is_preprint":false},{"pmid":"27565320","id":"PMC_27565320","title":"HELQ in cancer and reproduction.","date":"2016","source":"Neoplasma","url":"https://pubmed.ncbi.nlm.nih.gov/27565320","citation_count":8,"is_preprint":false},{"pmid":"35328029","id":"PMC_35328029","title":"Division of Labor by the HELQ, BLM, and FANCM Helicases during Homologous Recombination Repair in Drosophila melanogaster.","date":"2022","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/35328029","citation_count":8,"is_preprint":false},{"pmid":"26351136","id":"PMC_26351136","title":"Screening of HELQ in breast and ovarian cancer families.","date":"2016","source":"Familial cancer","url":"https://pubmed.ncbi.nlm.nih.gov/26351136","citation_count":8,"is_preprint":false},{"pmid":"37777152","id":"PMC_37777152","title":"Mitotic DNA Synthesis in Untransformed Human Cells Preserves Common Fragile Site Stability via a FANCD2-Driven Mechanism That Requires HELQ.","date":"2023","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/37777152","citation_count":8,"is_preprint":false},{"pmid":"34672775","id":"PMC_34672775","title":"Identification and Functional Investigation of Novel Heterozygous HELQ Mutations in Patients with Sertoli Cell-only Syndrome.","date":"2021","source":"Genetic testing and molecular biomarkers","url":"https://pubmed.ncbi.nlm.nih.gov/34672775","citation_count":7,"is_preprint":false},{"pmid":"36718939","id":"PMC_36718939","title":"Interaction of human HelQ with DNA polymerase delta halts DNA synthesis and stimulates DNA single-strand annealing.","date":"2023","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/36718939","citation_count":7,"is_preprint":false},{"pmid":"28101207","id":"PMC_28101207","title":"Structure-function analysis of DNA helicase HELQ: A new diagnostic marker in ovarian cancer.","date":"2016","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/28101207","citation_count":6,"is_preprint":false},{"pmid":"37897354","id":"PMC_37897354","title":"Human HELQ regulates DNA end resection at DNA double-strand breaks and stalled replication forks.","date":"2023","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/37897354","citation_count":6,"is_preprint":false},{"pmid":"37409572","id":"PMC_37409572","title":"Archaeal Hel308 suppresses recombination through a catalytic switch that controls DNA annealing.","date":"2023","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/37409572","citation_count":5,"is_preprint":false},{"pmid":"26190809","id":"PMC_26190809","title":"The screening of HELQ gene in Chinese patients with premature ovarian failure.","date":"2015","source":"Reproductive biomedicine online","url":"https://pubmed.ncbi.nlm.nih.gov/26190809","citation_count":5,"is_preprint":false},{"pmid":"38500564","id":"PMC_38500564","title":"Evolutionary and functional insights into the Ski2-like helicase family in Archaea: a comparison of Thermococcales ASH-Ski2 and Hel308 activities.","date":"2024","source":"NAR genomics and bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/38500564","citation_count":4,"is_preprint":false},{"pmid":"36183369","id":"PMC_36183369","title":"HELQ suppresses migration and proliferation of non-small cell lung cancer cells by repairing DNA damage and inducing necrosis.","date":"2022","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/36183369","citation_count":4,"is_preprint":false},{"pmid":"40082407","id":"PMC_40082407","title":"FAN1-mediated translesion synthesis and POLQ/HELQ-mediated end joining generate interstrand crosslink-induced mutations.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40082407","citation_count":3,"is_preprint":false},{"pmid":"32895148","id":"PMC_32895148","title":"[Expressions of HELQ and RAD51C in endometrial stromal sarcoma and their clinical significance].","date":"2020","source":"Nan fang yi ke da xue xue bao = Journal of Southern Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/32895148","citation_count":3,"is_preprint":false},{"pmid":"39965657","id":"PMC_39965657","title":"The human HELQ helicase and XRN2 exoribonuclease cooperate in R-loop resolution.","date":"2025","source":"Open biology","url":"https://pubmed.ncbi.nlm.nih.gov/39965657","citation_count":2,"is_preprint":false},{"pmid":"40381483","id":"PMC_40381483","title":"HELQ upregulates PARP1 to drive platinum resistance and predict therapeutic response in ovarian cancer.","date":"2025","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40381483","citation_count":2,"is_preprint":false},{"pmid":"38659927","id":"PMC_38659927","title":"CRISPR knockout genome-wide screens identify the HELQ-RAD52 axis in regulating the repair of cisplatin-induced single stranded DNA gaps.