scholarly journals Tunicate Gonadotropin-Releasing Hormone (GnRH) Peptides Selectively Activate Ciona intestinalis GnRH Receptors and the Green Monkey Type II GnRH Receptor

Endocrinology ◽  
2005 ◽  
Vol 146 (9) ◽  
pp. 4061-4073 ◽  
Author(s):  
Javier A. Tello ◽  
Jean E. Rivier ◽  
Nancy M. Sherwood
Keyword(s):  
Messenger Rna ◽  
Inositol Phosphate ◽  
Ciona Intestinalis ◽  
Positive Control ◽  
Gnrh Receptor ◽  
Biologically Active ◽  
Intracellular Camp ◽  
Type Ii ◽  
Gnrh Receptors ◽  
Green Monkey

Abstract In vertebrates, GnRH binds to its receptor and stimulates predominantly Gq/11-mediated signal transduction in gonadotropes. However, little is known about the GnRH receptor and its signaling pathway in tunicates, a group that arose before the vertebrates. Although tunicates have had duplications of a few genes in the last 600 million years, the early vertebrates had duplications of the full genome. Also unknown is the nature of GnRH signaling in the tunicate, which lacks both a pituitary gland and sex steroids. However, we know that tunicates have GnRH peptides because we previously reported six GnRH peptides encoded within the tunicate genome of Ciona intestinalis. Here we clone and sequence cDNAs for four putative GnRH receptors from C. intestinalis. These are the only invertebrate GnRH receptors found to date. Each Ciona GnRH receptor was expressed in COS-7 cells, incubated with each of the six C. intestinalis GnRHs and assayed for a signaling response. GnRH receptors 1, 2, and 3 responded to Ciona GnRH peptides to stimulate intracellular cAMP accumulation. In contrast, only GnRH receptor 1 activated inositol phosphate turnover in response to one of the Ciona GnRHs. The green monkey type II GnRH receptor cDNA was tested as a comparison and a positive control. In conclusion, the four GnRH receptors encoded within the C. intestinalis genome were all transcribed into messenger RNA, but only three of the Ciona GnRH receptors were biologically active in our assays. The Ciona GnRH receptors almost exclusively activated the cAMP pathway.

scholarly journals Conserved Amino Acid Residues that Are Important for Ligand Binding in the Type I Gonadotropin-Releasing Hormone (GnRH) Receptor Are Required for High Potency of GnRH II at the Type II GnRH Receptor

2007 ◽  
Vol 21 (1) ◽  
pp. 281-292 ◽  
Author(s):  
Sipho Mamputha ◽  
Zhi-liang Lu ◽  
Roger W. Roeske ◽  
Robert P. Millar ◽  
Arieh A. Katz ◽  
...  
Keyword(s):  
Inositol Phosphate ◽  
Gnrh Receptor ◽  
Type I ◽  
Type Ii ◽  
Amino Acid Residues ◽  
Binding Assays ◽  
Antagonist Activity ◽  
Conserved Residues ◽  
Gnrh Receptors ◽  
Mutant Receptors

Abstract GnRH I regulates reproduction. A second form, designated GnRH II, selectively binds type II GnRH receptors. Amino acids of the type I GnRH receptor required for binding of GnRH I (Asp2.61(98), Asn2.65(102), and Lys3.32(121)) are conserved in the type II GnRH receptor, but their roles in receptor function are unknown. We have delineated their functions using mutagenesis, signaling and binding assays, immunoblotting, and computational modeling. Mutating Asp2.61(97) to Glu or Ala, Asn2.65(101) to Ala, or Lys3.32(120) to Gln decreased potency of GnRH II-stimulated inositol phosphate production. Consistent with proposed roles in ligand recognition, mutations eliminated measurable binding of GnRH II, whereas expression of mutant receptors was not decreased. In detailed analysis of how these residues affect ligand-dependent signaling, [Trp2]-GnRH I showed lesser decreases in potency than GnRH I at the Asp2.61(97)Glu mutant. In contrast, [Trp2]-GnRH II showed the same loss of potency as GnRH II at this mutant. This suggests that Asp2.61(97) contributes to recognition of His2 of GnRH I, but not of GnRH II. GnRH II showed a large decrease in potency at the Asn2.65(101)Ala mutant compared with analogs lacking the C⋕O group of Gly10NH2. This suggests that Asn2.65(101) recognizes Gly10NH2 of GnRH II. GnRH agonists showed large decreases in potency at the Lys3.32(120)Gln mutant, but antagonist activity was unaffected. This suggests that Lys3.32(120) recognizes agonists, but not antagonists, as in the type I receptor. These data indicate that roles of conserved residues are similar, but not identical, in the type I and II GnRH receptors.

