Understanding the Role of Serine 26 Phosphorylation Changes in Peroxidemediated Trafficking of System x_c^- to the Cell Membrane

Student Author(s)

Katherine Lane, Hope College

Faculty Mentor(s)

Dr. Leah Chase, Biology and Chemistry

Document Type

Poster

Event Date

4-12-2024

Abstract

Composed of xCT and 4F2HC, System x_c^- is involved in importing cystine and exporting glutamate from the cell. xCT is directly involved in cystine-glutamate transport, and 4F2hc is responsible for stabilizing and moving xCT onto the cell membrane. Previous studies found that phosphorylating serine 26 (S26) on xCT inhibits xCT activity by moving system x_c^- off the cell membrane into lysosomes to be degraded (Figure 1). A previous study by the Chase lab showed that treating COS7 cells with hydrogen peroxide (H2O2) led to significantly higher amounts of xCT on the cell membrane. The objective of our research is to determine if a change in S26 phosphorylation on xCT plays a role in peroxide-mediated System x_c^- movement to the cell membrane. To explore the effects of H₂O₂ on S26 phosphorylation, we use two xCT mutants: S26A and S26D. S26A is an xCT mutant where S26 is replaced with alanine, mimicking a non-phosphorylated serine. S26D is an xCT mutant where S26 is replaced with aspartate, mimicking a phosphorylated serine. We treated half the S26A and S26D groups with H₂O₂ for 10 minutes, and used immunocytochemistry and biotinylation to compare the amount of membrane-bound xCT for the control and H₂O₂-treatment groups. Statistically significant results of a two-way ANOVA of a Western Blot biotinylation procedure showed that a higher proportion of membrane-bound xCT occurred in cells with the S26A mutation and cells treated with H₂O₂. Immunocytochemistry analysis results were not consistent with these findings, and the proportion of membrane-bound xCT was the highest in S26A mutant cells that were not treated with H₂O₂, and this group was statistically significantly higher than the rest of the groups. Unexpectedly, the control treatment S26D mutant cells had a higher proportion of membrane-bound xCT than the S26A mutant cells treated with H₂O₂. Ultimately, this work aims to understand the specific way that S26 phosphorylation regulates in system x_c^-.

Recommended Citation

Repository citation: Lane, Katherine, "Understanding the Role of Serine 26 Phosphorylation Changes in Peroxidemediated Trafficking of System x_c^- to the Cell Membrane" (2024). 23rd Annual A. Paul and Carol C. Schaap Celebration of Undergraduate Research and Creative Activity (2024). Paper 55.
https://digitalcommons.hope.edu/curca_23/55

April 12, 2024. Copyright © 2024 Hope College, Holland, Michigan.

Comments

This work was supported by the Herbert E. and Grace A. Dow Foundation and the Schaap Science Undergraduate Research Fund.