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38659927","citation_count":2,"is_preprint":false},{"pmid":"39530221","id":"PMC_39530221","title":"CRISPR knockout genome-wide screens identify the HELQ-RAD52 axis in regulating the repair of cisplatin-induced single-stranded DNA gaps.","date":"2024","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/39530221","citation_count":2,"is_preprint":false},{"pmid":"39201320","id":"PMC_39201320","title":"Helicase HELQ: Molecular Characters Fit for DSB Repair Function.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39201320","citation_count":1,"is_preprint":false},{"pmid":"40542648","id":"PMC_40542648","title":"HELQ Maintains Genome Stability of Primordial Germ Cells by Inhibiting LINE-1 Expression.","date":"2025","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/40542648","citation_count":0,"is_preprint":false},{"pmid":"38720471","id":"PMC_38720471","title":"HELQ deficiency impairs the induction of primordial germ cell-like cells.","date":"2024","source":"FEBS open bio","url":"https://pubmed.ncbi.nlm.nih.gov/38720471","citation_count":0,"is_preprint":false},{"pmid":"38540391","id":"PMC_38540391","title":"A Human Homozygous HELQ Missense Variant Does Not Cause Premature Ovarian Insufficiency in a Mouse Model.","date":"2024","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/38540391","citation_count":0,"is_preprint":false},{"pmid":"40176377","id":"PMC_40176377","title":"Correction to \"HELQ deficiency impairs the induction of primordial germ cell-like cells\".","date":"2025","source":"FEBS open bio","url":"https://pubmed.ncbi.nlm.nih.gov/40176377","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":18756,"output_tokens":4940,"usd":0.065184},"stage2":{"model":"claude-opus-4-6","input_tokens":8465,"output_tokens":3939,"usd":0.2112},"total_usd":0.276384,"stage1_batch_id":"msgbatch_01DzrsgVgYngY1hvM3DU1yF2","stage2_batch_id":"msgbatch_01KA9b7iRzKFdhoBUT7vCvSe","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2013,\n      \"finding\": \"HELQ directly interacts with the RAD51 paralogue complex BCDX2 and functions in parallel to the Fanconi anaemia pathway to promote efficient homologous recombination at damaged replication forks. Helq helicase-deficient mice exhibit subfertility, germ cell attrition, ICL sensitivity and tumour predisposition.\",\n      \"method\": \"Co-IP, mouse knockout model with defined phenotypic readouts (subfertility, ICL sensitivity, tumour predisposition), genetic epistasis with FA pathway\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal interaction, KO mouse with multiple orthogonal phenotypes, epistasis with FA pathway, independently confirmed by Takata et al. same year\",\n      \"pmids\": [\"24005329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Human HELQ is associated with the RAD51 paralogs RAD51B/C/D and XRCC2, and with the DNA damage-responsive kinase ATR. HELQ-knockout cells show reduced CHK1 phosphorylation after MMC treatment and reduced G2/M accumulation, placing HELQ in an ATR-CHK1 signaling arm during ICL repair.\",\n      \"method\": \"Proteomic/mass spectrometry interaction analysis, HELQ knockout cells, phosphorylation assay, cell cycle analysis after MMC treatment\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — MS-defined interactome, functional KO with defined signaling phenotype, corroborated by parallel Nature paper\",\n      \"pmids\": [\"24005565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HELQ possesses both DNA unwinding and DNA strand annealing activities that are differentially regulated: RAD51 forms a complex with HELQ and strongly stimulates translocation/unwinding, whereas RPA inhibits DNA unwinding but strongly stimulates DNA strand annealing. HELQ can capture RPA-bound DNA strands and displace RPA to facilitate annealing of complementary sequences. HELQ deficiency compromises single-strand annealing (SSA) and microhomology-mediated end-joining (MMEJ) pathways and biases towards long-tract gene conversion during HR.