{"gene":"ATRNL1","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2007,"finding":"ATRNL1 and ATRN are redundant from a gain-of-function but not loss-of-function perspective: transgenic overexpression of ATRNL1 in Atrn null mice rescued normal agouti-banded fur pigmentation and significantly delayed onset of spongiform neurodegeneration, demonstrating that ATRNL1 can compensate for ATRN loss. However, Atrnl1 knockout mice alone showed no pigmentation, CNS, or body weight phenotype.","method":"Loss-of-function and gain-of-function mouse genetics (Atrnl1 knockout mice, beta-actin promoter-driven Atrnl1 transgene in Atrn null background); phenotypic analysis of fur color, CNS pathology, body weight","journal":"Genesis (New York, N.Y. : 2000)","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic epistasis with both loss- and gain-of-function alleles in mouse, multiple phenotypic readouts, single lab but rigorous complementary experiments","pmids":["18064672"],"is_preprint":false},{"year":2008,"finding":"Transgenic overexpression of ATRNL1 did not rescue dark-like (dal) mutant phenotypes (dark fur, testicular vacuolation, spongiform neurodegeneration), and dal and Atrn showed additive effects on these phenotypes. Genetic crosses placed dal upstream of Mc1r and downstream of agouti. This places ATRNL1 and ATRN in the same pathway, but ATRNL1 overexpression cannot compensate for the dal locus, distinguishing dal from the ATRN pathway.","method":"Genetic epistasis by crosses between dal, Atrn, Mc1r, and agouti mutant mice; Atrnl1 transgenic rescue experiment","journal":"Genesis (New York, N.Y. : 2000)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with multiple mutant alleles, single lab, functional phenotypic readouts but dal gene identity unknown","pmids":["18821597"],"is_preprint":false},{"year":2025,"finding":"ATRNL1 acts as a transmembrane adapter that recruits the E3 ubiquitin ligase MGRN1 (via its RING domain) to promote ubiquitylation and degradation of the melanocortin receptors MC1R and MC4R at the cell surface. Loss of MGRN1 or ATRN leads to increased surface and ciliary localization of MC4R in fibroblasts and elevated MC1R levels in melanocytes, resulting in enhanced eumelanin production.","method":"Co-immunoprecipitation (showing ATRNL1/ATRN interaction with MGRN1 RING domain); functional ubiquitylation and receptor degradation assays; cell surface/ciliary localization assays; melanocyte eumelanin production assay; loss-of-function experiments","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, functional ubiquitylation assays, subcellular localization with functional consequence, multiple receptor substrates tested, peer-reviewed and preprint corroborate","pmids":["41178558","40196599"],"is_preprint":false},{"year":2024,"finding":"ATRNL1 is overexpressed in cardiomyocytes of patients with atrial fibrillation and localizes to intercalated disks. Both knockdown and overexpression of ATRNL1 in cardiomyocytes identified a role in the cell stress response and modulation of the cardiac action potential.","method":"Single-nucleus RNA-seq (snRNA-seq) on >175,000 nuclei from human left atrial samples; subcellular localization experiments; knockdown and overexpression functional experiments with action potential and stress response readouts","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with functional consequence (action potential modulation), KD and OE experiments, single lab, human tissue study","pmids":["39562555"],"is_preprint":false},{"year":2023,"finding":"CEBPB (CCAAT enhancer binding protein beta) transcriptionally upregulates ATRNL1 by binding to its promoter in cervical cancer cells. ATRNL1 upregulation suppresses cervical cancer cell viability, migration, and epithelial-mesenchymal transition (EMT), and the effects of CEBPB elevation on these processes are reversed by ATRNL1 depletion.","method":"ChIP assay (CEBPB binding to ATRNL1 promoter); luciferase reporter assay; gain-of-function and rescue experiments; RT-qPCR and western blotting","journal":"Cellular and molecular biology (Noisy-le-Grand, France)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and luciferase reporter for transcriptional regulation, functional rescue assays, single lab with two orthogonal