mu-Calpain mediated cleavage of the Na+/Ca2+ exchanger in isolated mitochondria under A23187 induced Ca2+ stimulation

Arch Biochem Biophys. 2009 Feb;482(1-2):66-76. doi: 10.1016/j.abb.2008.11.024. Epub 2008 Dec 10.

Abstract

Treatment of bovine pulmonary artery smooth muscle mitochondria with the calcium ionophore, A23187 (0.2 microM) stimulates mu-calpain activity and subsequently cleaves Na(+)/Ca(2+) exchanger (NCX). Pretreatment of the A23187 treated mitochondria with the calpain inhibitors, calpeptin or MDL28170 or with Ca(2+) chelator, EGTA does not cleave NCX. Treatment of the mitochondria with A23187 increases Ca(2+) level in the mitochondria, which subsequently dissociates mu-calpain-calpastatin association leading to the activation of mu-calpain. Immunoblot study of the A23187 treated mitochondria with the NCX polyclonal antibody indicates the degradation of mitochondrial inner membrane NCX (110kDa) resulting in the doublet of approximately 54-56kDa NCX fragments. Moreover, in vitro cleavage of mitochondrial purified NCX by mitochondrial purified mu-calpain supports our conclusion. This cleavage of NCX may be interpreted as the main cause of Ca(2+) overload and could lay a key role in the activation of apoptotic process in pulmonary smooth muscle.

MeSH terms

  • Animals
  • Calcimycin / pharmacology*
  • Calcium / metabolism*
  • Calcium-Binding Proteins / isolation & purification
  • Calcium-Binding Proteins / metabolism
  • Calpain / drug effects
  • Calpain / isolation & purification
  • Calpain / metabolism*
  • Cattle
  • Dipeptides / pharmacology
  • Intracellular Membranes / drug effects
  • Intracellular Membranes / metabolism
  • Mitochondria, Muscle / drug effects
  • Mitochondria, Muscle / metabolism*
  • Mitochondria, Muscle / ultrastructure
  • Mitochondrial Membranes / drug effects
  • Mitochondrial Membranes / metabolism
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / physiology*
  • Phosphatidylcholines / pharmacology
  • Phospholipid Ethers / pharmacology
  • Pulmonary Artery / drug effects
  • Pulmonary Artery / physiology*
  • Sodium-Calcium Exchanger / metabolism*

Substances

  • 1,2-dihexadecyl-sn-glycero-3-phosphocholine
  • Calcium-Binding Proteins
  • Dipeptides
  • Phosphatidylcholines
  • Phospholipid Ethers
  • Sodium-Calcium Exchanger
  • calpeptin
  • Calcimycin
  • calpastatin
  • Calpain
  • mu-calpain
  • 1,2-oleoylphosphatidylcholine
  • Calcium
  • calpain inhibitor III