2026-04-28T19:19:28Zhttps://uvadoc.uva.es/oai/request

oai:uvadoc.uva.es:10324/659232024-12-16T12:09:02Zcom_10324_1134com_10324_931com_10324_894col_10324_1213

NCLX Protein, but Not LETM1, Mediates Mitochondrial Ca2+ Extrusion, Thereby Limiting Ca2+-induced NAD(P)H Production and Modulating Matrix Redox State De Marchi, Umberto Santo Domingo Mayoral, Jaime Castelbou, Cyril Sekler, Israel Wiederkehr, Andreas Demaurex, Nicolas Producción Científica 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. 2024-02-07T14:59:11Z 2024-02-07T14:59:11Z 2014 info:eu-repo/semantics/article J Biol Chem., Jul 2014, vol. 289, n. 29, p. 20377-85. 0021-9258 https://uvadoc.uva.es/handle/10324/65923 10.1074/jbc.M113.540898 20377 29 20385 Journal of Biological Chemistry 289 spa info:eu-repo/semantics/openAccess Elsevier SI