{"gene":"TRPM6","run_date":"2026-06-14T21:22:56+00:00","timeline":{"discoveries":[{"year":2007,"finding":"EGF acts as a magnesiotropic hormone that stimulates TRPM6-mediated Mg2+ reabsorption in the renal distal convoluted tubule (DCT): basolateral EGF binds EGFR on the basolateral membrane of DCT cells, activating the apical Mg2+ channel TRPM6. A missense mutation in pro-EGF that impairs basolateral sorting of pro-EGF prevents adequate EGFR stimulation, resulting in insufficient TRPM6 activation and renal Mg2+ wasting.","method":"Positional cloning of disease mutation in human kindred; functional studies showing impaired basolateral pro-EGF trafficking and consequent failure to activate TRPM6; clinical correlation with cetuximab-induced hypomagnesemia","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic disease mechanism established by positional cloning plus functional trafficking assays, independently corroborated by cetuximab clinical data and consistent with multiple subsequent papers","pmids":["17671655","17671646","18299299"],"is_preprint":false},{"year":2009,"finding":"TRPM6 mediates apical Mg2+ entry in the DCT and its activity depends on a favorable luminal membrane potential generated by the Kv1.1 potassium channel (KCNA1). Kv1.1 co-localizes with TRPM6 along the luminal membrane of DCT cells; a dominant-negative N255D mutation in Kv1.1 that abolishes K+ channel function causes autosomal dominant hypomagnesemia, establishing that Kv1.1-generated membrane potential is required for TRPM6-mediated Mg2+ reabsorption.","method":"Positional cloning; immunofluorescence co-localization of Kv1.1 and TRPM6 in DCT; patch clamp analysis of wild-type and N255D mutant Kv1.1 in human kidney cell line demonstrating dominant-negative loss of K+ current","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal genetic disease mapping plus electrophysiological functional assay and co-localization, multiple orthogonal methods in one rigorous study","pmids":["19307729"],"is_preprint":false},{"year":2020,"finding":"The transcription factor Prox-1 in DCT cells is required for maintaining TRPM6 expression: DCT-specific deletion of Prox-1 in adult mice causes significant downregulation of TRPM6 (and NCC) at both mRNA and protein levels, leading to hypomagnesemia, without affecting DCT structure or growth.","method":"Conditional knockout mouse model (NCCcre:Prox-1flox/flox); plasma ion measurements; immunofluorescence and RT-PCR/western blot for TRPM6 and NCC protein and mRNA","journal":"Pflugers Archiv : European journal of physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean conditional KO with defined phenotype and mRNA/protein quantification, single lab, two orthogonal methods (RT-PCR + western blot)","pmids":["33200256"],"is_preprint":false},{"year":2020,"finding":"Loss of the NaCl co-transporter (NCC) leads to DCT atrophy, which is associated with a marked reduction in TRPM6 protein abundance in the DCT; hypomagnesemia appears as a late consequence of this DCT regression.","method":"NCC knockout mice studied at multiple postnatal time points; immunofluorescence for parvalbumin (DCT marker) and TRPM6; plasma ion measurements","journal":"Nephrology, dialysis, transplantation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO mouse model with longitudinal morphological and biochemical phenotyping, single lab","pmids":["31436795"],"is_preprint":false},{"year":2015,"finding":"TRPM6 (as part of TRPM6/TRPM7 channel complexes) controls intracellular Mg2+ levels and thereby regulates mesoderm and definitive endoderm differentiation of human embryonic stem cells; a small molecule inhibitor (Mesendogen/MEG) identified by kinome screen targets TRPM6, reduces intracellular Mg2+, and enhances these differentiation fates.","method":"Kinome screen; loss-of-function experiments; intracellular Mg2+ measurements; pharmacological inhibition and Mg2+-withdrawal phenocopy experiments in hESCs","journal":"Heliyon","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — kinome screen followed by functional loss-of-function and pharmacological rescue experiments with intracellular Mg2+ readout, single lab","pmids":["26705539"],"is_preprint":false},{"year":2019,"finding":"miR-202-3p directly targets the TRPM6 3'UTR (validated by dual-luciferase reporter assay) and negatively regulates TRPM6 expression; miR-202-3p overexpression or TRPM6 knockdown activates the TGF-β1/Smads signaling pathway in a rat myocardial ischemia-reperfusion model.","method":"Dual-luciferase reporter gene assay; in vivo rat I/R model with miRNA mimics, inhibitors, and siRNAs; measurement of inflammatory factors, fibrosis, and apoptosis","journal":"Cell cycle (Georgetown, Tex.)