title: NAD biosynthesis in humans--enzymes, metabolites and therapeutic aspects.
abstract: NAD plays a major role in all cells as substrate for signal transduction and as cofactor in metabolic redox reactions. Since NAD-dependent signaling involves degradation of the nucleotide, continuous restoration of cellular NAD pools is essential. Moreover, NAD-dependent signaling reactions, which include ADP-ribosylation, protein deacetylation by sirtuins and calcium messenger synthesis, are regulated by NAD availability. Consequently, perturbations of NAD supply can have severe consequences and, in fact, have been associated with major human diseases such as age- and diet-induced disorders, neurodegenerative diseases and cancer. Given the increasing awareness of the biological roles of NAD, the routes, molecular mechanisms and regulation of NAD biosynthesis have been the subject of intense research over the last decade. Impressive progress has been made regarding the molecular identification, functional and structural characterization as well as regulation of the human NAD biosynthetic enzymes. Exciting therapeutic concepts have emerged, which aim at modulation of NAD availability by interfering with the biosynthetic network to prevent, reduce or reverse pathological conditions. Since there are several entry points into NAD synthesis, including the known vitamin B3 precursors nicotinamide and nicotinic acid, targeted nutritional supplementation is likely to have beneficial effects in various diseases. On the other hand, inhibition of NAD synthesis promotes cell death and has emerged as a therapeutic concept for cancer treatment.
authors.affiliation: Department of Molecular Biology, University of Bergen, Thormøhlensgate 55, 5008 Bergen, Norway. Christian.Doelle@mbi.uib.no.
authors.forename: Christian
authors.initials: C
authors.lastname: Dölle
authors.forename: Renate Hvidsten
authors.initials: RH
authors.lastname: Skoge
authors.forename: Magali R
authors.initials: MR
authors.lastname: Vanlinden
authors.forename: Mathias
authors.initials: M
authors.lastname: Ziegler
mesh_terms: D035843:Biomedical Research; D004798:Enzymes / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D015394:Molecular Structure; D009243:NAD / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism / Q000627:therapeutic use; D009369:Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism
chemical_list: D004798:Enzymes; D009243:NAD