Wellcome Trust Clinical PhD Programme at the University of Oxford: The role of the Adapter Protein 2 sigma subunit (AP2S1) in calcium homeostasis (360G-Wellcome-099896_Z_12_Z)

G-protein coupled receptors (GPCRs) play a central role in facilitating cellular responses to diverse extracellular stimuli such as ions, metabolites and hormones. Moreover, GPCR mutations result in diseases that include endocrine dysregula tion. One such GPCR is the calcium-sensing receptor (CaSR), mutations of which cause familial benign hypocalciuric hypercalcaemia (FBHH) and autosomal dominant hypocalcaemic hypercalciuria {ADHH). However, only approximately 65% of FBHH or ADHH patients harbour CaSR mutations. GPCRs signal through association with heterotrimeric G-proteins and other downstream signalling e ffectors. Professor Thakkar's group therefore postula ted that FBHH patients without CaSR mutations may have muta tions in these downstream effectors and identified by exome capture and DNA sequence analysis of FBHH families, muta tions in the Adapter Protein 2 complex sigma subunit {AP2S1), which is involved in clathrin-media ed endocytosis. My key goal is to determineHhe role of AP2S1 in calcium homeostasis by: 1. Characterising additional AP2S1 mutations in FBHH and ADHH probands without CaSR mutations. 2. Determining the in vitro e ffects,by transient transfection assays,of the AP2S1 mutations in the CaSR signalling and endocytic pathways. Establishing the in vivo role of AP2S1 and its mutants by investigating wild-type and mutant AP2S1 mice,generated by knock-out,knock-in or N-ethyi-N-nitrosurea {ENU) stra tegies.