The Kaestner lab employs modern mouse genetic approaches, such as gene targeting, tissue-specific and inducible gene ablation, to understand the molecular mechanisms of organogenesis and physiology of the liver, pancreas and gastrointestinal tract. We also use next-generation sequencing to look at differences between the transcriptome and epigenome of normal vs diseased tissues.
Some of our current research includes:
The mammalian gut epithelium is a highly organized and dynamic system which requires continuous controlled proliferation and differentiation throughout life. Proliferation, cell migration and cell adhesion all must be tightly controlled in order to prevent either inflammatory diseases or epithelial cancers. As with many other vertebrate organs, the digestive tract develops from heterogeneous embryonic origins. While the musculature and the connective tissue are derived from lateral plate mesoderm, the epithelium is derived from the endoderm. We have identified a novel member of the winged helix gene family termed Foxl1 which is expressed in the gut mesoderm and have begun its functional analysis in vivo through targeted mutagenesis in mice. Null mutations in the mesodermal transcription factor Foxl1 result in dramatic alterations in endoderm development, including epithelial hyperproliferation. We have now identified APC/Min and GKLF as downstream targets of Foxl1 and have begun the analysis of these genes in gastrointestinal differentiation by tissue-specific gene ablation.
A better understanding of the liver’s response to toxic injury, which includes hepatocyte proliferation, activation and differentiation of facultative hepatic stem cells (“oval cells”), and – unfortunately – an increased risk for hepatocellular carcinoma, is a prerequisite for the development of novel clinical treatments for chronic liver disease and improved cancer prevention. Likewise, cell replacement therapy, either through direct hepatocyte transplantation or in bio-artificial liver devices, needs to be improved in order to become a reliable alternative to liver transplantation. To date, investigations of hepatocyte proliferation have frequently focused on the partial hepatectomy paradigm, a “non¬injury” model that is not reflective of liver injury in humans and which has therefore failed to identify specific targets for either improved regeneration following toxic injury or for limiting proliferation in HCC in humans.
In Specific Aim 1, we will determine which genes and gene combinations promote or repress hepatocyte repopulation following toxic liver injury using an innovative genetic approach. In Specific Aim 2, we will employ expression of key hepatic transcription factors to improve the differentiation of hepatic progenitor cells to functional hepatocytes. Together, these approaches will provide an improved understanding of the liver’s response to toxic injury, and facilitate the discovery of new cell replacement therapies to treat chronic liver disease and liver failure.
- Redox regulation during liver repopulation
- Mapping liver tumor signaling pathways in vivo
- In vivo CRISPR-Cas9 activation and inhibition screening during liver repopulation
- Hepatocyte polyploidy and its association with human liver disease
- Pairwise microRNA inhibition in the regenerating mouse liver
- Mitochondrial genome editing to alleviate a nuclear gene deficiency
- Single cell applications in liver triomics
- Liver regeneration to stimulate epigenetic rejuvenation of hepatocytes
- FoxA1/2 regulation of hepatocyte-specific DNA methylation patterns