scholarly journals Type II gonadotrophin-releasing hormone (GnRH-II) in reproductive biology

Reproduction ◽  
2003 ◽  
pp. 271-278 ◽  
Author(s):  
AJ Pawson ◽  
K Morgan ◽  
SR Maudsley ◽  
RP Millar
Keyword(s):  
Receptor Gene ◽  
Gnrh Receptor ◽  
Specific Gene ◽  
Type I ◽  
Type Ii ◽  
Releasing Hormone ◽  
Human Type ◽  
Gnrh Receptors ◽  
Gonadotrophin Releasing Hormone ◽  
Ligand Precursors

Humans may be particularly unusual with respect to the gonadotrophin-releasing hormone (GnRH) control of their reproductive axis in that they possess two distinct GnRH precursor genes, on chromosomes 8p11-p21 and 20p13, but only one conventional GnRH receptor subtype (type I GnRH receptor) encoded within the genome, on chromosome 4. A disrupted human type II GnRH receptor gene homologue is present on chromosome 1q12. The genes encoding GnRH ligand precursors and GnRH receptors have now been characterized in a broad range of vertebrate species, including fish, amphibians and mammals. Ligand precursors and receptors can be categorized into three phylogenetic families. Members of each family exist in primitive vertebrates, whereas mammals exhibit selective loss of ligand precursor and receptor genes. One interpretation of these findings is that each ligand-cognate receptor family may have evolved to fulfil a separate function in reproductive physiology and that species-specific gene inactivation, modification or loss may have occurred during evolution when particular roles have become obsolete or subject to regulation by a different biochemical pathway. Evidence in support of this concept is available following the characterization of the chromosomal loci encoding the human type II GnRH receptor homologue, a rat type II GnRH receptor gene remnant (on rat chromosome 18) and a mouse type II GnRH ligand precursor gene remnant (on mouse chromosome 2). Whether type I GnRH and type II GnRH peptides elicit different signalling responses in humans by activation of the type I GnRH receptor in a cell type-specific fashion remains to be shown. Recent structure-function studies of GnRH ligands and GnRH receptors and their expression patterns in different tissues add further intrigue to this hypothesis by indicating novel roles for GnRH such as neuromodulation of reproductive function and direct regulation of peripheral reproductive tissues. Surprises concerning the complexities of GnRH ligand and receptor function in reproductive endocrinology should continue to emerge in the future.

A Third Lamprey Novel GnRH Receptor Similar to Gnathostome Type-II GnRH Receptors.

2010 ◽  
pp. P3-205-P3-205
Author(s):  
A Aquilina-Beck ◽  
C MacDonald ◽  
SI Kavanaugh ◽  
M Freamat ◽  
SA Sower
Keyword(s):  
Gnrh Receptor ◽  
Type Ii ◽  
Gnrh Receptors

scholarly journals Cloning and Characterization of a Functional Type II Gonadotropin-Releasing Hormone Receptor with a Lengthy Carboxy-Terminal Tail from an Ancestral Vertebrate, the Sea Lamprey

