Project Abstract The overall goal of the lab is to study the role of energy homeostasis pathways in human disease using structural and chemical tools. Our lab focuses on two major fundamental pathways: O-GlcNAcylation and autophagy. The first major focus on the lab is on glycosylation, which plays a fundamental role in living organisms and is misregulated in several human diseases. A unique form of glycosylation in mammals involves the essential enzyme O-GlcNAc transferase (OGT), which dynamically transfers a single sugar on to nuclear and cytoplasmic proteins to modulate signaling, transcription, and protein degradation. This single enzyme is responsible for glycosylating over a thousand substrates. Aberrant OGT activity is associated with human diseases such as cancer, diabetes, obesity, and neurodegeneration. However, the biology of this modification is quite complex because of the abundance of substrates for a single enzyme. This complexity has prevented an understanding of which substrates are important for human diseases, how OGT recognizes them, and how metabolic changes alter the physiology of cells through this enzyme. We seek to better understand the mechanism of this fundamental enzyme through a combination of biochemistry, structural biology, and chemical biology. Our major goal is to clarify the complex role that nuclear and cytoplasmic protein glycosylation has in human disease. Autophagy is a conserved pathway that eukaryotic cells use to recycle materials from proteins to whole organelles for energy and quality control. It has recently been shown that cancer cells rely on autophagy to satisfy their increased energy demands and to resist chemotherapy. To study autophagy, our major goals are developing new chemical inhibitors of a key enzyme that initiates autophagy called ULK1. Our other goal is to find novel synthetic lethal interactors with autophagy by discovering other drugs that synergistically target cells when autophagy is inhibited. Our vision is to develop advance screening systems to better mimic tumors and look for new combinations of treatment that rely on blocking autophagy.