\",\n      \"method\": \"Biochemical reconstitution in vitro, single-molecule imaging, HELQ-deficient cell lines with SSA/MMEJ/HR reporter assays, direct protein-protein interaction\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution, single-molecule imaging, mutagenesis, multiple orthogonal cellular assays in one study\",\n      \"pmids\": [\"34937945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The non-catalytic N-terminal region of HelQ contains a PWI-like domain that mediates interaction with RPA, orchestrating loading of the helicase domains onto ssDNA. Once loaded, ATP-Mg2+ binding activates the helicase core, and HelQ translocates along ssDNA as a dimer.\",\n      \"method\": \"Domain characterization, in vitro binding assays, ATPase/helicase assays with mutant HelQ proteins, biochemical reconstitution\",\n      \"journal\": \"NAR cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — domain mutagenesis combined with biochemical reconstitution of loading and translocation\",\n      \"pmids\": [\"34316696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human HEL308 localizes to damaged replication forks (colocalizing with RAD51 and FANCD2) upon camptothecin treatment, requires a 3' ssDNA overhang for loading, preferentially unwinds the lagging strand of stalled replication fork substrates, and its unwinding is stimulated by human RPA.\",\n      \"method\": \"GFP-fusion live cell imaging/colocalization, purified protein helicase assays with fork-model substrates, RPA stimulation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiment linked to functional consequence, multiple in vitro assays with defined substrates\",\n      \"pmids\": [\"21398521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"C. elegans HEL-308 (HELQ ortholog) functions in ICL repair through a Fanconi anemia-dependent pathway, genetically distinct from the polq-1/BRCA1-dependent pathway, as established by epistasis analysis.\",\n      \"method\": \"Genetic epistasis analysis in C. elegans, survival assays, checkpoint/apoptosis readouts after ICL treatment\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic epistasis in model organism with defined phenotypic readouts\",\n      \"pmids\": [\"18472307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Mouse HELQ is non-epistatic with FANCC: Helq/Fancc double-mutant mice display significantly worse phenotypes than either single mutant (chromosome instability, micronuclei, 53BP1 nuclear bodies), establishing that HELQ operates in a pathway distinct from the FA core complex for suppression of spontaneous replication-associated genome instability.\",\n      \"method\": \"Double-mutant mouse model, epistasis analysis, cytogenetic assays (micronuclei, 53BP1 bodies), FANCD2 ubiquitination assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in vivo with multiple orthogonal readouts; FANCD2 monoubiquitination intact in Helq mutant confirms distinct pathway\",\n      \"pmids\": [\"24005041\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structure of archaeal Hel308 (HELQ homolog) reveals a five-domain architecture with a central pore lined with DNA-binding residues. Domain 5 acts as an autoinhibitory 'molecular brake' clamping ssDNA extruded through the pore to limit processivity. Hel308 can displace streptavidin from biotinylated DNA and partially displaces RPA/Alba1 but not RadA.\",\n      \"method\": \"X-ray crystallography, protein-streptavidin displacement assay, DNA unwinding assays with RPA/Alba1/RadA\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution crystal structure with functional domain validation by mutagenesis and biochemical assay\",\n      \"pmids\": [\"18056710\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Archaeal Hel308 physically interacts with RPA via a conserved C-terminal amino acid motif; this interaction does not require SSB and is proposed to recruit Hel308 to aberrant ssDNA at blocked replication forks rather than directly stimulating helicase activity.