T.A. Yarney

Bio: T.A. Yarney is an academic researcher. The author has contributed to research in topics: Follicle-stimulating hormone receptor & Receptor. The author has an hindex of 6, co-authored 6 publications receiving 291 citations.

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

Abstract: 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 carboxy-terminal extension that contributed a hypothetical single transmembrane domain. This cDNA, which lacked the conventional seven transmembrane motif of the full-length 695 residue wild-type receptor protein, was also efficiently expressed on the cell surface and exhibited high affinity and specificity for FSH binding. LH did not compete for FSH binding indicating that these structures contained all the motifs necessary for specific hormone recognition. Follow ing hormone binding and affinity crosslinking the deduced Mr of the expressed receptor was compatible with dimer formation. The expression of these altered FSH receptors on the cell surface was confirmed by immunohistochemistry, which revealed punctate labeling in a pattern comparable to that shown by cells transfected by wild-type receptor cDNA. Addition of FSH stimulated 3 H-thymidine incorporation in trasfected cells in a biphasic manner. By performing RT-PCR we could show that similar altered receptor transcripts were present in both the ovary and testis. Our results reveal for the first time that the seven transmembrane structure of FSH-receptor is not absolutely necessary for cell surface expression and hormone binding provided other compensating motifs are present in the protein structure for membrane insertion. Some of these features are typical of growth factor receptors. Our investigations also demonstrate that alternate splicing of the FSH receptor gene provides a mechanism for creating receptor diversity and suggest that multiple receptors could be involved in regulation of hormone action.

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

Abstract: 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. The results indicated that increases in Sertoli cell and testicular function normally seen during pubertal development are accompanied by age-dependent reductions in concentration of functional FSH receptors, as determined by binding of iodinated FSH to testicular membrane preparations. During the course of these changes, FSH release was either maintained at a steady level in Romanov lambs or it was gradually reduced in the Booroola x DLS cross, thus indicating that the testis had become more responsive to hormonal signal. This acquisition of heightened sensitivity was also associated with contrasting changes in the level of expression of FSH receptor mRNA transcripts. For both geno-types of sheep, 5 distinct species of mRNA transcripts of approximately 1.1, 1.5, 2.0, 2.5 and 6.5 kb were highly expressed from 11 to 22 weeks of age. Amongst these transcripts, the 1.1 kb molecular species was the most abundant. Specific probing for a previously cloned transcript called 151A1 representing the first 4 exons of the FSH receptor gene revealed a paradoxical increase in the level of expression from 11 weeks up to a maximum at 18-22 weeks of age for both genotypes. Collectively, the results indicated that contrasting changes in the production of specific alternatively spliced mRNA transcripts may mediate changes in FSH receptor expression which apparently accounts for the augmentation in sensitivity and function of the testis during pubertal development. Furthermore, the data provide the first important indication that the novel truncated transcript (151A1), which predictably encodes a soluble protein of either intra- or extracellular fate, could be physiologically relevant.

Genetic Inhibition by Double-Stranded RNA

Abstract: A process is provided of introducing an RNA into a living cell to inhibit gene expression of a target gene in that cell. The process may be practiced ex vivo or in vivo. The RNA has a region with double-stranded structure. Inhibition is sequence-specific in that the nucleotide sequences of the duplex region of the RNA and of a portion of the target gene are identical. The present invention is distinguished from prior art interference in gene expression by antisense or triple-strand methods.

The follicle-stimulating hormone receptor: biochemistry, molecular biology, physiology, and pathophysiology.

Abstract: I. Introduction II. Biochemical Properties of the FSH Receptor: A Historical Prelude III. Molecular Structure of the FSH Receptor A. Cloning of the FSH receptor B. Predicted primary structure of the FSH receptor C. Molecular mass of the FSH receptor IV. The FSH Receptor Gene A. Chromosomal localization B. Structure and organization of the FSH receptor gene C. The promoter of the FSH receptor gene V. Expression of the FSH Receptor and Its Regulation A. FSH receptor gene expression B. Expression of the FSH receptor in the testis C. Expression of the FSH receptor in the ovary VI. Expression of the FSH Receptor in Cell Lines A. Cell lines expressing the recombinant FSH receptor B. Measurement of FSH by means of “recombinant” in vitro bioassays C. FSH receptor function in cell lines VII. Structure-Function Relationships and Models of FSH-FSH Receptor Interaction A. General features B. Structure-function relationships C. Models of FSH-FSH receptor interaction VIII. Signal Transduction and Postreceptor Events A....

Impairing follicle-stimulating hormone (FSH) signaling in vivo: Targeted disruption of the FSH receptor leads to aberrant gametogenesis and hormonal imbalance

Abstract: Pituitary gonadotropins follicle-stimulating hormone (FSH) and luteinizing hormone stimulate the gonads by regulating germ cell proliferation and differentiation. FSH receptors (FSH-Rs) are localized to testicular Sertoli cells and ovarian granulosa cells and are coupled to activation of the adenylyl cyclase and other signaling pathways. Activation of FSH-Rs is considered essential for folliculogenesis in the female and spermatogenesis in the male. We have generated mice lacking FSH-R by homologous recombination. FSH-R-deficient males are fertile but display small testes and partial spermatogenic failure. Thus, although FSH signaling is not essential for initiating spermatogenesis, it appears to be required for adequate viability and motility of the sperms. FSH-R-deficient females display thin uteri and small ovaries and are sterile because of a block in folliculogenesis before antral follicle formation. Although the expression of marker genes is only moderately altered in FSH-R −/− mice, drastic sex-specific changes are observed in the levels of various hormones. The anterior lobe of the pituitary gland in females is enlarged and reveals a larger number of FSH- and thyroid-stimulating hormone (TSH)-positive cells. The phenotype of FSH-R −/− mice is reminiscent of human hypergonadotropic ovarian dysgenesis and infertility.

Mutations of gonadotropins and gonadotropin receptors: elucidating the physiology and pathophysiology of pituitary-gonadal function.

Abstract: The recent unraveling of structures of genes for the gonadotropin subunits and gonadotropin receptors has provided reproductive endocrinologists with new tools to study normal and pathological functions of the hypothalamic-pituitary-gonadal axis. Rare inactivating mutations that produce distinctive phenotypes of isolated LH or FSH deficiency have been discovered in gonadotropin subunit genes. In addition, there is a common polymorphism in the LHbeta subunit gene with possible clinical significance as a contributing factor to pathologies of LH-dependent gonadal functions. Both activating and inactivating mutations have been detected in the gonadotropin receptor genes, a larger number in the LH receptor gene, but so far only a few in the gene for the FSH receptor. These mutations corroborate and extend our knowledge of clinical consequences of gonadotropin resistance and inappropriate gonadotropin action. The information obtained from human mutations has been complemented by animal models with disrupted or inappropriately activated gonadotropin ligand or receptor genes. These clinical and experimental genetic disease models form a powerful tool for exploring the physiology and pathophysiology of gonadotropin function and provide an excellent example of the power of molecular biological approaches in the study of pathogenesis of diseases.