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Casarini L, Santi D, Brigante G, Simoni M. Two Hormones for One Receptor: Evolution, Biochemistry, Actions, and Pathophysiology of LH and hCG. Endocr Rev 2018; 39:549-592. [PMID: 29905829 DOI: 10.1210/er.2018-00065] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 06/08/2018] [Indexed: 01/03/2023]
Abstract
LH and chorionic gonadotropin (CG) are glycoproteins fundamental to sexual development and reproduction. Because they act on the same receptor (LHCGR), the general consensus has been that LH and human CG (hCG) are equivalent. However, separate evolution of LHβ and hCGβ subunits occurred in primates, resulting in two molecules sharing ~85% identity and regulating different physiological events. Pituitary, pulsatile LH production results in an ~90-minute half-life molecule targeting the gonads to regulate gametogenesis and androgen synthesis. Trophoblast hCG, the "pregnancy hormone," exists in several isoforms and glycosylation variants with long half-lives (hours) and angiogenic potential and acts on luteinized ovarian cells as progestational. The different molecular features of LH and hCG lead to hormone-specific LHCGR binding and intracellular signaling cascades. In ovarian cells, LH action is preferentially exerted through kinases, phosphorylated extracellular-regulated kinase 1/2 (pERK1/2) and phosphorylated AKT (also known as protein kinase B), resulting in irreplaceable proliferative/antiapoptotic signals and partial agonism on progesterone production in vitro. In contrast, hCG displays notable cAMP/protein kinase A (PKA)-mediated steroidogenic and proapoptotic potential, which is masked by estrogen action in vivo. In vitro data have been confirmed by a large data set from assisted reproduction, because the steroidogenic potential of hCG positively affects the number of retrieved oocytes, and LH affects the pregnancy rate (per oocyte number). Leydig cell in vitro exposure to hCG results in qualitatively similar cAMP/PKA and pERK1/2 activation compared with LH and testosterone. The supposed equivalence of LH and hCG has been disproved by such data, highlighting their sex-specific functions and thus deeming it an oversight caused by incomplete understanding of clinical data.
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Affiliation(s)
- Livio Casarini
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.,Center for Genomic Research, University of Modena and Reggio Emilia, Modena, Italy
| | - Daniele Santi
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.,Unit of Endocrinology, Department of Medical Specialties, Azienda Ospedaliero-Universitaria, Modena, Italy
| | - Giulia Brigante
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.,Unit of Endocrinology, Department of Medical Specialties, Azienda Ospedaliero-Universitaria, Modena, Italy
| | - Manuela Simoni
- Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy.,Center for Genomic Research, University of Modena and Reggio Emilia, Modena, Italy.,Unit of Endocrinology, Department of Medical Specialties, Azienda Ospedaliero-Universitaria, Modena, Italy
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Kim HG, Bhagavath B, Layman LC. Clinical manifestations of impaired GnRH neuron development and function. Neurosignals 2008; 16:165-82. [PMID: 18253056 DOI: 10.1159/000111561] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) and olfactory neurons migrate together in embryologic development, and disruption of this process causes idiopathic hypogonadotropic hypogonadism (IHH) with anosmia (Kallmann syndrome (KS)). Patients with IHH/KS generally manifest irreversible pubertal delay and subsequent infertility due to deficient pituitary gonadotropins or GnRH. The molecular basis of IHH/KS includes genes that: (1) regulate GnRH and olfactory neuron migration; (2) control the synthesis or secretion of GnRH; (3) disrupt GnRH action upon pituitary gonadotropes, or (4) interfere with pituitary gonadotropin synthesis or secretion. KS patients may also have midline facial defects indicating the diverse developmental functions of genes involved. Most causative genes cause either normosmic IHH or KS except FGFR1, which may cause either phenotype. Recently, several balanced chromosomal translocations have been identified in IHH/KS patients, which could lead to the identification of new disease-producing genes. Although there are two cases reported who have digenic disease, this awaits confirmation in future larger studies. The challenge will be to determine the importance of these genes in the 10-15% of couples with normal puberty who have infertility.
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Affiliation(s)
- Hyung-Goo Kim
- Department of Obstetrics and Gynecology, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912-3360, USA
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Huhtaniemi IT. Mutations of gonadotropins and gonadotropin receptors: elucidating the physiology and pathophysiology of pituitary-gonadal function. Endocr Rev 2000; 21:551-83. [PMID: 11041448 DOI: 10.1210/edrv.21.5.0409] [Citation(s) in RCA: 423] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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.
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MESH Headings
- Amino Acid Sequence
- Animals
- Female
- Gonadotropins, Pituitary/chemistry
- Gonadotropins, Pituitary/genetics
- Gonadotropins, Pituitary/physiology
- Humans
- Mice
- Mice, Knockout
- Mutation
- Ovary/physiology
- Pituitary Gland/physiology
- Receptors, FSH/chemistry
- Receptors, FSH/genetics
- Receptors, FSH/physiology
- Receptors, Gonadotropin/chemistry
- Receptors, Gonadotropin/genetics
- Receptors, Gonadotropin/physiology
- Receptors, LH/chemistry
- Receptors, LH/genetics
- Receptors, LH/physiology
- Structure-Activity Relationship
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Layman LC. Mutations in human gonadotropin genes and their physiologic significance in puberty and reproduction. Fertil Steril 1999; 71:201-18. [PMID: 9988386 DOI: 10.1016/s0015-0282(98)00431-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Human gene mutations provide an opportunity to study the pathophysiology of the disease process as well as normal physiology. The purpose of the present report was to review known human gene mutations that affect gonadotropin secretion. DESIGN A retrospective analysis of studies of human gene mutations that affect hypothalamic, pituitary, and gonadal function was conducted. RESULT(S) Mutations have been identified for at least three genes that cause inherited hypogonadotropic hypogonadism. In addition, gene mutations for the beta-subunits of FSH and LH have been characterized. Both activating and inactivating mutations have been identified for the gonadotropin receptor genes. CONCLUSION(S) The identification of human gene mutations has furthered our understanding of the normal processes of pubertal development and fertility.
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Affiliation(s)
- L C Layman
- Department of Obstetrics and Gynecology, The University of Chicago, Illinois 60637, USA.
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