Intracellular calcium signals regulating cytosolic phospholipase A2 translocation to internal membranes

J Biol Chem. 2001 Aug 10;276(32):30150-60. doi: 10.1074/jbc.M100943200. Epub 2001 May 24.

Abstract

Increased intracellular Ca(2+) concentrations ([Ca(2+)](i)) promote cytosolic phospholipase A(2) (cPLA(2)) translocation to intracellular membranes. The specific membranes to which cPLA(2) translocates and the [Ca(2+)](i) signals required were investigated. Plasmids of EGFP fused to full-length cPLA(2) (EGFP-FL) or to the cPLA(2) C2 domain (EGFP-C2) were used in Ca(2+)/EGFP imaging experiments of cells treated with [Ca(2+)](i)-mobilizing agonists. EGFP-FL and -C2 translocated to Golgi in response to sustained [Ca(2+)](i) greater than approximately 100-125 nm and to Golgi, ER, and perinuclear membranes (PNM) at [Ca(2+)](i) greater than approximately 210-280 nm. In response to short duration [Ca(2+)](i) transients, EGFP-C2 translocated to Golgi, ER, and PNM, but EGFP-FL translocation was restricted to Golgi. However, EGFP-FL translocated to Golgi, ER, and PNM in response to long duration transients. In response to declining [Ca(2+)](i), EGFP-C2 readily dissociated from Golgi, but EGFP-FL dissociation was delayed. Agonist-induced arachidonic acid release was proportional to the [Ca(2+)](i) and to the extent of cPLA(2) translocation. In summary, we find that the differential translocation of cPLA(2) to Golgi or to ER and PNM is a function of [Ca(2+)](i) amplitude and duration. These results suggest that the cPLA(2) C2 domain regulates differential, Ca(2+)-dependent membrane targeting and that the catalytic domain regulates both the rate of translocation and enzyme residence.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Arachidonic Acid / metabolism
  • Calcium / metabolism*
  • Cell Membrane / enzymology*
  • Cells, Cultured
  • Cytosol / enzymology*
  • DNA, Complementary / metabolism
  • Dogs
  • Endoplasmic Reticulum / enzymology
  • Enzyme Inhibitors / pharmacology
  • Golgi Apparatus / enzymology
  • Immunoblotting
  • Immunohistochemistry
  • Intracellular Membranes / enzymology
  • Ionomycin / pharmacology
  • Ionophores / pharmacology
  • Kinetics
  • Microscopy, Confocal
  • Phospholipases A / metabolism*
  • Phospholipases A2
  • Plasmids / metabolism
  • Protein Structure, Tertiary
  • Protein Transport
  • Recombinant Fusion Proteins / metabolism
  • Thapsigargin / pharmacology
  • Time Factors
  • Transfection

Substances

  • DNA, Complementary
  • Enzyme Inhibitors
  • Ionophores
  • Recombinant Fusion Proteins
  • Arachidonic Acid
  • Ionomycin
  • Thapsigargin
  • Adenosine Triphosphate
  • Phospholipases A
  • Phospholipases A2
  • Calcium