Endocrine Abstracts

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...

Advances in genetic approaches to bone physiology have expanded our understanding of the mechanisms by which bone and energy homeostasis interact. PHOSPHO1, a bone specific phosphatase is essential for the initiation of bone mineralisation. Here we now show that Phospho1 ablation confers a remarkable protection against obesity and diabetes in mice. To understand the mechanism whereby Phospho1 impacts metabolism, microarray analysis of osteoblasts, the primary...

A new genetic disorder has recently been identified that results from mutation of THRA, encoding thyroid hormone receptor α1 (TRα1). Affected children have a high serum T3:T4 ratio, constipation and a variable intellectual deficit, but exhibit a consistently severe skeletal dysplasia. Similar to these patients, Thra1PV/+ mice harbour a mutation that disrupts the C-terminal α-helix of TRα1 and express a domi...

Thyrotoxicosis results in osteoporosis and thyroid hormone (T3) stimulates osteoclastic bone resorption by unknown mechanisms. We previously demonstrated that knockout mice lacking thyroid hormone receptor α (TRα0/0) are euthyroid but have high bone mass, whereas mice lacking TRβ (TRβ−/−) are thyrotoxic and have osteoporosis. Tartrate resistant acid phosphatase (TRAcP) staining revealed osteoclast numbers were re...

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...

Renal calcification (nephrocalcinosis), which has a multi-factorial etiology involving environmental and genetic determinants, affects ~8% of adults by 70 years. Nephrocalcinosis may occur as a familial disorder in ~65% of patients, and in 70% of patients, nephrocalcinosis may be associated with endocrine and metabolic disorders that include primary hyperparathyroidism, renal tubular acidosis, hypercalciuria, cystinuria, and hyperoxaluria. Investigations of families with hered...