| Autor: |
Braeuning A; Department of Toxicology, Institute of Experimental and Clinical Pharmacology and Toxicology, University of Tübingen, Wilhelmstr. 56, 72074, Tübingen, Germany., Singh Y, Rignall B, Buchmann A, Hammad S, Othman A, von Recklinghausen I, Godoy P, Hoehme S, Drasdo D, Hengstler JG, Schwarz M |
| Jazyk: |
angličtina |
| Zdroj: |
Histochemistry and cell biology [Histochem Cell Biol] 2010 Nov; Vol. 134 (5), pp. 469-81. Date of Electronic Publication: 2010 Oct 01. |
| DOI: |
10.1007/s00418-010-0747-1 |
| Abstrakt: |
Signaling through the Wnt/β-catenin pathway is a crucial determinant of hepatic zonal gene expression, liver development, regeneration, and tumorigenesis. Transgenic mice with hepatocyte-specific knockout of Ctnnb1 (encoding β-catenin) have proven their usefulness in elucidating these processes. We now found that a small number of hepatocytes escape the Cre-mediated gene knockout in that mouse model. The remaining β-catenin-positive hepatocytes showed approximately 25% higher cell volumes compared to the β-catenin-negative cells and exhibited a marker protein expression profile similar to that of normal perivenous hepatocytes or hepatoma cells with mutationally activated β-catenin. Surprisingly, the expression pattern was observed independent of the cell's position within the liver lobule, suggesting a malfunction of physiological periportal repression of perivenously expressed genes in β-catenin-deficient liver. Clusters of β-catenin-expressing hepatocytes lacked expression of the gap junction proteins Connexin 26 and 32. Nonetheless, β-catenin-positive hepatocytes had no striking proliferative advantage, but started to grow out on treatment with phenobarbital, a tumor-promoting agent known to facilitate the formation of mouse liver adenoma with activating mutations of Ctnnb1. Progressive re-population of Ctnnb1 knockout livers with wild-type hepatocytes was seen in aged mice with a pre-cirrhotic phenotype. In these large clusters of β-catenin-expressing hepatocytes, perivenous-specific gene expression was re-established. In summary, our data demonstrate that the zone-specificity of a hepatocyte's gene expression profile is dependent on the presence of β-catenin, and that β-catenin provides a proliferative advantage to hepatocytes when promoted with phenobarbital, or in a pre-cirrhotic environment. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
|
