Defense Date

6-12-2024

Graduation Date

Summer 8-10-2024

Availability

Immediate Access

Submission Type

dissertation

Degree Name

PhD

Department

Biological Sciences

School

School of Science and Engineering

Committee Chair

Kyle W Selcer

Committee Member

Michael Jensen-Seaman

Committee Member

John F. Stolz

Committee Member

Paula Witt-Enderby

Keywords

mouse STS, STS mouse ontogeny, Curcumin, STS inhibition, NIH-3T3, STS regulation, Mouse primary fibroblast culture

Abstract

Inactive sulfated steroids are present in plasma at higher concentrations than unsulfated ones. Steroid sulfatase (STS) is the enzyme that removes the sulfate group from sulfated steroid hormones in local tissues, making them active. High levels of STS are linked to breast and prostate cancers, and low levels of STS cause behavioral disorders and X-linked ichthyosis. STS is present in most tissues, yet its physiological role is uncertain. We sought to characterize STS activity in several rodent model systems in order to learn more about its function. Three different sets of experiments were conducted. First, we examined STS in mouse tissues, including heart, liver, small intestine, skeletal muscle and gonads. Liver and testis showed the highest STS levels. Hepatic and testicular STS activities were low up to 5 weeks of age and were higher through 56 weeks. Immunofluorescence, using a specific STS rabbit polyclonal antibody, showed that STS protein was present in hepatocytes and also in testicular Leydig cells and seminiferous tubules. Second, we examined regulation of STS using the NIH-3T3 mouse fibroblast cell line. STS activity was present in whole cells and cell homogenates. Glucocorticoids downregulated fibroblastic STS activity and this effect was reversed by the glucocorticoid receptor antagonist RU-486. The presence of STS in actual fibroblasts was confirmed using fibroblast cells cultured from mouse tails. In the third set of experiments, we examined the effects of curcumin on STS activity. Curcumin is from turmeric spice plant and is reported to have beneficial health effects. STS activity of rat liver homogenates was inhibited by curcumin at 10µM and 20µM in a competitive manner. STS activity was also inhibited by curcumin in NIH-3T3 cells, revealing that it is effective on whole cells. Taken together, these experiments have provided new data on possible physiological functions of STS. STS in the liver is proposed to provide estrogens for energy homeostasis. STS in the testis appears to have a role in providing estrogens to testicular cells, supporting steroidogenesis and gametogenesis. Finally, the plant compound curcumin, or a derivative, might be useful in disease therapies involving inhibition of STS.

Language

English

Additional Citations

Selcer K, Balasubramonian B, Miller D, Kerr J, DiFrancesco M, Ojha S, Urbano R. Steroid sulfatase in the mouse NIH-3T3 fibroblast cell line: Characterization, and downregulation by glucocorticoids. Steroids. 2021 Oct;174:108890. doi: 10.1016/j.steroids.2021.108890. Epub 2021 Jul 17. PMID: 34280393.

Balasubramonian B, Selcer KW. The phytochemical curcumin inhibits steroid sulfatase activity in rat liver tissue and NIH-3T3 mouse fibroblast cells. Steroids. 2023 Mar;191:109163. doi: 10.1016/j.steroids.2022.109163. Epub 2022 Dec 27. PMID: 36581086.

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