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NAADP (nicotinic acid-adenine dinucleotide phosphate), the most potent Ca2+-mobilizing second messenger, is active in a wide range of organisms and cell types. Until now, all NAADP-producing enzymes have been thought to be members of the ADP-ribosyl cyclase family. ADP-ribosyl cyclases exhibit promiscuous substrate selectivity, synthesize a variety of products and are regulated in a limited manner, which may be non-physiological. In the present paper, we report the presence of an enzyme on the surface of sea urchin sperm that exhibits bell-shaped regulation by Ca2+ over a range (EC(50) of 10 nM and IC(50) of 50 microM) that is physiologically relevant. Uniquely, this surface enzyme possesses complete selectivity for nucleotides with a 2'-phosphate group and exhibits only base-exchange activity without any detectable cyclase activity. Taken together, these findings indicate that this novel enzyme should be considered as the first true NAADP synthase.
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http://dx.doi.org/10.1042/BJ20071616 | DOI Listing |
Autophagy
January 2022
B Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
CD38 is a cell surface receptor capable of generating calcium-mobilizing second messengers. It has been implicated in host defense and cancer biology, but signaling mechanisms downstream of CD38 remain unclear. Mutations in LRRK2 (leucine-rich repeat kinase 2) are the most common genetic cause of Parkinson disease; it is also a risk factor for Crohn disease, leprosy, and certain types of cancers.
View Article and Find Full Text PDFAdv Exp Med Biol
October 2019
Department of Pharmacology, University of Oxford, Oxford, UK.
The aim of this chapter is to discuss evidence concerning the many roles of calcium ions, Ca, in cell signaling pathways that control heart function. Before considering details of these signaling pathways, the control of contraction in ventricular muscle by Ca transients accompanying cardiac action potentials is first summarized, together with a discussion of how myocytes from the atrial and pacemaker regions of the heart diverge from this basic scheme. Cell signaling pathways regulate the size and timing of the Ca transients in the different heart regions to influence function.
View Article and Find Full Text PDFJ Cell Physiol
February 2020
Laboratory of General Physiology, Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy.
The neuromodulator histamine is able to vasorelax in human cerebral, meningeal and temporal arteries via endothelial histamine 1 receptors (H Rs) which result in the downstream production of nitric oxide (NO), the most powerful vasodilator transmitter in the brain. Although endothelial Ca signals drive histamine-induced NO release throughout the peripheral circulation, the mechanism by which histamine evokes NO production in human cerebrovascular endothelial cells is still unknown. Herein, we exploited the human cerebral microvascular endothelial cell line, hCMEC/D3, to assess the role of intracellular Ca signaling in histamine-induced NO release.
View Article and Find Full Text PDFJ Cell Physiol
April 2019
Laboratory of General Physiology, Department of Biology and Biotechnology "Lazzaro Spallanzani, " University of Pavia, Pavia, Italy.
The neurotransmitter glutamate increases cerebral blood flow by activating postsynaptic neurons and presynaptic glial cells within the neurovascular unit. Glutamate does so by causing an increase in intracellular Ca concentration ([Ca ] ) in the target cells, which activates the Ca /Calmodulin-dependent nitric oxide (NO) synthase to release NO. It is unclear whether brain endothelial cells also sense glutamate through an elevation in [Ca ] and NO production.
View Article and Find Full Text PDFPeerJ
April 2018
Laboratory of Marine Biotechnology, Faculty of Chemistry and Biology, Universidad de Santiago de Chile, Santiago, Región Metropolitana, Chile.
In certain multicellular photoautotrophs, such as plants and green macroalgae, it has been demonstrated that calcium signaling importantly mediates tolerance to copper excess. However, there is no information in brown macroalgae, which are phylogenetically distant from green algae and plants. We have previously shown that chronic copper levels (2.
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