Differential expression and localization of IGF-I and IGF binding proteins in inflamed rat colon.
Recent studies indicate increased insulin-like growth factor I (IGF-I) expression and altered expression of IGF binding proteins (IGFBP) in the bowel during experimental colitis. This study analyzes the cellular sites of altered IGF-I and IGFBP-expression in large bowel of rats with experimental colitis. Colitis was induced by colonic instillation of 2, 4, 6-trinitrobenzenesulfonic (TNB) acid in ethanol. Animals were sacrificed at 7 days after induction of colitis. Cryostat sections of colon from TNB-treated and control rats were hybridized with 35S-labeled antisense probes for IGF-I, IGFBP-3, IGFBP-4 and IGFBP-5. IGF-I mRNA was up-regulated in lamina propria cells, submucosa and smooth muscle of inflamed colon. IGFBP-3 mRNA was localized to lamina propria and was down-regulated in inflamed colon. IGFBP-4 and IGFBP-5 mRNAs were both up-regulated in inflamed colon. IGFBP-4 mRNA was increased in lamina propria, submucosa and smooth muscle, whereas IGFBP-5 mRNA was increased in smooth muscle. Increased IGF-I expression in mesenchymal layers of colon during experimental colitis supports the hypothesis that IGF-I contributes to hyperplasia and fibrosis in response to inflammation. Altered expression of IGFBP-3, IGFBP-4 and IGFBP-5 in specific bowel layers during colitis suggests that they play a role in modulating IGF-I action.
Zeeh
J M
JM
Harbor-UCLA Medical Center, Division of Gastroenterology, Torrance, CA, USA.
Mohapatra
N
N
Lund
P K
PK
Eysselein
V E
VE
McRoberts
J A
JA
D000818:Animals; D003092:Colitis / Q000378:metabolism*; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis* / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000235:genetics; D008297:Male; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley
D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I