Searchable abstracts of presentations at key conferences in endocrinology

ea0015s26 | Androgen receptors - physiology and disease | SFEBES2008

Loss of androgen receptor binding to selective androgen response elements causes a reproductive phenotype in the transgenic SPARKI mice

Claessens Frank

Androgens influence transcription of their target genes through the activation of the androgen receptor (AR). Binding of the AR to DNA motifs in these genes is a critical step in this signal transduction process. The DNA motifs, called androgen response elements (AREs), can be classified in two classes: the classical AREs, which are in vitro also recognized by the other steroid hormone receptors, and the AR-selective AREs, which display selectivity for the AR. For in...

ea0084ps1-05-44 | Miscellaneous | ETA2022

The effect of testosterone supplementation on the hpt axis in euthyroid hypogonadal adult men: a prospective observational study

David Karel , Antonio Leen , Claessens Frank , Vanderschueren Dirk , Decallonne Brigitte

Background and Objective: It is known that androgens decrease and estrogens increase TBG. In female to male transsexuals under testosterone replacement, decrease of TBG has been shown, but also an increased T3/T4 ratio despite stable free T4 and TSH, suggesting increased conversion to T3 by testosterone. We wanted to study the HPT axis in hypogonadal cis-males before and after testosterone replacement.Method: Prospective observational study in adult male...

ea0054is8 | (1) | NuclearReceptors2018

Direct and indirect effects of androgens on the musculoskeletal system

Claessens Frank , Michael Laurent , Dubois Vanessa , Khalil Rougin , Jardi Ferran , Vanderschueren Dirk

Global knockout models of the androgen receptor (ARKO) illustrates the many roles androgens and their receptor have in the development of male reproductive organs and the gender differences in many features like the musculoskeletal system. However, neither the global ARKO nor orchidectomy models discriminate between direct and indirect effects of androgens. To determine direct and indirect effects of androgens on muscle, we developed a muscle-specific ARKO (called satARKO for ...

ea0042oc11 | (1) | Androgens2016

Sex steroid deficiency alters renal calcium transporter expression independently of its effect on bone resorption

Khalil Rougin , Jardi Ferran , Laurent Michael , Claessens Frank , Vanderschueren Dirk , Decallonne Brigitte

It is well established that sex steroid deficiency induces bone loss, resulting in osteoporosis. Consequently, global androgen receptor knock out (ARKO) mice have trabecular and cortical osteopenia. Bone cell-specific ARKOs however, have a much less pronounced bone phenotype, suggesting that androgens have an influence on processes in other systems or organs which in turn have an impact on bone metabolism. The kidney is a likely candidate, as it plays an important role in calc...

ea0057005 | The effect of androgens on renal calcium and phosphate handling, independent of bone and in circumstances of low dietary calcium | BES2018

The effect of androgens on renal calcium and phosphate handling, independent of bone and in circumstances of low dietary calcium

Rougin Khalil , Ri Kim Na , Ferran Jardi , Frank Claessens , Dirk Vanderschueren , Brigitte Decallonne

Aims: We have previously shown that orchidectomy (ORX) in adult mice induces hypercalciuria and upregulation of renal Ca2+ and PO43− transporters, but also bone loss already after 2 weeks. Pretreatment with risedronate inhibited bone resorption and hypercalciuria but confirmed the upregulation of renal Ca2+ and PO43− transporters, suggesting bone-independent renal effects of androgens. We hypothesize...

ea0071028 | Fertility in men with 5-alpha reductase deficiency | BES2020

Fertility in men with 5-alpha reductase deficiency

Wout Devlies , Elisabet Van Loon , Steven Joniau , Frank Claessens , Leen Antonio , Dirk Vanderschueren

Introduction: 5 Alpha reductase deficiency (5-ARD) is a rare autosomal recessive disorder causing disturbance of sex development. 5 Alpha reductase is an enzyme involved in steroid metabolism, catalyzing testosterone into dihydrotestosterone (DHT), its potent form. 5-ARD therefore results in lower DHT and higher testosterone values. DHT is crucial for the differentiation of the urogenital sinus and genital tubercle into the external genitalia, urethra and prostate, while the v...

ea0042p2 | (1) | Androgens2016

Functional analysis of the AR LBD dimerization surface

Helsen Christine , Prekovic Stefan , van Royen Martin E , Houtsmuller Adriaan B , Fuentes-Prior Pablo , Estebanez-Perpina Eva , Claessens Frank

The androgen receptor (AR) is a multidomain transcription factor consisting of an aminoterminal domain (NTD), a DNA binding domain (DBD) and a ligand binding domain (LBD). Binding of androgens marks the start of a sequence of intra- and interdomain communications, DNA binding, coregulator recruitment and gene activation. Besides the DBD-mediated dimerization on the DNA, there is a functionally relevant N/C interaction. The contribution of the intra- and intermolecular N/C inte...

ea0064002 | Sexual Dimorphism in Bone Size is Mediated by Neuronal ER alpha (ERα) Signaling in Females during Late Puberty | BES2019

Sexual Dimorphism in bone size is mediated by neuronal ER alpha (ERα) signaling in females during late puberty

Nari Kim , Ferran Jardi , Rougin Khalil , Leen Antonio , Dieter Schollaert , Ludo Deboel , van Lenthe GH , Brigitte Decallonne , Geert Carmeliet , Claes Ohlsson , Lagerquist Marie K , Frank Claessens , Dirk Vanderschueren

Introduction: Pubertal sex steroids are indispensable for peak bone mass acquisition as well as skeletal sexual dimorphism. In males, both androgen receptor (AR) and estrogen receptor alpha (ERα) are required for optimal periosteal cortical bone expansion, while estrogens limit bone size in females. In early puberty, estrogens directly stimulate longitudinal growth via ERα in cartilage, but also indirectly via growth hormone (GH) and insulin-like growth factor I (IGF...

ea0042oc16 | (1) | Androgens2016

Genomic analysis of Enzalutamide-resistant cells

Prekovic Stefan , Van den Broeck Thomas , Smeets Elien , van Royen Martin , Houtsmuller Adriaan , Sahu Biswajyoti , Pihlajamaa Paivi , Janne Olli A. , Attard Gerhardt , Claessens Frank , Helsen Christine

Enzalutamide (Enza) is a second-generation antiandrogen currently used in the clinic for treatment of metastatic prostate cancer. It significantly prolonged survival of men with metastatic castration resistant prostate cancer after chemotherapy by a median of 4.8 months in comparison to the placebo group. However, in a subset of patient’s beneficial effect of Enza cannot be observed, while others who initially respond eventually develop resistance towards the treatment. U...