The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform

Monika Schmitz - One of the best experts on this subject based on the ideXlab platform.

  • expression of Gonadotropin and Gonadotropin Receptor genes during early sexual maturation in male atlantic salmon parr
    Molecular Reproduction and Development, 2008
    Co-Authors: Gersende Maugars, Monika Schmitz
    Abstract:

    Atlantic salmon males may mature already as small parr in freshwater. Sexual maturation in teleosts as in vertebrates is characterized by the activation of the brain–pituitary–gonad axis. The endocrine regulation of early puberty is still not well understood. In the present study, one-summer-old male Atlantic salmon parr were sampled regularly from December several months prior to the beginning of spermatogenesis until spawning in October. Pituitary expression levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) β subunit genes were analyzed in parallel with testis expression of FSH Receptor (FSHR) and LH Receptor (LHR) genes by RT-PCR and plasma 11-ketostestosterone (11-KT) was measured. Expression levels of FSHβ, low during winter and spring started to increase prior to the onset of gonadal growth at the end of May while LHβ mRNA levels were hardly detectable. Both Gonadotropin Receptor genes were expressed in immature testis with FSHR transcripts being more abundant (8-fold). FSHR transcript levels increased in parallel to FSHβ levels from early spermatogenesis onwards, while LHR mRNA started to increase prior to any large changes in LHβ expression. Both transcript levels of LHβ and LHR were highest during spermiation. Plasma 11-KT increased at the beginning of spermatogenesis reaching highest levels at spermiogenesis suggesting a possible role of FSH in inducing 11-KT production during early spermatogenesis while LH stimulates via its specific Receptor 11-KT production at spermiogenesis. The commitment into sexual maturation appears to be dependant on both the presence of FSHR in immature testis and the increase of FSH expression. Mol. Reprod. Dev. 75: 403–413, 2008. © 2007 Wiley-Liss, Inc.

  • Gonadotropin and Gonadotropin Receptor expression during the onset of sexual maturation in early maturing Atlantic salmon male parr, Salmo salar
    Molecular Reproduction and Development, 2008
    Co-Authors: Gersende Maugars, Monika Schmitz
    Abstract:

    Gonadotropin and Gonadotropin Receptor expression during the onset of sexual maturation in early maturing Atlantic salmon male parr, Salmo salar

Yoshitaka Nagahama - One of the best experts on this subject based on the ideXlab platform.

Yuichi Oba - One of the best experts on this subject based on the ideXlab platform.

Ilpo Huhtaniemi - One of the best experts on this subject based on the ideXlab platform.

  • Gonadotropin Receptor variants are linked to cumulative live birth rate after in vitro fertilization.
    Journal of assisted reproduction and genetics, 2018
    Co-Authors: Ida Lindgren, Hannah Nenonen, Emir Henic, Leif Bungum, A. Prahl, Mona Bungum, Irene Leijonhufvud, Ilpo Huhtaniemi, C. Yding Andersen, Y. Lundberg Giwercman
    Abstract:

    Purpose The objective was to investigate if the Gonadotropin Receptor variants N680S (N: asparagine, S: serine, rs6166) in the follicle-stimulating hormone Receptor (FSHR) and N312S (rs2293275) in the luteinizing hormone/human chorionic Gonadotropin Receptor (LHCGR) predicted cumulative live birth rate after in vitro fertilization (IVF).

  • Constitutive activity in Gonadotropin Receptors.
    Advances in pharmacology (San Diego Calif.), 2014
    Co-Authors: Alfredo Ulloa-aguirre, Eric Reiter, George R. Bousfield, James A. Dias, Ilpo Huhtaniemi
    Abstract:

    Abstract Constitutively active mutants (CAMs) of Gonadotropin Receptors are, in general, rare conditions. Luteinizing hormone–chorioGonadotropin Receptor (LHCGR) CAMs provoke the dramatic phenotype of familial Gonadotropin-independent isosexual male-limited precocious puberty, whereas in females, there is not yet any identified phenotype. Only one isolated follicle-stimulating hormone Receptor (FSHR) CAM (Asp567Gly) has so far been detected in a single male patient, besides other FSHR weak CAMs linked to pregnancy-associated ovarian hyperstimulation syndrome or to impaired desensitization and internalization. Several animal models have been developed for studying enhanced Gonadotropin action; in addition to unraveling valuable new information about the possible phenotypes of isolated FSHR and LHCGR CAMs in women, the information obtained from these mouse models has served multiple translational goals, including the development of new diagnostic and therapeutic targets as well as the prediction of phenotypes for mutations not yet identified in humans. Mutagenesis and computational studies have shed important information on the physiopathogenic mechanisms leading to constitutive activity of Gonadotropin Receptors; a common feature in these Receptor CAMs is the release of stabilizing interhelical interactions between transmembrane domains (TMDs) 3 and 6 leading to an increase, with respect to the wild-type Receptor, in the solvent accessibility at the cytosolic extension of TMDs 3, 5, and 6, which involves the highly conserved Glu/Asp-Arg-Tyr/Trp sequence. In this chapter, we summarize the structural features, functional consequences, and mechanisms that lead to constitutive activation of Gonadotropin Receptor CAMs and provide information on pharmacological approaches that might potentially modulate Gonadotropin Receptor CAM function.

