Date of Award
2024
Document Type
Dissertation
Degree Name
Philosophy (Ph.D)
Department
Pharmaceutical Sciences
First Advisor
Vikas V. Dukhande
Second Advisor
Sunil Kumar
Third Advisor
Ashley Martino
Abstract
Type 2 diabetes, an epidemic affecting an estimated 500 million people worldwide, is characterized by a combination of impaired glucose homeostasis and various extents of beta cell dysfunction and insulin resistance. Post-translational modifications (PTMs) of key players in the insulin signaling pathway are known to contribute to insulin resistance by regulating the activity and function of proteins such as IR, IRS, and Akt. Sustained hyperglycemia, inflammation, and obesity-induced lipid alterations activate serine/threonine kinases that phosphorylate insulin signaling proteins, leading to their deactivation. However, little is known about ubiquitination’s effect on insulin resistance. The ubiquitin-proteasome system regulates various cellular processes, and the aberrant function of this system is linked to various human ailments, such as neurodegenerative diseases, cancer, and immune disorders. Ubiquitination is a multistep process that utilizes E3 enzymes to ligate the C-terminal glycine of ubiquitin, a 76 amino acid tag, to target proteins. The addition of further ubiquitin molecules using various lysine (K) residues can build poly-ubiquitin chains of different topologies. The structural and functional diversity of ubiquitin linkages imparts unique abilities of this PTM in controlling normal physiology and pathophysiology. Moreover, several studies have implicated E3 ubiquitin ligases in the development of insulin resistance. Therefore, we studied hepatic ubiquitination patterns in a high-fat diet and low-dose streptozotocin (HF-STZ) animal model of diabetes. Affinity pull-down and proteomics techniques were employed to explore differential ubiquitination as well as K48- and K63-linkage-specific differences between control and diabetic animals. Both overall and linkage-specific ubiquitination were higher in diabetic rat livers. Bioinformatic analysis of the top 150 protein hits in each ubiquitination category revealed enrichment in metabolic processes involving glucose and lipid metabolism. Our study provides insight into hepatic ubiquitination in an animal model of insulin resistance. The identified ubiquitinated proteins could serve as potential targets for the pharmacotherapy of type 2 diabetes and merit further investigation.
Recommended Citation
Abo-Ali, Ehab M., "A UBIQUITIN-BASED PROTEOMIC ANALYSIS OF HF-STZ DIABETIC RAT LIVERS" (2024). Theses and Dissertations. 828.
https://scholar.stjohns.edu/theses_dissertations/828