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(2008). https://pubmed.ncbi.nlm.nih.gov/18287530/ DOI: 10.1091/mbc.e07-09-0973","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Intestinal epithelial cell model","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"e2c38ffd-d7f5-5cae-a281-e812e677c4cd","evidence_kind":"source_excerpt","locator":"Lines 617-631","start_line":617,"end_line":631,"excerpt":"### vdm-calcitriol-induces-cldn2\nCalcitriol increased Claudin-2 expression in human Caco-2 intestinal epithelial cells.\nCondition category: normal\nnutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Active vitamin D can increase a tight-junction protein involved in calcium movement between intestinal cells.\norganism: Homo sapiens\ntissue_or_cell_type: Intestinal epithelial cell model\nexperimental_model: Human Caco-2 cells; RT-PCR, immunoblotting and junctional localization\nlimitations: Cell-line expression response; the separately reused permeability experiments support function, but neither establishes a universal fraction of human dietary calcium absorption.\nexposure: Calcitriol-treated versus vehicle Caco-2 cultures; exact hormone dose/time not recovered in the primary passages used.\ncross_nutrient: Vitamin D–calcium–phosphate regulation.\nevidence_locator: Primary abstract and Results/Discussion on calcitriol-induced claudin expression; cached web-primary-excerpts.json\nnutrient: Vitamin D2 and D3\nevidence_scope: D3 active metabolite or VDR machinery experiment; not a direct D2-versus-D3 comparison.\n[vdm-fujita2008] Tight junction proteins claudin-2 and -12 are critical for vitamin D-dependent Ca2+ absorption between enterocytes. (2008). https://pubmed.ncbi.nlm.nih.gov/18287530/ DOI: 10.1091/mbc.e07-09-0973","model_system":"Human Caco-2 cells; RT-PCR, immunoblotting and junctional localization","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [vdm-fujita2008] Tight junction proteins claudin-2 and -12 are critical for vitamin D-dependent Ca2+ absorption between enterocytes. (2008). https://pubmed.ncbi.nlm.nih.gov/18287530/ DOI: 10.1091/mbc.e07-09-0973","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"c95c763c-5b31-5b3f-a2f8-2dfe5ef0d3ca","stable_key":"import-1deb434a-3547-51a0-a038-87b1ce79ec38","title":"Vitamin D2 and D3: 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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