Medical College of Wisconsin
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Structural and functional relationships between Ca2+ puffs and mitochondria in Xenopus oocytes. Am J Physiol Cell Physiol 2002 Jun;282(6):C1374-86 PMID: 11997252

Abstract

Ca2+ uptake and release from endoplasmic reticulum (ER) and mitochondrial Ca2+ stores play important physiological and pathological roles, and these processes are shaped by interactions that depend on the structural intimacy between these organelles. Here we investigate the morphological and functional relationships between mitochondria, ER, and the sites of intracellular Ca2+ release in Xenopus laevis oocytes by combining confocal imaging of local Ca2+ release events ("Ca2+ puffs") with mitochondrial localization visualized using vital dyes and subcellularly targeted fluorescent proteins. Mitochondria and ER are localized in cortical bands approximately 6-8 microm wide, with the mitochondria arranged as densely packed "islands" interconnected by discrete strands. The ER is concentrated more superficially than mitochondria, and the mean separation between Ca2+ puff sites and mitochondria is approximately 2.3 microm. However, a subpopulation of Ca2+ puff sites is intimately associated with mitochondria (approximately 28% within <600 nm), a greater number than expected if Ca2+ puff sites were randomly distributed. Ca2+ release sites close to mitochondria exhibit lower Ca2+ puff activity than Ca2+ puff sites in regions with lower mitochondrial density. Furthermore, Ca2+ puff sites in close association with mitochondria rarely serve as the sites for Ca2+ wave initiation. We conclude that mitochondria play important roles in regulating local ER excitability, Ca2+ wave initiation, and, thereby, spatial patterning of global Ca2+ signals.

Author List

Marchant JS, Ramos V, Parker I

Author

Jonathan S. Marchant PhD Chair, Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

3T3 Cells
Animals
Calcium Signaling
Endoplasmic Reticulum
Fibroblasts
Mice
Microscopy, Confocal
Microscopy, Video
Mitochondria
Oocytes
Xenopus laevis



View this publication's entry at the Pubmed website PMID: 11997252
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