\",\n      \"method\": \"Pulldown/interaction assay, motif mutagenesis, helicase stimulation assay\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single pulldown with motif mutation; archaeal system consistent with mammalian HELQ-RPA interaction\",\n      \"pmids\": [\"21195035\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Domain V (C-terminal) of archaeal Hel308 couples DNA binding to ATP hydrolysis and positions ssDNA relative to the helicase ratchet domain IV; mutagenesis of three arginine residues in domain V impairs DNA binding, unwinding, and ATPase activities.\",\n      \"method\": \"Site-directed mutagenesis, ATPase assay, helicase assay, DNA binding assay\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro mutagenesis with multiple biochemical assays, single lab\",\n      \"pmids\": [\"17991488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Archaeal Hel308 acts at stalled replication forks in vivo (synthetic lethality with E. coli dnaE stalled-fork strains) and in vitro specifically displaces lagging strands and the invading strand of D-loops.\",\n      \"method\": \"In vivo complementation/synthetic lethality assay, in vitro helicase assay with fork and D-loop substrates\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1/2 — in vitro biochemistry plus in vivo genetics, archaeal ortholog\",\n      \"pmids\": [\"15994460\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Human HelQ halts DNA synthesis by Pol δ and by the Pol δ-PCNA-RPA holoenzyme; this inhibition maps to a 70-amino-acid intrinsically disordered region (IDR) of HelQ and is independent of HelQ DNA binding. The Pol δ subunit POLD3 physically interacts with HelQ via this IDR and strongly stimulates HelQ DNA strand annealing activity.\",\n      \"method\": \"In vitro DNA synthesis inhibition assay, HelQ mutant proteins, Co-IP/pulldown of POLD3-HelQ interaction, strand annealing assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with mutant analysis, interaction mapping to specific domain, multiple orthogonal assays\",\n      \"pmids\": [\"36718939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HELQ helicase activity is required for EXO1-mediated DSB end resection, while HELQ's ssDNA-binding capacity is required for its recruitment to stalled replication forks where it protects nascent DNA from degradation and prevents chromosome aberrations. HELQ synergizes with CtIP (but not BRCA1/BRCA2) in fork protection.\",\n      \"method\": \"HELQ-deficient human cells, resection assays, fork protection assay (nascent DNA degradation), epistasis with CtIP/BRCA1/BRCA2, genetic complementation with helicase-dead and ssDNA-binding mutants\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO cells with structure-function mutants, multiple orthogonal readouts, epistasis analysis\",\n      \"pmids\": [\"37897354\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In archaeal Hel308, motif IVa (F/YHHAGL) in the RecA2 domain acts as a catalytic switch that modulates both DNA helicase and strand annealing activities; a single substitution in motif IVa generates hyper-active helicase/annealase and causes 160,000-fold increased recombination (gene conversion only) in archaeal cells, revealing that Hel308 suppresses recombination in vivo.\",\n      \"method\": \"Site-directed mutagenesis, in vitro helicase/annealing assays, all-atom MD simulation, in vivo recombination assay in archaea\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with mutagenesis, structural simulation, in vivo genetic assay, multiple orthogonal methods\",\n      \"pmids\": [\"37409572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FANCD2-driven mitotic DNA synthesis (MiDAS) in untransformed human cells requires HELQ at an early step, with a prerequisite of FANCD2 mono-ubiquitination by FA proteins, and functions to preserve common fragile site (CFS) stability.\",\n      \"method\": \"HELQ-deficient cells, MiDAS assay, CFS stability assay, epistasis with FA pathway components\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO cells with defined cellular phenotype, epistasis with FA proteins, single lab\",\n      \"pmids\": [\"37777152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In Drosophila, HELQ (MUS301 ortholog) promotes formation of recombination intermediates during synthesis-dependent strand annealing (SDSA), acting early in the process; double mutants of helq with blm or fancm show more severe SDSA defects than single mutants, indicating non-redundant roles.