Resveratrol inhibits collagen I synthesis by suppressing IGF-1R activation in intestinal fibroblasts.
OBJECTIVE
To investigate whether resveratrol (3,4,5-trihydroxy-trans-stilbene) inhibits collagen I synthesis induced by insulin growth factor-1 (IGF-1) in intestinal fibroblasts, and to explore the possible molecular mechanisms.


METHODS
Male Sprague-Dawley rats were randomly divided into two groups: a control group and a 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis group. After 21 d of TNBS administration, the degree of inflammation and fibrosis in colon was measured by HE staining and Masson's trichrome staining. Western blotting was used to examine collagen I, IGF-1 and silent information regulator 1 (SIRT1) protein expression in colitis tissues. Western blotting and quantitative real-time polymerase chain reaction were used to characterize collagen I protein and col1a2 mRNA expression in mouse intestinal fibroblasts and CCD-(18)Co cells treated with IGF-1. A MEK inhibitor (U0126) was used to determine whether IGF-1-induced collagen I expression was mediated by extracellular signal-regulated kinase 1/2 (ERK1/2)-dependent mechanism. Effects of resveratrol on collagen I protein level, insulin growth factor-1 receptor (IGF-1R) and ERK1/2 phosphorylation levels were also examined after IGF-1 treatment in fibroblasts. To evaluate whether SIRT1 was necessary for the anti-fibrosis effect of resveratrol, cells were transfected with SIRT1-specific small interfering RNAs, wild-type SIRT1, and deacetylase-inactive mutant SIRT1.


RESULTS
Collagen I and IGF-1 expression was increased, and SIRT1 expression was decreased (0.67 ± 0.04 vs 1.05 ± 0.07, P < 0.001) in TNBS-induced colitis compared with the control group. In vitro, IGF-1 could induce collagen I expression, mainly through the ERK 1/2 signal pathway. Resveratrol reduced basal and IGF-1-induced collagen I gene and protein expression in intestinal fibroblasts. Overexpression of wild-type SIRT1, not deacetylase-inactive mutant SIRT1, decreased expression of collagen I induced by IGF-1. Moreover, silencing SIRT1 restored collagen I expression in fibroblasts challenged with resveratrol. However, disruption of SIRT1 did not influence the anti-fibrotic effects of resveratrol and IGF-1-induced collagen I expression. Further analysis revealed that resveratrol significantly decreased phosphorylation of IGF-1R and its downstream signaling molecules by inhibiting IGF-1 binding to its receptor.


CONCLUSIONS
Our data suggest that resveratrol effectively inhibits collagen I synthesis in IGF-1-stimulated fibroblasts, partly by inhibiting IGF-1R activation, and SIRT1 is also responsible for the process.
Ping Li, Ying Zhu, Yao-Yao Gong, Yun Wang, Ding Heng, Lin Lin, Department of Gastroenterology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
Ping
P
Li
Ping Li, Ying Zhu, Yao-Yao Gong, Yun Wang, Ding Heng, Lin Lin, Department of Gastroenterology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
Mei-Lan
ML
Liang
Ping Li, Ying Zhu, Yao-Yao Gong, Yun Wang, Ding Heng, Lin Lin, Department of Gastroenterology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
Ying
Y
Zhu
Ping Li, Ying Zhu, Yao-Yao Gong, Yun Wang, Ding Heng, Lin Lin, Department of Gastroenterology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
Yao-Yao
YY
Gong
Ping Li, Ying Zhu, Yao-Yao Gong, Yun Wang, Ding Heng, Lin Lin, Department of Gastroenterology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
Yun
Y
Wang
Ping Li, Ying Zhu, Yao-Yao Gong, Yun Wang, Ding Heng, Lin Lin, Department of Gastroenterology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
Ding
D
Heng
Ping Li, Ying Zhu, Yao-Yao Gong, Yun Wang, Ding Heng, Lin Lin, Department of Gastroenterology, First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China.
Lin
L
Lin
D000818:Animals; D002460:Cell Line; D003092:Colitis / Q000139:chemically induced / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism*; D003106:Colon / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D015536:Down-Regulation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005355:Fibrosis; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008297:Male; D051379:Mice; D009154:Mutation; D010766:Phosphorylation; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D017526:Receptor, IGF Type 1 / Q000187:drug effects* / Q000378:metabolism; D000077185:Resveratrol; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism; D013267:Stilbenes / Q000494:pharmacology*; D014162:Transfection; D014302:Trinitrobenzenesulfonic Acid
D024042:Collagen Type I; D012333:RNA, Messenger; D013267:Stilbenes; C548904:insulin-like growth factor-1, rat; D007334:Insulin-Like Growth Factor I; D014302:Trinitrobenzenesulfonic Acid; D017526:Receptor, IGF Type 1; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; C470545:Sirt1 protein, mouse; C488368:Sirt1 protein, rat; D056564:Sirtuin 1; D000077185:Resveratrol
Fibroblasts; Insulin-like growth factor-1; Intestinal fibrosis; Resveratrol; Silent information regulator 1