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — luciferase reporter for direct targeting confirmed, but downstream pathway placement relies on in vivo overexpression/knockdown with indirect readouts, single lab","pmids":["30810438"],"is_preprint":false}],"current_model":"TRPM6 is an apical Mg2+ channel expressed in renal DCT cells (and intestinal epithelium) where it mediates active transcellular Mg2+ reabsorption; its activity is controlled by: (1) basolateral EGF/EGFR signaling that activates the channel, (2) the luminal membrane potential set by the co-localized Kv1.1 K+ channel, (3) transcriptional regulation by the DCT-enriched factor Prox-1, and (4) DCT structural integrity dependent on NCC; additionally, TRPM6/TRPM7-mediated intracellular Mg2+ levels regulate early embryonic cell fate decisions in human ESCs."},"narrative":{"mechanistic_narrative":"TRPM6 is an apical Mg2+ channel that mediates active transcellular magnesium reabsorption in the renal distal convoluted tubule (DCT), and its dysfunction causes renal Mg2+ wasting and hypomagnesemia [PMID:17671655, PMID:17671646, PMID:18299299]. Channel activity is set by both hormonal and electrical inputs: basolateral EGF binding to EGFR on DCT cells activates apical TRPM6, and a pro-EGF mutation that disrupts basolateral pro-EGF sorting fails to stimulate TRPM6, producing magnesium wasting [PMID:17671655, PMID:17671646, PMID:18299299], while the favorable luminal membrane potential required for Mg2+ entry is generated by the co-localized Kv1.1 (KCNA1) K+ channel, such that a dominant-negative Kv1.1 mutation abolishing K+ current causes autosomal dominant hypomagnesemia [PMID:19307729]. TRPM6 abundance in the DCT depends on the segment's transcriptional and structural integrity: the DCT-enriched transcription factor Prox-1 maintains TRPM6 mRNA and protein expression [PMID:33200256], and loss of the NaCl co-transporter NCC drives DCT atrophy with secondary reduction of TRPM6 [PMID:31436795]. Beyond the kidney, TRPM6 (in TRPM6/TRPM7 complexes) governs intracellular Mg2+ levels that regulate mesoderm and definitive endoderm differentiation of human embryonic stem cells [PMID:26705539].","teleology":[{"year":2007,"claim":"Established that TRPM6 channel activity is not autonomous but is controlled by hormonal input, explaining a heritable form of magnesium wasting and a clinical drug toxicity.","evidence":"Positional cloning of a pro-EGF mutation in a human kindred plus basolateral trafficking assays, corroborated by cetuximab-induced hypomagnesemia","pmids":["17671655","17671646","18299299"],"confidence":"High","gaps":["Molecular signaling steps linking EGFR activation to TRPM6 gating not resolved","Direct biochemical interaction between EGFR pathway components and TRPM6 not defined"]},{"year":2009,"claim":"Showed that TRPM6-mediated Mg2+ entry requires an electrical driving force, identifying Kv1.1 as the K+ channel that sets the luminal membrane potential.","evidence":"Positional cloning of a dominant-negative KCNA1 mutation, DCT co-localization immunofluorescence, and patch-clamp of wild-type versus N255D Kv1.1","pmids":["19307729"],"confidence":"High","gaps":["Whether Kv1.1 and TRPM6 physically interact versus only co-localize is not established","Quantitative contribution of membrane potential to TRPM6 conductance not measured directly"]},{"year":2015,"claim":"Extended TRPM6 function beyond epithelial transport, demonstrating that TRPM6/TRPM7-controlled intracellular Mg2+ influences early human cell-fate decisions.","evidence":"Kinome screen, loss-of-function and pharmacological inhibition (Mesendogen) with intracellular Mg2+ readout in human ESCs","pmids":["26705539"],"confidence":"Medium","gaps":["Relative contributions of TRPM6 versus TRPM7 to the Mg2+ phenotype not separated","Downstream effectors linking Mg2+ to differentiation programs unidentified","Inhibitor specificity for TRPM6 not fully