\",\n      \"method\": \"Double-strand gap repair assay in Drosophila, genetic epistasis (single and double mutants of helq, blm, fancm)\",\n      \"journal\": \"Genes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with defined SDSA repair assay in Drosophila ortholog\",\n      \"pmids\": [\"35328029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Human HELQ is recruited to R-loops via RPA interaction through its N-terminal disordered domain; HELQ resolves R-loops in an ATPase/helicase-dependent manner and functionally interacts with the nuclear 5'→3' exoribonuclease XRN2 to coordinate R-loop unwinding with RNA degradation.\",\n      \"method\": \"In-cell R-loop resolution assay, in vitro R-loop unwinding, Co-IP of HELQ-XRN2 interaction, catalytic mutant HELQ\",\n      \"journal\": \"Open biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in cellulo and in vitro with catalytic mutant, interaction confirmed by Co-IP, single lab\",\n      \"pmids\": [\"39965657\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HELQ specifically suppresses cisplatin sensitivity in PRIMPOL-overexpressing cells by reducing ssDNA gap accumulation; RAD52 acts as a mediator that promotes ssDNA gap accumulation through a BRCA-dependent mechanism, defining a HELQ-RAD52-BRCA axis in ssDNA gap repair.\",\n      \"method\": \"CRISPR genome-wide KO screen, HELQ-KO cell lines, ssDNA gap accumulation assay, epistasis with RAD52 and BRCA\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide screen followed by mechanistic validation with KO cells and epistasis, single lab\",\n      \"pmids\": [\"39530221\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The winged helix domain (WHD) of archaeal Hel308 directly binds duplex DNA (but not ssDNA); mutations in a solvent-exposed α-helix reduce DNA binding and unwinding. The interface between WHD and a RecA-like domain is essential for ATPase and helicase activities. The isolated WHD of human HelQ also binds duplex DNA, indicating conservation.\",\n      \"method\": \"In vitro mutagenesis, DNA binding assays (isolated WHD vs. full-length), ATPase assay, helicase assay, interface disruption mutants\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis with multiple biochemical assays, functional validation in both archaeal and human HelQ\",\n      \"pmids\": [\"28738244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HELQ interacts with the H3K9me3 demethylase KDM4B in primordial germ cells; absence of HELQ increases KDM4B protein levels, reduces H3K9me3 at LINE-1 retrotransposon loci, triggers LINE-1 expression and DNA damage accumulation, causing PGC proliferation defects reversible by retrotransposition inhibition.\",\n      \"method\": \"Co-IP of HELQ-KDM4B interaction, H3K9me3 ChIP, LINE-1 expression assay, retrotransposition inhibitor rescue, mouse embryo HELQ-KO\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP interaction, ChIP, rescue experiment, KO model with defined molecular mechanism, single lab\",\n      \"pmids\": [\"40542648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In C. elegans, HELQ (hel-308) contributes to ICL-induced deletion formation via end-joining, acting in parallel to POLQ-mediated end joining, as a mutagenic ICL repair mechanism distinct from translesion synthesis.\",\n      \"method\": \"C. elegans genetic knockout, whole-genome mutation spectrum analysis after psoralen ICL treatment\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with defined mutational spectrum readout; C. elegans ortholog\",\n      \"pmids\": [\"40082407\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HELQ is a conserved 3'→5' superfamily 2 DNA helicase that also possesses intrinsic DNA strand annealing activity; it is recruited to stalled replication forks and DNA double-strand breaks via its N-terminal PWI-like domain interaction with RPA, whereupon RAD51 (via the BCDX2 paralogue complex) stimulates its translocation/unwinding activity while RPA suppresses unwinding but promotes annealing, enabling HELQ to function in multiple DSB repair sub-pathways (homologous recombination, SSA, MMEJ, SDSA) as well as ICL repair in parallel to the Fanconi anaemia pathway, EXO1-dependent end resection, R-loop resolution in concert with XRN2, and suppression of ssDNA gap accumulation through a RAD52-BRCA axis, with its DNA-synthesis-inhibitory interaction with POLD3 providing an additional regulatory node that restrains Pol δ activity and promotes strand annealing during repair.