scholarly journals Complete Kisspeptin Receptor Inactivation Does Not Impede Exogenous GnRH-Induced LH Surge in Humans

2018 ◽  
Vol 103 (12) ◽  
pp. 4482-4490 ◽  
Author(s):  
Justine Hugon-Rodin ◽  
Keisuke Yoshii ◽  
Najiba Lahlou ◽  
Jennifer Flandrin ◽  
Anne Gompel ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Hypogonadotropic Hypogonadism ◽  
Pulse Therapy ◽  
Breast Development ◽  
Primary Amenorrhea ◽  
Lh Surge ◽  
Transfected Cells ◽  
Pulsatile Gnrh ◽  
Gnrh Therapy

Abstract Context Mutations in the kisspeptin receptor (KISS1R) gene have been reported in a few patients with normosmic congenital hypogonadotropic hypogonadism (nCHH) (OMIM #146110). Objectives To describe a female patient with nCHH and a novel homozygous KISS1R mutation and to assess the role of kisspeptin pathway to induce an ovulation by GnRH pulse therapy. Design, Setting, and Intervention Observational study of a patient including genetic and kisspeptin receptor functions and treatment efficiency using a GnRH pump. Main Outcome Measure Response to pulsatile GnRH therapy Results A partial isolated gonadotropic deficiency was diagnosed in a 28-year-old woman with primary amenorrhea and no breast development. A novel homozygous c.953T>C variant was identified in KISS1R. This mutation led to substitution of leucine 318 for proline (p.Leu318Pro) in the seventh transmembrane domain of KISS1R. Signaling via the mutated receptor was profoundly impaired in HEK293-transfected cells. The mutated receptor was not detected on the membrane of HEK293-transfected cells. After several pulsatile GnRH therapy cycles, an LH surge with ovulation and pregnancy was obtained. Conclusion GnRH pulsatile therapy can induce an LH surge in a woman with a mutated KISS1R, which was previously thought to be completely inactivated in vivo.

scholarly journals Resistance of Hypogonadic Patients with Mutated GnRH Receptor Genes to Pulsatile GnRH Administration

1999 ◽  
Vol 84 (3) ◽  
pp. 990-996 ◽  
Author(s):  
Philippe Caron ◽  
Stéphanie Chauvin ◽  
Sophie Christin-Maitre ◽  
Antoine Bennet ◽  
Najiba Lahlou ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Receptor Gene ◽  
Hypogonadotropic Hypogonadism ◽  
Chinese Hamster ◽  
Gnrh Receptor ◽  
Primary Amenorrhea ◽  
Recessive Trait ◽  
Intracellular Loop ◽  
Α Subunit ◽  
Pulsatile Gnrh

We have studied a kindred with three siblings with isolated hypogonadotropic hypogonadism caused by compound heterozygote mutations in the GnRH receptor gene. The disorder was transmitted as an autosomal recessive trait. The R262Q mutation in intracellular loop 3 of the receptor was associated with a mutation in the third transmembrane domain of the receptor, A129D, that has never been described before. This A129D mutation results in a complete loss of function, indicated by the lack of inositol triphosphate (TP3) 3 production by transfected Chinese hamster ovary (CHO) cells after GnRH stimulation. The two brothers had microphallus and bilateral cryptorchidism and were referred for lack of puberty, whereas their sister had primary amenorrhea and a complete lack of puberty. Their basal gonadotropin concentrations were below the reference range, and their endogenous LH secretory patterns were abnormal, with a low-normal frequency of small pulses or no apparent LH pulse. Pulsatile GnRH administration (10 μg/pulse every 90 min for 40 h) resulted in increased mean LH without any significant changes in testosterone levels in the two brothers, whereas the LH secretory profile of their sister remained apulsatile. Larger pulses of exogenous GnRH (20 μg every 90 min for 24 h) caused the sister to produce recognizable low amplitude LH pulses. The concentrations of free α-subunit significantly increased in all patients during the pulsatile GnRH administration. Thus, these hypogonadal patients are partially resistant to pulsatile GnRH administration, suggesting that they should be treated with gonadotropins to induce spermatogenesis or ovulation rather than with pulsatile GnRH.

scholarly journals Different dendritic domains of the GnRH neuron underlie the pulse and surge modes of GnRH secretion in female mice

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Li Wang ◽  
Wenya Guo ◽  
Xi Shen ◽  
Shel Yeo ◽  
Hui Long ◽  
...  
Keyword(s):  
Synaptic Integration ◽  
Secretory Process ◽  
Gnrh Neuron ◽  
Lh Surge ◽  
Synaptic Inputs ◽  
Gnrh Secretion ◽  
Pulsatile Gnrh ◽  
Lh Pulsatility ◽  
Neuron Soma

