JCB logo
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 4948K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hoth, M.
Right arrow Articles by Lewis, R. S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hoth, M.
Right arrow Articles by Lewis, R. S.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Facebook   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

© The Rockefeller University Press, 0021-9525/1997//633 $5.00
The Journal of Cell Biology, Volume 137, Number 3, , 1997 633-648

Article

Mitochondrial Regulation of Store-operated Calcium Signaling in T Lymphocytes



Markus Hoth, Christopher M. Fanger, and Richard S. Lewis

Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305-5426

Mitochondria act as potent buffers of intracellular Ca2+ in many cells, but a more active role in modulating the generation of Ca2+ signals is not well established. We have investigated the ability of mitochondria to modulate store-operated or "capacitative" Ca2+ entry in Jurkat leukemic T cells and human T lymphocytes using fluorescence imaging techniques. Depletion of the ER Ca2+ store with thapsigargin (TG) activates Ca2+ release-activated Ca2+ (CRAC) channels in T cells, and the ensuing influx of Ca2+ loads a TG- insensitive intracellular store that by several criteria appears to be mitochondria. Loading of this store is prevented by carbonyl cyanide m-chlorophenylhydrazone or by antimycin A1 + oligomycin, agents that are known to inhibit mitochondrial Ca2+ import by dissipating the mitochondrial membrane potential. Conversely, intracellular Na+ depletion, which inhibits Na+-dependent Ca2+ export from mitochondria, enhances store loading. In addition, we find that rhod-2 labels mitochondria in T cells, and it reports changes in Ca2+ levels that are consistent with its localization in the TG-insensitive store. Ca2+ uptake by the mitochondrial store is sensitive (threshold is <400 nM cytosolic Ca2+), rapid (detectable within 8 s), and does not readily saturate. The rate of mitochondrial Ca2+ uptake is sensitive to extracellular [Ca2+], indicating that mitochondria sense Ca2+ gradients near CRAC channels. Remarkably, mitochondrial uncouplers or Na+ depletion prevent the ability of T cells to maintain a high rate of capacitative Ca2+ entry over prolonged periods of >10 min. Under these conditions, the rate of Ca2+ influx in single cells undergoes abrupt transitions from a high influx to a low influx state. These results demonstrate that mitochondria not only buffer the Ca2+ that enters T cells via store-operated Ca2+ channels, but also play an active role in modulating the rate of capacitative Ca2+ entry.

Abbreviations used in this paper: BCECF, 2',7'-bis(2-carboxylethyl)- 5(6)-carboxyfluorescein; [Ca2+]i, cytosolic Ca2+ concentration; [Ca2+]m, mitochondrial Ca2+ concentration; CCCP, carbonyl cyanide m-chlorophenylhydrazone; CRAC, Ca2+ release-activated Ca2+; FCCP, carbonyl cyanide p-trifluoromethoxyphenylhydrazone; TG, thapsigargin.

M. Hoth would like to dedicate this paper to his late friend Kai Stockhusen, with whom he learned in school about the importance of the mitochondrial Ca2+ store.

Please address all correspondence to Markus Hoth, Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5426. Tel.: (415) 723-9623. Fax: (415) 725-8021. e-mail: mhoth{at}leland.stanford.edu


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Facebook Facebook   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents