Gene transfer of cGMP-dependent protein kinase I enhances the antihypertrophic effects of nitric oxide in cardiomyocytes.
NO acting through soluble guanylyl cyclase and cGMP formation is a negative regulator of cardiomyocyte hypertrophy. Downstream targets mediating the inhibitory effects of NO/cGMP on cardiomyocyte hypertrophy have not been elucidated. In addition to its antihypertrophic effects, NO promotes apoptosis in cardiomyocytes, presumably through cGMP-independent pathways. We investigated the role of cGMP-dependent protein kinase (PKG) in the antihypertrophic and proapoptotic effects of NO. Incubation of neonatal rat cardiomyocytes with the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) (250 micromol/L) or the PKG-selective cGMP analog 8-pCPT-cGMP (500 micromol/L) activated endogenous PKG type I, as shown by the site-specific phosphorylation of vasodilator-stimulated phosphoprotein, a well-characterized PKG substrate. SNAP (250 micromol/L) and 8-pCPT-cGMP (500 micromol/L) modestly attenuated the hypertrophic response to alpha(1)-adrenergic stimulation with phenylephrine. Although a high concentration of SNAP (1000 micromol/L) promoted apoptosis in cardiomyocytes, as evidenced by the formation of histone-associated DNA fragments, antihypertrophic concentrations of SNAP (250 micromol/L) and 8-pCPT-cGMP (500 micromol/L) did not promote cell death. Because chronic activation downregulated endogenous PKG I, we explored whether gene transfer of PKG I would enhance the sensitivity of cardiomyocytes to the antihypertrophic effects of NO/cGMP. Indeed, after adenoviral overexpression of PKG Ibeta, SNAP (250 micromol/L) and 8-pCPT-cGMP (500 micromol/L) completely suppressed the hypertrophic response to alpha(1)-adrenergic stimulation. As observed in noninfected cells, SNAP (250 micromol/L) and 8-pCPT-cGMP (500 micromol/L) did not promote apoptosis in cardiomyocytes overexpressing PKG Ibeta. Moreover, overexpression of PKG Ibeta did not enhance the proapoptotic effects of 1000 micromol/L SNAP, implying PKG-independent effects of NO on apoptosis. Endogenous PKG I mediates antihypertrophic but not proapoptotic effects of NO in a cell culture model of cardiomyocyte hypertrophy. Adenoviral gene transfer of PKG I selectively enhances the antihypertrophic effects of NO without increasing the susceptibility to apoptosis.
Wollert
Kai C
KC
Department of Cardiology and Angiology, Medizinische Hochschule Hannover, Hannover, Germany. wollert.kai@mh-hannover.de
Fiedler
Beate
B
Gambaryan
Stepan
S
Smolenski
Albert
A
Heineke
Jörg
J
Butt
Elke
E
Trautwein
Christian
C
Lohmann
Suzanne M
SM
Drexler
Helmut
H
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D006332:Cardiomegaly / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases / Q000096:biosynthesis / Q000235:genetics*; D015536:Down-Regulation; D004357:Drug Synergism; D018014:Gene Transfer Techniques; D006801:Humans; D009206:Myocardium / Q000166:cytology / Q000201:enzymology; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology
D020030:Nitric Oxide Donors; D018340:Receptors, Adrenergic, alpha-1; D013873:Thionucleotides; D009569:Nitric Oxide; C055656:8-((4-chlorophenyl)thio)cyclic-3',5'-GMP; D026423:S-Nitroso-N-Acetylpenicillamine; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases; C569718:PRKG1 protein, human; D006152:Cyclic GMP