The gonadotropin-releasing hormone (GnRH) neurons exhibit pulse and surge modes of activity to control fertility. They also exhibit an unusual bipolar morphology comprised of a classical soma-proximal dendritic zone and an elongated secretory process that can operate as both a dendrite and an axon, termed a ‘dendron’. We show using expansion microscopy that the highest density of synaptic inputs to a GnRH neuron exists at its distal dendron. In vivo, selective chemogenetic inhibition of the GnRH neuron distal dendron abolishes the luteinizing hormone (LH) surge and markedly dampens LH pulses. In contrast, inhibitory chemogenetic and optogenetic strategies targeting the GnRH neuron soma-proximal dendritic zone abolish the LH surge but have no effect upon LH pulsatility. These observations indicate that electrical activity at the soma-proximal dendrites of the GnRH neuron is only essential for the LH surge while the distal dendron represents an autonomous zone where synaptic integration drives pulsatile GnRH secretion.

scholarly journals Diagnosis and management of of primary amenorrhea and female delayed puberty

2021 ◽  
Author(s):  
Satu Seppä ◽  
Tanja Kuiri-Hänninen ◽  
Elina Holopainen ◽  
Raimo Voutilainen
Keyword(s):  
Pubertal Development ◽  
Hypogonadotropic Hypogonadism ◽  
Reproductive Capacity ◽  
Breast Development ◽  
Delayed Puberty ◽  
Primary Amenorrhea ◽  
Secondary Sexual Characteristics ◽  
Sexual Characteristics ◽  
Old Females ◽  
Secondary Sexual

Puberty is the period of transition from childhood to adulthood characterized by the attainment of adult height and body composition, accrual of bone strength and the acquisition of secondary sexual characteristics, psychosocial maturation and reproductive capacity. In girls, menarche is a late marker of puberty. Primary amenorrhea is defined as the absence of menarche in ≥15-year-old females with developed secondary sexual characteristics and normal growth or that in ≥13-year-old females without signs of pubertal development. Furthermore, evaluation for primary amenorrhea should be considered in the absence of menarche three years after thelarche (start of breast development) or five years after thelarce, if that occurred before the age of 10 years. A variety of disorders in the hypothalamus-pituitary-ovarian axis can lead to primary amenorrhea with delayed, arrested or normal pubertal development. Etiologies can be categorized as hypothalamic or pituitary disorders causing hypogonadotropic hypogonadism, gonadal disorders causing hypergonadotropic hypogonadism, disorders of other endocrine glands, and congenital utero-vaginal anomalies. This article gives a comprehensive review of the etiologies, diagnostics and management of primary amenorrhea from the perspective of pediatric endocrinologists and gynecologists. The goals of treatment vary depending on both the etiology and patient; with timely etiological diagnostics fertility may be attained even in those situations where no curable treatment exists.

scholarly journals Endocrine Aspects of 4H Leukodystrophy: A Case Report and Review of the Literature

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Emma Billington ◽  
Geneviève Bernard ◽  
William Gibson ◽  
Bernard Corenblum
Keyword(s):  
Rna Polymerase ◽  
Autosomal Recessive ◽  
Hypogonadotropic Hypogonadism ◽  
Rna Polymerase Iii ◽  
Autosomal Recessive Inheritance ◽  
Primary Amenorrhea ◽  
Dental Abnormalities ◽  
Pulsatile Gnrh ◽  
Polymerase Iii ◽  
Gonadotropin Therapy

Introduction. 4H leukodystrophy is an autosomal recessive RNA polymerase III-related leukodystrophy, characterized by hypomyelination, with or without hypodontia (or other dental abnormalities) and hypogonadotropic hypogonadism.Case Presentation. We describe a 28-year-old female who presented with primary amenorrhea at the age of 19. She had a history of very mild neurological and dental abnormalities. She was found to have hypogonadotropic hypogonadism, and magnetic resonance imaging of the brain showed hypomyelination. The diagnosis of 4H leukodystrophy was made. She was subsequently found to have mutations in thePOLR3Bgene, which encodes the second largest subunit of RNA polymerase III. She wished to become pregnant and failed to respond to pulsatile GnRH but achieved normal follicular growth and ovulation with subcutaneous gonadotropin therapy.Discussion. Patients with 4H leukodystrophy may initially present with hypogonadotropic hypogonadism, particularly if neurological and dental manifestations are subtle. Making the diagnosis has important implications for prognosis and management. Progressive neurologic deterioration is expected, and progressive endocrine dysfunction may occur. Patients with 4H leukodystrophy should be counseled about disease progression and about this disease’s autosomal recessive inheritance pattern. In those who wish to conceive, ovulation induction may be achieved with subcutaneous gonadotropin therapy, but pulsatile GnRH does not appear to be effective.

