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Authors: Simon, Alexandra
Karbach, Susanne
Habermeier, Alice
Closs, Ellen I.
Title: Decoding the substrate supply to human neuronal nitric oxide synthase
Online publication date: 11-Jul-2022
Language: english
Abstract: Nitric oxide, produced by the neuronal nitric oxide synthase (nNOS) from L-arginine is an important second messenger molecule in the central nervous system: It influences the synthesis and release of neurotransmitters and plays an important role in long-term potentiation, long-term depression and neuroendocrine secretion. However, under certain pathological conditions such as Alzheimer's or Parkinson's disease, stroke and multiple sclerosis, excessive NO production can lead to tissue damage. It is thus desirable to control NO production in these situations. So far, little is known about the substrate supply to human nNOS as a determinant of its activity. Measuring bioactive NO via cGMP formation in reporter cells, we demonstrate here that nNOS in both, human A673 neuroepithelioma and TGW-nu-I neuroblastoma cells can be fast and efficiently nourished by extracellular arginine that enters the cells via membrane transporters (pool I that is freely exchangeable with the extracellular space). When this pool was depleted, NO synthesis was partially sustained by intracellular arginine sources not freely exchangeable with the extracellular space (pool II). Protein breakdown made up by far the largest part of pool II in both cell types. In contrast, citrulline to arginine conversion maintained NO synthesis only in TGW-nu-I neuroblastoma, but not A673 neuroepithelioma cells. Histidine mimicked the effect of protease inhibitors causing an almost complete nNOS inhibition in cells incubated additionally in lysine that depletes the exchangeable arginine pool. Our results identify new ways to modulate nNOS activity by modifying its substrate supply.
DDC: 610 Medizin
610 Medical sciences
Institution: Johannes Gutenberg-Universität Mainz
Department: FB 04 Medizin
Place: Mainz
Version: Published version
Publication type: Zeitschriftenaufsatz
License: CC BY
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Journal: PLoS one
Pages or article number: e67707
Publisher: PLoS
Publisher place: Lawrence, Kan.
Issue date: 2013
ISSN: 1932-6203
Publisher URL:
Publisher DOI: 10.1371/journal.pone.0067707
Appears in collections:DFG-OA-Publizieren (2012 - 2017)

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