title: Expression of atrial natriuretic peptide receptor-A antagonizes the mitogen-activated protein kinases (Erk2 and P38MAPK) in cultured human vascular smooth muscle cells.
abstract: 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.
authors.affiliation: Department of Physiology, Tulane University Health Sciences Center, and School of Medicine New Orleans, LA 70112, USA.
authors.forename: Guru Dutt
authors.initials: GD
authors.lastname: Sharma
authors.forename: Huong T
authors.initials: HT
authors.lastname: Nguyen
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Antonov
authors.forename: Ross G
authors.initials: RG
authors.lastname: Gerrity
authors.forename: Thomas
authors.initials: T
authors.lastname: von Geldern
authors.forename: Kailash N
authors.initials: KN
authors.lastname: Pandey
mesh_terms: 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
chemical_list: 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