scholarly journals Syndecan Transmembrane Domain Specifically Regulates Downstream Signaling Events of the Transmembrane Receptor Cytoplasmic Domain

2021 ◽  
Vol 22 (15) ◽  
pp. 7918
Author(s):  
Jisun Hwang ◽  
Bohee Jang ◽  
Ayoung Kim ◽  
Yejin Lee ◽  
Joonha Lee ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Growth Factor Receptor ◽  
Cytoplasmic Domain ◽  
Nih3t3 Cells ◽  
C Elegans ◽  
Downstream Signaling ◽  
Downstream Effectors ◽  
Signaling Events

Despite the known importance of the transmembrane domain (TMD) of syndecan receptors in cell adhesion and signaling, the molecular basis for syndecan TMD function remains unknown. Using in vivo invertebrate models, we found that mammalian syndecan-2 rescued both the guidance defects in C. elegans hermaphrodite-specific neurons and the impaired development of the midline axons of Drosophila caused by the loss of endogenous syndecan. These compensatory effects, however, were reduced significantly when syndecan-2 dimerization-defective TMD mutants were introduced. To further investigate the role of the TMD, we generated a chimera, 2eTPC, comprising the TMD of syndecan-2 linked to the cytoplasmic domain of platelet-derived growth factor receptor (PDGFR). This chimera exhibited SDS-resistant dimer formation that was lost in the corresponding dimerization-defective syndecan-2 TMD mutant, 2eT(GL)PC. Moreover, 2eTPC specifically enhanced Tyr 579 and Tyr 857 phosphorylation in the PDGFR cytoplasmic domain, while the TMD mutant failed to support such phosphorylation. Finally, 2eTPC, but not 2eT(GL)PC, induced phosphorylation of Src and PI3 kinase (known downstream effectors of Tyr 579 phosphorylation) and promoted Src-mediated migration of NIH3T3 cells. Taken together, these data suggest that the TMD of a syndecan-2 specifically regulates receptor cytoplasmic domain function and subsequent downstream signaling events controlling cell behavior.

scholarly journals A Novel Golgi Membrane Protein Is a Partner of the ARF Exchange Factors Gea1p and Gea2p

2003 ◽  
Vol 14 (6) ◽  
pp. 2357-2371 ◽  
Author(s):  
Sophie Chantalat ◽  
Rëgis Courbeyrette ◽  
Francesca Senic-Matuglia ◽  
Catherine L. Jackson ◽  
Bruno Goud ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Protein Trafficking ◽  
Transmembrane Domain ◽  
Integral Membrane Protein ◽  
Membrane Dynamics ◽  
General Interest ◽  
Single Mutation ◽  
Golgi Membrane ◽  
Nucleotide Exchange

The Sec7 domain guanine nucleotide exchange factors (GEFs) for the GTPase ARF are highly conserved regulators of membrane dynamics and protein trafficking. The interactions of large ARF GEFs with cellular membranes for localization and/or activation are likely to participate in regulated recruitment of ARF and effectors. However, these interactions remain largely unknown. Here we characterize Gmh1p, the first Golgi transmembrane-domain partner of any of the high-molecular-weight ARF-GEFs. Gmh1p is an evolutionarily conserved protein. We demonstrate molecular interaction between the yeast Gmh1p and the large ARF-GEFs Gea1p and Gea2p. This interaction involves a domain of Gea1p and Gea2p that is conserved in the eukaryotic orthologues of the Gea proteins. A single mutation in a conserved amino acid residue of this domain is sufficient to abrogate the interaction, whereas the overexpression of Gmh1p can compensate in vivo defects caused by mutations in this domain. We show that Gmh1p is an integral membrane protein that localizes to the early Golgi in yeast and in human HeLa cells and cycles through the ER. Hence, we propose that Gmh1p acts as a positive Golgi-membrane partner for Gea function. These results are of general interest given the evolutionary conservation of both ARF-GEFs and the Gmh proteins.

scholarly journals Overexpression of CALNUC (Nucleobindin) Increases Agonist and Thapsigargin Releasable Ca2+ Storage in the Golgi

