NADPH Alters DUOX1 Calcium Responsiveness.

Autor: Conner GE; Department of Cell Biology, University of Miami Miller School of Medicine, 1600 NW 10th Avenue, Miami Fl, 33136, USA. Electronic address: gconner@miami.edu.
Jazyk: angličtina
Zdroj: Redox biology [Redox Biol] 2024 Sep; Vol. 75, pp. 103251. Date of Electronic Publication: 2024 Jun 20.
DOI: 10.1016/j.redox.2024.103251
Abstrakt: Hydrogen peroxide is a key element in redox signaling and in setting cellular redox tone. DUOX1 and DUOX2, that directly synthesize hydrogen peroxide, are the most abundant NADPH oxidase transcripts in most epithelia. DUOX1 and DUOX2 hydrogen peroxide synthesis is regulated by intracellular calcium transients and thus cells can respond to signals and initiate responses by increasing cellular hydrogen peroxide synthesis. Nevertheless, many details of their enzymatic regulation are still unexplored. DUOX1 and DUOXA1 were expressed in HEK293T cells and activity was studied in homogenates and membrane fractions. When DUOX1 homogenates or membranes were pre-incubated in NADPH and started with addition of Ca 2+ , to mimic intracellular activation, progress curves were distinctly different from those pre-incubated in Ca 2+ and started with NADPH. The Ca 2+ EC 50 for DUOX1's initial rate when pre-incubated in Ca 2+ , was three orders of magnitude lower (EC 50  ∼ 10 -6  M) than with preincubation in NADPH (EC 50  ∼ 10 -3  M). In addition, activity was several fold lower with Ca 2+ start. Identical results were obtained using homogenates and membrane fractions. The data suggested that DUOX1 Ca 2+ binding in expected physiological signaling conditions only slowly leads to maximal hydrogen peroxide synthesis and that full hydrogen peroxide synthesis activity in vivo only can occur when encountering extremely high concentration Ca 2+ signals. Thus, a complex interplay of intracellular NADPH and Ca 2+ concentrations regulate DUOX1 over a wide extent and may limit DUOX1 activity to a restricted range and spatial distribution.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 The Author. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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