Endocrinology ◽  
2005 ◽  
Vol 146 (8) ◽  
pp. 3351-3361 ◽  
Author(s):  
Matthew R. Silver ◽  
Nathaniel V. Nucci ◽  
Adam R. Root ◽  
Karen L. Reed ◽  
Stacia A. Sower
Keyword(s):  
Inositol Phosphate ◽  
Sea Lamprey ◽  
Structural Features ◽  
Gnrh Receptor ◽  
Type Ii ◽  
Functional Type ◽  
Vertebrate Lineage ◽  
Functional Features ◽  
Full Length Transcript ◽  
Carboxy Terminal

Abstract A full-length transcript encoding a functional type II GnRH receptor was cloned from the pituitary of the sea lamprey, Petromyzon marinus. The current study is the first to identify a pituitary GnRH receptor transcript in an agnathan, which is the oldest vertebrate lineage. The cloned receptor retains the conserved structural features and amino acid motifs of other known GnRH receptors and notably includes a C-terminal intracellular tail of approximately 120 amino acids, the longest C-terminal tail of any vertebrate GnRH receptor identified to date. The lamprey GnRH receptor was shown to activate the inositol phosphate (IP) signaling system; stimulation with either lamprey GnRH-I or lamprey GnRH-III led to dose-dependent responses in transiently transfected COS7 cells. Furthermore, analyses of serially truncated lamprey GnRH receptor mutants indicate perturbations of the C-terminal tail disrupts IP accumulation, however, the tailless lamprey GnRH receptor was not only functional but was also capable of stimulating IP levels equal to wild type. Expression of the receptor transcript was demonstrated in the pituitary and testes using RT-PCR, whereas in situ hybridization showed expression and localization of the transcript in the proximal pars distalis of the pituitary. The phylogenetic placement and structural and functional features of this GnRH receptor suggest that it is representative of an ancestral GnRH receptor. In addition to having an important role in lamprey reproductive processes, the extensive C-terminal tail of this lamprey GnRH receptor may have great significance for understanding the evolutionary change of this vital structural feature within the GnRH receptor family.

scholarly journals Amphioxus: Beginning of Vertebrate and End of Invertebrate Type GnRH Receptor Lineage

Endocrinology ◽  
2009 ◽  
Vol 150 (6) ◽  
pp. 2847-2856 ◽  
Author(s):  
Javier A. Tello ◽  
Nancy M. Sherwood
Keyword(s):  
Inositol Phosphate ◽  
Gnrh Receptor ◽  
The Other ◽  
Type I ◽  
Adipokinetic Hormone ◽  
Branchiostoma Floridae ◽  
Vertebrate Lineage ◽  
Functional Conservation ◽  
Gnrh Receptors ◽  
Amphioxus Genome

In vertebrates, activation of the GnRH receptor is necessary to initiate the reproductive cascade. However, little is known about the characteristics of GnRH receptors before the vertebrates evolved. Recently genome sequencing was completed for amphioxus, Branchiostoma floridae. To understand the GnRH receptors (GnRHR) from this most basal chordate, which is also classified as an invertebrate, we cloned and characterized four GnRHR cDNAs encoded in the amphioxus genome. We found that incubation of GnRH1 (mammalian GnRH) and GnRH2 (chicken GnRH II) with COS7 cells heterologously expressing the amphioxus GnRHRs caused potent intracellular inositol phosphate turnover in two of the receptors. One of the two receptors displayed a clear preference for GnRH1 over GnRH2, a characteristic not previously seen outside the type I mammalian GnRHRs. Phylogenetic analysis grouped the four receptors into two paralogous pairs, with one pair grouping basally with the vertebrate GnRH receptors and the other grouping with the octopus GnRHR-like sequence and the related receptor for insect adipokinetic hormone. Pharmacological studies showed that octopus GnRH-like peptide and adipokinetic hormone induced potent inositol phosphate turnover in one of these other two amphioxus receptors. These data demonstrate the functional conservation of two distinct types of GnRH receptors at the base of chordates. We propose that one receptor type led to vertebrate GnRHRs, whereas the other type, related to the mollusk GnRHR-like receptor, was lost in the vertebrate lineage. This is the first report to suggest that distinct invertebrate and vertebrate GnRHRs are present simultaneously in a basal chordate, amphioxus.

