{"id":"bda52845-07b2-53f9-9001-9c9f020572cd","stable_key":"8c946991-97f0-55ee-8df0-00e67621962f:nad-plus-ecto-cd38-nmn","predicate":"degrades","statement":"The study linked extracellular CD38 enzymatic activity to NMN degradation and lower precursor availability; selective blockade of ecto-CD38 increased NAD+ in mouse experiments.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"89f860d7-52ec-500d-a5a1-2a984481b212","mechanism_event_label":"A precursor can be destroyed before a neighboring cell uses it.","subject":{"id":"77c40786-fc17-5efb-887f-52a76163a9ba","slug":"mouse-cd38","display_name":"Mouse CD38","entity_type_key":"protein"},"object":{"id":"d1c59139-db61-5fa0-a25d-40c3e625152e","slug":"nmn","display_name":"NMN","entity_type_key":"small_molecule"},"evidence_count":1,"mechanism_event":{"id":"89f860d7-52ec-500d-a5a1-2a984481b212","stable_key":"8c946991-97f0-55ee-8df0-00e67621962f:nad-plus-ecto-cd38-nmn-event","event_type":"observed_relationship","label":"A precursor can be destroyed before a neighboring cell uses it.","description":"The study linked extracellular CD38 enzymatic activity to NMN degradation and lower precursor availability; selective blockade of ecto-CD38 increased NAD+ in mouse experiments.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"77c40786-fc17-5efb-887f-52a76163a9ba","slug":"mouse-cd38","display_name":"Mouse CD38","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"d1c59139-db61-5fa0-a25d-40c3e625152e","slug":"nmn","display_name":"NMN","entity_type_key":"small_molecule"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"283ed24b-06a1-50aa-9281-df3bac6ce37e","slug":"nad-plus","display_name":"NAD+","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"08c27a3f-552e-5c92-8688-321a9b64a0d6","slug":"nicotinamide","display_name":"Nicotinamide","entity_type_key":"small_molecule"},"role":"context_participant","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence_access","value_text":"Primary full text","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Mouse biochemical, cellular and ecto-CD38 antibody experiments.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Not established clinical benefit from an over-the-counter CD38 inhibitor.","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":"A precursor can be destroyed before a neighboring cell uses it.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"CD38 ecto-enzyme in immune cells is induced during aging and regulates NAD+ and NMN levels. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33199925/ · DOI 10.1038/s42255-020-00298-z","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"508a9f3b-777b-5b18-bf55-50d5b6bd940c","evidence_kind":"source_excerpt","locator":"Lines 116-122","start_line":116,"end_line":122,"excerpt":"## nad-plus-ecto-cd38-nmn\nA precursor can be destroyed before a neighboring cell uses it.\nThe study linked extracellular CD38 enzymatic activity to NMN degradation and lower precursor availability; selective blockade of ecto-CD38 increased NAD+ in mouse experiments.\nModel: Mouse biochemical, cellular and ecto-CD38 antibody experiments.\nLimitations: Not established clinical benefit from an over-the-counter CD38 inhibitor.\nEvidence access: Primary full text\nCD38 ecto-enzyme in immune cells is induced during aging and regulates NAD+ and NMN levels. · 2020 · https://pubmed.ncbi.nlm.nih.gov/33199925/ · DOI 10.1038/s42255-020-00298-z","model_system":"Mouse biochemical, cellular and ecto-CD38 antibody experiments.","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. 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