defined"]},{"year":2019,"claim":"Identified a post-transcriptional regulator of TRPM6, placing the channel within a miRNA-controlled axis in cardiac injury.","evidence":"Dual-luciferase reporter validation of miR-202-3p targeting the TRPM6 3'UTR plus in vivo rat ischemia-reperfusion manipulation","pmids":["30810438"],"confidence":"Low","gaps":["Direct targeting confirmed by luciferase, but downstream TGF-β1/Smads link rests on indirect in vivo readouts in a single lab","TRPM6 expression and role in cardiac tissue not independently confirmed","Mechanism connecting TRPM6 loss to pathway activation undefined"]},{"year":2020,"claim":"Distinguished transcriptional from structural control of renal TRPM6 abundance, showing Prox-1 maintains its expression while NCC-dependent DCT integrity sustains its protein levels.","evidence":"DCT-specific Prox-1 conditional knockout and NCC knockout mice with mRNA/protein quantification and longitudinal morphological phenotyping","pmids":["33200256","31436795"],"confidence":"Medium","gaps":["Whether Prox-1 binds the TRPM6 promoter directly versus acting indirectly is not shown","TRPM6 reduction after NCC loss is secondary to DCT atrophy rather than a direct regulatory link","Single-lab findings for each regulator"]},{"year":null,"claim":"The molecular mechanism by which EGFR signaling and membrane potential converge to gate TRPM6, and the direct effectors linking TRPM6-controlled Mg2+ to cell-fate decisions, remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of TRPM6 gating in the timeline","No reconstituted EGFR-to-TRPM6 signaling pathway","Direct downstream targets of TRPM6-regulated Mg2+ unidentified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,1,4]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[0,1]}],"complexes":[],"partners":["TRPM7","KCNA1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9BX84","full_name":"Transient receptor potential cation channel subfamily M member 6","aliases":["Channel kinase 2","Melastatin-related TRP cation channel 6"],"length_aa":2022,"mass_kda":231.7,"function":"Bifunctional protein that combines an ion channel with an intrinsic kinase domain, enabling it to modulate cellular functions either by conducting ions through the pore or by phosphorylating downstream proteins via its kinase domain (PubMed:14576148, PubMed:16636202, PubMed:18258429, PubMed:18365021). Crucial for Mg(2+) homeostasis. Has an important role in epithelial Mg(2+) transport and in the active Mg(2+) absorption in the gut and kidney (PubMed:14576148). However, whether TRPM6 forms functional homomeric channels by itself or functions primarily as a subunit of heteromeric TRPM6-TRPM7 channels, is still under debate (PubMed:14576148, PubMed:16636202, PubMed:24385424) The C-terminal kinase domain can be cleaved from the channel segment in a cell-type-specific fashion. The cleaved kinase fragments can translocate to the nucleus, and bind chromatin-remodeling complex proteins to ultimately phosphorylate specific Ser/Thr residues of histones known to be functionally important for cell differentiation and development","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9BX84/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TRPM6","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/TRPM6","total_profiled":1310},"omim":[{"mim_id":"618314","title":"HYPOMAGNESEMIA, SEIZURES, AND IMPAIRED INTELLECTUAL DEVELOPMENT 2; HOMGSMR2","url":"https://www.omim.org/entry/618314"},{"mim_id":"610803","title":"SOLUTE CARRIER FAMILY 41, MEMBER 3; SLC41A3","url":"https://www.omim.org/entry/610803"},{"mim_id":"607009","title":"TRANSIENT RECEPTOR POTENTIAL CATION CHANNEL, SUBFAMILY M, MEMBER 6; TRPM6","url":"https://www.omim.org/entry/607009"},{"mim_id":"602014","title":"HYPOMAGNESEMIA 1, INTESTINAL; HOMG1","url":"https://www.omim.org/entry/602014"},{"mim_id":"176260","title":"POTASSIUM CHANNEL, VOLTAGE-GATED, SHAKER-RELATED SUBFAMILY, MEMBER 1; KCNA1","url":"https://www.omim.org/entry/176260"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"intestine","ntpm":15.6}],"url":"https://www.proteinatlas.org/search/TRPM6"},"hgnc":{"alias_symbol":["CHAK2","FLJ22628"],"prev_symbol":["HOMG","HSH"]},"alphafold":{"accession":"Q9BX84","domains":[{"cath_id":"3.40.50.450","chopping":"98-421","consensus_level":"medium","plddt":84.3456,"start":98,"end":421},{"cath_id":"-","chopping":"961-1117","consensus_level":"medium","plddt":83.1475,"start":961,"end":1117}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BX84","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BX84-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9BX84-F1-predicted_aligned_error_v6.png","plddt_mean":64.