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beta-NAD(+) is as abundant as ATP in neuronal cells. beta-NAD(+) functions not only as a coenzyme but also as a substrate. beta-NAD(+)-utilizing enzymes are involved in signal transduction. We focus on ADP-ribosyl cyclase/CD38 which synthesizes cyclic ADP-ribose (cADPR), a universal Ca(2+) mobilizer from intracellular stores, from beta-NAD(+). cADPR acts through activation/modulation of ryanodine receptor Ca(2+) releasing Ca(2+) channels. cADPR synthesis in neuronal cells is stimulated or modulated via different pathways and various factors. Subtype-specific coupling of various neurotransmitter receptors with ADP-ribosyl cyclase confirms the involvement of the enzyme in signal transduction in neurons and glial cells. Moreover, cADPR/CD38 is critical in oxytocin release from the hypothalamic cell dendrites and nerve terminals in the posterior pituitary. Therefore, it is possible that pharmacological manipulation of intracellular cADPR levels through ADP-ribosyl cyclase activity or synthetic cADPR analogues may provide new therapeutic opportunities for treatment of neurodevelopmental disorders.
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http://dx.doi.org/10.1016/j.neuint.2007.06.023 | DOI Listing |
Adv Exp Med Biol
August 2025
The Laboratory of Physiological Hygiene and Exercise Science, School of Kinesiology, University of Minnesota Twin Cities, Minneapolis, MN, USA.
Hyperacetylation of proteins represents a stress to aged organisms. Increased consumption and loss of NAD+ homeostasis underlie a major mechanism for the disturbed acetylation/deacetylation balance during aging. Nicotinamide adenine dinucleotide (NAD) is a versatile chemical compound serving as a coenzyme in metabolic pathways and as a substrate to support the enzymatic functions of sirtuins (SIRTs), poly (ADP-ribose) polymerase-1 (PARP-1), and cyclic ADP ribose hydrolase (CD38).
View Article and Find Full Text PDFCell Death Dis
July 2025
Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.
Retinitis Pigmentosa (RP) is the most common inherited retinal degeneration, characterized by an initial loss of rod photoreceptor cells. Photoreceptor cell death has been associated with high levels of cyclic guanosine-3', 5'- monophosphate (cGMP) in animal models of autosomal recessive RP (ARRP) and autosomal dominant RP (ADRP). cGMP analogues inhibiting protein kinase G (PKG) have been found to prevent rod degeneration in ARRP disease models, but their effects on ADRP are unknown.
View Article and Find Full Text PDFJ Biol Chem
August 2025
Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada; David Braley Center for Antibiotic Discovery, McMaster University, Hamilton, Ontario, Canada
In metazoans, enzymes belonging to the bifunctional ADP-ribosyl cyclase/cyclic ADP-ribose (cADPr) hydrolase family regulate diverse cellular processes by synthesizing and hydrolyzing the intracellular second messenger cADPr, derived from the electron carrier NAD. However, bacterial enzymes belonging to this family have not been characterized. Here, we identify a bacterial ADP-ribosyl cyclase that is associated with the type VII secretion system and functions as an antibacterial toxin.
View Article and Find Full Text PDFNat Commun
July 2025
West China Centre of Excellence for Pancreatitis and Laboratory of Metabolism and Aging, Frontiers Science Center for Disease-related Molecular Network and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China.
Intestinal stem cell (ISC) aging diminishes the regenerative capacity of the intestinal epithelia, but effective therapeutic strategies to counteract human ISC aging remain elusive. Here, we find that the synthesis of α-lipoic acid (ALA) is reduced in old human small intestine. Notably, ALA supplementation inhibits ISC aging and decreases the number of atypical Paneth cells in old human intestinal organoids and in old mouse small intestines.
View Article and Find Full Text PDFRes Sq
June 2025
Departments of Medicine, State University of New York, Upstate Medical University, Norton College of Medicine, Syracuse, New York 13210.
Rab4A, a small GTPase overexpressed in T cells of patients with systemic lupus erythematosus (SLE), has been shown to activate mechanistic target of rapamycin (mTOR) signaling, which promotes proinflammatory T cell development and predisposes to nephritis in SLE. In this study, we demonstrate that Rab4A facilitates the endocytic recycling and surface expression of CD38, which, in turn, triggers NAD depletion, activates mTOR complex 1, and suppresses interleukin-2 (IL-2) production in CD4 T cells. Rab4A-driven CD38-mediated NAD depletion elicits the accumulation of nicotinamide and ADP-ribose and secondary depletion of cyclic ADP-ribose.
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