Translational regulation of PGC1alpha and oxidative metabolism

PROJECT SUMMARY As the prevalence of obesity and associated disorders rises, manipulation of adipocyte energy expenditure has gained attention as a potential means to treat metabolic disease. This strategy leverages the physiology of thermogenic adipocytes, a cell type that relies on oxidative phosphorylation metabolism to drive futile chemical cycles that release energy as heat. Recent work has suggested the potential for ribosomal control of thermogenic gene expression. Elucidating the responsible mechanisms may reveal novel means to manipulate adipocyte metabolism for the treatment of obesity and diabetes. This proposal tests the hypothesis that the distinct metabolism of thermogenic fat is enabled by specialized mRNA translation preferences inherent in this cell type. A first set of studies focuses on a single mRNA, PPARGC1A, and aims to purify the proteins that confer its cell-type-specific translational output. This mRNA encodes PGC1α, a dominant regulator of mitochondrial biogenesis. A second set of studies develops an in vivo mouse model to test the hypothesis that the helicase DDX3X, a regulator of mRNA translation and cytoplasmic stress granules, is a thermogenic-fat- selective translational regulator that supports expression of genes critical for oxidative metabolism. A third set of studies uses ribosome profiling technology to define the global mRNA translation dynamics associated with thermogenic activation. Together, these studies expand the scope of my work while generating foundational datasets and mouse models for my scientific independence. They will be carried out in the lab of a recognized leader in the field of molecular metabolism, Dr. Bruce Spiegelman, at the Dana-Farber Cancer Institute and Harvard Medical School. In this rich environment, I will benefit from a mentorship team committed to instruct me in: adipocyte biology, including in vivo genetic manipulation; mouse metabolic phenotyping; mass spectrometry; and bioinformatics. The technical training is complemented by formal instruction in human metabolic pathophysiology, as well as activities for honing my leadership, speaking, and writing skills. In this way the NIH Pathway to Independence Award supports my transition from mentored work to an independent stage in which I intend to use cutting-edge methods to broadly define the translational dynamics of thermogenic fat, identify the responsible regulators, and test how post-transcriptional dynamics such as stress granule assembly may contribute. My ultimate goal is to lead an academic research group that investigates how the gene expression programs that define cellular identity and metabolism are established, how they are perturbed in metabolic disease, and how they may be therapeutically manipulated to prevent or treat metabolic disease.