Investigation of human follicle stimulating hormone residency in membrane microdomains

Abstract

The human follicle stimulating hormone receptor (hFSHR) is a G protein‐coupled receptor involved in reproduction in both males and females. hFSHR is involved in complex networks of signaling molecules beyond the G proteins and understanding the ability of the receptor to participate in many signaling pathways is of significant interest for those looking to modulate receptor function. One possibility is that microdomains in the plasma membrane, such as lipid rafts, play an important role in signal transduction. The aim of this study was to determine the role of plasma membrane microdomains in hFSHR function. To analyze this, lipid rafts were disrupted using the cholesterol withdrawing agent methyl‐β ‐cylcodextrin (MβCD) and hFSH activation of MAP kinase pathways was investigated. Removal of membrane cholesterol caused the loss of hFSH induced p38‐MAP kinase activation but did not alter p42/44 MAP kinase activation. To investigate further the residency of hFSHR in lipid rafts, co‐immunoprecipitation experiments were performed to determine if caveolin‐1 interacted with hFSHR. Caveolin‐1 was overexpressed in cells stably transfected with hFSHR. A monoclonal antibody against hFSHR was used to immunoprecipitate the receptor and caveolin‐1 was shown to co‐immunoprecipitate. Although the physiological role of this interaction has not been determined, it presents a new opportunity to study hFSHR function.