UNIGE document Scientific Article
previous document  unige:7087  next document
add to browser collection
Title

Mitochondria recycle Ca(2+) to the endoplasmic reticulum and prevent the depletion of neighboring endoplasmic reticulum regions

Authors
Walsh, J. V.
Published in Journal of Biological Chemistry. 2001, vol. 276, no. 31, p. 29430-29439
Abstract To study Ca(2+) fluxes between mitochondria and the endoplasmic reticulum (ER), we used "cameleon" indicators targeted to the cytosol, the ER lumen, and the mitochondrial matrix. High affinity mitochondrial probes saturated in approximately 20% of mitochondria during histamine stimulation of HeLa cells, whereas a low affinity probe reported averaged peak values of 106 +/- 5 microm, indicating that Ca(2+) transients reach high levels in a fraction of mitochondria. In concurrent ER measurements, [Ca(2+)](ER) averaged 371 +/- 21 microm at rest and decreased to 133 +/- 14 microm and 59 +/- 5 microm upon stimulation with histamine and thapsigargin, respectively, indicating that substantial ER refilling occur during agonist stimulation. A larger ER depletion was observed when mitochondrial Ca(2+) uptake was prevented by oligomycin and rotenone or when Ca(2+) efflux from mitochondria was blocked by CGP 37157, indicating that some of the Ca(2+) taken up by mitochondria is re-used for ER refilling. Accordingly, ER regions close to mitochondria released less Ca(2+) than ER regions lacking mitochondria. The ER heterogeneity was abolished by thapsigargin, oligomycin/rotenone, or CGP 37157, indicating that mitochondrial Ca(2+) uptake locally modulate ER refilling. These observations indicate that some mitochondria are very close to the sites of Ca(2+) release and recycle a substantial portion of the captured Ca(2+) back to vicinal ER domains. The distance between the two organelles thus determines both the amplitude of mitochondrial Ca(2+) signals and the filling state of neighboring ER regions.
Keywords Calcium/ metabolismCalcium-Transporting ATPases/metabolismCell LineClonazepam/analogs & derivatives/pharmacologyCytosol/metabolismEndoplasmic Reticulum/drug effects/ metabolism/ultrastructureFluorescent DyesHela CellsHistamine/pharmacologyHumansHydrogen-Ion ConcentrationKineticsMitochondria/drug effects/ metabolism/ultrastructureOligomycins/pharmacologyRotenone/pharmacologySarcoplasmic Reticulum Calcium-Transporting ATPasesThapsigargin/pharmacologyThiazepines/pharmacology
Identifiers
PMID: 11358971
Full text
Article - document accessible for UNIGE members only Limited access to UNIGE
Other version: http://www.jbc.org/content/276/31/29430.full.pdf
Structures
Citation
(ISO format)
ARNAUDEAU, Serge et al. Mitochondria recycle Ca(2+) to the endoplasmic reticulum and prevent the depletion of neighboring endoplasmic reticulum regions. In: Journal of Biological Chemistry, 2001, vol. 276, n° 31, p. 29430-29439. https://archive-ouverte.unige.ch/unige:7087

177 hits

0 download

Update

Deposited on : 2010-06-21

Export document
Format :
Citation style :