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c-Src couples PI 3 kinase/Akt and MAPK signaling to PDGF-induced DNA synthesis in mesangial cells.

Authors: Choudhury, GG  Mahimainathan, L  Das, F  Venkatesan, B  Ghosh-Choudhury, N 
Citation: Choudhury GG, etal., Cell Signal. 2006 Nov;18(11):1854-64.
Pubmed: (View Article at PubMed) PMID:16530387
DOI: Full-text: DOI:10.1016/j.cellsig.2006.02.003

Platelet-derived growth factor BB (PDGF) and PDGF receptor-beta (PDGFR) play critical roles in mesangial cell proliferation during embryonic development and in mesangioproliferative glomerulonephritis. We have shown previously that phosphatidylinositol (PI) 3 kinase/Akt and Erk1/2 mitogen-activated protein kinase (MAPK) contribute to PDGF-dependent proliferation of mesangial cells, but the mechanism by which these two enzyme cascades are activated by PDGFR signaling is not precisely known. We examined the role of c-Src tyrosine kinase in this process. PDGF increased phosphorylation of c-Src in a time-dependent manner indicating its activation. A pharmacologic inhibitor of c-Src, PP1, blocked PDGF-induced DNA synthesis with concomitant inhibition of c-Src phosphorylation. Immune-complex kinase assays of c-Src and PDGFR demonstrated inhibition of c-Src tyrosine kinase activity by PP1, without an effect on PDGFR tyrosine phosphorylation. Both PP1 and expression of dominant negative c-Src inhibited PDGF-induced PI 3 kinase, resulting in attenuation of Akt kinase activity. Expression of constitutively active c-Src increased Akt activity to the same extent as with PDGF. Constitutively active c-Src augmented PDGF-induced Akt activity, thus contributing to Akt signaling. Inhibition of c-Src tyrosine kinase blocked PDGF-stimulated MAPK activity and resulted in attenuation of c-fos gene transcription with concomitant prevention of Elk-1 transactivation. Furthermore, inhibition of c-Src increased p27(Kip1) cyclin kinase inhibitor, and attenuated PDGF-induced pRb phosphorylation and CDK2 activity. These data provide the first evidence in mesangial cells that PDGF-activated c-Src tyrosine kinase relays signals to PI 3 kinase/Akt and MAPK. Furthermore our results demonstrate that c-Src integrates signals into the nucleus to activate CDK2, which is required for DNA synthesis.

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CRRD Object Information
CRRD ID: 8553998
Created: 2014-05-08
Species: All species
Last Modified: 2014-05-08
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.