{"id":"cf62069a-41f8-58ac-a9fc-9136350db881","stable_key":"dff9f743-3766-5f20-a71e-d6d2bd5bfb6f:va-isx-bco1-repression","predicate":"represses","statement":"ISX recognized upstream BCO1 regulatory motifs and repressed its expression.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"0c1c7dec-e0b3-5552-a717-3c12eda2cc40","mechanism_event_label":"The same feedback factor limits the carotenoid-cleaving enzyme.","subject":{"id":"720be86d-9f3e-5f54-9160-1772c0bcccfa","slug":"isx","display_name":"Intestine-specific homeobox protein / ISX","entity_type_key":"protein"},"object":{"id":"d908f2a5-bc6d-5c6f-a692-668c79fae71b","slug":"bco1","display_name":"Beta-carotene oxygenase 1 / BCO1","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"0c1c7dec-e0b3-5552-a717-3c12eda2cc40","stable_key":"dff9f743-3766-5f20-a71e-d6d2bd5bfb6f:va-isx-bco1-repression-event","event_type":"biochemical_relationship","label":"The same feedback factor limits the carotenoid-cleaving enzyme.","description":"ISX recognized upstream BCO1 regulatory motifs and repressed its expression.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"720be86d-9f3e-5f54-9160-1772c0bcccfa","slug":"isx","display_name":"Intestine-specific homeobox protein / ISX","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"d908f2a5-bc6d-5c6f-a692-668c79fae71b","slug":"bco1","display_name":"Beta-carotene oxygenase 1 / BCO1","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_location","value_text":"Abstract","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Isx, Bco1, Bco2 and Scarb1 mouse mutants; promoter binding and controlled diets.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"ISX binding and gene-expression experiments.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Does not establish a fixed carotenoid conversion ratio.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin A research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-a","display_name":"Vitamin A","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Mus musculus and promoter-binding preparations","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"outcome","value_text":"ISX recognized upstream BCO1 regulatory motifs and repressed its expression.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"The same feedback factor limits the carotenoid-cleaving enzyme.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[va-widjajaadhi-2015] A genetic dissection of intestinal fat-soluble vitamin and carotenoid absorption (2015). https://pmc.ncbi.nlm.nih.gov/articles/PMC4424956/ DOI: 10.1093/hmg/ddv072","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Intestinal epithelium","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"c405f048-858c-5492-805e-664f1f2835cd","evidence_kind":"source_excerpt","locator":"Lines 288-300","start_line":288,"end_line":300,"excerpt":"### va-isx-bco1-repression\nISX recognized upstream BCO1 regulatory motifs and repressed its expression.\nCondition category: normal\nnutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: The same feedback factor limits the carotenoid-cleaving enzyme.\norganism: Mus musculus and promoter-binding preparations\ntissue_or_cell_type: Intestinal epithelium\nexperimental_model: Isx, Bco1, Bco2 and Scarb1 mouse mutants; promoter binding and controlled diets.\nlimitations: Does not establish a fixed carotenoid conversion ratio.\nexposure: ISX binding and gene-expression experiments.\noutcome: ISX recognized upstream BCO1 regulatory motifs and repressed its expression.\nevidence_location: Abstract\n[va-widjajaadhi-2015] A genetic dissection of intestinal fat-soluble vitamin and carotenoid absorption (2015). https://pmc.ncbi.nlm.nih.gov/articles/PMC4424956/ DOI: 10.1093/hmg/ddv072","model_system":"Isx, Bco1, Bco2 and Scarb1 mouse mutants; promoter binding and controlled diets.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [va-widjajaadhi-2015] A genetic dissection of intestinal fat-soluble vitamin and carotenoid absorption (2015). https://pmc.ncbi.nlm.nih.gov/articles/PMC4424956/ DOI: 10.1093/hmg/ddv072","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"0c5474e2-be48-547b-b287-9c07a59c9ff1","stable_key":"import-dff9f743-3766-5f20-a71e-d6d2bd5bfb6f","title":"Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"b217224b262abbd77d6a0c8c9beefff9c022fae4d31e2a5273915d769b9a6546","revision_id":"61008909-871f-575c-b5e2-21542689ea3c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}