methods","pmids":["38158696"],"is_preprint":false},{"year":2024,"finding":"ATRNL1 and WNT9A are upregulated in both HCM cell models (isoproterenol-treated) and animal models, validating them as differentially expressed genes in hypertrophic cardiomyopathy. Propylthiouracil treatment significantly inhibited ATRNL1 expression in the HCM model.","method":"Isoproterenol-induced HCM cell and animal models; immunohistochemistry; bioinformatics integration; drug treatment experiments","journal":"Frontiers in molecular biosciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, primarily expression-based validation in cell/animal models, limited mechanistic resolution for ATRNL1 specifically","pmids":["39329089"],"is_preprint":false}],"current_model":"ATRNL1 is a type I transmembrane protein that acts as an adapter recruiting the E3 ubiquitin ligase MGRN1 (via its RING domain) to promote ubiquitylation and surface degradation of melanocortin receptors MC1R and MC4R; it is functionally redundant with its paralog ATRN and can compensate for ATRN loss when overexpressed; in cardiomyocytes it localizes to intercalated disks and modulates the cardiac action potential and stress response; and its transcription is directly activated by CEBPB binding its promoter, with ATRNL1 itself suppressing EMT in cervical cancer cells."},"narrative":{"mechanistic_narrative":"ATRNL1 is a transmembrane adapter that controls melanocortin receptor abundance and participates in pigmentation and cardiac physiology [PMID:18064672, PMID:41178558, PMID:40196599]. It recruits the RING-domain E3 ubiquitin ligase MGRN1 to promote ubiquitylation and surface/ciliary degradation of the melanocortin receptors MC1R and MC4R, such that loss of the ATRNL1/MGRN1 axis increases receptor levels and enhances eumelanin production in melanocytes [PMID:41178558, PMID:40196599]. ATRNL1 is functionally redundant with its paralog ATRN from a gain-of-function standpoint: transgenic overexpression rescues agouti pigmentation and delays spongiform neurodegeneration in Atrn-null mice, although Atrnl1 knockout alone produces no overt pigmentation, CNS, or body-weight phenotype, placing the two genes in a shared pathway [PMID:18064672, PMID:18821597]. Beyond pigmentation, ATRNL1 localizes to cardiomyocyte intercalated disks and modulates the cardiac action potential and stress response, and is overexpressed in atrial fibrillation [PMID:39562555]. Its transcription is directly activated by CEBPB binding its promoter, and in cervical cancer cells ATRNL1 suppresses cell viability, migration, and epithelial-mesenchymal transition [PMID:38158696].","teleology":[{"year":2007,"claim":"Established whether ATRNL1 and its paralog ATRN are functionally interchangeable, resolving that ATRNL1 can substitute for ATRN when overexpressed but is dispensable on its own.","evidence":"Atrnl1 knockout and beta-actin-driven Atrnl1 transgene in Atrn-null mice, scored for pigmentation, CNS pathology, and body weight","pmids":["18064672"],"confidence":"High","gaps":["Did not define the molecular basis of redundancy or the endogenous role masked by paralog compensation","No biochemical mechanism linking ATRNL1 to pigmentation identified at this stage"]},{"year":2008,"claim":"Positioned ATRNL1/ATRN within the pigmentation genetic hierarchy and distinguished this pathway from the dal locus, refining pathway placement relative to Mc1r and agouti.","evidence":"Genetic epistasis crosses among dal, Atrn, Mc1r, and agouti mutants plus Atrnl1 transgenic rescue","pmids":["18821597"],"confidence":"Medium","gaps":["Identity of the dal gene unknown, leaving the molecular relationship unresolved","No biochemical readout connecting ATRNL1 to melanocortin signaling"]},{"year":2023,"claim":"Identified an upstream transcriptional regulator of ATRNL1 and a tumor-suppressive function, showing CEBPB drives ATRNL1 expression to restrain cervical cancer cell behavior.","evidence":"ChIP and luciferase reporter for CEBPB promoter binding plus gain-of-function and rescue assays in cervical cancer cells","pmids":["38158696"],"confidence":"Medium","gaps":["Mechanism by which ATRNL1 suppresses EMT and migration not defined","Single lab; not linked to the melanocortin/MGRN1 axis"]},{"year":2024,"claim":"Extended ATRNL1 function