{"gene":"POLA2","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2017,"finding":"Human STN1 directly binds POLA2 (the accessory subunit of DNA polymerase α/primase) through its N-terminal OB fold domain, and this interaction is the primary mechanism by which STN1 stimulates primase-Pol α (PP) activity in vitro. The main binding target of STN1 on POLA2 is POLA2's central OB fold domain, which in the substrate-free PP structure is positioned to block nucleic acid entry to the Pol α active site; thus the STN1-POLA2 interaction is proposed to drive a conformational change enabling nucleic acid delivery. A disease-causing STN1 mutation selectively abrogates POLA2 binding and PP stimulation.","method":"Purified protein binding assays, in vitro PP activity assays with STN1 variants, domain-mapping experiments, structural context analysis","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro reconstitution of stimulatory activity with purified proteins, domain mutagenesis, and correlation of binding with activity across multiple variants in a single focused study","pmids":["28934486"],"is_preprint":false},{"year":2020,"finding":"Loss of POLA2 (by siRNA knockdown) increases spontaneous DNA double-strand break (DSB) formation, slows DSB repair kinetics after etoposide treatment, and inhibits both non-homologous end-joining (NHEJ) and homologous recombination (HR) repair pathways. POLA2 loss also increases cellular sensitivity to ionizing radiation and PARP1 inhibition.","method":"siRNA-mediated knockdown, γH2AX foci assay for DSB detection, neutral comet assay, reporter assays for NHEJ and HR, clonogenic survival after ionizing radiation and PARP1 inhibitor treatment","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO/KD with multiple orthogonal functional readouts (spontaneous DSBs, repair kinetics, NHEJ and HR reporters, survival assays) in a single lab study","pmids":["32549188"],"is_preprint":false},{"year":2024,"finding":"Biallelic loss-of-function variants in POLA2 (identified by whole-genome sequencing) cause a telomere biology disorder with Coats plus features, characterised by abnormally short telomeres, consistent with POLA2's essential role as the accessory subunit of Pol α/primase in telomere C-strand fill-in after replication.","method":"Whole-genome sequencing, segregation analysis, telomere length measurement in affected individuals from two unrelated families","journal":"European journal of human genetics : EJHG","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — human genetic epistasis via biallelic variants in two independent families with telomere length phenotype, but mechanism inferred from genetic data rather than direct biochemical reconstitution","pmids":["39616267"],"is_preprint":false},{"year":2016,"finding":"siRNA-mediated knockdown of POLA2 in H1299 lung cancer cells increases resistance to gemcitabine, indicating that POLA2 expression is required for gemcitabine sensitivity and suggesting POLA2 cooperates with other partners in the cellular response to this nucleoside analogue.","method":"siRNA knockdown of POLA2, cell viability assay after gemcitabine treatment","journal":"BMC genomics","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single-lab, single-method (siRNA + viability assay), no pathway placement or mechanistic follow-up","pmids":["28155658"],"is_preprint":false},{"year":2024,"finding":"POLA2 knockdown in HCC cell lines inhibits cell proliferation and alters cell cycle progression, and Western blot analysis associates POLA2 with PI3K/AKT/mTOR pathway activity.","method":"siRNA/shRNA knockdown, CCK-8, colony formation, EDU proliferation assay, flow cytometry cell cycle analysis, Western blot for PI3K/AKT/mTOR pathway components","journal":"Combinatorial chemistry & high throughput screening","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single-lab cell line study; PI3K/AKT/mTOR link is based solely on Western blot correlation after knockdown, no direct mechanistic validation","pmids":["37861044"],"is_preprint":false}],"current_model":"POLA2 is the accessory (B) subunit of the DNA polymerase α/primase complex; it directly binds STN1 via an OB-fold interaction that stimulates primase-Pol α activity and likely facilitates nucleic acid delivery to the Pol α active site, and it is required for efficient telomere C-strand fill-in (biallelic loss causes a telomere biology disorder), for normal replication-associated DSB prevention, and for proficient DSB repair via both NHEJ and HR."