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"HELQ is a conserved 3′→5′ superfamily 2 DNA helicase that couples DNA unwinding with intrinsic strand annealing activity to maintain genome integrity at stalled replication forks and DNA double-strand breaks [PMID:34937945, PMID:21398521]. Its N-terminal PWI-like domain mediates RPA-dependent recruitment to ssDNA substrates, where RAD51 paralogues (BCDX2 complex) stimulate translocation and unwinding while RPA suppresses unwinding but promotes annealing, enabling HELQ to participate in homologous recombination, single-strand annealing, microhomology-mediated end joining, synthesis-dependent strand annealing, and interstrand crosslink repair in parallel to the Fanconi anaemia pathway [PMID:24005329, PMID:34937945, PMID:34316696, PMID:24005041]. HELQ additionally inhibits Pol δ–mediated DNA synthesis through a direct POLD3-binding intrinsically disordered region, promotes EXO1-dependent end resection, resolves R-loops in concert with XRN2, and suppresses ssDNA gap accumulation through a RAD52–BRCA axis [PMID:36718939, PMID:37897354, PMID:39965657, PMID:39530221]. Helq-deficient mice exhibit subfertility, germ cell attrition, ICL hypersensitivity, and tumour predisposition, with germ cell defects linked to derepression of LINE-1 retrotransposons via dysregulated KDM4B-dependent H3K9me3 maintenance [PMID:24005329, PMID:40542648].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Establishing that the Hel308 family acts at stalled replication forks — archaeal Hel308 was shown to specifically displace lagging strands and D-loop invading strands, defining the substrate specificity of this helicase family for replication-associated structures.\",\n      \"evidence\": \"In vitro helicase assays with fork/D-loop substrates and in vivo synthetic lethality in E. coli stalled-fork strains\",\n      \"pmids\": [\"15994460\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Archaeal system; relevance to mammalian HELQ not yet tested\", \"No protein interaction partners identified\", \"No structural information available\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Determining the structural basis for Hel308 unwinding — the crystal structure revealed a five-domain architecture with domain V acting as an autoinhibitory 'molecular brake' that clamps extruded ssDNA, explaining how processivity is regulated.\",\n      \"evidence\": \"X-ray crystallography of archaeal Hel308, mutagenesis, streptavidin displacement and DNA unwinding assays\",\n      \"pmids\": [\"18056710\", \"17991488\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure solved for archaeal ortholog only\", \"Mechanism of autoinhibition relief unknown\", \"No co-crystal with DNA fork substrate\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identifying RPA as a physical partner that recruits Hel308 to ssDNA — archaeal Hel308 was found to bind RPA through a conserved C-terminal motif, suggesting a recruitment rather than direct stimulation mechanism.\",\n      \"evidence\": \"Pulldown assay, motif mutagenesis, helicase stimulation assay in archaeal system\",\n      \"pmids\": [\"21195035\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single pulldown without reciprocal validation\", \"Interaction mapped in archaea, not yet confirmed for human HELQ\", \"Functional consequence of recruitment not demonstrated in cells\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Demonstrating that human HELQ localizes to damaged replication forks and preferentially unwinds lagging-strand DNA — this placed HELQ at the site of replication stress alongside RAD51 and FANCD2 in human cells.\",\n      \"evidence\": \"GFP-fusion live-cell imaging after camptothecin, helicase assays with fork-model substrates, RPA stimulation assay\",\n      \"pmids\": [\"21398521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional requirement at forks not tested by depletion\", \"Mechanism of substrate strand selection unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Placing HELQ in a DNA repair pathway parallel to Fanconi anaemia — mouse knockouts and epistasis analyses revealed that HELQ interacts with the BCDX2 RAD51 paralogue complex, operates non-epistatically with FANCC, and contributes to ATR-CHK1 signaling during ICL repair, with Helq-deficient mice showing subfertility, germ cell loss, and tumour predisposition.