Pyk2- and Src-dependent tyrosine phosphorylation of PDK1 regulates focal adhesions.
3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a signal integrator that activates the AGC superfamily of serine/threonine kinases. PDK1 is phosphorylated on tyrosine by oxidants, although its regulation by agonists that stimulate G-protein-coupled receptor signaling pathways and the physiological consequences of tyrosine phosphorylation in this setting have not been fully identified. We found that angiotensin II stimulates the tyrosine phosphorylation of PDK1 in vascular smooth muscle in a calcium- and c-Src-dependent manner. The calcium-activated tyrosine kinase Pyk2 acts as a scaffold for Src-dependent phosphorylation of PDK1 on Tyr9, which permits phosphorylation of Tyr373 and -376 by Src. This critical function of Pyk2 is further supported by the observation that Pyk2 and tyrosine-phosphorylated PDK1 colocalize in focal adhesions after angiotensin II stimulation. Importantly, infection of smooth muscle cells with a Tyr9 mutant of PDK1 inhibits angiotensin II-induced tyrosine phosphorylation of paxillin and focal adhesion formation. These observations identify a novel interaction between PDK1 and Pyk2 that regulates the integrity of focal adhesions, which are major compartments for integrating signals for cell growth, apoptosis, and migration.
Department of Medicine, Division of Cardiology, Emory University School of Medicine, 1639 Pierce Drive, Atlanta, GA 30322, USA.
Yoshihiro
Y
Taniyama
David S
DS
Weber
Petra
P
Rocic
Lula
L
Hilenski
Marjorie L
ML
Akers
Jongsun
J
Park
Brian A
BA
Hemmings
R Wayne
RW
Alexander
Kathy K
KK
Griendling
D064413:3-Phosphoinositide-Dependent Protein Kinases; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics; D051418:Focal Adhesion Kinase 2; D022001:Focal Adhesions / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D014443:Tyrosine / Q000737:chemistry; D019061:src-Family Kinases / Q000378:metabolism*
D018076:DNA, Complementary; D000804:Angiotensin II; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C496054:Ptk2b protein, rat; D019061:src-Family Kinases; D064413:3-Phosphoinositide-Dependent Protein Kinases; C578579:Pdpk1 protein, rat; D017346:Protein Serine-Threonine Kinases