scholarly journals Functional characterization and kinetic studies of an ancestral lamprey GnRH-III selective type II GnRH receptor from the sea lamprey, Petromyzon marinus

2006 ◽  
Vol 36 (3) ◽  
pp. 601-610 ◽  
Author(s):  
M R Silver ◽  
S A Sower
Keyword(s):  
Intact Cell ◽  
Functional Characterization ◽  
Kinetic Studies ◽  
Receptor Activation ◽  
Gnrh Receptor ◽  
Type I ◽  
Type Ii ◽  
Binding Assays ◽  
Gnrh Receptors ◽  
Series Of Experiments

The recently cloned lamprey GnRH receptor was shown to have several unique features, including the longest intracellular C-terminal tail (120 amino acids (aa)) of any previously described GnRH receptor. In the current study, a series of experiments were performed examining cAMP responses, binding kinetics, whole cell competitive binding assays and internalization studies of the lamprey GnRH receptor using a series of three C-terminal tail truncations (80 aa, 40 aa and 0 aa) to better describe the functional significance of this unique vertebrate GnRH receptor. Activation of the lamprey GnRH receptor was shown to stimulate cAMP production in a dose-dependant manner when treated with either lamprey GnRH-I (LogEC50 −6.57±0.15) or lamprey GnRH-III (LogEC50 −8.29±0.09). Truncation analysis indicated that the membrane proximal 40 aa of the lamprey GnRH receptor C-terminal tail contain a motif required for cAMP accumulation. Saturation binding assays using the wild type and truncated lamprey GnRH receptors revealed that all of three truncated lamprey GnRH receptors were capable of binding lamprey GnRH-I. Competitive, intact cell-binding assays suggested that the lamprey GnRH receptor is lamprey GnRH-III selective, based on the observed pharmacological profile: lamprey GnRH-III (Inhibitory constant (Ki) 0.708±0.245 nM)=chicken GnRH-II (Ki 0.765±0.160 nM) > mammalian GnRH (Ki 12.9±1.96 nM) > dAla6Pro9NEt mammalian GnRH (Ki 21.6±9.68 nM) > lamprey GnRH-I (Ki 118.0±23.6). Finally, the lamprey GnRH receptor was shown to undergo rapid ligand-dependant internalization, which was significantly diminished in the tail-less truncated form. We have shown from our current and our previous structural studies that this unique lamprey GnRH receptor shares several characteristics of both type I and type II GnRH receptors which suggests that this receptor has retained ancestral characteristics that can provide insight into the function and evolution of the vertebrate GnRH receptor family.

scholarly journals Hepatoprotective Effect of Mixture of Dipropyl Polysulfides in Concanavalin A-Induced Hepatitis

Nutrients ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 1022
Author(s):  
Dragana Arsenijevic ◽  
Bojana Stojanovic ◽  
Jelena Milovanovic ◽  
Aleksandar Arsenijevic ◽  
Milos Simic ◽  
...  
Keyword(s):  
Concanavalin A ◽  
Messenger Rna ◽  
T Regulatory Cells ◽  
Mononuclear Cells ◽  
Biological Activities ◽  
Biologically Active ◽  
Organosulfur Compounds ◽  
Liver Inflammation ◽  
Regulatory Cells ◽  
Active Components