},"narrative":{"mechanistic_narrative":"POLA2 is the accessory (B) subunit of the DNA polymerase α/primase complex and supports genome replication, telomere maintenance, and double-strand break repair [PMID:28934486, PMID:32549188, PMID:39616267]. Its central OB-fold domain is the principal docking site for STN1, whose N-terminal OB fold binds POLA2 directly; in the substrate-free primase–Pol α complex this domain is positioned to occlude nucleic acid entry to the Pol α active site, and the STN1–POLA2 interaction drives the conformational change that stimulates primase–Pol α activity and enables nucleic acid delivery to the active site [PMID:28934486]. Consistent with this role in completing replication, biallelic loss-of-function variants in POLA2 cause a telomere biology disorder with Coats plus features and abnormally short telomeres, reflecting impaired telomere C-strand fill-in [PMID:39616267]. Beyond replication, POLA2 also restrains spontaneous DSB formation and is required for efficient DSB repair through both NHEJ and homologous recombination, such that its loss sensitizes cells to ionizing radiation and PARP1 inhibition [PMID:32549188].","teleology":[{"year":2017,"claim":"Established the molecular basis by which the telomere factor STN1 engages the Pol α/primase machinery, answering how STN1 stimulates primase–Pol α activity.","evidence":"Purified protein binding and domain-mapping with in vitro primase–Pol α activity assays using STN1 variants","pmids":["28934486"],"confidence":"High","gaps":["The proposed STN1-driven conformational change in POLA2's OB fold is inferred from structural context, not captured in a bound structure","Does not establish how this interaction is regulated in vivo at telomeres versus bulk replication"]},{"year":2020,"claim":"Showed that POLA2 has a role in genome stability beyond primer synthesis, by linking its loss to DSB accumulation and impaired repair.","evidence":"siRNA knockdown with γH2AX foci, neutral comet, NHEJ and HR reporter assays, and clonogenic survival after IR and PARP1 inhibition","pmids":["32549188"],"confidence":"Medium","gaps":["Whether the repair defects are direct or secondary to defective replication is not resolved","No physical partner or molecular mechanism placing POLA2 within NHEJ or HR machinery identified"]},{"year":2024,"claim":"Connected POLA2 loss-of-function to human disease, establishing it as a causative gene for a telomere biology disorder.","evidence":"Whole-genome sequencing, segregation analysis, and telomere length measurement in two unrelated families","pmids":["39616267"],"confidence":"Medium","gaps":["Telomere C-strand fill-in mechanism is inferred from genetics rather than directly reconstituted with patient variants","Genotype–phenotype relationship across the variant spectrum not characterized"]},{"year":2024,"claim":"Examined POLA2's contribution to cancer cell proliferation, raising the possibility of a role in proliferative signaling.","evidence":"siRNA/shRNA knockdown in HCC lines with proliferation, cell cycle, and Western blot for PI3K/AKT/mTOR components","pmids":["37861044"],"confidence":"Low","gaps":["PI3K/AKT/mTOR link rests solely on Western blot correlation after knockdown with no direct mechanistic validation","Single cell-line context; causal direction unresolved"]},{"year":null,"claim":"How POLA2's roles in replication, telomere C-strand fill-in, and DSB repair are mechanistically coordinated, and whether its repair function is direct, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of the STN1-bound, activated primase–Pol α complex","No defined physical link between POLA2 and NHEJ/HR factors","Mechanism of telomere-specific recruitment unestablished"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140098","term_label":"catalytic activity, acting on RNA","supporting_discovery_ids":[0]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[0]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[1]}],"complexes":["DNA polymerase α/primase"],"partners":["STN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q14181","full_name":"DNA polymerase alpha subunit B","aliases":["DNA polymerase alpha 70 kDa subunit"],"length_aa":598,"mass_kda":65.9,"function":"Accessory subunit of the DNA polymerase alpha complex (also known as the alpha DNA polymerase-primase complex) which plays an essential role in the initiation of DNA synthesis (PubMed:9705292). During the S phase of the cell cycle, the DNA polymerase alpha complex (composed of a catalytic subunit POLA1, an accessory subunit POLA2 and two primase subunits, the catalytic subunit PRIM1 and the regulatory subunit PRIM2) is recruited to DNA at the replicative forks via direct interactions with MCM10 and WDHD1 (By similarity). The primase subunit of the polymerase alpha complex initiates DNA synthesis by oligomerising short RNA primers on both leading and lagging strands (By similarity). These primers are initially extended by the polymerase