Identification of a suppressor mutant of slc16a6a deficiency in zebrafish, and development of tools for studying the role of slc16a6 in Melanoma

Obesity is a major burden on public health, responsible for a myriad of complicated, dysfunctional metabolic phenotypes. In particular, the accumulation of fat outside of adipocytes is a serious area of concern. Non-alcoholic fatty liver disease (NAFLD) is one such obesity-related disorder, about which little is known on a molecular level and for which successful treatment has yet to be established. My thesis lab took a genetic approach in zebrafish to identify new genes that participate in lipid metabolism in hope of finding mutants with ectopic lipid accumulation. A mutant with hepatic steatosis, or fatty liver, was identified. In this mutant, red moon (rmn), slc16a6a is nonfunctional, rendering hepatocytes unable to release ketone bodies during fasting. The trapped carbon atoms from these partially oxidized, short chain fatty acids critical to meeting the energy demands of the brain during starvation are diverted to de novo lipogenesis, and storage as triacylglycerol in cytoplasmic lipid droplets. My thesis work begins to build on known aspects of slc16a6a function. I started with a genetic screen to identify dominant modifying mutants and have discovered one such mutation, total eclipse of red moon (term), which suppresses the slc16a6a-/- phenotype. I have begun to determine its genomic position with RNA-seq mapping and have cloned several candidate genes. I have tested the candidates for mutations that could explain physiological insight into how hepatic steatosis can be attenuated. The hope is this new information can be used to develop novel therapeutic approaches to NAFLD. I have also established a platform to evaluate this gene’s role in a different disease context: cancer. Human melanomas show increased expression of SLC16A6. With Tol2 transgenesis techniques, I made a transgenic construct that will be used to test whether this gene promotes cancer, measuring tumor growth and metastasis. This begins to look at whether ketone body uptake is a significant aspect of melanoma metabolism. The outcome of experiments done on the platform I have established could reveal a novel therapeutic avenue for melanoma.