TY - JOUR
T1 - Increased myocardial collagen content in transgenic rats overexpressing cardiac angiotensin-converting enzyme is related to enhanced breakdown of N-acetyl-Ser-Asp-Lys-Pro and increased phosphorylation of Smad2/3
AU - Pokharel, Saraswati
AU - van Geel, Peter P.
AU - Sharma, Umesh C.
AU - Cleutjens, Jack P. M.
AU - Bohnemeier, Holger
AU - Tian, Xiao-Li
AU - Schunkert, Heribert
AU - Crijns, Harry J. G. M.
AU - Paul, Martin
AU - Pinto, Yigal M.
PY - 2004
Y1 - 2004
N2 - BACKGROUND: Although increased activity of angiotensin-converting enzyme (ACE) has been associated with increased cardiac collagen, no studies to date have established a direct cause-and-effect relation between the two. METHODS AND RESULTS: We used transgenic rats that overexpress human ACE selectively in the myocardium. Two independent heterozygous transgenic rat lines were studied, one expressing 2 to 3 copies (L1172) and the other expressing 5 to 10 copies (L1173) of the ACE transgene. These rats were normotensive but developed a proportionate increase in myocardial collagen depending on the ACE gene dose (up to 2.5-fold, P <0.01), but cardiac angiotensin II levels remained normal, whereas collagen content reversed to control levels on ACE inhibition. To explain these changes, we investigated N-acetyl-Ser-Asp-Lys-Pro (AcSDKP), an alternative substrate that is catabolized exclusively by ACE. Increased cardiac expression of ACE was paralleled by a reciprocal decrease in cardiac AcSDKP and a proportionate increase in phosphorylated Smad2 and Smad3, all of which normalized after both ACE inhibition and AcSDKP infusion. Furthermore, a functional link of this signaling cascade was demonstrated, because AcSDKP inhibited Smad3 phosphorylation in a dose-dependent manner in cultured cardiac fibroblasts and in vivo. CONCLUSIONS: Our findings suggest that increased cardiac ACE activity can increase cardiac collagen content by degradation of AcSDKP, an inhibitor of the phosphorylation of transforming growth factor-beta signaling molecules Smad2 and Smad3. This implies that the antifibrotic effects of ACE inhibitors are mediated in part by increasing cardiac AcSDKP, with subsequent inhibition of Smad 2/3 phosphorylation
AB - BACKGROUND: Although increased activity of angiotensin-converting enzyme (ACE) has been associated with increased cardiac collagen, no studies to date have established a direct cause-and-effect relation between the two. METHODS AND RESULTS: We used transgenic rats that overexpress human ACE selectively in the myocardium. Two independent heterozygous transgenic rat lines were studied, one expressing 2 to 3 copies (L1172) and the other expressing 5 to 10 copies (L1173) of the ACE transgene. These rats were normotensive but developed a proportionate increase in myocardial collagen depending on the ACE gene dose (up to 2.5-fold, P <0.01), but cardiac angiotensin II levels remained normal, whereas collagen content reversed to control levels on ACE inhibition. To explain these changes, we investigated N-acetyl-Ser-Asp-Lys-Pro (AcSDKP), an alternative substrate that is catabolized exclusively by ACE. Increased cardiac expression of ACE was paralleled by a reciprocal decrease in cardiac AcSDKP and a proportionate increase in phosphorylated Smad2 and Smad3, all of which normalized after both ACE inhibition and AcSDKP infusion. Furthermore, a functional link of this signaling cascade was demonstrated, because AcSDKP inhibited Smad3 phosphorylation in a dose-dependent manner in cultured cardiac fibroblasts and in vivo. CONCLUSIONS: Our findings suggest that increased cardiac ACE activity can increase cardiac collagen content by degradation of AcSDKP, an inhibitor of the phosphorylation of transforming growth factor-beta signaling molecules Smad2 and Smad3. This implies that the antifibrotic effects of ACE inhibitors are mediated in part by increasing cardiac AcSDKP, with subsequent inhibition of Smad 2/3 phosphorylation
U2 - https://doi.org/10.1161/01.CIR.0000147180.87553.79
DO - https://doi.org/10.1161/01.CIR.0000147180.87553.79
M3 - Article
C2 - 15520311
SN - 0009-7322
VL - 110
SP - 3129
EP - 3135
JO - Circulation
JF - Circulation
IS - 19
ER -