Immunogold electron microscopic demonstration of distinct submembranous localization of the activated gammaPKC depending on the stimulation

J Histochem Cytochem. 2008 Mar;56(3):253-65. doi: 10.1369/jhc.7A7291.2007. Epub 2007 Nov 26.

Abstract

We examined the precise intracellular translocation of gamma subtype of protein kinase C (gammaPKC) after various extracellular stimuli using confocal laser-scanning fluorescent microscopy (CLSM) and immunogold electron microscopy. By CLSM, treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA) resulted in a slow and irreversible accumulation of green fluorescent protein (GFP)-tagged gammaPKC (gammaPKC-GFP) on the plasma membrane. In contrast, treatment with Ca(2+) ionophore and activation of purinergic or NMDA receptors induced a rapid and transient membrane translocation of gammaPKC-GFP. Although each stimulus resulted in PKC localization at the plasma membrane, electron microscopy revealed that gammaPKC showed a subtle but significantly different localization depending on stimulation. Whereas TPA and UTP induced a sustained localization of gammaPKC-GFP on the plasma membrane, Ca(2+) ionophore and NMDA rapidly translocated gammaPKC-GFP to the plasma membrane and then restricted gammaPKC-GFP in submembranous area (<500 nm from the plasma membrane). These results suggest that Ca(2+) influx alone induced the association of gammaPKC with the plasma membrane for only a moment and then located this enzyme at a proper distance in a touch-and-go manner, whereas diacylglycerol or TPA tightly anchored this enzyme on the plasma membrane. The distinct subcellular targeting of gammaPKC in response to various stimuli suggests a novel mechanism for PKC activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Calcimycin / pharmacology
  • Calcium / metabolism
  • Cell Membrane / metabolism
  • Cricetinae
  • Cricetulus
  • Enzyme Activation
  • Enzyme Activators / pharmacology*
  • Ionophores / pharmacology
  • Isoenzymes / metabolism
  • Microscopy, Confocal
  • Microscopy, Electron
  • Microscopy, Fluorescence
  • N-Methylaspartate / pharmacology
  • Protein Kinase C / metabolism*
  • Protein Transport
  • Receptors, N-Methyl-D-Aspartate / agonists
  • Receptors, N-Methyl-D-Aspartate / metabolism
  • Subcellular Fractions / metabolism
  • Tetradecanoylphorbol Acetate / pharmacology
  • Uridine Triphosphate / pharmacology

Substances

  • Enzyme Activators
  • Ionophores
  • Isoenzymes
  • Receptors, N-Methyl-D-Aspartate
  • Calcimycin
  • N-Methylaspartate
  • protein kinase C gamma
  • Protein Kinase C
  • Tetradecanoylphorbol Acetate
  • Calcium
  • Uridine Triphosphate