1999 ◽  
Vol 145 (2) ◽  
pp. 279-289 ◽  
Author(s):  
Ping Lin ◽  
Yong Yao ◽  
Robert Hofmeister ◽  
Roger Y. Tsien ◽  
Marilyn Gist Farquhar
Keyword(s):  
Endoplasmic Reticulum ◽  
Cho Cells ◽  
Binding Capacity ◽  
Binding Protein ◽  
Ip3 Receptor ◽  
Transfected Cells ◽  
Permeabilized Cells ◽  
Endoplasmic Reticulum Calcium ◽  
Golgi Protein

We previously demonstrated that CALNUC, a Ca2+-binding protein with two EF-hands, is the major Ca2+-binding protein in the Golgi by 45Ca2+ overlay (Lin, P., H. Le-Niculescu, R. Hofmeister, J.M. McCaffery, M. Jin, H. Henneman, T. McQuistan, L. De Vries, and M. Farquhar. 1998. J. Cell Biol. 141:1515–1527). In this study we investigated CALNUC's properties and the Golgi Ca2+ storage pool in vivo. CALNUC was found to be a highly abundant Golgi protein (3.8 μg CALNUC/mg Golgi protein, 2.5 × 105 CALNUC molecules/NRK cell) and to have a single high affinity, low capacity Ca2+-binding site (Kd = 6.6 μM, binding capacity = 1.1 μmol Ca2+/μmol CALNUC). 45Ca2+ storage was increased by 2.5- and 3-fold, respectively, in HeLa cells transiently overexpressing CALNUC-GFP and in EcR-CHO cells stably overexpressing CALNUC. Deletion of the first EF-hand α helix from CALNUC completely abolished its Ca2+-binding capability. CALNUC was correctly targeted to the Golgi in transfected cells as it colocalized and cosedimented with the Golgi marker, α-mannosidase II (Man II). Approximately 70% of the 45Ca2+ taken up by HeLa and CHO cells overexpressing CALNUC was released by treatment with thapsigargin, a sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) (Ca2+ pump) blocker. Stimulation of transfected cells with the agonist ATP or IP3 alone (permeabilized cells) also resulted in a significant increase in Ca2+ release from Golgi stores. By immunofluorescence, the IP3 receptor type 1 (IP3R-1) was distributed over the endoplasmic reticulum and codistributed with CALNUC in the Golgi. These results provide direct evidence that CALNUC binds Ca2+ in vivo and together with SERCA and IP3R is involved in establishment of the agonist-mobilizable Golgi Ca2+ store.

scholarly journals Saccharomyces cerevisiae Grx6 and Grx7 Are Monothiol Glutaredoxins Associated with the Early Secretory Pathway

2008 ◽  
Vol 7 (8) ◽  
pp. 1415-1426 ◽  
Author(s):  
Alicia Izquierdo ◽  
Celia Casas ◽  
Ulrich Mühlenhoff ◽  
Christopher Horst Lillig ◽  
Enrique Herrero
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Active Site ◽  
Secretory Pathway ◽  
Transmembrane Domain ◽  
Inhibitory Effect ◽  
Protein Accumulation ◽  
Oxidoreductase Activity ◽  
Early Secretory Pathway ◽  
Glycosylation Inhibitor

ABSTRACT Saccharomyces cerevisiae Grx6 and Grx7 are two monothiol glutaredoxins whose active-site sequences (CSYS and CPYS, respectively) are reminiscent of the CPYC active-site sequence of classical dithiol glutaredoxins. Both proteins contain an N-terminal transmembrane domain which is responsible for their association to membranes of the early secretory pathway vesicles, facing the luminal side. Thus, Grx6 localizes at the endoplasmic reticulum and Golgi compartments, while Grx7 is mostly at the Golgi. Expression of GRX6 is modestly upregulated by several stresses (calcium, sodium, and peroxides) in a manner dependent on the Crz1-calcineurin pathway. Some of these stresses also upregulate GRX7 expression under the control of the Msn2/4 transcription factor. The N glycosylation inhibitor tunicamycin induces the expression of both genes along with protein accumulation. Mutants lacking both glutaredoxins display reduced sensitivity to tunicamycin, although the drug is still able to manifest its inhibitory effect on a reporter glycoprotein. Grx6 and Grx7 have measurable oxidoreductase activity in vivo, which is increased in the presence of tunicamycin. Both glutaredoxins could be responsible for the regulation of the sulfhydryl oxidative state at the oxidant conditions of the early secretory pathway vesicles. However, the differences in location and expression responses against stresses suggest that their functions are not totally overlapping.

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