Date of Award

6-2018

Document Type

Union College Only

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Brian D. Cohen

Language

English

Keywords

human follicle stimulating hormone receptor, lipid raft, hFSHR, FSH, follicle stimulating hormone, hormone signaling, lipid raft disruption, caveolin binding motif, caveolin interaction motif, follitropin

Abstract

Infertility affects 7.4 million women and their partners in the United States. One cause for infertility in women is human follicle stimulating hormone (hFSH) dysfunction. hFSH is involved in follicle maturation and estrogen production in females and spermatogenesis in males. Lack of normal hFSH function in either the ligand or receptor leads to infertility in women, however does not fully inhibit fertility in males. hFSH is secreted from the pituitary gland and binds to its g-protein coupled receptor (hFSHR) located in the ovaries or the testis. Previous research in our lab has shown that hFSHR resides in cholesterol, sphingolipid, and caveolin enriched microdomains called lipid rafts. It has been previously shown that hFSHR interacts with caveolin although the specific mechanism of this interaction is unknown. One possibility is that the interaction is through a specific amino acid sequence in hFSHR consistent with caveolin binding motifs identified in other proteins. The current study investigated how lipid rafts regulate hFSHR signaling. It was hypothesized that disruption of lipid rafts or interference with the caveolin binding motif will alter hFSHR signaling. Lipid rafts in human granulosa cells (the hGrC1 cell line) were disrupted through cholesterol depletion with methyl-β-cyclodextrin (MβCD) and FSH signaling differences were observed by western blot. It was observed that MβCD treatment resulted in an increase of cAMP signaling compared to control cells. In parallel, mutations in the hFSHR caveolin binding motif were made and expression plasmids were transiently transfected into HEK 293 cells. Western blot analysis revealed that some of the mutants showed increased basal signaling relative to the wild type receptor. Taken together, these results suggest that lipid rafts may be acting act as an inhibitory mechanism for hFSHR and that caveolin may play a role in receptor recruitment to the lipid raft. Researching hFSH signaling after lipid raft manipulation can provide a better understanding of the cellular mechanisms of hFSHR, which could lead to innovative ideas in infertility treatment for women.

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