Inhibitory effect of 14-3-3 proteins on serum-induced proliferation of cardiac fibroblasts.
Proliferation in cardiac fibroblasts (CFs) can be induced by a wide variety of growth factors that recruit multiple signal transduction pathways, including mitogen-activated protein kinase, phosphatidylinositol 3-kinase and protein kinase C. As a family of dimeric phophoserine-binding proteins, 14-3-3s are associated with a multitude of proteins that regulate signal transduction, apoptosis and checkpoint control pathways. However, it remains unknown whether the 14-3-3 proteins play an active role in cardiac proliferation and alter their expression patterns in response to growth factors in CFs. R18 peptide, an isoform-independent 14-3-3 inhibitor, was used to disrupt 14-3-3 function by adenovirus-mediated transfer of R18-EYFP (AdR18). Our results demonstrate that the 14-3-3 isoforms gamma, zeta and epsilon were highly expressed in CFs and the expression of 14-3-3 epsilon was elevated following serum stimulation. Inhibition of 14-3-3 proteins by AdR18 potentiated mitogen-induced DNA synthesis in CFs. This potentiation was presumably due to the increased inactivated glycogen synthase kinase-3 beta by Ser9 phosphorylation and nuclear factor of activated T-cell nuclear accumulation. However, AdR18 had no effect on extracellular signal-regulated kinase phosphorylation and reduced p70 S6 kinase (p70S6K) phosphorylation upon mitogenic stimulation. Furthermore, though R18 can block 14-3-3 binding abilities, it did not affect the serum-induced upregulation of 14-3-3 epsilon protein. Collectively, these findings reveal that the expression of 14-3-3 epsilon can be upregulated by serum in CFs and 14-3-3s may exert an inhibitory effect on serum-induced proliferation.
Du
Jianhai
J
Institute of Vascular Medicine, Peking University Third Hospital and Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing 100083, P.R China.
Liao
Wenqiang
W
Wang
Yongyu
Y
Han
Chide
C
Zhang
Youyi
Y
D048948:14-3-3 Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002070:Butadienes / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D015870:Gene Expression; D009025:Morpholines / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology*; D050778:NFATC Transcription Factors / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology; D020033:Protein Isoforms; D051381:Rats; D044967:Serum / Q000737:chemistry*; D015854:Up-Regulation / Q000235:genetics
D048948:14-3-3 Proteins; D002070:Butadienes; D002867:Chromones; D009025:Morpholines; D050778:NFATC Transcription Factors; D009570:Nitriles; D020033:Protein Isoforms; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D048049:Extracellular Signal-Regulated MAP Kinases