Changes in WNT/beta-catenin pathway during regulated growth in rat liver regeneration

Hepatology. 2001 May;33(5):1098-109. doi: 10.1053/jhep.2001.23786.

Abstract

The wnt/beta-catenin pathway is important during embryogenesis and carcinogenesis. beta-Catenin interaction with E-cadherin has been shown to be crucial in cell-cell adhesion. We report novel findings in the wnt pathway during rat liver regeneration after 70% partial hepatectomy using Western blot analyses, immunoprecipitation studies, and immunofluorescence. We found wnt-1 and beta-catenin proteins to be predominantly localized in hepatocytes. Immediately following partial hepatectomy, we observed an initial increase in beta-catenin protein during the first 5 minutes with its translocation to the nucleus. We show this increase to be the result of decreased degradation of beta-catenin (decrease in serine phosphorylated beta-catenin) as seen by immunoprecipitation studies. We observed activation of beta-catenin degradation complex comprising of adenomatous polyposis coli gene product (APC) and serine-phosphorylated axin protein, beginning at 5 minutes after hepatectomy, leading to its decreased levels after this time. Quantitative changes observed in E-cadherin protein during liver regeneration are, in general, reverse to those seen in beta-catenin. In addition, using immunoprecipitation, we observe elevated levels of tyrosine-phosphorylated beta-catenin at 6 hours onward. Thus, changes in the wnt pathway during regulated growth seem to tightly regulate cytosolic beta-catenin levels and may be contributing to induce cell proliferation and target gene expression. Furthermore, these changes might also be intended to negatively regulate cell-cell adhesion for structural reorganization during the process of liver regeneration.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Axin Protein
  • Biological Transport / physiology
  • Cadherins / metabolism
  • Cytoskeletal Proteins / metabolism*
  • Liver / metabolism*
  • Liver Regeneration / physiology*
  • Male
  • Phosphorylation
  • Proteins / metabolism
  • Proto-Oncogene Proteins / metabolism*
  • Rats
  • Rats, Inbred F344
  • Reference Values
  • Repressor Proteins*
  • Time Factors
  • Tissue Distribution
  • Trans-Activators*
  • Tyrosine / metabolism
  • Wnt Proteins
  • Wnt1 Protein
  • Zebrafish Proteins*
  • beta Catenin

Substances

  • Axin Protein
  • Cadherins
  • Ctnnb1 protein, rat
  • Cytoskeletal Proteins
  • Proteins
  • Proto-Oncogene Proteins
  • Repressor Proteins
  • Trans-Activators
  • Wnt Proteins
  • Wnt1 Protein
  • Wnt1 protein, rat
  • Zebrafish Proteins
  • beta Catenin
  • Tyrosine