Date of Award

5-2023

Degree Type

Honors Thesis

Major

Biology

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Christina Tzagarakis-Foster

Second Advisor

Mary Jane Niles

Third Advisor

Sangman Kim

Abstract

DAX-1 is a nuclear hormone orphan receptor that plays a key role in the development of reproductive tissues and steroid hormone production. The hypothalamic-pituitary-adrenal axis is the pathway for steroid hormone production, primarily glucocorticoids, mineralocorticoids, and adrenal androgens, in the human body. The mechanisms of DAX-1 in hormone production in the adrenal cortex of the HPA axis are not completely understood and, therefore, were the focus of this honors thesis research project. Due to the high level of DAX-1 expression, SW13 adrenal carcinoma cells were conducted for these experiments. We investigated whether glucocorticoids, specifically the synthetic glucocorticoid dexamethasone, had any positive or negative feedback on DAX-1 expression in SW13 cells. To identify key proteins that regulate DAX-1 gene expression following dexamethasone exposure, chromatin immunoprecipitation (ChIP) assays were utilized. My results, specifically utilizing quantitative PCR, found that dexamethasone-treated SW13 cells increased DAX-1 expression, with the highest level of upregulation following treatment with 10-6M dexamethasone. A time course treatment of the SW13 cells found that the maximum change in DAX-1 expression required exposure to dexamethasone (10-6M) for 6 hours. The ChIP results show expressions of those proteins playing a role in the DAX-1 promoter, but the results were inconclusive. These include the EWS/FLI1 oncoprotein (Mendiola et al., 2006), beta-catenin (Mizusaki et al., 2003), Androgen Receptor (Lanzino et al., 2013), as well as the orphan NHR, SF1 (Kawabe et al., 1999). The results presented in this thesis demonstrate the effect of glucocorticoid exposure on DAX-1 expression, providing a more complete picture of the H-P-A axis and the role of DAX-1 in this pathway. Understanding the role of DAX-1 in this important physiological process and its connection to diseases such as Adrenal Hypoplasia Congenita (AHC) may provide an alternative therapeutic target in the future.

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