Analysis of Caveolin-1 Expression and Interaction with Human Follicle Stimulating Hormone Receptor in Lipid Rafts

For thousands of women in the United States ovarian cysts, tumors, and hormonal imbalances contribute to reduced fertility and fecundity. In addition to these factors, many other unexplained physiological mechanisms may play a role in women's reproductive health. Specifically, human follicle stimulating hormone (hFSH) binds to a G protein coupled receptor (GPCR) called human follicle stimulating hormone receptor (hFSHR). This interaction helps to regulate the reproductive system in both males and females indicating that it may be a key player to target in order to promote fertility. Previous work in our lab has demonstrated that hFSHR, like other GPCR, has been shown to preferentially localize within microdomains in the cell membrane known as lipid rafts in order to facilitate proper signaling. This localization is thought to be mediated in part by a protein known as caveolin. In order to investigate the relationship hFSHR and caveolin, a cell line expressing hFSHR (HEK293-hFSHR) was transfected with a plasmid to transiently express caveolin. Immunoprecipitations were used to investigate the interaction between caveolin and full length hFSHR. Western blot analysis was subsequently performed to detect protein interactions. Based on the data generated from this experiment, the previously established relationship between FSHR and lipid raft residency was not confirmed because it was not shown that caveolin co-precipitated with FSHR. These findings may suggest that previous studies used methods that resulted in artifactual phenomenon. However, it is equally possible that the conditions, plasmids, or cells used in these experiments contributed to the inability to replicate the results found previously. Understanding the possible interaction between hFSHR and caveolin is crucial in the future development of therapeutics that will allow us to fine tune receptor function for infertility treatments.