beyond pigmentation to the heart, localizing it to intercalated disks and tying it to action potential modulation and the cardiac stress response.","evidence":"snRNA-seq of >175,000 human left atrial nuclei plus subcellular localization and knockdown/overexpression functional assays in cardiomyocytes","pmids":["39562555"],"confidence":"Medium","gaps":["Molecular partners mediating cardiac effects not identified","Whether the MGRN1/melanocortin adapter activity underlies cardiac function untested"]},{"year":2025,"claim":"Defined the biochemical mechanism: ATRNL1 acts as a transmembrane adapter recruiting the E3 ligase MGRN1 to ubiquitylate and degrade melanocortin receptors, unifying earlier pigmentation genetics with a molecular pathway.","evidence":"Reciprocal Co-IP mapping interaction to the MGRN1 RING domain, ubiquitylation and receptor degradation assays, surface/ciliary localization assays, and melanocyte eumelanin assays","pmids":["41178558","40196599"],"confidence":"High","gaps":["Structural basis of ATRNL1-MGRN1 and ATRNL1-receptor recognition not determined","Whether this adapter activity operates in cardiomyocytes or cancer cells untested"]},{"year":null,"claim":"How a single transmembrane adapter integrates melanocortin receptor turnover, cardiac electrophysiology, and EMT suppression across tissues remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No mechanism connecting the MGRN1/receptor adapter role to cardiac or cancer phenotypes","Endogenous loss-of-function phenotype in human tissues uncharacterized","No structural model of the ATRNL1-MGRN1 complex"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2]}],"complexes":[],"partners":["MGRN1","ATRN","MC1R","MC4R","CEBPB"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5VV63","full_name":"Attractin-like protein 1","aliases":[],"length_aa":1379,"mass_kda":152.6,"function":"May play a role in melanocortin signaling pathways that regulate energy homeostasis","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/Q5VV63/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ATRNL1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ATRNL1","total_profiled":1310},"omim":[{"mim_id":"612869","title":"ATTRACTIN-LIKE 1; ATRNL1","url":"https://www.omim.org/entry/612869"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Mitochondria","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":17.2}],"url":"https://www.proteinatlas.org/search/ATRNL1"},"hgnc":{"alias_symbol":["KIAA0534","FLJ45344","ALP"],"prev_symbol":[]},"alphafold":{"accession":"Q5VV63","domains":[{"cath_id":"2.60.120.290","chopping":"92-211","consensus_level":"high","plddt":87.3689,"start":92,"end":211},{"cath_id":"2.10.25.10","chopping":"249-285","consensus_level":"medium","plddt":90.0992,"start":249,"end":285},{"cath_id":"3.30.1680,3.30.1680","chopping":"663-709","consensus_level":"medium","plddt":87.2768,"start":663,"end":709},{"cath_id":"3.10.100.10","chopping":"746-876","consensus_level":"medium","plddt":85.155,"start":746,"end":876},{"cath_id":"3.30.1680,3.30.1680","chopping":"890-940","consensus_level":"medium","plddt":86.6088,"start":890,"end":940},{"cath_id":"2.60.120","chopping":"1084-1233","consensus_level":"high","plddt":80.5851,"start":1084,"end":1233},{"cath_id":"3.30.1680","chopping":"712-744","consensus_level":"medium","plddt":78.903,"start":712,"end":744}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5VV63","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5VV63-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5VV63-F1-predicted_aligned_error_v6.png","plddt_mean":80.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ATRNL1","jax_strain_url":"https://www.jax.org/strain/search?query=ATRNL1"},"sequence":{"accession":"Q5VV63","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5VV63.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5VV63/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5VV63"}},"corpus_meta":[{"pmid":"30018746","id":"PMC_30018746","title":"Circular RNA CpG island hypermethylation-associated silencing in human cancer.","date":"2018","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/30018746","citation_count":39,"is_preprint":false},{"pmid":"33633287","id":"PMC_33633287","title":"Exploring the genetic architecture of feed efficiency traits in chickens.