The additional N-glycosylation site of the equine LH/CG receptor is not responsible for the limited cyclic AMP pathway activation by equine chorionic gonadotropin relative to luteinizing hormone.

This study investigates whether a specific site on the equine luteinizing hormone/chorionic gonadotropin receptor (eLHCGR) is responsible for activating the cAMP pathway, and whether it affects the potency of two hormones on this receptor. The research concludes that this site does not impact these functions.

Research Methods

• The team focused on the unique seventh N23-glycosylation site on the equine LH/CG receptor (eLHCGR). This site is exclusive to equine species, making it of particular interest.
• They used COS-7 cells (a type of kidney cell line in monkeys) for their experiments. These cells were transiently transfected, a process that introduces a piece of foreign DNA into the cells temporarily, to allow researchers to study the interaction of this foreign DNA with the cell functions. In this case, the foreign DNA included either:
• The wild-type eLHCGR – the natural, unaltered version of the receptor.
• The mutant eLHCGR(N23Q) which has a mutation at the N23-glycosylation site.
• These cells were then treated with two hormones: porcine luteinizing hormone (pLH) and equine chorionic gonadotropin (eCG), to measure the production of the molecule cyclic AMP (cAMP).

Research Findings

• The experiments demonstrated that the N23-glycosylation site on the eLHCGR is not necessary for the functional interaction of the receptor with the cAMP pathway. This pathway is a signal transduction pathway that is important for diverse cellular responses including gene expression, secretion, immune response, cell growth and differentiation.
• Furthermore, the study also found that the N23-glycosylation site does not affect the difference in potencies between eCG and pLH in activating the eLHCGR. Therefore, the potentially unique role that this glycosylation site played in the eLHCGR in equines compared to other species is dismissed.