Ca(2+) homeostasis during mitochondrial fragmentation and perinuclear clustering induced by hFis1

Article Article scientifique Article Ca(2+) homeostasis during mitochondrial fragmentation and perinuclear clustering induced by hFis1 eng 2004 author Frieden Maud 0000-0001-7135-0874 45900 author James Dominic 539217 author Castelbou Cyril 30263 author Danckaert Anne 135157 author Martinou Jean-Claude 27293 author Demaurex Nicolas 0000-0002-9933-6772 24642 22704-22714 10.1074/jbc.M312366200 15024001 0021-9258 Mitochondria modulate Ca(2+) signals by taking up, buffering, and releasing Ca(2+) at key locations near Ca(2+) release or influx channels. The role of such local interactions between channels and organelles is difficult to establish in living cells because mitochondria form an interconnected network constantly remodeled by coordinated fusion and fission reactions. To study the effect of a controlled disruption of the mitochondrial network on Ca(2+) homeostasis, we took advantage of hFis1, a protein that promotes mitochondrial fission by recruiting the dynamin-related protein, Drp1. hFis1 expression in HeLa cells induced a rapid and complete fragmentation of mitochondria, which redistributed away from the plasma membrane and clustered around the nucleus. Despite the dramatic morphological alteration, hFis1-fragmented mitochondria maintained a normal transmembrane potential and pH and took up normally the Ca(2+) released from intracellular stores upon agonist stimulation, as measured with a targeted ratiometric pericam probe. In contrast, hFis1-fragmented mitochondria took up more slowly the Ca(2+) entering across plasma membrane channels, because the Ca(2+) ions reaching mitochondria propagated faster and in a more coordinated manner in interconnected than in fragmented mitochondria. In parallel cytosolic fura-2 measurements, the capacitative Ca(2+) entry (CCE) elicited by store depletion was only marginally reduced by hFis1 expression. Regardless of mitochondria shape and location, disruption of mitochondrial potential with uncouplers or oligomycin/rotenone reduced CCE by approximately 35%. These observations indicate that close contact to Ca(2+) influx channels is not required for CCE modulation and that the formation of a mitochondrial network facilitates Ca(2+) propagation within interconnected mitochondria. Calcium/metabolism Cell Membrane/metabolism Cell Nucleus/metabolism Cytosol/metabolism Endoplasmic Reticulum/metabolism Green Fluorescent Proteins HeLa Cells Humans Hydrogen-Ion Concentration Ions Luminescent Proteins/metabolism Membrane Potentials Membrane Proteins Microscopy, Fluorescence Mitochondria/metabolism Mitochondrial Proteins/metabolism Time Factors Transfection Dewey 612 134 Département de physiologie cellulaire et métabolisme 21C false 168 Signaux intracellulaires 210 The Journal of biological chemistry 279 21 4f83f0b0-fe84-4354-b473-c5088b8f3ac3 Article (Published version) Public Ca2+ Homeostasis during Mitochondrial Fragmentation.pdf 969569 application/pdf openAccess Faculté de médecine / Section de médecine fondamentale / Département de physiologie cellulaire et métabolisme

Title	Published in	Access level	OA Policy	Year	Views	Downloads

Ca(2+) homeostasis during mitochondrial fragmentation and perinuclear clustering induced by hFis1	The Journal of biological chemistry			2004	679	528

Archive ouverte UNIGE

Danckaert, Anne