Novel hypothalamic G protein-coupled receptors involved in the control of reproduction

In the hypothalamus, various G-protein coupled receptors (GPCRs) form part of the regulatory pathways of the hypothalamus-pituitary-gonadal (HPG) axis. The master hormone regulator of the HPG axis is the gonadotropin-releasing hormone (GnRH). Defects in GnRH neuron activity are associated with reproductive dysfunctions including normosmic congenital hypogonadotropic hypogonadism (nCHH) and Kallmann syndrome (KS). DNA from a cohort of European nCHH/KS patients was exome sequenced. Mutations in GPCR genes were identified and two hypothalamic GPCRs of interest were identified; oxytocin receptor (OXTR) and Y4 neuropeptide Y receptor (NPY4R). Both receptors have been shown to have a role in reproduction, however, mutations in neither have been previously implicated in causing KS/nCHH respectively. The aim was to determine whether identified mutations in the receptors affected their functionality and may therefore potentially be causative to the reproductive dysfunctions. Using six different online tools, the compound heterozygous (L282V+E339K) mutation identified in OXTR and the double heterozygous (V40M/L287P) mutation identified in NPY4R were examined for prediction of deleterious effects. These mutant GPCRs were then cloned into a mammalian N-terminal epitope-tagging expression vector. A receptor ELISA assay and receptor signalling assay were utilized to compare wild-type (WT) and mutant receptor cell surface expression and functionality in vitro. 2/6 bioinformatic tools predicted the L282V mutation would be deleterious and 3/6 predicted that the E339K mutation would be deleterious. The in vitro results indicated a significant decrease (p

Advisor dc:contributor.advisor

• Newton, Claire

• Reproductive dysfunctions
• oxytocin receptor
• Y4 neuropeptide Y receptor

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/2263/110107

OAI identifier oai:identifier

oai:repository.up.ac.za:2263/110107