Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Ryan Shaw - University of the Virgin Islands
Co-Author(s): Sayeepriyadarshini Anakk, the University of Illinois at Urbana Champaign, Urbana; Hanna Erickson, the University of Illinois at Urbana Champaign, Urbana; Bhoomika Mathur, the University of Illinois at Urbana Champaign, Urbana
Bile acids, the amphipathic molecules that are components of bile, facilitate absorption and the transportation of lipid molecules in mammals and vertebrates. Bile is synthesized in the liver and subsequently released into the gastrointestinal tract, before being excreted into the feces. SHP is a nuclear receptor expressed in the liver and is known to inhibit the genes responsible for bile acid synthesis. Apart from synthesis, SHP can also modulate bile acid transport and excretion. Whole body deletion of SHP (SHP knock out) mice have been characterized in depth but it is hard to delineate the tissue-specific role for SHP from these findings. Therefore, this project was designed to compare the liver-specific versus the intestine-specific role for SHP in maintaining biliary homeostasis. By specifically deleting SHP in the hepatocyte and in the enterocyte independently, we will be able to delineate the importance for SHP in maintaining the gut-liver axis and in protection against cholestasis.
Wild type mice, intestine, and liver SHPKO mice were fed either a normal chow diet or a 1% cholic acid to see how bile acid homeostasis was altered when excessive amounts of bile acids were present in the liver of SHPKO mice. The livers of these mice were extracted and then used to synthesize cDNA. The cDNA was used to perform qPCR to quantify the expression of bile acid synthesis, transport and excretion genes in the liver. In addition to multiple qPCRs, a bile acid assay was performed to quantify the concentration of bile acids in the liver samples. The goal of this project was to evaluate the role of SHP in regulating the accumulation of bile acids in the liver as well as SHP?s ability to upregulate and downregulate the relative expression of bile acid synthesis, transport and excretion genes in the liver, and lastly evaluate SHP’s effect on proliferation in the liver. We hypothesized that the liver specific knock-out of nuclear receptor SHP would result in the upregulation of bile acid synthesis genes and increase in the overall quantity of bile acid present in the liver. We also hypothesized that intestine specific SHPKO mice would exhibit no change in the bile acid synthesis, transportation and excretion gene expression
. The bile acid negative feedback loop regulated by nuclear receptors FXR and SHP is absent in liver-specific SHPKO mice as bile acid synthesis gene expression is still significant when there is an excess of bile acids in the system. Cellular proliferation was significantly increased in liver-specific SHPKO mice on the cholic acid diet indicating the loss of SHP and a state of increased bile acids triggers increased cellular activity. Intestine specific SHPKO mice showed no changes in the expression of bile acid synthesis, transportation, and excretion genes. SHPKO mice displayed an overall lower quantity of bile acids when compared to wild type mice. Data suggest that the loss of SHP may be beneficial in preventing cholestasis.
Funder Acknowledgement(s): Summer Research Opportunity Program (SROP @ UIUC)
Faculty Advisor: Sayeepriyadarshini Anakk, email@example.com
Role: Synthesized RNA, Synthesized cDNA, Performed qPCR, Performed Ki-67 Immunohistochemistry staining, Performed H & E staining, Compared relative gene expression between experimental groups, Performed colorimetric bile acid assay, Complied data.