The main biologically active components of plants belonging to the genus Allium, responsible for their biological activities, including anti-inflammatory, antioxidant and immunomodulatory, are organosulfur compounds. The aim of this study was to synthetize the mixture of dipropyl polysulfides (DPPS) and to test their biological activity in acute hepatitis. C57BL/6 mice were administered orally with DPPS 6 h before intravenous injection of Concanavalin A (ConA). Liver inflammation, necrosis and hepatocytes apoptosis were determined by histological analyses. Cytokines in liver tissue were determined by ELISA, expression of adhesive molecules and enzymes by RT PCR, while liver mononuclear cells were analyzed by flow cytometry. DPPS pretreatment significantly attenuated liver inflammation and injury, as evidenced by biochemical and histopathological observations. In DPPS-pretreated mice, messenger RNA levels of adhesion molecules and NADPH oxidase complex were significantly reduced, while the expression of SOD enzymes was enhanced. DPPS pretreatment decreased protein level of inflammatory cytokines and increased percentage of T regulatory cells in the livers of ConA mice. DPPS showed hepatoprotective effects in ConA-induced hepatitis, characterized by attenuation of inflammation and affection of Th17/Treg balance in favor of T regulatory cells and implicating potential therapeutic usage of DPPS mixture in inflammatory liver diseases.

scholarly journals Differential Effects of Gonadotropin-Releasing Hormone (GnRH) Pulse Frequency on Gonadotropin Subunit and GnRH Receptor Messenger Ribonucleic Acid Levels in Vitro*

Endocrinology ◽  
1997 ◽  
Vol 138 (3) ◽  
pp. 1224-1231 ◽  
Author(s):  
Ursula B. Kaiser ◽  
Andrzej Jakubowiak ◽  
Anna Steinberger ◽  
William W. Chin
Keyword(s):  
Gene Expression ◽  
Messenger Rna ◽  
Pulse Frequency ◽  
Gnrh Receptor ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Subunit Gene ◽  
Differential Effects ◽  
Messenger Ribonucleic Acid

Abstract The hypothalamic hormone, GnRH, is released and transported to the anterior pituitary in a pulsatile manner, where it binds to specific high-affinity receptors and regulates gonadotropin biosynthesis and secretion. The frequency of GnRH pulses changes under various physiological conditions, and varying GnRH pulse frequencies have been shown to regulate differentially the secretion of LH and FSH and the expression of the gonadotropin α, LHβ, and FSHβ subunit genes in vivo. We demonstrate differential effects of varying GnRH pulse frequency in vitro in superfused primary monolayer cultures of rat pituitary cells. Cells were treated with 10 nm GnRH pulses for 24 h at a frequency of every 0.5, 1, 2, or 4 h. α, LHβ, and FSHβ messenger RNA (mRNA) levels were increased by GnRH at all pulse frequencies. α and LHβ mRNA levels and LH secretion were stimulated to the greatest extent at a GnRH pulse frequency of every 30 min, whereas FSHβ mRNA levels and FSH secretion were stimulated maximally at a lower GnRH pulse frequency, every 2 h. GnRH receptor (GnRHR) mRNA levels also were increased by GnRH at all pulse frequencies and were stimulated maximally at a GnRH pulse frequency of every 30 min. Similar results were obtained when the dose of each pulse of GnRH was adjusted to maintain a constant total cumulative dose of GnRH over 24 h. These data show that gonadotropin subunit gene expression is regulated differentially by varying GnRH pulse frequencies in vitro, suggesting that the differential effects of varying GnRH pulse frequencies on gonadotropin subunit gene expression occur directly at the level of the pituitary. The pattern of regulation of GnRHR mRNA levels correlated with that of α and LHβ but was different from that of FSHβ. This suggests that α and LHβ mRNA levels are maximally stimulated when GnRHR levels are relatively high, whereas FSHβ mRNA levels are maximally stimulated at lower levels of GnRHR expression, and that the mechanism for differential regulation of the gonadotropins by varying pulse frequencies of GnRH may involve levels of GnRHR. Furthermore, these data suggest that the mechanisms whereby varying GnRH pulse frequencies stimulate α, LHβ, and GnRHR gene expression are similar, whereas the stimulation of FSHβ mRNA levels may be different.

Sign in / Sign up

Export Citation Format

Share Document