Activins and activin receptors in the rat testis

Inhibin and activin are gonadal protein hormones, which were originally defined by their negative and positive feedback action on the release of follicle stimulating hormone (FSH) from the pituitary gland. However, recent studies revealed that inhibin and activin do not only control FSH release but can also affect the functions of a large number of other cell types, as will be discussed in section 1.7. This section is preceded by short descriptions of the testicular cell types (section 1.2), the structures of inhibins, activins and other members of the TGF·-B family of growth and differentiation factors (sections 1.3 and 1.4), and of receptors and non-receptor binding proteins for inhibin and activin (sections 1.6 and 1.7). Finally, events occurring after binding of activin to its receptor are discussed in section 1.8. The aim of the experiments described in this thesis was the elucidation of intratesticular effects of activin. The expression of activin receptors, the secretion of activins and the effects of activins in the rat testis have been investigated

Diagnosis of Fanconi Anemia: Mutation Analysis by Multiplex Ligation-Dependent Probe Amplification and PCR-Based Sanger Sequencing

Fanconi anemia (FA) is a rare inherited disease characterized by developmental defects, short stature, bone marrow failure, and a high risk of malignancies. FA is heterogeneous: 15 genetic subtypes have been distinguished so far. A clinical diagnosis of FA needs to be confirmed by testing cells for sensitivity to cross-linking agents in a chromosomal breakage test. As a second step, DNA testing can be employed to elucidate the genetic subtype of the patient and to identify the familial mutations. This knowledge allows preimplantation genetic diagnosis (PGD) and enables prenatal DNA testing in future pregnancies. Although simultaneous testing of all FA genes by next generation sequencing will be possible in the near future, this technique will not be available immediately for all laboratories. In addition, in populations with strong founder mutations, a limited test using Sanger sequencing and MLPA will be a cost-effective alternative. We describe a strategy and optimized conditions for the screening of FANCA, FANCB, FANCC, FANCE, FANCF, and FANCG and present the results obtained in a cohort of 54 patients referred to our diagnostic service since 2008. In addition, the follow up with respect to genetic counseling and carrier screening in the families is discussed

Activin is produced by rat Sertoli cells in vitro and can act as an autocrine regulator of Sertoli cell function

Regulation of androgen receptor (AR) mRNA expression was studied in Sertoli cells and peritubular myoid cells isolated from immature rat testis, and in the lymph node carcinoma cell line derived from a human prostate (LNCaP). Addition of dibutyryl-cyclic AMP (dbcAMP) to Sertoli cell cultures resulted in a rapid transient decrease in AR mRNA expression (5 h), which was followed by a gradual increase in AR mRNA expression (24-72 h). This effect of dbcAMP mimicked follicle-stimulating hormone (FSH) action. In peritubular myoid cells, there was only a moderate but prolonged decrease during incubation in the presence of dbcAMP, and in LNCaP cells no effect of dbcAMP on AR mRNA expression was observed. When Sertoli cells or peritubular myoid cells were cultured in the presence of androgens, AR mRNA expression in these cell types did not change. This is in contrast to LNCaP cells, that showed a marked reduction of AR mRNA expression during androgen treatment. In the present experiments, transcriptional regulation of AR gene expression in Sertoli cells and LNCaP cells was also examined. Freshly isolated Sertoli cell clusters were transfected with a series of luciferase reporter gene constructs, driven by the AR promoter. It was found that addition of dbcAMP to the transfected Sertoli cells resulted in a small but consistent increase in reporter gene expression (which was interpreted as resulting from AR promoter activity); a construct that only contained the AR 5' untranslated region of the cDNA sequence did not show such a regulation. The same constructs, transfected into LNCaP cells, did not show any transcriptional down-regulation when the synthetic androgen R1881 was added to the cell cultures. A nuclear transcription elongation experiment (run-on), however, demonstrated that androgen-induced AR mRNA down-regulation in LNCaP cells resulted from an inhibition of AR gene transcription. The present results indicate that in Sertoli cells and LNCaP cells, hormonal effects on AR gene transcription play a role in regulation of AR expression. However, AR gene transcription in these cells is differentially regulated

Inhibin interferes with activin signaling at the level of the activin receptor complex in Chinese hamster ovary cells

To gain more insight in the mechanism of action of inhibin, we studied the effect of inhibin on activin signaling in Chinese hamster ovary cells. Inhibin specifically counteracted activin-induced expression of a plasminogen activator inhibitor 1 promoter element (3TP) and of the junB gene, but was ineffective when the responses were induced by transforming growth factor-beta. This indicates that inhibin acts only on the activin-specific part of these signaling cascades. Using a constitutively active activin type IB receptor we determined whether inhibin acted at the level of the activin-receptor complex or downstream of it. The mutant activin receptor stimulated the expression of the 3TP promoter in the absence of activin. This stimulation was insensitive to inhibin

A novel member of the transmembrane serine/threonine kinase receptor family is specifically expressed in the gonads and in mesenchymal cells adjacent to the mullerian duct

The activin and TGF-beta type II receptors are members of a separate subfamily of transmembrane receptors with intrinsic protein kinase activity, wh