Up-regulation of surface CD34 is associated with protein kinase C-mediated hyperphosphorylation of CD34

M. J. Fackler, C. I. Civin, W. S. May

Research output: Contribution to journalArticlepeer-review

Abstract

CD34 is a transmembrane sialoglycoprotein expressed by early hematopoietic progenitor cells as well as endothelial cells. Previously we found that CD34 is rapidly and stoichiometrically phosphorylated by activated protein kinase C (PKC) (Fackler, M. J., Civin, C. I., Sutherland, D. R., Baker, M. A., and May, W. S. (1990) J. Biol. Chem. 265, 11056-11061). In the present study, we find dose-dependent up-regulation of CD34 surface expression following treatment of normal human CD34+ bone marrow progenitor cells, cord blood- derived KMT-2, or KG1a myeloid leukemia cells with the PKC activator 12-O- tetradecanoylphorbol-13-acetate. Up-regulation begins within 1 min of treatment, is maximal by 30 min, is maintained for at least 3 h, and is associated with CD34 hyperphosphorylation. A specific inhibitor of PKC, 2,6- diamino-N-([1-(1-oxotridecyl)-2-piperidinyl]methyl)hexan-amide (NPC 15437), blocks both up-regulation and hyperphosphorylation of CD34. CD34 up- regulation is independent of transcription and/or translation and results from the recruitment of preformed intracellular CD34. The endocytosis rate of surface CD34 is unaltered by 12-O-tetradecanoylphorbol-13-acetate. Thus, activation of PKC mediates increased surface expression of the CD34 molecule possibly as a result of phosphorylation of CD34.

Original languageEnglish (US)
Pages (from-to)17540-17546
Number of pages7
JournalJournal of Biological Chemistry
Volume267
Issue number25
StatePublished - 1992

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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