Alcoholic hepatitis (AH) is a life-threatening condition characterized by profound hepatocellular dysfunction for which targeted treatments are urgently needed. Identification of molecular drivers is hampered by the lack of suitable animal models. By performing RNA sequencing in livers from patients with different phenotypes of alcohol-related liver disease (ALD), we show that development of AH is characterized by defective activity of liver-enriched transcription factors (LETFs). TGF β 1 is a key upstream transcriptome regulator in AH and induces the use of HNF4 α P2 promoter in hepatocytes, which results in defective metabolic and synthetic functions. Gene polymorphisms in LETFs including HNF4 α are not associated with the development of AH. In contrast, epigenetic studies show that AH livers have profound changes in DNA methylation state and chromatin remodeling, affecting HNF4 α -dependent gene expression. We conclude that targeting TGF β 1 and epigenetic drivers that modulate HNF4 α -dependent gene expression could be beneficial to improve hepatocellular function in patients with AH.

Wnt/beta-catenin signaling plays an important role in normal development. However, its aberrant activation is associated with several cancers. The aim of this study is to examine the Wnt/beta-catenin pathway in patients with advanced pancreatic adenocarcinoma (n = 31). Paraffin sections from tumors (n = 16) and normal pancreata (n = 3) were used to determine the localization of beta-catenin. An additional 15 frozen tumors, adjacent normal pancreata (n = 5), or normal pancreata (n = 4) were utilized for protein isolation. Tumors were also examined for mutations in exon 3 of the CTNNB1 gene. More than 65% of the tumors showed an increase in total beta-catenin, consistent with its enhanced membranous, cytoplasmic, and nuclear localization, but only two showed mutations in CTNNB1. The majority of the remaining tumors demonstrated concurrent increases in Wnt-1 and frizzled-2 (positive regulators) and a decrease in Ser45/Thr41-phospho-beta-catenin. Electrophoretic mobility shift assay demonstrated beta-catenin-T-cell factor binding in tumors only. Adenomatous polyposis coli and axin, which are both negative regulators, remained unchanged. Unexpectedly, total glycogen synthase kinase-3beta protein was elevated in these tumors. Elevated levels of E-cadherin were also observed, although E-cadherin-beta-catenin association in tumors remained unaffected. Thus, Wnt/beta-catenin activation was observed in 65% of pancreatic adenocarcinomas, independently of beta-catenin gene mutations in most tumors.

Background & Aims-Wnt/β-catenin activation is observed in normal liver development, regeneration, and liver cancer. Our aim was to elucidate the regulation and mechanism of this pathway in liver.

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The Notch/Jagged signaling pathway is important for cellular differentiation and proliferation. Its dysfunction is associated with human pathologies in several tissues including liver. Point mutations in Jagged-1 gene are the cause for Alagille syndrome, associated with paucity of intrahepatic bile ducts. To determine the putative role of the trans-membrane receptor Notch and its ligand Jagged-1 in liver regeneration, we investigated the expression of Notch and Jagged-1 in rat liver following 2/3 partial hepatectomy. Immunohistochemical staining of normal rat liver showed that Notch was expressed in hepatocytes, bile duct cells and endothelial cells, whereas Jagged-1 was expressed in bile duct cells and hepatocytes. Both Notch-1 and Jagged-1 proteins were upregulated in hepatocytes after partial hepatectomy up to day 4. After partial hepatectomy, nuclear translocation of the intracellular cytoplasmic domain of Notch (NICD) increased and peaked within 15 minutes, indicating the activation of Notch. Expression of the Notch-dependent target gene (HES-1) expression increased within 30 -60 minutes. Addition of recombinant Jagged-1 protein to primary cultures of hepatocytes stimulated hepatocyte DNA synthesis. Furthermore, injection of silencing RNA for Notch and Jagged-1 to livers 2 days before partial hepatectomy significantly suppressed proliferation of hepatocytes at days 2 to 4 of the regenerative response. In conclusion, Notch/Jagged signaling pathway is activated during liver regeneration and is potentially contributing to signals affecting cell growth and differentiation. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/ 0270-9139/suppmat/index.html).

Signaling initiated by Class Ia phosphatidylinositol-3-kinases (PI3Ks) is essential for cell proliferation and survival. We discovered a novel protein we call PI3K Interacting Protein 1 (PIK3IP1) that shares homology with the p85 regulatory PI3K subunit. Using a variety of in vitro and cell based assays, we demonstrate that PIK3IP1 directly binds to the p110 catalytic subunit and modulates PI3K activity. Our studies suggest that PIK3IP1 is a new type of PI3K regulator.

Abstractβ-Catenin, a key component of the canonical Wnt pathway is also regulated by tyrosine phosphorylation that regulates its association to E-cadherin. Previously, we reported its association with the hepatocyte growth factor (HGF) receptor-Met, at the membrane. HGF induced met-β-catenin dissociation and nuclear translocation of β-catenin, which was tyrosine-phosphorylation dependent. Here, we further investigate the met-β-catenin interaction, by selectively mutating several tyrosine residues alone or in combination, in β-catenin. The mutants were subcloned into FLAG-CMV vector & stably transfected into rat hepatoma cells, which were treated with HGF. All single or double mutant-transfected cells continued to show HGF induced nuclear translocation of FLAG-β-catenin except the mutations affecting 654 and 670 simultaneously (Y654/670F), which coincided with the lack of formation of β-catenin-TCF complex and DNA synthesis, in response to the HGF treatment. In addition, the Y654/670F-transfected cells also showed no phosphorylation of β-catenin or dissociation from Met in response to HGF. Thus, intact 654 and 670 tyrosine residues in β-catenin are crucial in HGF-mediated β-catenin translocation, activation, and mitogenesis.

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