Drp-1-dependent division of the mitochondrial network blocks intraorganellar Ca2+ waves and protects against Ca2+-mediated apoptosis.
By transiently or stably overexpressing the mitochondrial fission factor dynamin-related protein-1 (Drp-1), we evaluated the role of mitochondrial division in organelle Ca2+ homeostasis and apoptotic signaling. Quantitative 3D digital microscopy revealed a split mitochondrial network in Drp-1-overexpressing cells without changes in cell viability. High-speed mitochondrial [Ca2+] ([Ca2+]m) imaging revealed propagating intramitochondrial Ca2+ waves in intact cells, which were blocked in the Drp-1-fragmented network, leaving a fraction of individual mitochondria without substantial [Ca2+]m elevation. Consequently, in Drp-1-expressing cells the apoptotic efficacy of ceramide, which causes a Ca2+-dependent perturbation of mitochondrial structure and function, was drastically reduced. Conversely, the sensitivity to staurosporine-induced apoptosis, previously shown to be directly triggered by Drp-1-dependent recruitment of proapoptotic proteins to mitochondria, was enhanced. These results demonstrate that the regulated process of mitochondrial fusion and fission controls the spatiotemporal properties of mitochondrial Ca2+ responses and, thus, physiological and pathological consequences of cellular Ca2+ signals.
Szabadkai
György
G
Department of Experimental and Diagnostic Medicine, Section of General Pathology and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, 44100 Ferrara, Italy.
Simoni
Anna Maria
AM
Chami
Mounia
M
Wieckowski
Mariusz R
MR
Youle
Richard J
RJ
Rizzuto
Rosario
R
D017209:Apoptosis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D000098855:Collapsin Response Mediator Protein 1
D002118:Calcium; D009419:Nerve Tissue Proteins; C102924:CRMP1 protein, human; D000098855:Collapsin Response Mediator Protein 1