Screening Metabolites of Host Microbial Origin that Activate Ligand-Dependent Transcription Factors
Open Access
Author:
Carbaugh, Logan
Area of Honors:
Veterinary and Biomedical Sciences
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Andrew Patterson, Thesis Supervisor Joshua J Kellogg, Thesis Honors Advisor
Keywords:
Microbiome Metabolism Biology Dose-Response
Abstract:
The microbiome is a complex symbiosis of microorganisms that inhabit the human body. Numbering in the trillions, these microorganisms play essential roles in human health and maintaining overall homeostasis. Gut microbiota work to metabolize a large number of natural products in concert with host metabolism. Many of these metabolites produce their physiological effects through the binding of transcription factors that mediate expression of genes important in metabolism. One such transcription factor is the pregnane X receptor (PXR), a type II nuclear receptor important in regulating the expression of proteins that function in host metabolism. To gain a better understanding of how gut microbiota metabolism affects expression of genes important in host metabolism, we screened 200 metabolites of microbial origin for their potential to activate PXR. We performed a firefly luciferase reporter gene assay utilizing human hepatocyte cells engineered to express a modified form of PXR that binds to and initiates transcription of the firefly luciferase gene. Expression of luciferase leads to quantifiable bioluminescence that acted as a proxy for PXR activation. After screening each microbial metabolite for its ability to activate PXR, we chose the most active metabolites and generated dose-response curves for PXR activation. Our results furthered the paradigm that the microbiome is highly involved in human physiology, especially the metabolism of xenobiotic materials.
