Z Gastroenterol 2009; 47 - P329
DOI: 10.1055/s-0029-1241577

Functional analysis of IGFBP-2 overexpression in mouse liver myofibroblasts

R Pannem 1, A Hoeflich 2, E Wolf 3, JG Scharf 1
  • 1Abteilung Gastroenterologie und Endokrinologie, Universitätsmedizin Göttingen, Göttingen, Germany
  • 2Research Unit Genetics and Biometry, FBN Dummerstorf, Dummerstorf, Germany
  • 3Lehrstuhl für Molekulare Tierzucht, LMU München, München, Germany

Background/aims: In liver cirrhosis hepatic expression and circulating levels of IGFBP-2 are significantly increased. However, the role of IGFBP-2 in liver fibrogenesis is unclear. Therefore, liver myofibroblats (LMFs) were isolated from livers of wild type (wt) and IGFBP-2 transgenic (IGFBP-2 (±)) mice and used to study the role of IGFBP-2 in cellular functions of mLMFs.

Methods: LMFs were obtained by outgrowth from primary hepatocytes isolated from wt or CMV-IGFBP-2 transgenic mice. Expression of IGF-IR, IGF-II/M6-PR, IGFBP-2 and -3 mRNA was investigated by Northern blot hybridization. IGF-IRβ protein expression was confirmed by Western immunoblot. IGFBP secretion was evaluated by [125I]-IGF-I ligand blot. Determination of DNA synthesis in mLMF was assessed by means of BrdU incorporation assay. mRNA expression of fibulin-2 and fibronectin-1 was assessed by quantitative real-time PCR.

Results: IGFBP-2 (±) mLMFs showed a four to five-fold increased mRNA expression of IGFBP-2 as compared with wt mLMFs at days 2 to 5. IGF-I dose-dependently stimulated DNA synthesis in wt mLMFs whereas in IGFBP-2 (±) mLMFs IGF-I-induced DNA synthesis was diminished compared with untreated control. Similarly, IGF-I increased mRNA expression of fibulin-2 and fibronectin-1, two of the ECM proteins deposited during liver fibrosis, in wt mLMFs whereas IGF-I-dependent mRNA expression of fibulin-2 and fibronectin-1 was inhibited in IGFBP-2 (±) mLMFs.

Conclusions: Overexpression of IGFBP-2 in mLMFs was associated with reduced DNA replication and biosynthesis of ECM components in these cells. These data point to an important role of IGFBP-2 during liver fibrogenesis and indicate IGFBP-2 as a potential target in antifibrotic therapy.