\",\n      \"evidence\": \"Co-IP, MS interactome, mouse KO models (single and double mutants with FA genes), ICL sensitivity, phosphorylation assays, cytogenetic readouts\",\n      \"pmids\": [\"24005329\", \"24005565\", \"24005041\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical mechanism of HELQ in ICL processing not resolved\", \"How BCDX2 regulates HELQ enzymatically unknown\", \"Tumour spectrum and penetrance not fully characterized\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defining the winged helix domain as a conserved duplex-DNA-binding module — mutagenesis showed that the WHD binds dsDNA and its interface with the RecA-like domain is essential for ATPase activity, a feature conserved from archaea to human HELQ.\",\n      \"evidence\": \"Isolated domain DNA binding assays, mutagenesis in archaeal and human HELQ, ATPase and helicase assays\",\n      \"pmids\": [\"28738244\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No full-length human HELQ structure\", \"How WHD-dsDNA binding coordinates with N-terminal RPA-loading domain unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealing HELQ's dual enzymatic nature — reconstitution showed that HELQ possesses intrinsic strand annealing activity alongside unwinding, with RAD51 stimulating unwinding and RPA switching the enzyme toward annealing, explaining HELQ's roles in SSA, MMEJ, and SDSA repair pathways.\",\n      \"evidence\": \"Biochemical reconstitution, single-molecule imaging, SSA/MMEJ/HR reporter assays in HELQ-deficient cells, PWI-like domain characterization\",\n      \"pmids\": [\"34937945\", \"34316696\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How the annealing-unwinding switch is structurally controlled unknown\", \"In vivo stoichiometry of RAD51/RPA regulation of HELQ not determined\", \"Contribution of dimerization to pathway choice unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Establishing HELQ as an early actor in synthesis-dependent strand annealing — Drosophila HELQ ortholog was shown to promote formation of recombination intermediates during SDSA, non-redundantly with BLM and FANCM helicases.\",\n      \"evidence\": \"Double-strand gap repair assay in Drosophila, genetic epistasis with blm and fancm\",\n      \"pmids\": [\"35328029\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Precise step in SDSA where HELQ acts not biochemically defined\", \"Conservation of this specific SDSA role in mammals not directly tested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Discovering that HELQ inhibits Pol δ and is reciprocally stimulated by POLD3 — a 70-amino-acid IDR of HELQ directly binds POLD3, halting DNA synthesis while POLD3 stimulates HELQ's strand annealing, establishing a regulatory handoff between DNA synthesis and annealing during repair.\",\n      \"evidence\": \"In vitro DNA synthesis inhibition assay, HELQ mutant mapping, Co-IP/pulldown of POLD3-HELQ, strand annealing assay\",\n      \"pmids\": [\"36718939\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of Pol δ inhibition not tested\", \"Whether other replisome components modulate this interaction unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Separating HELQ's helicase and fork-protection functions — helicase activity was shown to be required for EXO1-mediated end resection, while ssDNA binding mediates fork recruitment and nascent DNA protection in synergy with CtIP, revealing separable structure-function contributions.\",\n      \"evidence\": \"HELQ-KO human cells, resection and fork protection assays, epistasis with CtIP/BRCA1/BRCA2, complementation with separation-of-function mutants\",\n      \"pmids\": [\"37897354\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for separable functions not resolved\", \"How HELQ coordinates with EXO1 biochemically undefined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identifying a catalytic switch controlling recombination — motif IVa in the RecA2 domain toggles between helicase and annealase modes; a single mutation caused 160,000-fold increased gene conversion, demonstrating that HELQ normally suppresses recombination in vivo.