Protein Kinase C in Primary Astrocyte Cultures: Cytoplasmic Localization and Translocation by a Phorbol Ester

J. T. Neary, L. O.B. Norenberg, M. D. Norenberg

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

The distribution of calcium-activated, phospholipid-dependent protein kinase (protein kinase C) in supernatant and particulate fractions of primary cultures of rat astrocytes and its transocation by a phorbol ester were studied. We observed that 91% of protein kinase C activity in astrocytes was in the supernatant fraction, as measured by lysine-rich histone phosphorylation assay. Attempts to uncover latent activity in the particulate fraction were unsuccessful. Approximately 75% of the supernatant protein kinase C activity could be translocated to the particulate fraction by prior treatment (30-60 min) of the cultures whith 100 nM 12-O-tetradecanoyl-phorbol 13-acetate (TPA), but not with 4α-phorbol, an inactive phorbol ester. Investigation of endogenous substrates for protein kinase C showed that TPA treatment brought about an increase in phosphorylation in membrane proteins and a decrease in phosphorylation of supernatant proteins. These findings indicate that the distribution of protein kinase C in astrocytes differs substantially from that in whole brain tissue, where approximately two-thirds of the protein kinase C activity is associated with the particulate fraction. Because protein kinase C is concentrated in the cytosol of astrocytes and most of this activity can be translocated to membranes, astrocytes may be particularly well-suited to respond to signals that activate phosphoinositide-linked receptors in brain.

Original languageEnglish (US)
Pages (from-to)1179-1184
Number of pages6
JournalJournal of neurochemistry
Volume50
Issue number4
DOIs
StatePublished - Apr 1988

Keywords

  • Astrocytes
  • Phorbol esters
  • Protein kinase C

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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