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Pyk2- and Src-dependent tyrosine phosphorylation of PDK1 regulates focal adhesions

Yoshihiro Taniyama1, David S Weber, Petra Rocic

  • 1Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1639 Pierce Drive, Atlanta, GA 30322, USA.

Molecular and Cellular Biology
|October 31, 2003
PubMed

Insights

Angiotensin II triggers tyrosine phosphorylation of 3-phosphoinositide-dependent protein kinase 1 (PDK1) in vascular smooth muscle. This interaction with Pyk2 kinase is crucial for focal adhesion integrity and cell signaling.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • 3-Phosphoinositide-dependent protein kinase 1 (PDK1) integrates signals and activates AGC kinases.
  • Regulation of PDK1 by G-protein-coupled receptor agonists and its tyrosine phosphorylation consequences are not fully understood.

Purpose of the Study:

  • To investigate the regulation of PDK1 tyrosine phosphorylation by angiotensin II in vascular smooth muscle.
  • To elucidate the role of Pyk2 and Src kinases in this process and its physiological impact.

Main Methods:

  • Utilized vascular smooth muscle cells and angiotensin II stimulation.
  • Employed techniques to assess tyrosine phosphorylation, kinase activity (c-Src, Pyk2), protein colocalization, and cell morphology.
  • Used a Tyr9 mutant of PDK1 to study its function.

Main Results:

  • Angiotensin II stimulates calcium- and c-Src-dependent tyrosine phosphorylation of PDK1 in vascular smooth muscle.
  • Pyk2 acts as a scaffold for Src-mediated phosphorylation of PDK1 at Tyr9, enabling further phosphorylation at Tyr373 and -376.
  • Pyk2 and tyrosine-phosphorylated PDK1 colocalize in focal adhesions; a Tyr9 PDK1 mutant impairs angiotensin II-induced paxillin phosphorylation and focal adhesion formation.

Conclusions:

  • Identified a novel interaction between PDK1 and Pyk2 in regulating focal adhesion integrity.
  • This PDK1-Pyk2 interaction is critical for integrating signals involved in cell growth, apoptosis, and migration in vascular smooth muscle cells.

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