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Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells
08:29

Analyses of Mitochondrial Calcium Influx in Isolated Mitochondria and Cultured Cells

Published on: April 27, 2018

Protein kinases reduce mitochondrial Ca2+ uptake through an action on the outer mitochondrial membrane

Gergö Szanda1, Eszter Halász, András Spät

  • 1Department of Physiology, Semmelweis University, Budapest, Hungary.

Cell Calcium
|September 14, 2010
PubMed

Insights

Protein kinases p38 MAPK and novel-type PKC isoforms regulate mitochondrial calcium uptake. Their activation impedes calcium entry by affecting the outer mitochondrial membrane, controlling calcium availability to inner mitochondrial transporters.

Area of Science:

  • Cellular Biology
  • Mitochondrial Physiology
  • Signal Transduction

Background:

  • Cytosolic calcium signals are crucial for cellular functions, involving mitochondrial calcium uptake.
  • Previously, p38 MAPK and novel-type PKC isoforms were shown to attenuate mitochondrial calcium uptake in H295R cells.

Purpose of the Study:

  • To investigate the mechanism by which p38 MAPK and novel-type PKC isoforms inhibit mitochondrial calcium uptake.
  • To determine the role of the outer mitochondrial membrane in this kinase-mediated regulation.

Main Methods:

  • Experiments were conducted in H295R cells.
  • Mitochondrial membrane potential was clamped or dissipated.
  • Calcium uptake rates were measured in permeabilized cells.
  • The integrity of the outer mitochondrial membrane was assessed.

Main Results:

  • Kinase-mediated inhibition of mitochondrial calcium uptake was observed even with altered mitochondrial membrane potential.
  • Kinase activation increased the calcium concentration required for half-maximal uptake.
  • Inhibition was dependent on an intact outer mitochondrial membrane.
  • The outer mitochondrial membrane limits calcium diffusion when kinases are active.

Conclusions:

  • The outer mitochondrial membrane impedes mitochondrial calcium uptake by controlling calcium availability at the inner mitochondrial membrane.
  • p38 MAPK and novel-type PKC isoforms regulate calcium transport through the outer mitochondrial membrane.

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