Stimulation of the platelet-derived growth factor beta receptor signaling pathway activates protein kinase C-delta.
The murine myeloid progenitor cell line 32D was recently shown to undergo monocytic differentiation when protein kinase C-delta (PKC-delta) was overexpressed and activated by 12-O-tetradecanoylphorbol-13-acetate (TPA) (H. Mischak, J.H. Pierce, J. Goodnight, M.G. Kazanietz, P.M. Blumberg, and J.F. Mushinski, J. Biol. Chem. 268:20110-20115, 1993). Tyrosine phosphorylation of PKC-delta occurred when PKC-delta-transfected 32D cells were stimulated by TPA (W. Li, H. Mischak, J.-C. Yu, L.-M. Wang, J.F. Mushinski, M.A. Heidaran, and J.H. Pierce, J. Biol. Chem. 269:2349-2352, 1994). In order to elucidate the role played by PKC-delta in response to activation of a receptor tyrosine kinase, we transfected platelet-derived growth factor beta receptor (PDGF-beta R) alone (32D/PDGF-beta R) or together with PKC-delta (32D/PDGF-beta R/PKC-delta) into 32D cells. NIH 3T3 cells which endogenously express both PDGF-alpha R and PDGF-beta R were also transfected with PKC-delta (NIH 3T3/PKC-delta). Like TPA treatment, PDGF-BB stimulation caused striking phosphorylation of PKC-delta in vivo and translocation of some PKC-delta from the cytosol fraction to the membrane fraction in both cell systems. Some of the phosphorylation induced by PDGF-BB treatment was found to be on a tyrosine residue(s). Tyrosine-phosphorylated PKC-delta was observed only for the membrane fraction after stimulation with PDGF-BB or TPA. The enzymatic activity of PKC-delta in the membrane fraction also increased after stimulation with TPA or PDGF, providing a positive correlation between PKC-delta tyrosine phosphorylation and its activation. Overnight treatment of 32D/PDGF-beta R/PKC-delta cells with PDGF-BB induced monocytic differentiation as judged by an increase in expression of cell surface macrophage differentiation markers. PDGF-BB had much weaker effects on 32D/PDGF-beta R cell differentiation, suggesting that increased PKC-delta expression enhanced monocytic differentiation. These results indicate that PKC-delta is a downstream molecule in the PDGFR signaling pathway and may play a pivotal role in PDGF-beta R-mediated cell differentiation.
Li
W
W
Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892.
Yu
J C
JC
Michieli
P
P
Beeler
J F
JF
Ellmore
N
N
Heidaran
M A
MA
Pierce
J H
JH
D000818:Animals; D001692:Biological Transport; D002451:Cell Compartmentation; D002454:Cell Differentiation; D002460:Cell Line; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D007527:Isoenzymes / Q000378:metabolism*; D008566:Membranes / Q000201:enzymology; D051379:Mice; D009000:Monocytes / Q000502:physiology; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic; D014443:Tyrosine / Q000378:metabolism; D015854:Up-Regulation
D007527:Isoenzymes; D010982:Platelet-Derived Growth Factor; D014443:Tyrosine; C497259:Prkcd protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D011493:Protein Kinase C; D051745:Protein Kinase C-delta