alpha catalytic subunit and subsequently transferred to polymerase delta and polymerase epsilon for processive synthesis on the lagging and leading strand, respectively (By similarity)","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q14181/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/POLA2","classification":"Common Essential","n_dependent_lines":1194,"n_total_lines":1208,"dependency_fraction":0.9884105960264901},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SSRP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/POLA2","total_profiled":1310},"omim":[{"mim_id":"620063","title":"DNA POLYMERASE ALPHA-2, ACCESSORY SUBUNIT; POLA2","url":"https://www.omim.org/entry/620063"},{"mim_id":"614539","title":"HELICASE, DNA, B; HELB","url":"https://www.omim.org/entry/614539"},{"mim_id":"613128","title":"STN1, CST COMPLEX SUBUNIT; STN1","url":"https://www.omim.org/entry/613128"},{"mim_id":"176636","title":"PRIMASE POLYPEPTIDE 2A; PRIM2A","url":"https://www.omim.org/entry/176636"},{"mim_id":"176635","title":"PRIMASE POLYPEPTIDE 1; PRIM1","url":"https://www.omim.org/entry/176635"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Basal body","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/POLA2"},"hgnc":{"alias_symbol":["FLJ21662"],"prev_symbol":[]},"alphafold":{"accession":"Q14181","domains":[{"cath_id":"1.10.8.530","chopping":"2-65","consensus_level":"medium","plddt":85.6588,"start":2,"end":65}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14181","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q14181-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q14181-F1-predicted_aligned_error_v6.png","plddt_mean":84.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=POLA2","jax_strain_url":"https://www.jax.org/strain/search?query=POLA2"},"sequence":{"accession":"Q14181","fasta_url":"https://rest.uniprot.org/uniprotkb/Q14181.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q14181/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14181"}},"corpus_meta":[{"pmid":"32511866","id":"PMC_32511866","title":"CircRNA circ_POLA2 promotes lung cancer cell stemness via regulating the miR-326/GNB1 axis.","date":"2020","source":"Environmental toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/32511866","citation_count":53,"is_preprint":false},{"pmid":"28934486","id":"PMC_28934486","title":"STN1-POLA2 interaction provides a basis for primase-pol α stimulation by human STN1.","date":"2017","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/28934486","citation_count":38,"is_preprint":false},{"pmid":"33981162","id":"PMC_33981162","title":"CircRNA circ_POLA2 is Upregulated in Acute Myeloid Leukemia (AML) and Promotes Cell Proliferation by Suppressing the Production of Mature miR-34a.","date":"2021","source":"Cancer management and research","url":"https://pubmed.ncbi.nlm.nih.gov/33981162","citation_count":23,"is_preprint":false},{"pmid":"32766125","id":"PMC_32766125","title":"CircRNA circ_POLA2 Promotes Cervical Squamous Cell Carcinoma Progression via Regulating miR-326/GNB1.","date":"2020","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/32766125","citation_count":20,"is_preprint":false},{"pmid":"32549188","id":"PMC_32549188","title":"Involvement of POLA2 in Double Strand Break Repair and Genotoxic Stress.","date":"2020","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32549188","citation_count":17,"is_preprint":false},{"pmid":"28155658","id":"PMC_28155658","title":"Knockdown of POLA2 increases gemcitabine resistance in lung cancer cells.","date":"2016","source":"BMC genomics","url":"https://pubmed.ncbi.nlm.nih.gov/28155658","citation_count":12,"is_preprint":false},{"pmid":"39616267","id":"PMC_39616267","title":"Identification of biallelic POLA2 variants in two families with an autosomal recessive telomere biology disorder.","date":"2024","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/39616267","citation_count":10,"is_preprint":false},{"pmid":"36730613","id":"PMC_36730613","title":"CircRNA circ_POLA2 overexpression suppresses cell apoptosis by downregulating PTEN in glioblastoma.","date":"2022","source":"Anti-cancer drugs","url":"https://pubmed.ncbi.nlm.nih.gov/36730613","citation_count":7,"is_preprint":false},{"pmid":"34539866","id":"PMC_34539866","title":"circRNA circ_POLA2 increases microRNA-31 methylation to promote endometrial cancer cell proliferation.","date":"2021","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/34539866","citation_count":7,"is_preprint":false},{"pmid":"37595073","id":"PMC_37595073","title":"Circ-POLA2-mediated miR-138-5p/SEMA4C axis affects colon cancer cell activities.","date":"2023","source":"Acta biochimica Polonica","url":"https://pubmed.ncbi.nlm.nih.gov/37595073","citation_count":4,"is_preprint":false},{"pmid":"37861044","id":"PMC_37861044","title":"The