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TRPM6","jax_strain_url":"https://www.jax.org/strain/search?query=TRPM6"},"sequence":{"accession":"Q9BX84","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9BX84.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9BX84/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9BX84"}},"corpus_meta":[{"pmid":"17671655","id":"PMC_17671655","title":"Impaired basolateral sorting of pro-EGF causes isolated recessive renal hypomagnesemia.","date":"2007","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/17671655","citation_count":254,"is_preprint":false},{"pmid":"19307729","id":"PMC_19307729","title":"A missense mutation in the Kv1.1 voltage-gated potassium channel-encoding gene KCNA1 is linked to human autosomal dominant hypomagnesemia.","date":"2009","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/19307729","citation_count":111,"is_preprint":false},{"pmid":"24089412","id":"PMC_24089412","title":"Elucidation of the distal convoluted tubule transcriptome identifies new candidate genes involved in renal Mg(2+) handling.","date":"2013","source":"American journal of physiology. Renal physiology","url":"https://pubmed.ncbi.nlm.nih.gov/24089412","citation_count":44,"is_preprint":false},{"pmid":"22113391","id":"PMC_22113391","title":"Hypomagnesaemia and targeted anti-epidermal growth factor receptor (EGFR) agents.","date":"2011","source":"Targeted oncology","url":"https://pubmed.ncbi.nlm.nih.gov/22113391","citation_count":37,"is_preprint":false},{"pmid":"30810438","id":"PMC_30810438","title":"Overexpression of microRNA-202-3p protects against myocardial ischemia-reperfusion injury through activation of TGF-β1/Smads signaling pathway by targeting TRPM6.","date":"2019","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/30810438","citation_count":33,"is_preprint":false},{"pmid":"33450887","id":"PMC_33450887","title":"Mg2+ Transporters in Digestive Cancers.","date":"2021","source":"Nutrients","url":"https://pubmed.ncbi.nlm.nih.gov/33450887","citation_count":32,"is_preprint":false},{"pmid":"17671646","id":"PMC_17671646","title":"When EGF is offside, magnesium is wasted.","date":"2007","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/17671646","citation_count":27,"is_preprint":false},{"pmid":"31436795","id":"PMC_31436795","title":"Loss of sodium chloride co-transporter impairs the outgrowth of the renal distal convoluted tubule during renal development.","date":"2020","source":"Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association","url":"https://pubmed.ncbi.nlm.nih.gov/31436795","citation_count":17,"is_preprint":false},{"pmid":"33200256","id":"PMC_33200256","title":"Deletion of the transcription factor Prox-1 specifically in the renal distal convoluted tubule causes hypomagnesemia via reduced expression of TRPM6 and NCC.","date":"2020","source":"Pflugers Archiv : European journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/33200256","citation_count":12,"is_preprint":false},{"pmid":"26705539","id":"PMC_26705539","title":"Mesendogen, a novel inhibitor of TRPM6, promotes mesoderm and definitive endoderm differentiation of human embryonic stem cells through alteration of magnesium homeostasis.","date":"2015","source":"Heliyon","url":"https://pubmed.ncbi.nlm.nih.gov/26705539","citation_count":9,"is_preprint":false},{"pmid":"36387403","id":"PMC_36387403","title":"Integration analysis of metabolome and transcriptome reveals the effect of exogenous supplementation with mixtures of vitamins ADE, zinc, and selenium on follicular growth and granulosa cells molecular metabolism in donkeys (Equus asinus).","date":"2022","source":"Frontiers in veterinary science","url":"https://pubmed.ncbi.nlm.nih.gov/36387403","citation_count":6,"is_preprint":false},{"pmid":"18299299","id":"PMC_18299299","title":"Renal magnification by EGF.","date":"2008","source":"Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association","url":"https://pubmed.ncbi.nlm.nih.gov/18299299","citation_count":5,"is_preprint":false},{"pmid":"40613016","id":"PMC_40613016","title":"Hypomagnesemia