| Autor: |
Kowaltowski AJ; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil., Menezes-Filho SL; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil., Assali EA; Department of Molecular and Medical Pharmacology and Department of Medicine, Division of Endocrinology, David Geffen School of Medicine, (UCLA), Los Angeles, California, USA., Gonçalves IG; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil., Cabral-Costa JV; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil., Abreu P; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil., Miller N; Department of Molecular and Medical Pharmacology and Department of Medicine, Division of Endocrinology, David Geffen School of Medicine, (UCLA), Los Angeles, California, USA., Nolasco P; Laboratório de Biologia Vascular, Biologia Cardiovascular Translacional (LIM-64), Instituto do Coração (InCor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil., Laurindo FRM; Laboratório de Biologia Vascular, Biologia Cardiovascular Translacional (LIM-64), Instituto do Coração (InCor), Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil., Bruni-Cardoso A; Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil., Shirihai OS; Department of Molecular and Medical Pharmacology and Department of Medicine, Division of Endocrinology, David Geffen School of Medicine, (UCLA), Los Angeles, California, USA. |
| Abstrakt: |
Changes in mitochondrial size and shape have been implicated in several physiologic processes, but their role in mitochondrial Ca 2+ uptake regulation and overall cellular Ca 2+ homeostasis is largely unknown. Here we show that modulating mitochondrial dynamics toward increased fusion through expression of a dominant negative (DN) form of the fission protein [dynamin-related protein 1 (DRP1)] markedly increased both mitochondrial Ca 2+ retention capacity and Ca 2+ uptake rates in permeabilized C2C12 cells. Similar results were seen using the pharmacological fusion-promoting M1 molecule. Conversely, promoting a fission phenotype through the knockdown of the fusion protein mitofusin (MFN)-2 strongly reduced the mitochondrial Ca 2+ uptake speed and capacity in these cells. These changes were not dependent on modifications in mitochondrial calcium uniporter expression, inner membrane potentials, or the mitochondrial permeability transition. Implications of mitochondrial morphology modulation on cellular calcium homeostasis were measured in intact cells; mitochondrial fission promoted lower basal cellular calcium levels and lower endoplasmic reticulum (ER) calcium stores, as indicated by depletion with thapsigargin. Indeed, mitochondrial fission was associated with ER stress. Additionally, the calcium-replenishing process of store-operated calcium entry was impaired in MFN2 knockdown cells, whereas DRP1-DN-promoted fusion resulted in faster cytosolic Ca 2+ increase rates. Overall, our results show a novel role for mitochondrial morphology in the regulation of mitochondrial Ca 2+ uptake, which impacts cellular Ca 2+ homeostasis.-Kowaltowski, A. J., Menezes-Filho, S. L., Assali, E. A., Gonçalves, I. G., Cabral-Costa, J. V., Abreu, P., Miller, N., Nolasco, P., Laurindo, F. R. M., Bruni-Cardoso, A., Shirihai, O. Mitochondrial morphology regulates organellar Ca 2+ uptake and changes cellular Ca 2+ homeostasis. |
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