IGF-I induces collagen and IGFBP-5 mRNA in rat intestinal smooth muscle.
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 alpha1(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.
Zimmermann
E M
EM
Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109-0586, USA.
Li
L
L
Hou
Y T
YT
Cannon
M
M
Christman
G M
GM
Bitar
K N
KN
D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis*; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D003513:Cycloheximide / Q000494:pharmacology; D004760:Enterocolitis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D005260:Female; D017403:In Situ Hybridization; D007249:Inflammation; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000096:biosynthesis*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D010457:Peptidoglycan; D011135:Polysaccharides, Bacterial; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011917:Rats, Inbred Lew; D012016:Reference Values; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects*
D018975:Insulin-Like Growth Factor Binding Protein 5; D010457:Peptidoglycan; D011135:Polysaccharides, Bacterial; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D003094:Collagen; D003513:Cycloheximide