{"id":"4f3b0e5f-05d6-5132-ba68-a55bc7f394e4","stable_key":"8c946991-97f0-55ee-8df0-00e67621962f:nad-plus-repair-precursor-rescue","predicate":"restores","statement":"Extracellular NAD+ or NMN restored intracellular NAD availability, PAR-dependent signaling and XRCC1 recruitment in the tested NAD-depleted human cells independently of CD73 status.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"6b069071-3e13-5bc4-a609-cc2f5d0bf943","mechanism_event_label":"Supplying precursor material restored part of a repair response in this model.","subject":{"id":"283ed24b-06a1-50aa-9281-df3bac6ce37e","slug":"nad-plus","display_name":"NAD+","entity_type_key":"small_molecule"},"object":{"id":"a3282ce5-a1dc-5ccb-a0bb-cf90d2652d96","slug":"human-nad-dependent-xrcc1-recruitment","display_name":"NAD-dependent XRCC1 recruitment and PAR signaling in human cells","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"6b069071-3e13-5bc4-a609-cc2f5d0bf943","stable_key":"8c946991-97f0-55ee-8df0-00e67621962f:nad-plus-repair-precursor-rescue-event","event_type":"observed_relationship","label":"Supplying precursor material restored part of a repair response in this model.","description":"Extracellular NAD+ or NMN restored intracellular NAD availability, PAR-dependent signaling and XRCC1 recruitment in the tested NAD-depleted human cells independently of CD73 status.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"283ed24b-06a1-50aa-9281-df3bac6ce37e","slug":"nad-plus","display_name":"NAD+","entity_type_key":"small_molecule"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"a3282ce5-a1dc-5ccb-a0bb-cf90d2652d96","slug":"human-nad-dependent-xrcc1-recruitment","display_name":"NAD-dependent XRCC1 recruitment and PAR signaling in human cells","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"d1c59139-db61-5fa0-a25d-40c3e625152e","slug":"nmn","display_name":"NMN","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"3e700717-6e07-59d4-96ec-3692c77c6266","slug":"nt5e","display_name":"Human ecto-5-prime-nucleotidase / CD73 / NT5E","entity_type_key":"protein"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"37cf3686-8964-56c4-8805-15dcc36216a0","slug":"xrcc1","display_name":"Human XRCC1","entity_type_key":"protein"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full text","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Human MCF-7 cells with NAMPT inhibition, CD73 comparison and serum-containing medium; NMN/NR XRCC1 rescue is reported as data not shown.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Rescue depended on medium and incubation time; serum-free and heat-inactivated-serum conditions did not give the same early rescue. No proof of intact cellular NAD uptake or clinical benefit.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"NAD+ collection; molecular form, preparation, species, exposure and manipulation remain explicit.","comparator":null,"unit":null,"notes":"","entity":{"slug":"nad-plus","display_name":"NAD+","entity_type_key":"small_molecule"}},{"dimension":"plain_language","value_text":"Supplying precursor material restored part of a repair response in this model.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Extracellular NAD+ enhances PARP-dependent DNA repair capacity independently of CD73 activity. · 2020 · https://pubmed.ncbi.nlm.nih.gov/31959836/ · DOI 10.1038/s41598-020-57506-9","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"b3d4dc45-ab2f-598f-9ea9-07bf776294b5","evidence_kind":"source_excerpt","locator":"Lines 260-266","start_line":260,"end_line":266,"excerpt":"## nad-plus-repair-precursor-rescue\nSupplying precursor material restored part of a repair response in this model.\nExtracellular NAD+ or NMN restored intracellular NAD availability, PAR-dependent signaling and XRCC1 recruitment in the tested NAD-depleted human cells independently of CD73 status.\nModel: Human MCF-7 cells with NAMPT inhibition, CD73 comparison and serum-containing medium; NMN/NR XRCC1 rescue is reported as data not shown.\nLimitations: Rescue depended on medium and incubation time; serum-free and heat-inactivated-serum conditions did not give the same early rescue. No proof of intact cellular NAD uptake or clinical benefit.\nEvidence access: Primary full text\nExtracellular NAD+ enhances PARP-dependent DNA repair capacity independently of CD73 activity. · 2020 · https://pubmed.ncbi.nlm.nih.gov/31959836/ · DOI 10.1038/s41598-020-57506-9","model_system":"Human MCF-7 cells with NAMPT inhibition, CD73 comparison and serum-containing medium; NMN/NR XRCC1 rescue is reported as data not shown.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Original curation paraphrase; evidence access and experimental limitations specified.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"f59aa302-d463-5462-876f-e21e64861eac","stable_key":"import-8c946991-97f0-55ee-8df0-00e67621962f","title":"NAD+: compartmental supply, consumption and cross-nutrient mechanisms (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text.","file_path":"","sha256":"9f5324d0d652c80ad630b3100e28ce34cd2ce260ea2e1324332a4262ce72ae09","revision_id":"0e07909c-e8bc-5950-bafc-61371d9d6412","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}