Differential regulation of vascular smooth muscle and endothelial cell proliferation in vitro and in vivo by cAMP/PKA-activated p85alphaPI3K.
cAMP inhibits proliferation in most cell types, triggering different and sometimes opposing molecular pathways. p85alpha (phosphatidylinositol 3-kinase regulatory subunit) is phosphorylated by cAMP/PKA in certain cell lineages, but its effects on vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) are unknown. In the present study, we evaluated 1) the role of p85alpha in the integration of cAMP/PKA-dependent signaling on the regulation of VSMC and EC growth in vitro; and 2) the effects of PKA-modified p85alpha on neointimal hyperplasia and endothelial healing after balloon injury in vivo. Plasmid constructs carrying wild-type and PKA-modified p85alpha were employed in VSMCs and ECs in vitro and after balloon injury in rat carotid arteries in vivo. cAMP/PKA reduced VSMC proliferation through p85alpha phosphorylation. Transfected PKA-activated p85alpha binds p21ras, reducing ERK1/2 activation and VSMC proliferation in vitro. In contrast, EC proliferation inhibition by cAMP is independent from PKA modification of p85alpha and ERK1/2 inhibition; indeed, PKA-activated p85alpha did not inhibit per se ERK1/2 activation and proliferation in ECs in vitro. Interestingly, cAMP reduced both VSMC and EC apoptotic death through p85alpha phosphorylation. Accordingly, PKA-activated p85alpha triggered Akt activation, reducing both VSMC and EC apoptosis in vitro. Finally, compared with controls, vascular gene transfer of PKA-activated p85alpha significantly reduced neointimal formation after balloon injury in rats, without inhibiting endothelial regeneration of the injured arterial segment. In conclusions, PKA-activated p85alpha integrates cAMP/PKA signaling differently in VSMCs and ECs. By reducing neointimal hyperplasia without inhibiting endothelial regeneration, it exerts a protective effect against restenosis after balloon injury.
Torella
Daniele
D
Laboratory of Molecular and Cellular Cardiology, Magna Graecia University, Campus S. Venuta, Viale Europa-Germaneto, Catanzaro 88100, Italy.
Gasparri
Cosimo
C
Ellison
Georgina M
GM
Curcio
Antonio
A
Leone
Angelo
A
Vicinanza
Carla
C
Galuppo
Valentina
V
Mendicino
Isabella
I
Sacco
Walter
W
Aquila
Iolanda
I
Surace
Francesca Chiara
FC
Luposella
Maria
M
Stillo
Gilda
G
Agosti
Valter
V
Cosentino
Claudia
C
Avvedimento
Enrico V
EV
Indolfi
Ciro
C
D000818:Animals; D017209:Apoptosis; D020212:Carotid Artery Injuries / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D002404:Catheterization; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000201:enzymology* / Q000473:pathology; D004789:Enzyme Activation; D006965:Hyperplasia; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000201:enzymology* / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism
D000242:Cyclic AMP; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D018631:ras Proteins