VASCULAR ENDOTHELIAL GROWTH FACTOR INDUCES PROTEIN KINASE C (PKC)-DEPENDENT Akt/PKB ACTIVATION AND PHOSPHATIDYLINOSITOL 3′-KINASE-MEDIATED PKCδ PHOSPHORYLATION: ROLE OF PKC IN ANGIOGENESIS

Abstract

Activation of the protein kinase Akt/PKB mediates VEGF-dependent endothelial cell survival and eNOS activation. Here we examined the role of PKC in mediating VEGF-induced Akt activation. The PKC inhibitors GF109203X and calphostin C inhibited VEGF-induced Akt activation. Rottlerin and Go6976, inhibitors with specificities for PKC delta and alpha, respectively, also strongly inhibited VEGF-induced Akt activation. VEGF-induced Akt activation was prevented by down-regulation of PKC induced by prolonged pretreatment with the phorbol ester, PMA. VEGF induced phosphorylation of PKC delta at Thr 505 in the activation loop, and this phosphorylation was inhibited by LY294002, suggesting that modulation of PKC delta activation by VEGF occurs distal to phosphatidylinositol 3'-kinase. PKC and PI3K inhibitors both strongly reduced the stimulation of branching tubulogenesis by VEGF in vitro. The finding that PKC mediates VEGF-induced Akt activation identifies a novel signal transduction pathway through which Akt can be regulated by growth factors acting through receptor protein tyrosine kinases, and indicates that PKC-mediated Akt activity may play an essential role in VEGF-stimulated angiogenesis.

VEGF-mediated PI3K class IA and PKC signaling in cardiomyogenesis and vasculogenesis of mouse embryonic stem cells

“…PI3K catalytic subunit p110a and p110 are essential for cardiovascular differentiation upon treatment of EBs with VEGF As previously described, VEGF plays a crucial role in cardiac and vascular differentiation, and acts on Flk-1 + cardiovascular progenitor cells (Chen et al, 2006;Cheung, 1997;Gerber et al, 1998;Gliki et al, 2002;Song et al, 2007;Yang et al, 2002;Zisa et al, 2009;Lange et al, 2009). To investigate whether PI3K class IA isoforms are essential for VEGF signaling pathways leading to cardiac and vascular differentiation of ES cells, p110a, p110b and p110 gene-inactivated EBs were treated from day 4 to day 10 of cell culture with VEGF (500 pM).…”

“…The importance of PKC in the VEGF-PI3K pathway was suggested by several authors (Chou et al, 1998;Dutil et al, 1998;Gliki et al, 2002;Le Good et al, 1998), but the actual mechanisms of PKC stimulation by VEGF are not known. To evaluate the role of PKC during cardiovascular differentiation of ES cells, EBs were treated from day 4 to day 10 of cell culture with inhibitors of the PKC family, i.e.…”

“…However, relatively little is known about the involvement of distinct phosphoinositide 3-kinase (PI3K) catalytic subunits and protein kinase C (PKC) isoforms in VEGF action (Hamada et al, 2005;Gliki et al, 2002;Gerber et al, 1998). VEGF receptors (VEGFR1 and VEGFR2) are present on vascular endothelial cells and their signaling is mediated by receptor dimerization leading to autophosphorylation of the cytosolic domains of the receptors.…”

“…All four class I PI3Ks are heterodimers composed of a catalytic subunit with a molecular weight of 110 kDa and a tightly associated regulatory subunit that controls activation and subcellular localization (Whitman et al, 1988;Stephens et al, 1991). The importance of PKC regarding the VEGF-PI3K pathway was suggested by several authors (Chou et al, 1998;Dutil et al, 1998;Gliki et al, 2002;Le Good et al, 1998), although a detailed VEGF-related mechanism involving PKC has not been determined until now in differentiating ES cells. PKC is a family of protein kinases and phospholipid-dependent enzymes that consists of at least of 11 isozymes (Teicher, 2006).…”

Atorvastatin Induction of VEGF and BDNF Promotes Brain Plasticity after Stroke in Mice

“…Vascular endothelial growth factor/VEGFR2 has been shown to be essential for endothelial cell proliferation and differentiation (Breier et al, 1992). Binding of VEGF to VEGFR2 leads to the receptor phosphorylation and subsequent activation of PI3K/Akt and other downstream signaling proteins (Gliki et al, 2002;Nakashio et al, 2002). Statin-induced capillary-like tube formation is inhibited by a neutralizing antibody against VEGFR2 and inhibition of PI3K (Chen et al, 2003b).…”