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/33633287","citation_count":33,"is_preprint":false},{"pmid":"18064672","id":"PMC_18064672","title":"Genetic analysis of attractin homologs.","date":"2007","source":"Genesis (New York, N.Y. : 2000)","url":"https://pubmed.ncbi.nlm.nih.gov/18064672","citation_count":17,"is_preprint":false},{"pmid":"33734580","id":"PMC_33734580","title":"Regulating effect of Circ_ATRNL1 on the promotion of SOX9 expression to promote chondrogenic differentiation of hAMSCs mediated by MiR-145-5p.","date":"2021","source":"Journal of tissue engineering and regenerative medicine","url":"https://pubmed.ncbi.nlm.nih.gov/33734580","citation_count":16,"is_preprint":false},{"pmid":"20670697","id":"PMC_20670697","title":"De novo 325 kb microdeletion in chromosome band 10q25.3 including ATRNL1 in a boy with cognitive impairment, autism and dysmorphic features.","date":"2010","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/20670697","citation_count":15,"is_preprint":false},{"pmid":"18821597","id":"PMC_18821597","title":"Genetic and phenotypic studies of the dark-like mutant mouse.","date":"2008","source":"Genesis (New York, N.Y. : 2000)","url":"https://pubmed.ncbi.nlm.nih.gov/18821597","citation_count":13,"is_preprint":false},{"pmid":"38533040","id":"PMC_38533040","title":"Comprehensive single-cell analysis reveals heterogeneity of fibroblast subpopulations in ovarian cancer tissue microenvironment.","date":"2024","source":"Heliyon","url":"https://pubmed.ncbi.nlm.nih.gov/38533040","citation_count":12,"is_preprint":false},{"pmid":"39562555","id":"PMC_39562555","title":"Large-scale single-nuclei profiling identifies role for ATRNL1 in atrial fibrillation.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/39562555","citation_count":11,"is_preprint":false},{"pmid":"36553445","id":"PMC_36553445","title":"Genomic Analysis of Gastrointestinal Parasite Resistance in Akkaraman Sheep.","date":"2022","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/36553445","citation_count":11,"is_preprint":false},{"pmid":"25601488","id":"PMC_25601488","title":"Identification of atypical ATRNL1 insertion to EML4-ALK fusion gene in NSCLC.","date":"2015","source":"Lung cancer (Amsterdam, Netherlands)","url":"https://pubmed.ncbi.nlm.nih.gov/25601488","citation_count":7,"is_preprint":false},{"pmid":"32857815","id":"PMC_32857815","title":"Whole genome sequencing analysis of high confidence variants of B-cell lymphoma in Canis familiaris.","date":"2020","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/32857815","citation_count":7,"is_preprint":false},{"pmid":"35504053","id":"PMC_35504053","title":"CircATRNL1 increases acid-sensing ion channel 1 to advance epithelial-mesenchymal transition in endometriosis by binding to microRNA-103a-3p.","date":"2022","source":"Reproductive biology","url":"https://pubmed.ncbi.nlm.nih.gov/35504053","citation_count":6,"is_preprint":false},{"pmid":"41178558","id":"PMC_41178558","title":"The E3 ubiquitin ligase MGRN1 targets melanocortin receptors MC1R and MC4R via interactions with transmembrane adapters.","date":"2025","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/41178558","citation_count":5,"is_preprint":false},{"pmid":"38158696","id":"PMC_38158696","title":"Transcriptional factor CCAAT enhancer binding protein beta inhibits epithelial-mesenchymal transition in cervical cancer via regulating attractin-like 1.","date":"2023","source":"Cellular and molecular biology (Noisy-le-Grand, France)","url":"https://pubmed.ncbi.nlm.nih.gov/38158696","citation_count":4,"is_preprint":false},{"pmid":"40196599","id":"PMC_40196599","title":"The E3 ubiquitin ligase MGRN1 targets melanocortin receptors MC1R and MC4R via interactions with transmembrane adapters.