SAT-193 Evaluating Levels of Luteinizing Hormone Receptor Dimers and Larger Oligomers

Luteinizing hormone (LH) receptors are found in female and male reproductive organs where they play important roles in ovulation and sperm maturation, respectively. LH receptors are members of the G protein-coupled receptor (GPCR) superfamily and serve as drug targets. The role of GPCR oligomerization in LH receptor function is considerable interest. We evaluated the cluster size of LH receptors, cells express less than 9,000, express approximately 10,000-30,000, express approximately 35,000-80,00, and express more than 85,000 LH receptors per cell, that tagged with YFP (yellow fluorescence protein) and stably expressed in CHO (Chinese hamster ovary) cells, in the absence of hormone (human chorionic gonadotropin, hCG) and in cells treated with various concentrations of hCG. The effect of expression level of LH receptors and hormone on its oligomerization state were evaluated using polarization homo-transfer fluorescence resonance energy transfer methods which can detect changes in the cluster size of LH receptors found in the plasma membrane on viable cell. Here we have determined whether the formation of dimers/oligomers has any relationship to the expression level of LH receptor. We found that there is a strong relationship between the oligomerization state of LH receptors and its expression. In response to increasing concentrations of hCG or increasing expression level of LH receptors, the size of LH receptor-containing clusters increases. This result will help to cognizance the effect of expression level of receptors on cluster size. Thus, will contribute to better understanding of LH receptor-related diseases, which can be caused by mis-oligomerization events that caused by increase the expression of LH receptors within cell. Additionally, this knowledge may lead to a rational approach to design improved therapeutics. This research was supported by NIH and USDA Animal Health and Disease Program at CSU.