Functional significance of protein kinase A activation by endothelin-1 and ATP: negative regulation of SRF-dependent gene expression by PKA.
Endothelin-1 (ET1) and ATP stimulate contraction and hypertrophy of vascular smooth muscle cells (VSMC) by activating diverse signalling pathways. In this study, we show that in VSMC, ET1 and ATP stimulate transient and sustained activation of protein kinase A (PKA), respectively. Using a dominant negative PKA mutant (PKA-DN), we examined the functional significance of PKA activation in the signalling of ET1 and ATP. Overexpression of PKA-DN did not alter the ET1- or ATP-induced phosphorylation of the extracellular signal-regulated protein kinase, Erk2. ATP stimulated a profound, PKA-dependent activation of cAMP-response element (CRE), whereas the effect of ET1 was negligible. Both ET1 and ATP stimulated serum response factor (SRF)-dependent gene expression. Overexpression of PKA-DN potentiated the effects of ET1 and ATP on SRF activity, whereas stimulation of PKA by isoproterenol, forskolin or by overexpression of the PKA catalytic subunit decreased SRF activity. These data demonstrate that (i) PKA negatively regulates SRF activity and (ii) ET1 and ATP stimulate opposing pathways, whose balance determines the net activity of SRF.
Davis
Amanda
A
Section of Pulmonary and Critical Care Medicine, Department of Medicine, The University of Chicago, 5841 S. Maryland Avenue, MC 6076, Chicago, IL 60637, USA.
Hogarth
Kyle
K
Fernandes
Darren
D
Solway
Julian
J
Niu
Jiaxin
J
Kolenko
Vladimir
V
Browning
Darren
D
Miano
Joseph M
JM
Orlov
Sergei N
SN
Dulin
Nickolai O
NO
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism* / Q000502:physiology; D015536:Down-Regulation; D019332:Endothelin-1 / Q000494:pharmacology*; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D011921:Rats, Inbred WKY; D020218:Response Elements; D026362:Serum Response Factor / Q000378:metabolism*; D015533:Transcriptional Activation
D019332:Endothelin-1; D026362:Serum Response Factor; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases