title: N-Acetyl-seryl-aspartyl-lysyl-proline inhibits ET-1-induced collagen production by preserving Src homology 2-containing protein tyrosine phosphatase-2 activity in cardiac fibroblasts.
abstract: N-Acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) inhibits endothelin-1 (ET-1)-induced activation of p44/42 mitogen-activated protein kinase (p44/42 MAPK) and collagen production in cultured rat cardiac fibroblasts (RCFs). However, we do not know whether its inhibitory effect on p44/42 MAPK is due to the altered activity of protein tyrosine phosphatases (PTPs), which in turn downregulate the p44/42 MAPK signaling pathway. The activity of Src homology 2-containing protein tyrosine phosphatase-2 (SHP-2) is downregulated by ET-1 in RCFs; thus, we hypothesized that Ac-SDKP inhibits ET-1-stimulated collagen production in part by preserving SHP-2 activity and thereby inhibiting p44/42 MAPK phosphorylation. When we stimulated RCFs with ET-1 in the presence or absence of Ac-SDKP, we found that (a) PTP activity was reduced by ET-1 and (b) this effect was counteracted by Ac-SDKP in a dose-dependent fashion. Next, we extracted SHP-2 from RCF lysates by immunoprecipitation and determined that (a) ET-1 inhibited SHP-2 by 40 % and (b) this effect was prevented by Ac-SDKP. However, Ac-SDKP failed to inhibit ET-1-induced p44/42 MAPK phosphorylation in RCFs treated with SHP-2 short hairpin RNA (shRNA); in contrast, in cells transfected with control shRNA, Ac-SDKP's inhibitory effect on ET-1-induced p44/42 MAPK activation remained intact. Moreover, the inhibitory effect of Ac-SDKP on ET-1-stimulated collagen production was blunted in cells treated with the SHP-1/2 inhibitor NSC-87877. Thus, we concluded that the inhibitory effect of Ac-SDKP on ET-1-stimulated collagen production by RCFs is mediated in part by preserving SHP-2 activity and thereby preventing p44/42 MAPK activation. Ac-SDKP or its analogs could represent a new therapeutic tool to treat fibrotic diseases in the cardiovascular system.
authors.affiliation: Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, E & R Bldg 7121, 2799 West Grand Blvd, Detroit, MI, USA.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Peng
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Carretero
authors.forename: Edward L
authors.initials: EL
authors.lastname: Peterson
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Yang
authors.forename: Kastuv
authors.initials: K
authors.lastname: Santra
authors.forename: Nour-Eddine
authors.initials: NE
authors.lastname: Rhaleb
mesh_terms: D000818:Animals; D003094:Collagen / Q000096:biosynthesis*; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology*; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D011804:Quinolines / Q000494:pharmacology; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D019332:Endothelin-1; C512715:NSC-87877; D009842:Oligopeptides; D011804:Quinolines; D034741:RNA, Small Interfering; D003094:Collagen; D020928:Mitogen-Activated Protein Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; C058504:goralatide