By immunofluorescence, four KO livers showed less than 1% β-catenin-positive hepatocytes, whereas two KO livers had around 20%-30% spontaneous repopulation (Fig. 3C). Five additional KO livers showed less than 1% hepatocytes to be β-catenin-positive in the KO by IHC as well (data not shown). Thus, a majority of the KO livers did not show many β-catenin-positive hepatocytes at baseline, suggesting only a DDC injury-dependent spontaneous repopulation
with β-catenin-positive hepatocytes, which may have initially escaped albumin-cre driven β-catenin deletion. However, a very small subset of KO livers did show the presence of greater numbers click here of β-catenin-positive cells for unknown reasons, albeit nowhere to the extent observed after DDC exposure. Previously, we reported that β-catenin is strongly positive in bile duct epithelia in normal liver, whereas it is lacking in the KO despite the fact that conditional deletion of the floxed gene was brought about by the albumin-cre, perhaps due to embryonal expression of albumin in a common progenitor of hepatocytes and cholangiocytes.9 Next we address if β-catenin-positive biliary epithelial cells, which have also been shown to be the precursors of oval cells, may be the source of β-catenin-positive hepatocytes in the KO liver.11 A comprehensive analysis selleck compound showed that
none of the bile ducts in the KO livers were β-catenin-positive at baseline and 7 or 30 days of DDC exposure, as indicated by a lack of colocalization of β-catenin and A6, which is known to be a marker of biliary ductular epithelia and oval cells in the liver (Fig. 3B).1, 12 Most bile ducts continued to be β-catenin-negative in the KO livers after 80 days of DDC exposure, whereas in WT livers all bile ducts (atypical and atypical) were strongly β-catenin-positive (Fig. 3D). At this
stage only an occasional bile duct was lined by β-catenin-positive epithelia, whereas at 150 days a few additional ducts Adenosine triphosphate were β-catenin-positive (Fig. 3D). Thus, appearance of β-catenin-positive hepatocytes precedes the appearance of β-catenin-positive bile ducts in the KO liver at baseline as well as after chronic DDC injury and hence cannot be the source of repopulation. To examine whether the increase in the number of β-catenin-positive hepatocytes correlates with a decrease in expression of the transgene, we performed real-time PCR analysis for Cre-recombinase at 30, 80, and 150 days after DDC feeding. Real-time PCR analysis was performed for Cre-recombinase in three separate mouse livers using three different reference genes. The analysis showed that there was no significant difference in mRNA expression of Cre-recombinase between untreated age- and sex-matched KO mouse livers and the 30 days DDC-fed KO livers (data not shown).