Biological Function of POLA2 in Hepatocellular Carcinoma.","date":"2024","source":"Combinatorial chemistry & high throughput screening","url":"https://pubmed.ncbi.nlm.nih.gov/37861044","citation_count":3,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7475,"output_tokens":1418,"usd":0.021847,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8137,"output_tokens":1796,"usd":0.042792,"stage2_stop_reason":"end_turn"},"total_usd":0.064639,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2017,\n      \"finding\": \"Human STN1 directly binds POLA2 (the accessory subunit of DNA polymerase α/primase) through its N-terminal OB fold domain, and this interaction is the primary mechanism by which STN1 stimulates primase-Pol α (PP) activity in vitro. The main binding target of STN1 on POLA2 is POLA2's central OB fold domain, which in the substrate-free PP structure is positioned to block nucleic acid entry to the Pol α active site; thus the STN1-POLA2 interaction is proposed to drive a conformational change enabling nucleic acid delivery. A disease-causing STN1 mutation selectively abrogates POLA2 binding and PP stimulation.\",\n      \"method\": \"Purified protein binding assays, in vitro PP activity assays with STN1 variants, domain-mapping experiments, structural context analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro reconstitution of stimulatory activity with purified proteins, domain mutagenesis, and correlation of binding with activity across multiple variants in a single focused study\",\n      \"pmids\": [\"28934486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Loss of POLA2 (by siRNA knockdown) increases spontaneous DNA double-strand break (DSB) formation, slows DSB repair kinetics after etoposide treatment, and inhibits both non-homologous end-joining (NHEJ) and homologous recombination (HR) repair pathways. POLA2 loss also increases cellular sensitivity to ionizing radiation and PARP1 inhibition.\",\n      \"method\": \"siRNA-mediated knockdown, γH2AX foci assay for DSB detection, neutral comet assay, reporter assays for NHEJ and HR, clonogenic survival after ionizing radiation and PARP1 inhibitor treatment\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO/KD with multiple orthogonal functional readouts (spontaneous DSBs, repair kinetics, NHEJ and HR reporters, survival assays) in a single lab study\",\n      \"pmids\": [\"32549188\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Biallelic loss-of-function variants in POLA2 (identified by whole-genome sequencing) cause a telomere biology disorder with Coats plus features, characterised by abnormally short telomeres, consistent with POLA2's essential role as the accessory subunit of Pol α/primase in telomere C-strand fill-in after replication.\",\n      \"method\": \"Whole-genome sequencing, segregation analysis, telomere length measurement in affected individuals from two unrelated families\",\n      \"journal\": \"European journal of human genetics : EJHG\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — human genetic epistasis via biallelic variants in two independent families with telomere length phenotype, but mechanism inferred from genetic data rather than direct biochemical reconstitution\",\n      \"pmids\": [\"39616267\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"siRNA-mediated knockdown of POLA2 in H1299 lung cancer cells increases resistance to gemcitabine, indicating that POLA2 expression is required for gemcitabine sensitivity and suggesting POLA2 cooperates with other partners in the cellular response to this nucleoside analogue.\",\n      \"method\": \"siRNA knockdown of POLA2, cell viability assay after gemcitabine treatment\",\n      \"journal\": \"BMC genomics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single-lab, single-method (siRNA + viability assay), no pathway placement or mechanistic follow-up\",\n      \"pmids\": [\"28155658\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"POLA2 knockdown in HCC cell lines inhibits cell proliferation and alters cell cycle progression, and Western blot analysis associates POLA2 with PI3K/AKT/mTOR pathway activity.\",\n      \"method\": \"siRNA/shRNA knockdown, CCK-8, colony formation, EDU proliferation assay, flow cytometry cell cycle analysis, Western blot for PI3K/AKT/mTOR pathway components\",\n      \"journal\": \"Combinatorial chemistry & high throughput screening\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single-lab cell line study; PI3K/AKT/mTOR link is based solely on Western blot correlation after knockdown, no direct mechanistic validation\",\n      \"pmids\": [\"37861044\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"POLA2 is the accessory (B) subunit of the DNA polymerase α/primase complex; it directly binds STN1 via an OB-fold interaction that stimulates primase-Pol α activity and likely facilitates nucleic acid delivery to the Pol α active site, and it is required for efficient telomere C-strand fill-in (biallelic loss causes a telomere biology disorder), for normal replication-associated DSB prevention, and for proficient DSB repair via both NHEJ and HR.