Fructose consumption is not only a major risk factor for development of non-alcoholic fatty liver disease (NAFLD),
but also promotes hypercholesterolemia and atherosclerosis in humans and rodents. Identification of the
mechanisms linking NAFLD to cardiovascular disease (CVD) remains poorly understand. This proposal focuses
on identifying the influence dietary fructose has on synthesis and metabolism of cholesterol. Using a mouse
model of sugar-sweetened beverage consumption, the candidate shows that fructose metabolism increases
citrate, acetyl-CoA, and hepatic cholesterol levels. In addition, the candidate demonstrates fructose decreases
the protein expression of carnitine palmitoyltransferase 1a (Cpt1a), a mitochondrial fatty acid transport protein.
Moreover, conditional CPT1a knockout mice exhibit similar lipid perturbations as mice fed fructose. Therefore,
aim 1 utilizes dual stable isotope techniques coupled with NMR and mass spectrometry to quantify cholesterol
synthesis and fructose-derived carbon enrichment into the cholesterol biosynthetic pathway in male and female
mice. Livers from the mice will be used for acetyl-proteomics to delineate potential mechanisms linking fructose
to cholesterol biosynthesis. Aim 2 determines how transcriptional regulation of Cpt1a alters fructose-induced
suppression of fatty acid oxidation and enhanced cholesterol synthesis using both in-vitro and in-vivo
approaches. The purpose of this aim is to uncover a previous unrecognized role of Cpt1a in coordinating the
regulation of both lipid-signaling pathways (fatty acid oxidation and cholesterol synthesis) in response to fructose.
Completion of these aims will yield mechanistic insight linking dietary sugar metabolism to hypercholesterolemia.
The novelty of the proposed research is the comprehensive dual-stable isotope approach in conjunction with
analytical techniques to measure cholesterol synthesis and fructose-derived carbon enrichment into the sterol
synthesis pathway in the same cohort of animals. In addition, the proposed research reveals several innovative
mechanisms that have yet to be explored, including acetylation of cholesterol synthesis enzymes and regulation
of Cpt1a through transcriptional mechanisms. Strong collaborations among the Metabolomics Core at the
University of Kentucky, Mass Spectrometry Core at the Buck Institute for Research on Aging, and scientific
advisory committee members ensure successful completion of the proposed research by the candidate. This
research is complimented by a career development plan in which the candidate will learn new experimental
methodology in stable isotope metabolomics, broaden his scientific network through attending workshops and
conferences, and develop his communication skills so that he is poised to become an independent investigator.
This K01 award will allow him to reach his long-term goals of establishing a well-funded laboratory studying
dietary mechanisms in cardiometabolic disease.