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/40196599","citation_count":3,"is_preprint":false},{"pmid":"35502705","id":"PMC_35502705","title":"Modulation of autoimmune diabetes by N-ethyl-N-nitrosourea- induced mutations in non-obese diabetic mice.","date":"2022","source":"Disease models & mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/35502705","citation_count":3,"is_preprint":false},{"pmid":"40184718","id":"PMC_40184718","title":"The fusion characteristics of RET fusion in pan-cancer among the Chinese population: A comprehensive genomic analysis.","date":"2025","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40184718","citation_count":3,"is_preprint":false},{"pmid":"40678382","id":"PMC_40678382","title":"Genome-wide association and functional annotation analyses reveal candidate genes and pathways associated with various ewe longevity indicators in U.S. Katahdin sheep.","date":"2025","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/40678382","citation_count":2,"is_preprint":false},{"pmid":"39329089","id":"PMC_39329089","title":"Identification of ATRNL1 and WNT9A as novel key genes and drug candidates in hypertrophic cardiomyopathy: integrative bioinformatics and experimental validation.","date":"2024","source":"Frontiers in molecular biosciences","url":"https://pubmed.ncbi.nlm.nih.gov/39329089","citation_count":1,"is_preprint":false},{"pmid":"40023986","id":"PMC_40023986","title":"Embryonic temperature influences transcriptomic and methylation profiles in the liver of juvenile largemouth bass.","date":"2025","source":"Journal of thermal biology","url":"https://pubmed.ncbi.nlm.nih.gov/40023986","citation_count":1,"is_preprint":false},{"pmid":"42061003","id":"PMC_42061003","title":"A predictive insight into the ATRNL1-mediated ceRNA network driving abdominal aortic aneurysm progression via VSMC phenotypic switching.","date":"2026","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/42061003","citation_count":0,"is_preprint":false},{"pmid":"38590442","id":"PMC_38590442","title":"Initial Insights into the Genetic Variation Associated with Metformin Treatment Failure in Youth with Type 2 Diabetes.","date":"2023","source":"Pediatric diabetes","url":"https://pubmed.ncbi.nlm.nih.gov/38590442","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13906,"output_tokens":1835,"usd":0.034621,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8671,"output_tokens":2304,"usd":0.050478,"stage2_stop_reason":"end_turn"},"total_usd":0.085099,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"ATRNL1 and ATRN are redundant from a gain-of-function but not loss-of-function perspective: transgenic overexpression of ATRNL1 in Atrn null mice rescued normal agouti-banded fur pigmentation and significantly delayed onset of spongiform neurodegeneration, demonstrating that ATRNL1 can compensate for ATRN loss. However, Atrnl1 knockout mice alone showed no pigmentation, CNS, or body weight phenotype.\",\n      \"method\": \"Loss-of-function and gain-of-function mouse genetics (Atrnl1 knockout mice, beta-actin promoter-driven Atrnl1 transgene in Atrn null background); phenotypic analysis of fur color, CNS pathology, body weight\",\n      \"journal\": \"Genesis (New York, N.Y. : 2000)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic epistasis with both loss- and gain-of-function alleles in mouse, multiple phenotypic readouts, single lab but rigorous complementary experiments\",\n      \"pmids\": [\"18064672\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Transgenic overexpression of ATRNL1 did not rescue dark-like (dal) mutant phenotypes (dark fur, testicular vacuolation, spongiform neurodegeneration), and dal and Atrn showed additive effects on these phenotypes. Genetic crosses placed dal upstream of Mc1r and downstream of agouti. This places ATRNL1 and ATRN in the same pathway, but ATRNL1 overexpression cannot compensate for the dal locus, distinguishing dal from the ATRN pathway.\",\n      \"method\": \"Genetic epistasis by crosses between dal, Atrn, Mc1r, and agouti mutant mice; Atrnl1 transgenic rescue experiment\",\n      \"journal\": \"Genesis (New York, N.Y. : 2000)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with multiple mutant alleles, single lab, functional phenotypic readouts but dal gene identity unknown\",\n      \"pmids\": [\"18821597\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ATRNL1 acts as a transmembrane adapter that recruits the E3 ubiquitin ligase MGRN1 (via its RING domain) to promote ubiquitylation and degradation of the melanocortin receptors MC1R and MC4R at the cell surface. Loss of MGRN1 or ATRN leads to increased surface and ciliary localization of MC4R in fibroblasts and elevated MC1R levels in melanocytes, resulting in enhanced eumelanin production.