Uncovering the role of RFT1 in growth and developmental signaling

PROJECT SUMMARY/ABSTRACT: In the last 50 years, over 150 types of congenital disorders of glycosylation (CDG) have been described, while available treatment options have severely lagged. CDG are early onset childhood diseases that often present with severe symptoms that span most organ systems. Collectively, heterogeneity in the genetic causes and clinical presentations of CDG have made treatment challenging, and thus, there is a significant need to elucidate the mechanisms of individual CDG to provide available treatment options for patients. One CDG with no available treatment and often severe symptoms is RFT1-CDG, caused by mutations in the transmembrane protein RFT1. RFT1 is proposed to function in N-glycosylation and/or GPI-anchoring, however, its role in glycosylation remains undefined. Many RFT1-CDG symptoms are related to defects in growth and development. My preliminary work in C. elegans suggests that RFTH-1 (RFT1 homolog) may activate Hedgehog signaling, a key regulator of development and growth, and that downstream signaling occurs through the pro-growth mTOR Complex 2 (mTORC2) pathway. Glycosylation can dramatically alter protein function or activity, and interestingly, multiple Hedgehog signaling components are glycosylated. Thus, impaired developmental and pro-growth signaling may underlie RFT1-CDG pathophysiology. This proposal seeks to investigate how RFT1 governs development and growth via regulation of Hedgehog and downstream homeostatic signaling, as well as to deconvolute the role of RFT1 in the glycosylation of Hedgehog signaling factors and establish how these events alter organismal physiology. This work will be conducted using genetic, cell biological, and biochemical approaches in two complementary model systems: C. elegans, to gain a whole organism perspective, and mammalian cell culture, with the goal of translating our C. elegans work to understand the disease pathophysiology in humans. In doing so, I aim to elucidate the mechanisms by which RFT1 mutations cause CDG-associated symptoms, while establishing a framework to study other CDG types to inform the development of effective treatment options. This research will take place at the University of North Carolina at Chapel Hill (UNC-CH) in the Rob Dowen Lab as part of the Genetics and Molecular Biology (GMB) Curriculum. UNC-GMB upholds a collaborative, innovative, and rigorous research program with excellent resources, outstanding facilities, and a substantiated commitment to trainee success. In addition to building my scientific skillset through this proposed work, my training will include strengthening my scientific communication and leadership skills to prepare for a career as a principal investigator. Through GMB and its affiliated career development office, TIBBS, I will have abundant resources to hone these skills. Additionally, my dedicated, interdisciplinary team of mentors, including my advisor and thesis committee, will support both my scientific and career development training endeavors. Altogether, my scientific environment and training plan will equip me to execute this proposal and become a well-rounded, independent scientist.