Searchable abstracts of presentations at key conferences in endocrinology

ea0031s7.1 | Thyroid hormone receptors – mutations and implications (Supported by <emphasis role="italic">Journal of Molecular Endocrinology</emphasis>) | SFEBES2013

Physiologically distinct roles for thyroid hormone receptor isoforms

Williams Graham R

The majority of T3 actions are mediated by nuclear thyroid hormone receptors (TRα and TRβ), which act as hormone-inducible transcription factors. TRs are constitutively localised to the nucleus and, in the absence of hormone, bind to T3-response elements (TREs) located in the promoter regions of T3 target genes to mediate transcriptional repression. Entry of T3 to the nucleus and high affinity binding to TRs results in de-r...

ea0025pl6 | Society for Endocrinology Medal Lecture | SFEBES2011

The bare bones of thyroid hormones

Williams Graham R

Hypothyroidism delays bone formation, whilst thyrotoxicosis accelerates skeletal development but is a risk factor for osteoporosis. We characterized mice with mutation or deletion of T3 receptors, TRα and TRβ, in several genetic backgrounds. Delayed ossification and growth retardation were observed in TRα mutants, whereas TRβ mutants had advanced bone age. Adult TRα mutants had high bone mass, whereas TRβ mutants were osteoporotic. Targ...

ea0015s23 | Thyroid hormones in development: physiology and clinical implications | SFEBES2008

The HPT axis in control of skeletal development

Williams Graham R

Hypothyroidism delays bone development, whilst thyrotoxicosis causes osteoporosis. Recent studies have challenged understanding of skeletal responses to thyroid hormone by proposing TSH as a negative regulator of bone turnover and suggesting bone loss in hyperthyroidism results from TSH deficiency and not T3-excess. To investigate, we characterised mice with mutations or deletions of the genes encoding T3 receptor (TR) α and TRβ. Endochondral ossification was retarde...

ea0034oc4.4 | Thyroid and bone | SFEBES2014

Thyroid hormones stimulate osteoclastogenesis via TRα-dependent actions in osteoblasts

Logan John G , Bassett J H Duncan , Williams Graham R

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...

ea0034p421 | Thyroid | SFEBES2014

Treatment with a TRα1 antagonist increases bone mineral content

Waung Julian A , Bassett J H Duncan , Williams Graham R

Thyroid hormones regulate adult bone turnover. Thyrotoxicosis results in high turnover osteoporosis whilst hypothyroidism leads to low bone turnover with increased bone mass and mineralisation. T3-target tissues express thyroid hormone receptor alpha (TRα), thyroid hormone receptor beta (TRβ)or both receptors. TRα1 mediates the actions of T3 in bone and in skeletal cells TRα1 mRNA expression is 12-fold higher than TRβ1. Accordingl...

ea0025p339 | Thyroid | SFEBES2011

Thyroid hormone receptor alpha is a permissive factor that regulates osteoclastogenesis indirectly

Nicholls Jonathan J , Combs Charlotte E , Williams Graham R , Bassett J H Duncan

Thyrotoxicosis is characterised by increased osteoclast activity. Thyroid hormone receptor alpha (TRα) is the predominant TR-isoform in bone and mice lacking TRα have skeletal hypothyroidism with impaired osteoclastic bone resorption. By contrast, mice lacking TRβ have skeletal hyperthyroidism and increased bone resorption. Thus, we hypothesized that T3 acts via TRα to stimulate osteoclastogenesis. Osteoclasts were differentiated in vitro ...

ea0015oc33 | Thyroid | SFEBES2008

Effect of thyroid status on the skeleton in post-menopausal women: the OPUS study

Murphy Elaine , Gluer Claus C , Reid David M , Felsenberg Dieter , Roux Christian , Eastell Richard , Williams Graham R

OPUS is a population-based prospective cohort study of post-menopausal women from five European cities. We investigated whether TSH, fT4 and fT3 are associated with fracture risk, bone mineral density (BMD) at hip and spine, bone formation (osteocalcin, procollagen type 1 N-terminal propeptide), bone resorption (N- and C-telopeptides of type 1 collagen, NTX, CTX), pulse rate, grip strength and balance. Vertebral fractures were determined at baseline and 6 years follow-up. Usin...

ea0013p16 | Bone | SFEBES2007

Wnt/β-catenin signalling is abrogated in mice with a targeted mutation in the thyroid hormone receptor (TR) β gene and a thyrotoxic skeletal phenotype

O’Shea Patrick J , Davis Sean , Walker Robert L , Meltzer Paul S , Williams Graham R , Cheng Sheue-yann

Thyroid hormone (T3) is an important regulator of skeletal development and bone turnover. Thyrotoxicosis is associated with accelerated growth, advanced bone age and osteoporosis. T3-action in bone is mediated mainly by T3-receptors (TRs). TRβPV mice harbour a dominant-negative mutation in the TRβ gene that impairs negative feedback control of the hypothalamic-pituitary-thyroid axis resulting in elevated thyroid hormone and TSH concentrations. TRβ<sup...

ea0034oc4.3 | Thyroid and bone | SFEBES2014

TRα mutation causes a severe and thyroxine-resistant skeletal dysplasia

Bassett J H Duncan , Boyde Alan , Zikmund Tomas , Evans Holly , Croucher Peter I , Zhu Xuguang , Park Jeong Won , Cheng Sheue-yann , Williams Graham R

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...

ea0015oc36 | Thyroid | SFEBES2008

Increased skeletal mineralisation in mice lacking type 2 iodothyronine deiodinase

Bassett JH Duncan , Boyde Alan , Howell Peter GT , Galliford Thomas M , Archanco Marta , St Germain Donald L , Galton Valerie A , Williams Graham R

The prohormone T4 represents the majority of circulating thyroid hormones, whereas 80% of the active hormone T3 is derived from T4 by the actions of the type 1 and type 2 deiodinase enzymes (D1 and D2). Local generation of T3 by D2 regulates ligand supply to the nuclear T3-receptor in pituitary, brown adipose tissue and brain, and this enzyme is also expressed in bone. Hypothyroidism in children causes delayed bone age and growth retardation, whereas thyrotoxicosis in adults c...