Endocrine Abstracts

Lactation promotes infant development and confers long-term health benefits to mothers and infants. However, the endocrine and paracrine mechanisms mediating milk synthesis remain to be fully elucidated. Hormones such as prolactin and progesterone trigger the onset of lactation, whereas local mammary factors are considered to play a greater role in the maintenance of milk synthesis. We hypothesised that mammary epithelial cytokines are required for established lactation, and u...

The calcium-sensing receptor (CaSR) is a G-protein coupled receptor that predominantly signals via Gαq/11-mediated pathways to regulate extracellular calcium (Ca2+e) homeostasis. Germline Gα11 inactivating and activating mutations cause familial hypocalciuric hypercalcaemia type-2 (FHH2) and autosomal dominant hypocalcaemia type-2 (ADH2), respectively. To date, four FHH2 and six ADH2 mutations have been reported. To identif...

Familial hypocalciuric hypercalcaemia (FHH) is an inherited disorder of calcium homeostasis, which is caused by germline loss-of-function mutations of the calcium-sensing receptor (CaSR) in ˜70% of cases. We report a 22 year old woman who was referred with asymptomatic hypercalcaemia. Biochemical investigations revealed hypercalcaemia on 3 of 4 occasions with adjusted serum calcium ranging from 2.59–2.80 mmol/l (normal range 2.20–2.60 mmol/l). Parathyroid hormon...

Case History: X-linked hypophosphataemia (XLH) manifests as rickets in infancy or childhood, and is caused by mutations of the phosphate-regulating neutral endopeptidase (PHEX) gene, which leads to excess production of the fibroblast growth factor-23 (FGF-23) hormone. We present a case illustrating that mutation of PHEX can also cause hypophosphataemia presenting in adulthood. The proband is a 56-year-old male, who was referred with persistent hypophosphataem...

The CaSR, a G-protein-coupled receptor that regulates extracellular calcium (Ca2+o), predominantly signals via G-protein-αq/11 (Gαq/11), initiating IP3-mediated intracellular calcium (Ca2+i) accumulation, and mitogen-activated protein kinase (MAPK) signalling. CaSR also activates MAPK signalling via Gαi/o, or by associating with the scaffolding protein β-arrestin. CaSR g...

Adaptor protein-2 (AP2) is a heterotetramer of α, β, μ, and σ subunits that is pivotal in clathrin-mediated endocytosis and facilitates internalisation of plasma membrane constituents such as the calcium-sensing receptor (CaSR). AP2 σ subunit (AP2σ) missense mutations (Arg15Cys, Arg15His and Arg15Leu) result in familial hypocalciuric hypercalcaemia type 3 (FHH3) and decrease the sensitivity of CaSR-expressing cells to changes in extracellular calc...

The calcium-sensing receptor (CaSR) is a guanine-nucleotide-binding protein (G-protein)-coupled receptor that has a central role in calcium homeostasis. Loss-of-function mutations of the CaSR result in familial hypocalciuric hypercalcemia type 1 (FHH1) and loss-of-function coding mutations in the CaSR-associated G-protein subunit Gα11 have been reported to cause FHH2 in only two patients to date. The aim of our study was therefore to characterise additional <em...

Autosomal dominant hypocalcaemia (ADH) is a disorder that needs to be distinguished from hypoparathyroidism, as ADH patients are at risk of nephrocalcinosis and renal failure when treated with activated vitamin D preparations. ADH types 1 and 2 are due to gain-of-function mutations of the calcium-sensing receptor (CaSR) and G-protein α 11 (Gα11), respectively. CaSR targeted drugs, known as calcilytics, rectify the gain-of-function associated with ADH1-causing mutatio...

The calcium-sensing receptor (CaSR) is a guanine-nucleotide-binding protein (G-protein)-coupled receptor that has a central role in calcium homeostasis. Loss-of-function mutations of the CaSR result in familial hypocalciuric hypercalcemia type 1 (FHH1) and gain-of-function mutations in autosomal dominant hypocalcemia (ADH). Recently, loss-of-function Gα11 mutations have been identified to cause FHH2 and we hypothesised that gain-of-function Gα11...

The calcium-sensing receptor (CaSR) is a G-protein coupled receptor that regulates extracellular calcium concentration. The CaSR is also implicated in the pathogenesis of non-calcium disorders such as vascular calcification and diabetes, which are leading causes of cardiovascular disease. Common CaSR single nucleotide polymorphisms (SNPs) have been demonstrated to be determinants of calcium metabolism. The aim of this study was to investigate whether CaSR SNPs may influence va...