{"id":"cf41ceb0-60f3-5090-885d-f2220e2c519b","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-cons-nnmt-histone-methylation","predicate":"reduces","statement":"At 10–20 micromolar medium methionine, NNMT-overexpressing 769P cells had reduced methylation of several histone lysine marks compared with controls.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"ddbfe3ed-4487-5590-97e2-a9e38af442f0","mechanism_event_label":"NNMT changed several histone methylation marks in this culture model.","subject":{"id":"68273ca3-19da-57e0-85bb-2f1245928df5","slug":"nnmt","display_name":"Human NNMT","entity_type_key":"protein"},"object":{"id":"e05713b0-d3fc-5a27-b450-cf0a4d52b9c3","slug":"histone-methylation","display_name":"Histone methylation","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"ddbfe3ed-4487-5590-97e2-a9e38af442f0","stable_key":"a9dd23c6-978a-5755-8bd8-f29bd1fe0cda:b3-cons-nnmt-histone-methylation-event","event_type":"biochemical_relationship","label":"NNMT changed several histone methylation marks in this culture model.","description":"At 10–20 micromolar medium methionine, NNMT-overexpressing 769P cells had reduced methylation of several histone lysine marks compared with controls.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"68273ca3-19da-57e0-85bb-2f1245928df5","slug":"nnmt","display_name":"Human NNMT","entity_type_key":"protein"},"role":"enzyme","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"9d39f561-740b-5f67-bba7-8a72ef612a99","slug":"methionine","display_name":"L-Methionine","entity_type_key":"small_molecule"},"role":"culture_nutrient","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"825f2da2-01bc-5874-a3c6-64f5ac867db5","slug":"s-adenosylmethionine","display_name":"S-Adenosyl-L-methionine","entity_type_key":"small_molecule"},"role":"methyl_donor","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"e84829b1-0607-558e-8add-aaa3af4747e7","slug":"s-adenosylhomocysteine","display_name":"S-Adenosyl-L-homocysteine","entity_type_key":"small_molecule"},"role":"coproduct","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"e05713b0-d3fc-5a27-b450-cf0a4d52b9c3","slug":"histone-methylation","display_name":"Histone methylation","entity_type_key":"cellular_process"},"role":"outcome","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"true","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/niacin-consumption-sources/nnmt2013.txt\", \"locator\": \"Full text, normalized paragraph 35\", \"start_char\": 19327, \"end_char\": 21089, \"file_sha256\": \"7d88fd656ba772962185234a9bd021e40a9b83f9156db836f723eba06b68acca\", \"text_sha256\": \"5b6ea17ec741ecc064f97de9d83d49809db5e62588ffc1164e6e771fc9fc50c3\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Immunoblotting of histone methylation in engineered cells","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"NNMT overexpression; 10 or 20 micromolar methionine; GFP and inactive NNMT controls","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Engineered human cancer-cell culture, not healthy-human niacin repletion. SAM consumption does not establish systemic methyl depletion or a need for folate/B12 supplements. Not every histone mark changed; this does not establish global DNA hypomethylation.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Niacin research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"niacin","display_name":"Niacin (vitamin B3)","entity_type_key":"nutrient_element"}},{"dimension":"organism","value_text":"Human","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"NNMT changed several histone methylation marks in this culture model.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[b3-cons-nnmt2013] NNMT promotes epigenetic remodeling in cancer by creating a metabolic methylation sink. (2013). https://pubmed.ncbi.nlm.nih.gov/23455543/ DOI: 10.1038/nchembio.1204","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Human 769P renal carcinoma cells","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"51a681c4-eb76-58bf-b8c1-e69cbb7398f2","evidence_kind":"source_excerpt","locator":"Lines 803-815","start_line":803,"end_line":815,"excerpt":"### b3-cons-nnmt-histone-methylation\nAt 10–20 micromolar medium methionine, NNMT-overexpressing 769P cells had reduced methylation of several histone lysine marks compared with controls.\nCondition category: normal\nnutrient_topic: Niacin research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: NNMT changed several histone methylation marks in this culture model.\norganism: Human\ntissue_or_cell_type: Human 769P renal carcinoma cells\nexperimental_model: Immunoblotting of histone methylation in engineered cells\nlimitations: Engineered human cancer-cell culture, not healthy-human niacin repletion. SAM consumption does not establish systemic methyl depletion or a need for folate/B12 supplements. Not every histone mark changed; this does not establish global DNA hypomethylation.\nexposure: NNMT overexpression; 10 or 20 micromolar methionine; GFP and inactive NNMT controls\ncross_nutrient: true\nevidence_span: {\"source_cache\": \"artifacts/niacin-consumption-sources/nnmt2013.txt\", \"locator\": \"Full text, normalized paragraph 35\", \"start_char\": 19327, \"end_char\": 21089, \"file_sha256\": \"7d88fd656ba772962185234a9bd021e40a9b83f9156db836f723eba06b68acca\", \"text_sha256\": \"5b6ea17ec741ecc064f97de9d83d49809db5e62588ffc1164e6e771fc9fc50c3\"}\n[b3-cons-nnmt2013] NNMT promotes epigenetic remodeling in cancer by creating a metabolic methylation sink. (2013). https://pubmed.ncbi.nlm.nih.gov/23455543/ DOI: 10.1038/nchembio.1204","model_system":"Immunoblotting of histone methylation in engineered cells","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [b3-cons-nnmt2013] NNMT promotes epigenetic remodeling in cancer by creating a metabolic methylation sink. (2013). https://pubmed.ncbi.nlm.nih.gov/23455543/ DOI: 10.1038/nchembio.1204","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"a62b7b5b-786a-57e9-85e9-67c6912a5054","stable_key":"import-a9dd23c6-978a-5755-8bd8-f29bd1fe0cda","title":"Niacin: NAD metabolism, 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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