IGF-I induces collagen and IGFBP-5 mRNA in rat intestinal smooth muscle

• Published in: American journal of physiology: Gastrointestinal and liver physiology Vol. 273; no. 4; pp. G875 - G882
• Main Authors: Zimmermann, E M, Li, L, Hou, Y T, Cannon, M, Christman, G M, Bitar, K N
• Format: Journal Article
• Language: English
• Published: United States 01.10.1997
• Subjects: insulin-like growth factor binding protein 5; growth factors; insulin-like growth factor I; intestinal fibrosis; inflammatory bowel disease; Crohn’s disease
• ISSN: 0193-1857; 1522-1547
• DOI: 10.1152/ajpgi.1997.273.4.g875

Insulin-like growth factor (IGF) binding protein 5 (IGFBP-5) mRNA was studied in intestines of rats with peptidoglycan-polysaccharide enterocolitis by Northern analysis and in situ hybridization. IGFBP-5 mRNA was increased 2.4 ± 0.5-fold in inflamed rat colon compared with controls and was highly expressed in smooth muscle. Cultured rat intestinal smooth muscle cells were used to study the regulation of IGFBP-5 and type I collagen synthesis. IGF-I (100 ng/ml) increased IGFBP-5 mRNA (1.9 ± 0.1-fold) and collagen type α (I) mRNA (1.6 ± 0.2-fold) in cultured smooth muscle cells. IGF-I induced a dose- and time-dependent increase in IGFBP-5 in conditioned medium by Western ligand blot and by immunoblot. IGF-I did not affect the IGFBP-5 mRNA decay rate after transcriptional blockade. Cycloheximide abolished IGFBP-5 mRNA. In conclusion, IGFBP-5 mRNA is expressed by intestinal smooth muscle and is increased during chronic inflammation. IGF-I increases IGFBP-5 and collagen mRNAs in intestinal smooth muscle cells.