Intermittent increases in cytosolic Ca2 stimulate mitochondrial biogenesis in muscle cells
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Date
2002
Journal Title
Journal ISSN
Volume Title
Publisher
Am J Physiol Endocrinol Metab 283
Abstract
Intermittent increases in cytosolic Ca2
stimulate mitochondrial biogenesis in muscle cells. Am J
Physiol Endocrinol Metab 283: E1040–E1045, 2002. First
published July 24, 2002; 10.1152/ajpendo.00242.2002.—Muscle
contractions cause numerous disturbances in intracellular
homeostasis. This makes it impossible to use contracting
muscle to identify which of the many signals generated by
contractions are responsible for stimulating mitochondrial
biogenesis. One purpose of this study was to evaluate the
usefulness of L6 myotubes, which do not contract, for studying
mitochondrial biogenesis. A second purpose was to evaluate
further the possibility that increases in cytosolic Ca2
can stimulate mitochondrial biogenesis. Continuous exposure
to 1 Mionomycin, a Ca2 ionophore, for 5 days induced
an increase in mitochondrial enzymes but also caused a loss
of myotubes, as reflected in an 40% decrease in protein per
dish. However, intermittent (5 h/day) exposure to ionomycin,
or to caffeine or W7, which release Ca2 from the sarcoplasmic
reticulum, did not cause a decrease in protein per dish.
Raising cytosolic Ca2 intermittently with these agents induced
significant increases in mitochondrial enzymes. EGTA
blocked most of this effect of ionomycin, whereas dantrolene,
which blocks Ca2 release from the sarcoplasmic reticulum,
largely prevented the increases in mitochondrial enzymes
induced by W7 and caffeine. These findings provide evidence
that intermittently raising cytosolic Ca2 stimulates mitochondrial
biogenesis in muscle cells.
caffeine; exercise; gene expression; ionomycin; L6 myotubes
Description
Keywords
mitochondrial biogenesis in muscle cells, Intermittent increases in cytosolic Ca2
Citation
Ojuka, E. O., Jones, T. E., Han, D. H., Chen, M., Wamhoff, B. R., Sturek, M., & Holloszy, J. O. (2002). Intermittent increases in cytosolic Ca2+ stimulate mitochondrial biogenesis in muscle cells. American Journal of Physiology-Endocrinology and Metabolism, 283(5), E1040-E1045.