Related Experiment Videos
IGF-I induces collagen and IGFBP-5 mRNA in rat intestinal smooth muscle
E M Zimmermann1, L Li, Y T Hou
1Department of Internal Medicine, University of Michigan Medical School, Ann Arbor 48109-0586, USA.
Abstract:
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.
Insights
Insulin-like growth factor binding protein 5 (IGFBP-5) mRNA increases in inflamed rat intestines, particularly in smooth muscle. Insulin-like growth factor-I (IGF-I) boosts IGFBP-5 and collagen mRNA in these cells.
Area of Science:
- Gastroenterology
- Molecular Biology
- Cell Biology
Background:
- Intestinal inflammation, such as peptidoglycan-polysaccharide enterocolitis, can alter gene expression in the gut.
- Insulin-like growth factor (IGF) binding proteins play crucial roles in regulating IGF bioavailability and function.
- IGF binding protein 5 (IGFBP-5) is implicated in various cellular processes, including cell growth and extracellular matrix production.
Purpose of the Study:
- To investigate the expression and regulation of IGFBP-5 mRNA in the rat intestine during enterocolitis.
- To determine the effect of IGF-I on IGFBP-5 and collagen type I mRNA synthesis in cultured intestinal smooth muscle cells.
Main Methods:
- Northern analysis and in situ hybridization were used to quantify IGFBP-5 mRNA levels in rat colon tissue.
- Primary rat intestinal smooth muscle cells were cultured to assess the impact of IGF-I on gene expression.
- Western ligand blot and immunoblotting were employed to measure IGFBP-5 protein levels.
- Transcriptional blockade and cycloheximide treatment were used to investigate mRNA stability and protein synthesis dependence.
Main Results:
- IGFBP-5 mRNA levels were significantly elevated (2.4-fold) in the inflamed colon of rats compared to controls.
- IGFBP-5 mRNA showed high expression in the smooth muscle layer of the rat intestine.
- In cultured smooth muscle cells, IGF-I treatment increased IGFBP-5 mRNA (1.9-fold) and collagen type alpha1(I) mRNA (1.6-fold).
- IGF-I also dose- and time-dependently increased secreted IGFBP-5 protein levels, without affecting mRNA decay rate.
Conclusions:
- IGFBP-5 mRNA is expressed in intestinal smooth muscle cells and its expression is upregulated during chronic intestinal inflammation.
- IGF-I stimulates the synthesis of IGFBP-5 and collagen type I in intestinal smooth muscle cells, suggesting a role in inflammation-associated tissue remodeling.