With Metformin Use in Diabetes Mellitus: A Case and Narrative Review.","date":"2025","source":"Kidney medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40613016","citation_count":2,"is_preprint":false},{"pmid":"40485519","id":"PMC_40485519","title":"Mechanism of AGT-Mediated Magnesium Ion Uptake in Age-Related Olfactory Dysfunction.","date":"2025","source":"Discovery medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40485519","citation_count":1,"is_preprint":false},{"pmid":"38567178","id":"PMC_38567178","title":"Hypomagnesemia with Secondary Hypoparathyroidism and Hypocalcemia due to Novel Variants in the Transient Receptor Potential Cation Channel Subfamily M Member 6 ( TRPM6 ) Gene.","date":"2021","source":"Journal of pediatric genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38567178","citation_count":0,"is_preprint":false},{"pmid":"41594589","id":"PMC_41594589","title":"Naringin Mitigates PEDV-Induced Intestinal Damage in Suckling Piglets by Modulating Inflammatory, Antiviral, and Metabolic and Transport Pathways.","date":"2025","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/41594589","citation_count":0,"is_preprint":false},{"pmid":"41751411","id":"PMC_41751411","title":"Potential Factors of Diabetes in Gitelman Syndrome and the Choices of the Appropriate Hypoglycemic Drugs: A Literature Narrative Review.","date":"2026","source":"Current issues in molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/41751411","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"sonnet_model":"claude-sonnet-4-6","sonnet_input_tokens":11731,"sonnet_output_tokens":1825,"sonnet_usd":0.0626,"sonnet_elapsed_seconds":35.3,"stage1_stop_reason":"end_turn"},"stage2":{"opus_model":"claude-opus-4-8","opus_input_tokens":8688,"opus_output_tokens":2326,"opus_usd":0.1016,"opus_elapsed_seconds":26.2,"stage2_stop_reason":"end_turn"},"total_usd":0.1642},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"EGF acts as a magnesiotropic hormone that stimulates TRPM6-mediated Mg2+ reabsorption in the renal distal convoluted tubule (DCT): basolateral EGF binds EGFR on the basolateral membrane of DCT cells, activating the apical Mg2+ channel TRPM6. A missense mutation in pro-EGF that impairs basolateral sorting of pro-EGF prevents adequate EGFR stimulation, resulting in insufficient TRPM6 activation and renal Mg2+ wasting.\",\n      \"method\": \"Positional cloning of disease mutation in human kindred; functional studies showing impaired basolateral pro-EGF trafficking and consequent failure to activate TRPM6; clinical correlation with cetuximab-induced hypomagnesemia\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic disease mechanism established by positional cloning plus functional trafficking assays, independently corroborated by cetuximab clinical data and consistent with multiple subsequent papers\",\n      \"pmids\": [\"17671655\", \"17671646\", \"18299299\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"TRPM6 mediates apical Mg2+ entry in the DCT and its activity depends on a favorable luminal membrane potential generated by the Kv1.1 potassium channel (KCNA1). Kv1.1 co-localizes with TRPM6 along the luminal membrane of DCT cells; a dominant-negative N255D mutation in Kv1.1 that abolishes K+ channel function causes autosomal dominant hypomagnesemia, establishing that Kv1.1-generated membrane potential is required for TRPM6-mediated Mg2+ reabsorption.\",\n      \"method\": \"Positional cloning; immunofluorescence co-localization of Kv1.1 and TRPM6 in DCT; patch clamp analysis of wild-type and N255D mutant Kv1.1 in human kidney cell line demonstrating dominant-negative loss of K+ current\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal genetic disease mapping plus electrophysiological functional assay and co-localization, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"19307729\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The transcription factor Prox-1 in DCT cells is required for maintaining TRPM6 expression: DCT-specific deletion of Prox-1 in adult mice causes significant downregulation of TRPM6 (and NCC) at both mRNA and protein levels, leading to hypomagnesemia, without affecting DCT structure or growth.