Rescue of cGMP kinase I knockout mice by smooth muscle specific expression of either isozyme.
Smooth muscle expresses the Ialpha and the Ibeta isoforms of cGMP-dependent protein kinase I (cGKI). Inactivation of the murine cGKI gene prkg1 leads to multiple phenotypes and premature death at approximately 6 weeks. We reconstituted mice with the cGKIalpha or -Ibeta isozyme to test which isozyme was needed to support basic smooth muscle functions. Mice were generated by gene targeting. The cGKIalpha or the -Ibeta coding sequences were placed under the control of the SM22alpha promoter to express either isoform selectively in smooth muscle cells (SM-Ialpha or SM-Ibeta transgene). To generate smooth muscle-specific cGKIalpha or cGKIbeta rescue mice, the SM-Ialpha or SM-Ibeta transgenes were crossed on a cGKI-/- genetic background. The levels of cGKIalpha or -Ibeta expression were comparable to endogenous cGKI expression in wild-type aortic and intestinal smooth muscles. In cGKIalpha or -Ibeta rescue mice, expression of the isozymes was not detectable in non-smooth muscle tissues and cells. Median survival time of the Ialpha and Ibeta rescue mice was 52 weeks. Both isozymes mediated the 8-bromo-cGMP-induced relaxation of precontracted jejunum and aorta muscle strips. Activation of both isozymes reduced hormone- or K+-induced [Ca2+]i levels. The cGKIalpha and cGKIbeta rescue mice did not show a significant difference in intestinal passage time of BaSO4 in comparison with wild-type animals. Telemetric blood pressure measurements in conscious freely moving animals did not show differences between rescues and control mice in basal blood pressure and its regulation by DETA-NO, sodium nitroprusside, carbachol, or Y-27632. These results show that cGKI in smooth muscle is essential and that either cGKI isozyme alone can rescue basic vascular and intestinal smooth muscle functions.
Weber
Silke
S
Institut für Pharmakologie und Toxikologie der Technischen Universität, Biedersteiner Str. 29, D-80802 München, Germany.
Bernhard
Dominik
D
Lukowski
Robert
R
Weinmeister
Pascal
P
Wörner
René
R
Wegener
Jörg W
JW
Valtcheva
Nadejda
N
Feil
Susanne
S
Schlossmann
Jens
J
Hofmann
Franz
F
Feil
Robert
R
D000818:Animals; D001011:Aorta; D001794:Blood Pressure; D002118:Calcium / Q000032:analysis; D006152:Cyclic GMP / Q000502:physiology; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases / Q000235:genetics* / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D066298:In Vitro Techniques; D007527:Isoenzymes; D007583:Jejunum; D051379:Mice; D018345:Mice, Knockout; D009126:Muscle Relaxation; D009130:Muscle, Smooth / Q000201:enzymology*; D015996:Survival Rate
D007527:Isoenzymes; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases; C569720:Prkg1 protein, mouse; D006152:Cyclic GMP; D002118:Calcium