{"id":"648bf39e-2407-5d1e-897f-c7c8b7bc493f","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-abs-megalin-kidney-store","predicate":"reduces","statement":"Kidney cortex B12 content in megalin-deficient mice was approximately fourfold lower than in controls.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"7794f13e-dc64-5ac4-a9ef-d1dd56374dbe","mechanism_event_label":"Impaired renal uptake depleted the kidney B12 pool in mice.","subject":{"id":"b502a986-43a0-574b-bc4a-95f7fb7a39b7","slug":"mouse-lrp2-null-genotype","display_name":"Mouse Lrp2-null genotype","entity_type_key":"gene"},"object":{"id":"385ac833-697e-5e1b-9b92-8f3fd0130aef","slug":"kidney-cortex-cobalamin-content","display_name":"Kidney cortex cobalamin content","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"7794f13e-dc64-5ac4-a9ef-d1dd56374dbe","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-abs-megalin-kidney-store-event","event_type":"biochemical_relationship","label":"Impaired renal uptake depleted the kidney B12 pool in mice.","description":"Kidney cortex B12 content in megalin-deficient mice was approximately fourfold lower than in controls.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"b6d9b937-895d-5e0a-8cc5-0454a0b7d373","slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"},"role":"nutrient","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"249ecc7c-b115-508f-acda-94c954e5cd2b","slug":"mouse-lrp2","display_name":"Mouse megalin / Lrp2","entity_type_key":"protein"},"role":"deleted-protein","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"b502a986-43a0-574b-bc4a-95f7fb7a39b7","slug":"mouse-lrp2-null-genotype","display_name":"Mouse Lrp2-null genotype","entity_type_key":"gene"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"385ac833-697e-5e1b-9b92-8f3fd0130aef","slug":"kidney-cortex-cobalamin-content","display_name":"Kidney cortex cobalamin content","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"cross_nutrient","value_text":"false","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Megalin-deficient versus control mice","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Genetic megalin deficiency","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Renal content is not a universal marker of whole-body or neural B12 sufficiency; reserve function remains an interpretation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Mus musculus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Impaired renal uptake depleted the kidney B12 pool in mice.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[birn-2002-megalin] Megalin is essential for renal proximal tubule reabsorption and accumulation of transcobalamin-B(12). (2002). https://pubmed.ncbi.nlm.nih.gov/11832420/ DOI: 10.1152/ajprenal.00206.2000","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Kidney cortex","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"330ec17b-f1de-5c12-aa56-f95b446608ee","evidence_kind":"source_excerpt","locator":"Lines 426-437","start_line":426,"end_line":437,"excerpt":"### b12-abs-megalin-kidney-store\nKidney cortex B12 content in megalin-deficient mice was approximately fourfold lower than in controls.\nCondition category: machinery_impairment\nnutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Impaired renal uptake depleted the kidney B12 pool in mice.\norganism: Mus musculus\ntissue_or_cell_type: Kidney cortex\nexperimental_model: Megalin-deficient versus control mice\nlimitations: Renal content is not a universal marker of whole-body or neural B12 sufficiency; reserve function remains an interpretation.\nexposure: Genetic megalin deficiency\ncross_nutrient: false\n[birn-2002-megalin] Megalin is essential for renal proximal tubule reabsorption and accumulation of transcobalamin-B(12). (2002). https://pubmed.ncbi.nlm.nih.gov/11832420/ DOI: 10.1152/ajprenal.00206.2000","model_system":"Megalin-deficient versus control mice","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [birn-2002-megalin] Megalin is essential for renal proximal tubule reabsorption and accumulation of transcobalamin-B(12). (2002). https://pubmed.ncbi.nlm.nih.gov/11832420/ DOI: 10.1152/ajprenal.00206.2000","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"73145023-2982-5848-aff2-8d8875d6b9c5","stable_key":"import-7fc92b9e-9cbf-556e-8719-6b5244625250","title":"Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. 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