UNIGE document Scientific Article
previous document  unige:40238  next document
add to browser collection
Title

NCLX Protein, but Not LETM1, Mediates Mitochondrial Ca2+ Extrusion, Thereby Limiting Ca2+-induced NAD(P)H Production and Modulating Matrix Redox State

Authors
Sekler, Israel
Published in Journal of Biological Chemistry. 2014, vol. 289, no. 29, p. 20377-20385
Abstract Mitochondria capture and subsequently release Ca(2+) ions, thereby sensing and shaping cellular Ca(2+) signals. The Ca(2+) uniporter MCU mediates Ca(2+) uptake, whereas NCLX (mitochondrial Na/Ca exchanger) and LETM1 (leucine zipper-EF-hand-containing transmembrane protein 1) were proposed to exchange Ca(2+) against Na(+) or H(+), respectively. Here we study the role of these ion exchangers in mitochondrial Ca(2+) extrusion and in Ca(2+)-metabolic coupling. Both NCLX and LETM1 proteins were expressed in HeLa cells mitochondria. The rate of mitochondrial Ca(2+) efflux, measured with a genetically encoded indicator during agonist stimulations, increased with the amplitude of mitochondrial Ca(2+) ([Ca(2+)]mt) elevations. NCLX overexpression enhanced the rates of Ca(2+) efflux, whereas increasing LETM1 levels had no impact on Ca(2+) extrusion. The fluorescence of the redox-sensitive probe roGFP increased during [Ca(2+)]mt elevations, indicating a net reduction of the matrix. This redox response was abolished by NCLX overexpression and restored by the Na(+)/Ca(2+) exchanger inhibitor CGP37157. The [Ca(2+)]mt elevations were associated with increases in the autofluorescence of NAD(P)H, whose amplitude was strongly reduced by NCLX overexpression, an effect reverted by Na(+)/Ca(2+) exchange inhibition. We conclude that NCLX, but not LETM1, mediates Ca(2+) extrusion from mitochondria. By controlling the duration of matrix Ca(2+) elevations, NCLX contributes to the regulation of NAD(P)H production and to the conversion of Ca(2+) signals into redox changes.
Identifiers
PMID: 24898248
Full text
Article (Published version) (1.8 MB) - public document Free access
Structures
Research group Signaux intracellulaires (210)
Project FNS: 310030B_133126
Citation
(ISO format)
DE MARCHI, Umberto et al. NCLX Protein, but Not LETM1, Mediates Mitochondrial Ca2+ Extrusion, Thereby Limiting Ca2+-induced NAD(P)H Production and Modulating Matrix Redox State. In: Journal of Biological Chemistry, 2014, vol. 289, n° 29, p. 20377-20385. https://archive-ouverte.unige.ch/unige:40238

220 hits

137 downloads

Update

Deposited on : 2014-09-17

Export document
Format :
Citation style :