Faculty Mentor(s)

Dr. Leah Chase, Biology and Chemistry

Document Type

Poster

Event Date

4-12-2024

Abstract

System xc- imports cystine and exports glutamate. Its presence on the plasma membrane has been shown to increase directly with oxidative insults. Ubiquitin, a small protein, is directly involved in the trafficking and degradation of numerous proteins within cells and has been shown to bind to System xc-. Moreover, upon oxidative insult, protein ubiquitination increases. However, it is not understood how ubiquitination of the transporter impacts its activity. Therefore, the objective of this project is to directly assess how ubiquitination affects the protein’s stability, turnover rate, and localization in the context of oxidative stress. We expressed System xc- in COS7 cells transfected with increasing levels of ubiquitin and observed a decrease in xCT expression and increase in xCT turnover rate as ubiquitin levels rose. However, we also observed an increase in membrane localization in the presence of ubiquitin relative to control. Thus, ubiquitin appears to have a complex effect on xCT activity, and suggests that perhaps that rapid and reversible ubiquitination of the transporter may be responsible for dynamic increases in transporter activity, while extended ubiquitination of the transporter may target the transporter for degradation. Ultimately, this work will allow us to better understand the mechanisms by which System xc- activity is regulated under oxidative stress.

Comments

This work was supported by the Schaap Science UndergraduateResearch Fund and the Hope College Biology Department.

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