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Structural and functional relationships between Ca2+ puffs and mitochondria in Xenopusoocytes

Structural and functional relationships between Ca2+ puffs and mitochondria in Xenopusoocytes Abstract Ca 2+ uptake and release from endoplasmic reticulum (ER) and mitochondrial Ca 2+ 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 Ca 2+ release in Xenopus laevis oocytes by combining confocal imaging of local Ca 2+ release events (“Ca 2+ puffs”) with mitochondrial localization visualized using vital dyes and subcellularly targeted fluorescent proteins. Mitochondria and ER are localized in cortical bands ∼6–8 μm 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 Ca 2+ puff sites and mitochondria is ∼2.3 μm. However, a subpopulation of Ca 2+ puff sites is intimately associated with mitochondria (∼28% within <600 nm), a greater number than expected if Ca 2+ puff sites were randomly distributed. Ca 2+ release sites close to mitochondria exhibit lower Ca 2+ puff activity than Ca 2+ puff sites in regions with lower mitochondrial density. Furthermore, Ca 2+ puff sites in close association with mitochondria rarely serve as the sites for Ca 2+ wave initiation. We conclude that mitochondria play important roles in regulating local ER excitability, Ca 2+ wave initiation, and, thereby, spatial patterning of global Ca 2+ signals. endoplasmic reticulum calcium release Footnotes Address for reprint requests and other correspondence: I. Parker, Dept. of Neurobiology and Behavior, University of California, Irvine, CA 92697-4550 (E-mail: iparker@uci.edu ). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “ advertisement ” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. First published February 6, 2002;10.1152/ajpcell.00446.2001 Copyright © 2002 the American Physiological Society http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Cell Physiology The American Physiological Society

Structural and functional relationships between Ca2+ puffs and mitochondria in Xenopusoocytes

Marchant, Jonathan S.; Ramos, Viviana; Parker, Ian
AJP - Cell Physiology , Volume 282 (6): C1374 – Jun 1, 2002
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References (54)

Publisher
The American Physiological Society
Copyright
Copyright © 2010 the American Physiological Society
ISSN
0363-6143
eISSN
1522-1563
DOI
10.1152/ajpcell.00446.2001
pmid
11997252
Publisher site
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Abstract

Abstract Ca 2+ uptake and release from endoplasmic reticulum (ER) and mitochondrial Ca 2+ 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 Ca 2+ release in Xenopus laevis oocytes by combining confocal imaging of local Ca 2+ release events (“Ca 2+ puffs”) with mitochondrial localization visualized using vital dyes and subcellularly targeted fluorescent proteins. Mitochondria and ER are localized in cortical bands ∼6–8 μm 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 Ca 2+ puff sites and mitochondria is ∼2.3 μm. However, a subpopulation of Ca 2+ puff sites is intimately associated with mitochondria (∼28% within <600 nm), a greater number than expected if Ca 2+ puff sites were randomly distributed. Ca 2+ release sites close to mitochondria exhibit lower Ca 2+ puff activity than Ca 2+ puff sites in regions with lower mitochondrial density. Furthermore, Ca 2+ puff sites in close association with mitochondria rarely serve as the sites for Ca 2+ wave initiation. We conclude that mitochondria play important roles in regulating local ER excitability, Ca 2+ wave initiation, and, thereby, spatial patterning of global Ca 2+ signals. endoplasmic reticulum calcium release Footnotes Address for reprint requests and other correspondence: I. Parker, Dept. of Neurobiology and Behavior, University of California, Irvine, CA 92697-4550 (E-mail: iparker@uci.edu ). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “ advertisement ” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. First published February 6, 2002;10.1152/ajpcell.00446.2001 Copyright © 2002 the American Physiological Society

Journal

AJP - Cell Physiology – The American Physiological Society

Published: Jun 1, 2002

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