Ac-SDKP inhibits transforming growth factor-beta1-induced differentiation of human cardiac fibroblasts into myofibroblasts.
N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) inhibits collagen production and cell proliferation in cultured rat cardiac fibroblasts, but its effect on differentiation of fibroblasts into myofibroblasts is not known. High amounts of transforming growth factor-beta1 (TGF-beta1) have been found in fibrotic cardiac tissue. TGF-beta1 converts fibroblasts into myofibroblasts, which produce more extracellular matrix proteins than fibroblasts. We hypothesized that 1) Ac-SDKP inhibits TGF-beta1-induced differentiation of fibroblasts into myofibroblasts; and 2) this effect is mediated in part by blocking phosphorylation of small-mothers-against-decapentaplegic (Smad) 2 and extracellular signal-regulated kinase (ERK) 1/2. For this study, we used human fetal cardiac fibroblasts (HCFs), which do not spontaneously become myofibroblasts when cultured at low passages. We investigated the effect of Ac-SDKP on TGF-beta1-induced HCF transformation into myofibroblasts, Smad2 and ERK1/2 phosphorylation, Smad7 expression, cell proliferation, and collagen production. We also investigated TGF-beta1 production by HCFs stimulated with endothelin-1 (ET-1). As expected, HCFs treated with TGF-beta1 transformed into myofibroblasts as indicated by increased expression of alpha-smooth muscle actin and a higher proportion of the embryonic isoform of smooth muscle myosin compared with untreated cells. TGF-beta1 also increased Smad2 and ERK1/2 phosphorylation but did not affect Smad7 expression. In addition, TGF-beta1 stimulated HCF proliferation as indicated by an increase in mitochondrial dehydrogenase activity and collagen production (hydroxyproline assay). Ac-SDKP significantly inhibited all of the effects of TGF-beta1. It also inhibited ET-1-stimulated TGF-beta1 production. We concluded that Ac-SDKP markedly suppresses differentiation of human cardiac fibroblasts into myofibroblasts, probably by inhibiting the TGF-beta/Smad/ERK1/2 signaling pathway, and thus mediating its anti-fibrotic effects.
Peng
Hongmei
H
Hypertension and Vascular Research Division, Henry Ford Hospital, 2799 West Grand Blvd., Detroit, MI 48202, USA.
Carretero
Oscar A
OA
Peterson
Edward L
EL
Rhaleb
Nour-Eddine
NE
D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D019332:Endothelin-1 / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D006131:Growth Inhibitors / Q000494:pharmacology*; D006801:Humans; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D009206:Myocardium / Q000166:cytology*; D009218:Myosins / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D051906:Smad7 Protein / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology*
D019332:Endothelin-1; D006131:Growth Inhibitors; D009842:Oligopeptides; C497806:SMAD7 protein, human; D051906:Smad7 Protein; D053773:Transforming Growth Factor beta1; D003094:Collagen; D048049:Extracellular Signal-Regulated MAP Kinases; D009218:Myosins; C058504:goralatide