Hepatocyte nuclear factor 4-alpha involvement in liver and intestinal inflammatory networks

Abstract

Hepatocyte nuclear factor 4-alpha (HNF4-α) is a nuclear receptor regulating metabolism, cell junctions, differentiation and proliferation in liver and intestinal epithelial cells. Mutations within the HNF4A gene are associated with human diseases such as maturity-onset diabetes of the young. Recently, HNF4A has also been described as a susceptibility gene for ulcerative colitis in genome-wide association studies. In addition, specific HNF4A genetic variants have been identified in pediatric cohorts of Crohn’s disease. Results obtained from knockout mice supported that HNF4-α can protect the intestinal mucosae against inflammation. However, the exact molecular links behind HNF4-α and inflammatory bowel diseases remains elusive. In this review, we will summarize the current knowledge about the role of HNF4-α and its isoforms in inflammation. Specific nature of HNF4-α P1 and P2 classes of isoforms will be summarized. HNF4-α role as a hepatocyte mediator for cytokines relays during liver inflammation will be integrated based on documented examples of the literature. Conclusions that can be made from these earlier liver studies will serve as a basis to extrapolate correlations and divergences applicable to intestinal inflammation. Finally, potential functional roles for HNF4-α isoforms in protecting the intestinal mucosae from chronic and pathological inflammation will be presented.

Keywords: Hepatocyte nuclear factor 4-alpha, Inflammatory bowel diseases, Colitis-associated cancer, Gastrointestinal tract, Intestinal epithelium barrier, Inflammation

Core tip: Hepatocyte nuclear factor 4-alpha (HNF4-α) is an important regulator of liver and intestinal epithelial cells function. Over the last years, HNF4-α has been associated with inflammatory bowel diseases following results obtained from knockout mice and human genome-wide association studies. However, no review has been published on the subject yet and no link with its known role in liver inflammation has been discussed. This review will gather for the first time all the current knowledge about the role of HNF4-α in gut inflammation, the potential impact of its isoforms in its role and hypotheses about the possible biological mechanisms involved.