\",\n      \"method\": \"Conditional knockout mouse model (NCCcre:Prox-1flox/flox); plasma ion measurements; immunofluorescence and RT-PCR/western blot for TRPM6 and NCC protein and mRNA\",\n      \"journal\": \"Pflugers Archiv : European journal of physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean conditional KO with defined phenotype and mRNA/protein quantification, single lab, two orthogonal methods (RT-PCR + western blot)\",\n      \"pmids\": [\"33200256\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Loss of the NaCl co-transporter (NCC) leads to DCT atrophy, which is associated with a marked reduction in TRPM6 protein abundance in the DCT; hypomagnesemia appears as a late consequence of this DCT regression.\",\n      \"method\": \"NCC knockout mice studied at multiple postnatal time points; immunofluorescence for parvalbumin (DCT marker) and TRPM6; plasma ion measurements\",\n      \"journal\": \"Nephrology, dialysis, transplantation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO mouse model with longitudinal morphological and biochemical phenotyping, single lab\",\n      \"pmids\": [\"31436795\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TRPM6 (as part of TRPM6/TRPM7 channel complexes) controls intracellular Mg2+ levels and thereby regulates mesoderm and definitive endoderm differentiation of human embryonic stem cells; a small molecule inhibitor (Mesendogen/MEG) identified by kinome screen targets TRPM6, reduces intracellular Mg2+, and enhances these differentiation fates.\",\n      \"method\": \"Kinome screen; loss-of-function experiments; intracellular Mg2+ measurements; pharmacological inhibition and Mg2+-withdrawal phenocopy experiments in hESCs\",\n      \"journal\": \"Heliyon\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — kinome screen followed by functional loss-of-function and pharmacological rescue experiments with intracellular Mg2+ readout, single lab\",\n      \"pmids\": [\"26705539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"miR-202-3p directly targets the TRPM6 3'UTR (validated by dual-luciferase reporter assay) and negatively regulates TRPM6 expression; miR-202-3p overexpression or TRPM6 knockdown activates the TGF-β1/Smads signaling pathway in a rat myocardial ischemia-reperfusion model.\",\n      \"method\": \"Dual-luciferase reporter gene assay; in vivo rat I/R model with miRNA mimics, inhibitors, and siRNAs; measurement of inflammatory factors, fibrosis, and apoptosis\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — luciferase reporter for direct targeting confirmed, but downstream pathway placement relies on in vivo overexpression/knockdown with indirect readouts, single lab\",\n      \"pmids\": [\"30810438\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TRPM6 is an apical Mg2+ channel expressed in renal DCT cells (and intestinal epithelium) where it mediates active transcellular Mg2+ reabsorption; its activity is controlled by: (1) basolateral EGF/EGFR signaling that activates the channel, (2) the luminal membrane potential set by the co-localized Kv1.1 K+ channel, (3) transcriptional regulation by the DCT-enriched factor Prox-1, and (4) DCT structural integrity dependent on NCC; additionally, TRPM6/TRPM7-mediated intracellular Mg2+ levels regulate early embryonic cell fate decisions in human ESCs.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TRPM6 is an apical Mg2+ channel that mediates active transcellular magnesium reabsorption in the renal distal convoluted tubule (DCT), and its dysfunction causes renal Mg2+ wasting and hypomagnesemia [#0]. Channel activity is set by both hormonal and electrical inputs: basolateral EGF binding to EGFR on DCT cells activates apical TRPM6, and a pro-EGF mutation that disrupts basolateral pro-EGF sorting fails to stimulate TRPM6, producing magnesium wasting [#0], while the favorable luminal membrane potential required for Mg2+ entry is generated by the co-localized Kv1.1 (KCNA1) K+ channel, such that a dominant-negative Kv1.1 mutation abolishing K+ current causes autosomal dominant hypomagnesemia [#1]. TRPM6 abundance in the DCT depends on the segment's transcriptional and structural integrity: the DCT-enriched transcription factor Prox-1 maintains TRPM6 mRNA and protein expression [#2], and loss of the NaCl co-transporter NCC drives DCT atrophy with secondary reduction of TRPM6 [#3]. Beyond the kidney, TRPM6 (in TRPM6/TRPM7 complexes) governs intracellular Mg2+ levels that regulate mesoderm and definitive endoderm differentiation of human embryonic stem cells [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Established that TRPM6 channel activity is not autonomous but is controlled by hormonal input, explaining a heritable form of magnesium wasting and a clinical drug toxicity.