  • mutations in human Gonadotropin and Gonadotropin Receptor genes
    Endocrine, 2005
    Co-Authors: Ilpo Huhtaniemi, A P N Themmen
    Abstract:

    This short review provides an update on the new information that has become available in the recent years about mutations and polymorphisms in the genes for Gonadotropins and their Receptors. Combining the types and locations of the mutations, their phenotypic effects, and the recently emerged information about the crystal structure of these molecules is providing us with increasingly detailed picture about the structurefunction relationships of Gonadotropin action.

  • Mutations of Gonadotropin and Gonadotropin Receptor genes: the clinical spectrum
    Current Opinion in Endocrinology & Diabetes, 2001
    Co-Authors: Ilpo Huhtaniemi, Axel P. N. Themmen
    Abstract:

    Mutational analysis of the Gonadotropin and Gonadotropin Receptor genes is an exciting and continuously developing field. Much has been learned from the first mutants identified in patients with clear and expected phenotypes: infertility or extreme precocious puberty in boys. Absence of follicle-stimulating hormone or luteinizing hormone action as result of gene alterations has strong effects on the gonadal targets of these hormones. However, most patients in the clinic are not examined for such severe phenotypes, but show symptoms such as decreased fertility with no obvious cause or widespread complex clinical syndromes such as polycystic ovary syndrome. This review discusses some of the recent advances in the field: new and interesting mutations in the luteinizing hormone Receptor gene, polymorphisms in genes for the Gonadotropins and their Receptors, the findings in the luteinizing hormone Receptor null mouse, and the possible significance of nongonadal luteinizing hormone Receptor expression.

  • Mutations of Gonadotropins and Gonadotropin Receptors: elucidating the physiology and pathophysiology of pituitary-gonadal function.
    Endocrine reviews, 2000
    Co-Authors: Axel P. N. Themmen, Ilpo Huhtaniemi
    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.

Wai-yee Chan - One of the best experts on this subject based on the ideXlab platform.

  • Testicular seminoma in a patient with a constitutively activating mutation of the luteinizing hormone/chorionic Gonadotropin Receptor
    European journal of endocrinology, 1998
    Co-Authors: Malcolm M. Martin, Arline L.a. Martin, Owen M. Rennert, Wai-yee Chan
    Abstract:

    A white man who had been diagnosed, 35 years previously at the age of 27 months, to have precocious puberty, was later determined to have familial male-limited precocious puberty (FMPP), on the basis of his family history, increased serum testosterone, prepubertal concentrations of follicle stimulating hormone and luteinizing hormone, and Leydig cell hyperplasia. Recently, this diagnosis was confirmed by molecular genetic analysis that demonstrated the presence of a heterozygous constitutive activating mutation of the luteinizing hormone/chorionic Gonadotropin Receptor. This dominant gain-of-function Asp578Gly mutation has been shown constitutively to activate the Receptor in the absence of the agonist, leading to enhanced synthesis of cAMP and, in turn, to increased, sustained production of testosterone. In 1994, this patient was found to have a testicular seminoma. He represents the first case of a testicular germ cell tumor described in an FMPP patient, raising the possibility of a potentially harmful effect of prolonged increased concentrations of sex hormones, with onset early in life, upon the cellular components of the testes.

  • Molecular Genetic, Biochemical, and Clinical Implications of Gonadotropin Receptor Mutations
    Molecular genetics and metabolism, 1998
    Co-Authors: Wai-yee Chan
    Abstract:

    Human reproductive function is regulated mainly by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Mutations of the human LH/ chorionic Gonadotropin Receptor (LHR) and the FSH Receptor (FSHR) leading to either constitutive activation or inactivation of the Receptors have been identified. All activating mutations of the LHR and the FSHR are located within the exon encoding the transmembrane domain while the inactivating mutations are scattered throughout the coding sequence. A number of activating and inactivating mutations of the LHR have been found while only one activating and three inactivating mutations of the FSHR are known. Activating mutations of the LHR cause familial male-limited precocious puberty (FMPP) while that of the FSHR has been shown to restore the reproductive capability of a hypophysectomized male. Inactivating mutations of the LHR cause Leydig cell hypoplasia (LCH) in males while that of the FSHR causes hereditary hypergonadotropic ovarian dysgenesis (ODG) in females. Activating mutations of both Receptors are dominant while inactivating mutations are recessive. Genotype-phenotype correlation is best established for the inactivating mutations of LHR. Severity of clinical phenotype in LCH correlates with the amount of residual activity of the mutated LHR. Comparison of the clinical impact of the activating and the inactivating mutations of the Receptors indicates that male reproductive capacity depends primarily on LH while female reproductive capacity depends primarily on FSH.

  • COMPOUND HETEROZYGOUS MUTATIONS OF THE LUTEINIZING HORMONE/CHORIONIC Gonadotropin Receptor GENE IN A FAMILY WITH TWO CHILDREN AFFECTED BY LEYDIG CELL HYPOPLASIA (LCH). • 387
    Pediatric Research, 1997
    Co-Authors: Karen Hallermeier, Louisa Laue, Jim E. Griffin, Jean D. Wilson, Caroline Brain, A. Caroline Berry, David B. Grant, Gordon B. Cutler, Wai-yee Chan
    Abstract:

    COMPOUND HETEROZYGOUS MUTATIONS OF THE LUTEINIZING HORMONE/CHORIONIC Gonadotropin Receptor GENE IN A FAMILY WITH TWO CHILDREN AFFECTED BY LEYDIG CELL HYPOPLASIA (LCH). • 387