\",\n      \"method\": \"Co-immunoprecipitation (showing ATRNL1/ATRN interaction with MGRN1 RING domain); functional ubiquitylation and receptor degradation assays; cell surface/ciliary localization assays; melanocyte eumelanin production assay; loss-of-function experiments\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, functional ubiquitylation assays, subcellular localization with functional consequence, multiple receptor substrates tested, peer-reviewed and preprint corroborate\",\n      \"pmids\": [\"41178558\", \"40196599\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ATRNL1 is overexpressed in cardiomyocytes of patients with atrial fibrillation and localizes to intercalated disks. Both knockdown and overexpression of ATRNL1 in cardiomyocytes identified a role in the cell stress response and modulation of the cardiac action potential.\",\n      \"method\": \"Single-nucleus RNA-seq (snRNA-seq) on >175,000 nuclei from human left atrial samples; subcellular localization experiments; knockdown and overexpression functional experiments with action potential and stress response readouts\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with functional consequence (action potential modulation), KD and OE experiments, single lab, human tissue study\",\n      \"pmids\": [\"39562555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CEBPB (CCAAT enhancer binding protein beta) transcriptionally upregulates ATRNL1 by binding to its promoter in cervical cancer cells. ATRNL1 upregulation suppresses cervical cancer cell viability, migration, and epithelial-mesenchymal transition (EMT), and the effects of CEBPB elevation on these processes are reversed by ATRNL1 depletion.\",\n      \"method\": \"ChIP assay (CEBPB binding to ATRNL1 promoter); luciferase reporter assay; gain-of-function and rescue experiments; RT-qPCR and western blotting\",\n      \"journal\": \"Cellular and molecular biology (Noisy-le-Grand, France)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and luciferase reporter for transcriptional regulation, functional rescue assays, single lab with two orthogonal methods\",\n      \"pmids\": [\"38158696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ATRNL1 and WNT9A are upregulated in both HCM cell models (isoproterenol-treated) and animal models, validating them as differentially expressed genes in hypertrophic cardiomyopathy. Propylthiouracil treatment significantly inhibited ATRNL1 expression in the HCM model.\",\n      \"method\": \"Isoproterenol-induced HCM cell and animal models; immunohistochemistry; bioinformatics integration; drug treatment experiments\",\n      \"journal\": \"Frontiers in molecular biosciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, primarily expression-based validation in cell/animal models, limited mechanistic resolution for ATRNL1 specifically\",\n      \"pmids\": [\"39329089\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ATRNL1 is a type I transmembrane protein that acts as an adapter recruiting the E3 ubiquitin ligase MGRN1 (via its RING domain) to promote ubiquitylation and surface degradation of melanocortin receptors MC1R and MC4R; it is functionally redundant with its paralog ATRN and can compensate for ATRN loss when overexpressed; in cardiomyocytes it localizes to intercalated disks and modulates the cardiac action potential and stress response; and its transcription is directly activated by CEBPB binding its promoter, with ATRNL1 itself suppressing EMT in cervical cancer cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ATRNL1 is a transmembrane adapter that controls melanocortin receptor abundance and participates in pigmentation and cardiac physiology [#0, #2]. It recruits the RING-domain E3 ubiquitin ligase MGRN1 to promote ubiquitylation and surface/ciliary degradation of the melanocortin receptors MC1R and MC4R, such that loss of the ATRNL1/MGRN1 axis increases receptor levels and enhances eumelanin production in melanocytes [#2]. ATRNL1 is functionally redundant with its paralog ATRN from a gain-of-function standpoint: transgenic overexpression rescues agouti pigmentation and delays spongiform neurodegeneration in Atrn-null mice, although Atrnl1 knockout alone produces no overt pigmentation, CNS, or