Publication Date

2024

Document Type

Thesis

Committee Members

Lucile E. Wrenshall, M.D., Ph.D. (Advisor); Dawn Wooley, Ph.D. (Committee Member); Yong-Jie Xu, Ph.D. (Committee Member)

Degree Name

Master of Science (MS)

Abstract

The interleukin 2 receptor alpha (IL-2Rα), which is integral to the functioning of the cytokine interleukin 2, has recently been found to be present in different cell types besides just lymphocytes. Previous studies done by our laboratory showed that several other non-lymphoid cells including smooth muscle cells express IL-2Rα. Vascular smooth muscle cell (VSMC) deficient in IL-2Rα exhibited increased proliferation, decreased size, and hypodiploid DNA content when compared to wild type (WT) cells. Previous studies also suggested that VSMC proliferate in response to IL-2 and that IL-2 increases following interventions to stimulate intimal hyperplasia in vivo. These findings, in total, suggest that IL-2/IL2R may contribute to the development of intimal hyperplasia. Understanding how IL-2Rα regulates VSMC proliferation may therefore lead to new therapeutic targets for the treatment of intimal hyperplasia and, in turn, atherosclerosis. Our initial findings regarding the differences between WT and IL-2Rα KO VSMC, described above, suggested that pathways related to senescence and/or responses to DNA damage may be impaired. To address this question, I compared the viability of human and WT VSMCs versus IL-2Rα knockout (KO) VSMCs post-treatment with DNA-damaging agents such as etoposide. Survival of IL-2Rα KO cells was decreased in response to DNA damage when compared to WT or human VSMC. Further experiments involved inducing DNA damage in cells through two different methods to assess the expression levels of key DDR markers—γH2AX, p53, and pChk1—using indirect immunofluorescence. IL-2Rα deficient cells exhibited diminished expression of these markers and did not undergo senescence. IL-2Rα KO cells, as compared to WT, also exhibited hyperpolarized mitochondrial membranes and reduced mitochondrial health following DNA damage. In summary, this study not only adds to the previous understanding of the IL-2Rα, but also correlates the receptor with crucial cellular pathways such as DDR. The finding that the DDR pathway is impaired in IL-2Rα-deficient cells suggests the need for further study of this receptor, since IL-2Rα is also found in numerous other cell types.

Page Count

46

Department or Program

Microbiology and Immunology

Year Degree Awarded

2024

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