2008 — 2010 |
Edmondson, Andrew Charles |
F30Activity Code Description: Individual fellowships for predoctoral training which leads to the combined M.D./Ph.D. degrees. |
Endothelial Lipase: a Modulator of Hdl Metabolism and Atherosclerosis in Humans @ University of Pennsylvania
[unreadable] DESCRIPTION (provided by applicant): Endothelial lipase (EL) is an extracellular protein with significant hydrolysis activity against HDL. Studies in model organisms suggest that EL is important in HDL metabolism; however, the significance of EL in human HDL metabolism is unknown. The objective of this proposal is to investigate variation in human EL and the effects of this variation on HDL levels. Deep resequencing of EL in subjects with high HDL has identified potentially functional nonsynonymous and promoter variants. We hypothesize that rare EL coding variants increase HDL by decreasing EL activity. We also hypothesize that EL promoter variants modulate HDL levels by affecting levels of EL protein via alterations in transcriptional efficiency. Specific Aim 1: To determine if coding variants of EL increase HDL by decreasing EL activity. To test for decreased activity, coding variants will be recreated in an EL expression plasmid via site-directed mutagenesis, expressed in 293 cells, and their specific activities assayed in vitro against synthetic phospholipids substrates and native HDL. To test for an influence on HDL levels in vivo, the coding variants will be cloned into AAV-based vectors, injected into EL-KO mice, and HDL levels assessed over 6 weeks. Association of the variants with human HDL levels will be tested statistically by comparing frequencies among subjects from HDL extremes and by analyzing cosegregation with HDL levels within families. Specific Aim 2: To determine if promoter variants of EL modulate HDL levels through their influence on the rate of transcription of the EL gene. To test for altered rates of transcription, promoter variants will be recreated via site-directed mutagenesis in a firefly luciferase expression plasmid driven by the EL promoter, and transfected into HUVEC cells. Expression results will be validated by allele-specific HaploChIP analysis on endothelial cells isolated from heterozygous subjects. Association of the variants with human HDL levels will be tested statistically by comparing frequencies among subjects from HDL extremes and by analyzing cosegregation with HDL levels within families. HDL levels correlate with protection from coronary heart disease, the leading cause of mortality among men and women. This proposal will attempt to determine the significance of endothelial lipase in human HDL metabolism, and validate it as a target for pharmacologic inhibition to raise HDL levels. [unreadable] [unreadable] [unreadable]
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1 |
2020 — 2021 |
Edmondson, Andrew Charles |
K08Activity Code Description: To provide the opportunity for promising medical scientists with demonstrated aptitude to develop into independent investigators, or for faculty members to pursue research aspects of categorical areas applicable to the awarding unit, and aid in filling the academic faculty gap in these shortage areas within health profession's institutions of the country. |
O-Glycosylation Mechanisms of Neurological Deficits in Congenital Disorders of Glycosylation @ Children's Hosp of Philadelphia
PROJECT SUMMARY/ABSTRACT Glycosylation is an essential, post-translational modification with complex and poorly understood roles in protein function. My long-term objective is to elucidate the neurobiological functions of glycosylation, including identifying the roles of critical glycosylation sites in neuronal protein function. The importance of glycosylation is emphasized by the congenital disorders of glycosylation (CDG), a group of genetic disorders that disrupt cellular glycosylation machinery. Affected patients exhibit severe neurological deficits. The genetic basis of CDG provides an opportunity to identify the neurobiological functions of glycosylation using mouse models and glycoproteomics. Understanding glycosylation in the nervous system will elucidate the pathophysiology of CDGs and other neurological diseases, enable therapeutic advances targeting glycosylation pathways, and inform normal function of glycosylation. GALNT2-CDG is a new CDG type caused by biallelic mutations in GALNT2, which encodes a critical glycosyltransferase initiating the first step in mucin-type O-glycosylation. GALNT2-CDG patients suffer from epilepsy and global developmental delay. Galnt2 constitutional knock-out mice recapitulate many of the patient neurological deficits. My central hypothesis is that site-specific loss of O-glycosylation on neural proteins contributes to neurological dysfunction. The specific objective of this project is to identify the cause of neurological dysfunction in GALNT2-CDG. This will be achieved by determining cellular origins of Galnt2 deficiency-mediated neurological deficits using Cre-mediated deletion of Galnt2 in neural cells and by identifying disrupted O-glycosylation in these cells using glycoproteomics. This proposed five-year career development plan focuses on achieving four objectives: develop research skills in mouse models and glycoproteomics, increase my knowledgebase in neuroscience and glycobiology, establish a body of work focusing on the role of glycosylation in the context of neurobiology, and obtain the necessary skills to transition to independence. Mentoring will be provided by Dr. Zhaolan Zhou, a recognized leader in the development and investigation of mouse models of genetic disorders that affect brain development and function, and Dr. Benjamin Garcia, a recognized expert in developing quantitative mass spectrometry techniques to interrogate post-translational modifications. The skill set developed through these investigations and career development plan will make me uniquely poised to uncover glycosylation-mediated mechanisms of CDG and other neurological diseases, as well as to elucidate the critical roles of glycosylation in human neurological function. These studies will generate new tools and a foundation to establish a long-term research program to investigate the pathophysiology of various glycosylation-related disorders in the nervous system and prepare me to become an independent R01-funded physician scientist.
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0.913 |