\",\n      \"evidence\": \"Site-directed mutagenesis, in vitro helicase/annealing assays, MD simulation, in vivo recombination assay in archaea\",\n      \"pmids\": [\"37409572\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether motif IVa switch operates identically in human HELQ not tested\", \"Structural basis for the conformational switch at atomic resolution unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Linking HELQ to mitotic DNA synthesis — HELQ was shown to be required at an early step for FANCD2-driven MiDAS at common fragile sites, placing HELQ downstream of FANCD2 mono-ubiquitination.\",\n      \"evidence\": \"HELQ-deficient cells, MiDAS assay, CFS stability assay, epistasis with FA components\",\n      \"pmids\": [\"37777152\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical mechanism of HELQ at MiDAS not determined\", \"Whether HELQ acts directly on CFS structures or indirectly through downstream effectors unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defining a HELQ–RAD52–BRCA axis in ssDNA gap suppression — HELQ was found to specifically suppress cisplatin sensitivity caused by PRIMPOL overexpression by reducing ssDNA gap accumulation, with RAD52 promoting gaps through a BRCA-dependent mechanism.\",\n      \"evidence\": \"Genome-wide CRISPR KO screen, HELQ-KO cells, ssDNA gap assay, epistasis with RAD52 and BRCA\",\n      \"pmids\": [\"39530221\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical mechanism by which HELQ fills or seals gaps unknown\", \"Single-lab finding not independently replicated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extending HELQ's substrate repertoire to R-loops — HELQ was shown to be recruited to R-loops via RPA and to resolve them in an ATPase-dependent manner, coordinating with XRN2 for RNA degradation, revealing a new non-DSB function.\",\n      \"evidence\": \"In-cell R-loop resolution assay, in vitro R-loop unwinding, Co-IP of HELQ–XRN2, catalytic mutant HELQ\",\n      \"pmids\": [\"39965657\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo significance for transcription-replication conflicts not tested\", \"Single-lab finding, no independent replication\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Uncovering a chromatin-regulatory role in germ cells — HELQ was found to interact with KDM4B, and its absence leads to derepression of LINE-1 retrotransposons via reduced H3K9me3, causing DNA damage and PGC proliferation failure reversible by retrotransposition inhibition.\",\n      \"evidence\": \"Co-IP of HELQ–KDM4B, H3K9me3 ChIP, LINE-1 expression assay, retrotransposition inhibitor rescue, mouse embryo HELQ-KO\",\n      \"pmids\": [\"40542648\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether HELQ regulates KDM4B degradation or activity not distinguished\", \"Generalizability beyond PGCs unclear\", \"Single-lab Co-IP without reciprocal confirmation\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: (1) the atomic structure of full-length human HELQ, (2) the structural mechanism by which the annealing-unwinding switch is controlled in the mammalian enzyme, (3) the in vivo stoichiometry and regulation of the HELQ–RAD51/BCDX2–RPA tripartite complex, and (4) the biological significance of HELQ's Pol δ inhibition during repair in cells.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No full-length mammalian HELQ structure\", \"Annealing-unwinding switch mechanism not structurally resolved\", \"In vivo reconstitution of regulatory complexes lacking\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [2, 3, 7, 9, 13]},\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [2, 4, 10, 13]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [3, 7, 12, 18]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4, 12, 16]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [4, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 2, 5, 6, 12, 15]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [4, 12, 14]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 14]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"complexes\": [\n      \"HELQ–BCDX2 complex\"\n    ],\n    \"partners\": [\n      \"RAD51B\",\n      \"RAD51C\",\n      \"RAD51D\",\n      \"XRCC2\",\n      \"RPA1\",\n      \"POLD3\",\n      \"XRN2\",\n      \"KDM4B\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}