body-weight phenotype, placing the two genes in a shared pathway [#0, #1]. Beyond pigmentation, ATRNL1 localizes to cardiomyocyte intercalated disks and modulates the cardiac action potential and stress response, and is overexpressed in atrial fibrillation [#3]. Its transcription is directly activated by CEBPB binding its promoter, and in cervical cancer cells ATRNL1 suppresses cell viability, migration, and epithelial-mesenchymal transition [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established whether ATRNL1 and its paralog ATRN are functionally interchangeable, resolving that ATRNL1 can substitute for ATRN when overexpressed but is dispensable on its own.\",\n      \"evidence\": \"Atrnl1 knockout and beta-actin-driven Atrnl1 transgene in Atrn-null mice, scored for pigmentation, CNS pathology, and body weight\",\n      \"pmids\": [\"18064672\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not define the molecular basis of redundancy or the endogenous role masked by paralog compensation\",\n        \"No biochemical mechanism linking ATRNL1 to pigmentation identified at this stage\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Positioned ATRNL1/ATRN within the pigmentation genetic hierarchy and distinguished this pathway from the dal locus, refining pathway placement relative to Mc1r and agouti.\",\n      \"evidence\": \"Genetic epistasis crosses among dal, Atrn, Mc1r, and agouti mutants plus Atrnl1 transgenic rescue\",\n      \"pmids\": [\"18821597\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Identity of the dal gene unknown, leaving the molecular relationship unresolved\",\n        \"No biochemical readout connecting ATRNL1 to melanocortin signaling\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified an upstream transcriptional regulator of ATRNL1 and a tumor-suppressive function, showing CEBPB drives ATRNL1 expression to restrain cervical cancer cell behavior.\",\n      \"evidence\": \"ChIP and luciferase reporter for CEBPB promoter binding plus gain-of-function and rescue assays in cervical cancer cells\",\n      \"pmids\": [\"38158696\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which ATRNL1 suppresses EMT and migration not defined\",\n        \"Single lab; not linked to the melanocortin/MGRN1 axis\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended ATRNL1 function beyond pigmentation to the heart, localizing it to intercalated disks and tying it to action potential modulation and the cardiac stress response.\",\n      \"evidence\": \"snRNA-seq of >175,000 human left atrial nuclei plus subcellular localization and knockdown/overexpression functional assays in cardiomyocytes\",\n      \"pmids\": [\"39562555\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular partners mediating cardiac effects not identified\",\n        \"Whether the MGRN1/melanocortin adapter activity underlies cardiac function untested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined the biochemical mechanism: ATRNL1 acts as a transmembrane adapter recruiting the E3 ligase MGRN1 to ubiquitylate and degrade melanocortin receptors, unifying earlier pigmentation genetics with a molecular pathway.\",\n      \"evidence\": \"Reciprocal Co-IP mapping interaction to the MGRN1 RING domain, ubiquitylation and receptor degradation assays, surface/ciliary localization assays, and melanocyte eumelanin assays\",\n      \"pmids\": [\"41178558\", \"40196599\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of ATRNL1-MGRN1 and ATRNL1-receptor recognition not determined\",\n        \"Whether this adapter activity operates in cardiomyocytes or cancer cells untested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single transmembrane adapter integrates melanocortin receptor turnover, cardiac electrophysiology, and EMT suppression across tissues remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No mechanism connecting the MGRN1/receptor adapter role to cardiac or cancer phenotypes\",\n        \"Endogenous loss-of-function phenotype in human tissues uncharacterized\",\n        \"No structural model of the ATRNL1-MGRN1 complex\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"MGRN1\", \"ATRN\", \"MC1R\", \"MC4R\", \"CEBPB\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}