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"POLA2 is the accessory (B) subunit of the DNA polymerase α/primase complex and supports genome replication, telomere maintenance, and double-strand break repair [#0, #1, #2]. Its central OB-fold domain is the principal docking site for STN1, whose N-terminal OB fold binds POLA2 directly; in the substrate-free primase–Pol α complex this domain is positioned to occlude nucleic acid entry to the Pol α active site, and the STN1–POLA2 interaction drives the conformational change that stimulates primase–Pol α activity and enables nucleic acid delivery to the active site [#0]. Consistent with this role in completing replication, biallelic loss-of-function variants in POLA2 cause a telomere biology disorder with Coats plus features and abnormally short telomeres, reflecting impaired telomere C-strand fill-in [#2]. Beyond replication, POLA2 also restrains spontaneous DSB formation and is required for efficient DSB repair through both NHEJ and homologous recombination, such that its loss sensitizes cells to ionizing radiation and PARP1 inhibition [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2017,\n      \"claim\": \"Established the molecular basis by which the telomere factor STN1 engages the Pol α/primase machinery, answering how STN1 stimulates primase–Pol α activity.\",\n      \"evidence\": \"Purified protein binding and domain-mapping with in vitro primase–Pol α activity assays using STN1 variants\",\n      \"pmids\": [\"28934486\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The proposed STN1-driven conformational change in POLA2's OB fold is inferred from structural context, not captured in a bound structure\",\n        \"Does not establish how this interaction is regulated in vivo at telomeres versus bulk replication\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed that POLA2 has a role in genome stability beyond primer synthesis, by linking its loss to DSB accumulation and impaired repair.\",\n      \"evidence\": \"siRNA knockdown with γH2AX foci, neutral comet, NHEJ and HR reporter assays, and clonogenic survival after IR and PARP1 inhibition\",\n      \"pmids\": [\"32549188\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether the repair defects are direct or secondary to defective replication is not resolved\",\n        \"No physical partner or molecular mechanism placing POLA2 within NHEJ or HR machinery identified\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Connected POLA2 loss-of-function to human disease, establishing it as a causative gene for a telomere biology disorder.\",\n      \"evidence\": \"Whole-genome sequencing, segregation analysis, and telomere length measurement in two unrelated families\",\n      \"pmids\": [\"39616267\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Telomere C-strand fill-in mechanism is inferred from genetics rather than directly reconstituted with patient variants\",\n        \"Genotype–phenotype relationship across the variant spectrum not characterized\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Examined POLA2's contribution to cancer cell proliferation, raising the possibility of a role in proliferative signaling.\",\n      \"evidence\": \"siRNA/shRNA knockdown in HCC lines with proliferation, cell cycle, and Western blot for PI3K/AKT/mTOR components\",\n      \"pmids\": [\"37861044\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"PI3K/AKT/mTOR link rests solely on Western blot correlation after knockdown with no direct mechanistic validation\",\n        \"Single cell-line context; causal direction unresolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How POLA2's roles in replication, telomere C-strand fill-in, and DSB repair are mechanistically coordinated, and whether its repair function is direct, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structure of the STN1-bound, activated primase–Pol α complex\",\n        \"No defined physical link between POLA2 and NHEJ/HR factors\",\n        \"Mechanism of telomere-specific recruitment unestablished\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [\"DNA polymerase α/primase\"],\n    \"partners\": [\"STN1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":3,"faith_total":4,"faith_pct":75.0}}