Proteomic Profiling of Histone Posttranslational Modifications in Late Gestation Fetal Hepatocytes Capable of Liver Repopulation

Abstract

Hepatocyte transplantation has the potential to be an effective therapy for acute liver disease and metabolic disorders. Our laboratory has focused on late gestation (E19) liver development in the rodent. We have identified a fetal hepatocyte phenotype defined by differences in signaling pathways and gene expression. We recently found that E19 hepatocytes expressing the hepatic marker leucine aminopeptidase (LAP) have the ability to repopulate an injured adult liver. Our current studies are based on the hypothesis that histone posttranslational modifications (PTMs) acting through effects on chromatin structure account for the E19 hepatocyte signaling phenotype and the repopulating ability of these cells. We employed a bottom‐up mass spectrometry based approach to profile PTMs on histone H3 and H4 in freshly isolated LAP+ E19 hepatocytes and adult hepatocytes, and cultured adult hepatocytes. In order to mimic the asynchronously proliferating E19 hepatocytes, adult hepatocytes were cultured in the presence of EGF and insulin for time points ranging from 0 to 72 hr and combined into pooled samples for mass spectrometry. We identified significant differences in 10 of the 26 histone PTMs on H3 and H4 comparing the asynchronously proliferating LAP+ E19 and cultured adult hepatocytes. In summary, late gestation fetal hepatocytes capable of liver repopulation possess a histone PTM profile that is distinct from that of adult hepatocytes.