Expression of atrial natriuretic peptide receptor-A antagonizes the mitogen-activated protein kinases (Erk2 and P38MAPK) in cultured human vascular smooth muscle cells.
To understand the signaling mechanisms of atrial natriuretic peptide (ANP) receptor-A (NPRA), we studied the effect of the ANP/NPRA system on mitogen-activated protein kinases (MAPKs), with particular emphasis on the extracellular-regulated kinase (Erk2) and stress-activated protein kinase (p38MAPK) in cultured human vascular smooth muscle cells (HVSMC). Angiotensin II (ANG II) and platelet-derived growth factor (PDGF) stimulated the immunoreactive Erk2 and p38MAPK activities and their protein levels by 2-4 fold. The pretreatment of cells with ANP significantly inhibited the agonist-stimulated Erk2 and p38MAPK activities and protein expression by 65-75% in HVSMC transiently transfected with NPRA, as compared with only 18-22% inhibition in vector-transfected cells. The pretreatment of cells with KT5823, an inhibitor of cGMP-dependent protein kinase (PKG), reversed the inhibitory effects of ANP on MAPK activities and protein expression by 90-95%. PD98059, which inhibits Erk2 by directly inhibiting the MAPK-kinase (MEK), and SB202192, a selective antagonist of p38MAPK, blocked the Erk2 and p38MAPK activities, respectively. Interestingly, ANP stimulated the MAPK-phosphatase-3 (MKP-3) protein levels by more than 3-fold in HVSMC over-expressing NPRA, suggesting that ANP-dependent inhibition of MAPKs may also proceed by stimulating the phosphatase cascade. These present findings provide the evidence that ANP exerts inhibitory effects on agonist-stimulated MAPKs (Erk2 and p38MAPK) activities and protein levels in a 2-fold manner: by antagonizing the up-stream signaling pathways and by activation of MKP-3 to counter-regulate MAPKs in a cGMP and PKG-dependent manner. Our results identify a signal transduction pathway in HVSMC that could contribute to vascular remodeling and structural changes in human hypertension.
Sharma
Guru Dutt
GD
Department of Physiology, Tulane University Health Sciences Center, and School of Medicine New Orleans, LA 70112, USA.
Nguyen
Huong T
HT
Antonov
Alexander S
AS
Gerrity
Ross G
RG
von Geldern
Thomas
T
Pandey
Kailash N
KN
D000804:Angiotensin II / Q000378:metabolism; D009320:Atrial Natriuretic Factor / Q000378:metabolism; D001344:Autopsy; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000378:metabolism; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D017461:Receptors, Atrial Natriuretic Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
D004791:Enzyme Inhibitors; D010982:Platelet-Derived Growth Factor; D000804:Angiotensin II; D009320:Atrial Natriuretic Factor; D017869:Cyclic GMP-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C091715:atrial natriuretic factor receptor A; D006152:Cyclic GMP