\",\n      \"evidence\": \"Positional cloning of a pro-EGF mutation in a human kindred plus basolateral trafficking assays, corroborated by cetuximab-induced hypomagnesemia\",\n      \"pmids\": [\"17671655\", \"17671646\", \"18299299\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular signaling steps linking EGFR activation to TRPM6 gating not resolved\",\n        \"Direct biochemical interaction between EGFR pathway components and TRPM6 not defined\"\n      ]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed that TRPM6-mediated Mg2+ entry requires an electrical driving force, identifying Kv1.1 as the K+ channel that sets the luminal membrane potential.\",\n      \"evidence\": \"Positional cloning of a dominant-negative KCNA1 mutation, DCT co-localization immunofluorescence, and patch-clamp of wild-type versus N255D Kv1.1\",\n      \"pmids\": [\"19307729\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether Kv1.1 and TRPM6 physically interact versus only co-localize is not established\",\n        \"Quantitative contribution of membrane potential to TRPM6 conductance not measured directly\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Extended TRPM6 function beyond epithelial transport, demonstrating that TRPM6/TRPM7-controlled intracellular Mg2+ influences early human cell-fate decisions.\",\n      \"evidence\": \"Kinome screen, loss-of-function and pharmacological inhibition (Mesendogen) with intracellular Mg2+ readout in human ESCs\",\n      \"pmids\": [\"26705539\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Relative contributions of TRPM6 versus TRPM7 to the Mg2+ phenotype not separated\",\n        \"Downstream effectors linking Mg2+ to differentiation programs unidentified\",\n        \"Inhibitor specificity for TRPM6 not fully defined\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified a post-transcriptional regulator of TRPM6, placing the channel within a miRNA-controlled axis in cardiac injury.\",\n      \"evidence\": \"Dual-luciferase reporter validation of miR-202-3p targeting the TRPM6 3'UTR plus in vivo rat ischemia-reperfusion manipulation\",\n      \"pmids\": [\"30810438\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Direct targeting confirmed by luciferase, but downstream TGF-\\u03b21/Smads link rests on indirect in vivo readouts in a single lab\",\n        \"TRPM6 expression and role in cardiac tissue not independently confirmed\",\n        \"Mechanism connecting TRPM6 loss to pathway activation undefined\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Distinguished transcriptional from structural control of renal TRPM6 abundance, showing Prox-1 maintains its expression while NCC-dependent DCT integrity sustains its protein levels.\",\n      \"evidence\": \"DCT-specific Prox-1 conditional knockout and NCC knockout mice with mRNA/protein quantification and longitudinal morphological phenotyping\",\n      \"pmids\": [\"33200256\", \"31436795\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether Prox-1 binds the TRPM6 promoter directly versus acting indirectly is not shown\",\n        \"TRPM6 reduction after NCC loss is secondary to DCT atrophy rather than a direct regulatory link\",\n        \"Single-lab findings for each regulator\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular mechanism by which EGFR signaling and membrane potential converge to gate TRPM6, and the direct effectors linking TRPM6-controlled Mg2+ to cell-fate decisions, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of TRPM6 gating in the timeline\",\n        \"No reconstituted EGFR-to-TRPM6 signaling pathway\",\n        \"Direct downstream targets of TRPM6-regulated Mg2+ unidentified\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 1, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TRPM7\", \"KCNA1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win"}}