Bisindolylmaleimide I suppresses fibroblast growth factor-mediated activation of Erk MAP kinase in chondrocytes by preventing Shp2 association with the Frs2 and Gab1 adaptor proteins.
Fibroblast growth factors (FGFs) inhibit chondrocyte proliferation via the Erk MAP kinase pathway. Here, we explored the role of protein kinase C in FGF signaling in chondrocytes. Erk activity in FGF2-treated RCS (rat chondrosarcoma) chondrocytes or human primary chondrocytes was abolished by the protein kinase C inhibitor bisindolylmaleimide I (Bis I). Bis I inhibited FGF2-induced activation of MEK, Raf-1, and Ras members of Erk signaling module but not the FGF2-induced tyrosine phosphorylation of Frs2 or the kinase activity of FGFR3, demonstrating that it targets the Erk cascade immediately upstream of Ras. Indeed, Bis I abolished the FGF2-mediated association of Shp2 tyrosine phosphatase with Frs2 and Gab1 adaptor proteins necessary for proper Ras activation. We also determined which PKC isoform is involved in FGF2-mediated activation of Erk. When both conventional and novel PKCs expressed by RCS chondrocytes (PKCalpha, -gamma, -delta, and -epsilon) were down-regulated by phorbol ester, cells remained responsive to FGF2 with Erk activation, and this activation was sensitive to Bis I. Moreover, treatment with PKClambda/zeta pseudosubstrate lead to significant reduction of FGF2-mediated activation of Erk, suggesting involvement of an atypical PKC.
Krejci
Pavel
P
Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048, USA. pavel.krejci@cshs.org
Masri
Bernard
B
Salazar
Lisa
L
Farrington-Rock
Claire
C
Prats
Herve
H
Thompson
Leslie Michels
LM
Wilcox
William R
WR
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D045744:Cell Line, Tumor; D019902:Chondrocytes / Q000187:drug effects / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005346:Fibroblast Growth Factors / Q000502:physiology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors*; D008301:Maleimides / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism*; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors*; D051381:Rats
D048868:Adaptor Proteins, Signal Transducing; D004791:Enzyme Inhibitors; C106534:FRS2 protein, human; C098587:GAB1 protein, human; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins; D008301:Maleimides; D008565:Membrane Proteins; D005346:Fibroblast Growth Factors; D048049:Extracellular Signal-Regulated MAP Kinases; C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; C516727:Ptpn11 protein, rat; C070515:bisindolylmaleimide I