Akt kinase targets association of CBP with SMAD 3 to regulate TGFβ-induced expression of plasminogen activator inhibitor-1

Falguni Das, Nandini Ghosh-Choudhury, Balachandar Venkatesan, Xiaonan Li, Lenin Mahimainathan, Goutam Ghosh Choudhury

Research output: Contribution to journalArticle

56 Scopus citations

Abstract

Transforming growth factor-β (TGFβ) controls expression of plasminogen activator inhibitor type 1 (PAI-1), which regulates degradation of extracellular matrix proteins in fibrotic diseases. The TGFβ receptor-specific Smad 3 has been implicated in the PAI-1 expression. The mechanism by which non-Smad signaling contributes to this process is not known. We studied the cross-talk between Smad 3 and PI 3 kinase/Akt signaling in TGFβ-induced PAI-1 expression in renal mesangial cells. Inhibition of PI 3 kinase and Akt kinase blocked TGFβ- and Smad 3-mediated expression of PAI-1. In contrast, constitutively active PI 3 kinase and Akt kinase increased PAI-1 expression, similar to TGFβ. Inhibition of PI 3 kinase and Akt kinase had no effect on TGFβ-induced Smad 3 phosphorylation and its translocation to the nucleus. Notably, inhibition of PI 3 kinase-dependent Akt kinase abrogated TGFβ-induced PAI-1 transcription, without affecting binding of Smad 3 to the PAI-1 Smad binding DNA element. However, PI 3 kinase inhibition and dominant negative Akt kinase antagonized the association of the transcriptional coactivator CBP with Smad 3 in response to TGFβ, resulting in inhibition of Smad 3 acetylation. Together our findings identify TGFβ-induced PI 3 kinase/Akt signaling as a critical regulator of Smad 3-CBP interaction and Smad 3 acetylation, which cause increased PAI-1 expression.

Original languageEnglish (US)
Pages (from-to)513-527
Number of pages15
JournalJournal of Cellular Physiology
Volume214
Issue number2
DOIs
StatePublished - Feb 2008

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Cell Biology

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