Role of FSH, numbers of FSH receptors and testosterone in the regulation of inhibin secretion during the seasonal testicular cycle of adult rams.

The regulation of inhibin secretion has not been elucidated fully in male ruminants. The aim of this study was to determine the relative importance of FSH and testosterone concentrations, and FSH receptors, in the control of secretion of immunoactive inhibin in rams. In Expt 1, temporal changes in hormone concentrations and testicular FSH binding were determined for two groups of rams (n = 4) kept under opposite, alternating 4 month periods of long (16 h light:8 h dark) and short (8 h light:16 h dark) days.

Alternative splicing converts the G-protein coupled follitropin receptor gene into a growth factor type I receptor: implications for pleiotropic actions of the hormone.

Pituitary follitropin (FSH) has pleiotropic actions on gonads, but it is not certain if all these events are mediated by a single receptor. A single gene for the FSH receptor undergoes extensive alternate splicing generating multiple transcripts, and several of these have been cloned and characterized from the sheep testis. In this study we have investigated the expression in HEK (human embryonic kidney) 293 cells of a cloned cDNA encoding the first eight exons of the FSH receptor along with a carboxyterminal extension that contributed a hypothetical single transmembrane domain.

Molecular cloning, structure, and expression of a testicular follitropin receptor with selective alteration in the carboxy terminus that affects signaling function.

During the molecular cloning of the ovine testicular follicle-stimulating (FSH) receptor that couples to the Gs-type effector systems, we discovered novel cDNA clones that were highly homologous. Some of these clones contained an insert of 1,584 bp, which consisted of a divergent 3' region spliced with a 5' region that was identical to nucleotides 724-1,924, forming part of the 9th and 10th exons, of the coding region of the ovine FSH receptor gene. The prominence of alternately spliced clone, which suggested important functional implications, prompted this detailed investigation.

Recognition of follicle stimulating hormone (alpha-subunit) by a recombinant receptor protein domain coded by an alternately spliced mRNA and expressed in Escherichia coli.

To assess the functional significance of putative proteins encoded by alternately spliced mRNA of the sheep testicular FSH receptor, a short form cDNA comprising of the first four exons (117 residues mature protein) was engineered for expression in Escherichia coli. The expressed protein of molecular mass 15 kDa was purified to homogeneity and verified by reaction with an antibody against a synthetic peptide sequence unique to the amino (N)-terminal region FSH receptor. The purified FSH receptor domain protein bound 125I-labeled hFSH in a ligand blot on polyvinylidine difluoride membranes.

Ontogeny of FSH receptor messenger ribonucleic acid transcripts in relation to FSH secretion and testicular function in sheep.

The role of alternative splicing of the FSH receptor gene in the generation of FSH receptor proteins and testicular function remains an enigma. To address this issue, this investigation was conducted to determine variations in the expression of alternate FSH receptor mRNA transcripts in relation to changes in FSH release, hormone binding activity and testicular function during pubertal development of ram lambs from two genotypes of sheep (Romanov and a cross between Booroola x DLS) with different sexual precocity. Serum 17 beta-estradiol and testosterone concentrations were used as indices of Sertoli cell and testicular function.