Impact of HMG CoA reductase inhibition on small GTPases in the heart.
OBJECTIVE
Members of the Rho GTPase family, Rac1 and RhoA have been suggested to be mediators of cardiac hypertrophy in mice. Rho proteins are posttranslationally isoprenylated. In addition to cholesterol-lowering, statins inhibit the isoprenylation of small G proteins. Therefore, it was tested if these drugs inhibit Rac1 and RhoA activity in cardiomyocytes and, thereby, prevent angiotensin II-mediated expression of atrial natriuretic factor (ANF) and myosin light chain (MLC)-2 in the heart.


RESULTS
Western and Northern analysis of rat neonatal cardiomyocytes and H9C2 cells showed inhibition of basal and angiotensin-stimulated Rac1 expression, membrane-translocation and activity after statin treatment. Similarly, basal and stimulated RhoA membrane expression was inhibited. Statins concentration- and time-dependently downregulated basal as well as angiotensin-induced expression of ANF by 86+/-2.3% and 89+/-1.7%, as well as MLC-2 by 75+/-4.1% and 84+/-6%, respectively. Direct inhibition of Rac GTPase by overexpression of the dominant negative mutant RacN17 or by Clostridium sordellii lethal toxin in rat H9C2 cells inhibited ANF expression by 70+/-4.9% and 78+/-10%, respectively. Inhibition of RhoA by Clostridium botulinum C3 transferase or the dominant negative mutant RhoN19 reduced ANF mRNA by 19+/-11% and 23+/-8%, respectively. To test these findings in vivo, spontaneously hypertensive rats were treated with atorvastatin, leading to a decrease in cardiac Rac1 and RhoA activity as determined by [35S]-GTP gamma S-binding assays by 61+/-16% and 72+/-24%, and downregulation of MLC-2 as well as ANF mRNA expression by 31+/-16% and 80+/-24%, respectively.


CONCLUSIONS
(1) Statins downregulate the activity of small G proteins in cardiomyocytes in culture as well as in vivo. (2) Inhibition of Rac1 and RhoA by statins reduces myocardial expression of ANF and MLC-2. (3) Targeting myocardial Rho GTPases by statins may be a novel treatment strategy to prevent cardiac hypertrophy.
Laufs
Ulrich
U
Medizinische Klinik und Poliklinik der Universität des Saarlandes, Innere Medizin III, 66421 Homburg/Saar, Germany. ulrich@laufs.com
Kilter
Heiko
H
Konkol
Christian
C
Wassmann
Sven
S
Böhm
Michael
M
Nickenig
Georg
G
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000069059:Atorvastatin; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism; D024722:Cardiac Myosins / Q000378:metabolism; D006332:Cardiomegaly / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D020558:GTP Phosphohydrolases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006538:Heptanoic Acids / Q000494:pharmacology; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D000960:Hypolipidemic Agents / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D008297:Male; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D018994:Myosin Light Chains / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D019821:Simvastatin / Q000494:pharmacology; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism
D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D000960:Hypolipidemic Agents; D018994:Myosin Light Chains; D011758:Pyrroles; D012333:RNA, Messenger; C107184:myosin light chain 2; D000804:Angiotensin II; D009320:Atrial Natriuretic Factor; D000069059:Atorvastatin; D019821:Simvastatin; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D024722:Cardiac Myosins; D020558:GTP Phosphohydrolases; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein