scholarly journals The Nematode Leucine-Rich Repeat-Containing, G Protein-Coupled Receptor (LGR) Protein Homologous to Vertebrate Gonadotropin and Thyrotropin Receptors is Constitutively Activated in Mammalian Cells

2000 ◽  
Vol 14 (2) ◽  
pp. 272-284 ◽  
Author(s):  
Masataka Kudo ◽  
Thomas Chen ◽  
Koji Nakabayashi ◽  
Sheau Yu Hsu ◽  
Aaron J. W. Hsueh
Keyword(s):  
G Protein ◽  
Hormone Receptors ◽  
Receptor Activation ◽  
Leucine Rich Repeat ◽  
Camp Production ◽  
Glycoprotein Hormone ◽  
Lh Receptor ◽  
Glycoprotein Hormone Receptors ◽  
Leucine Rich Repeats ◽  
G Protein Coupled

Abstract The receptors for LH, FSH, and TSH belong to the large G protein-coupled, seven-transmembrane (TM) protein family and are unique in having a large N-terminal extracellular (ecto-) domain containing leucine-rich repeats important for interactions with the large glycoprotein hormone ligands. Recent studies indicated the evolution of an expanding family of homologous leucine-rich repeat-containing, G protein-coupled receptors (LGRs), including the three known glycoprotein hormone receptors; mammalian LGR4 and LGR5; and LGRs in sea anemone, fly, and snail. We isolated nematode LGR cDNA and characterized its gene from the Caenorhabditis elegans genome. This receptor cDNA encodes 929 amino acids consisting of a signal peptide for membrane insertion, an ectodomain with nine leucine-rich repeats, a seven-TM region, and a long C-terminal tail. The nematode LGR has five potential N-linked glycosylation sites in its ectodomain and multiple consensus phosphorylation sites for protein kinase A and C in the cytoplasmic loop and C tail. The nematode receptor gene has 13 exons; its TM region and C tail, unlike mammalian glycoprotein hormone receptors, are encoded by multiple exons. Sequence alignments showed that the TM region of the nematode receptor has 30% identity and 50% similarity to the same region in mammalian glycoprotein hormone receptors. Although human 293T cells expressing the nematode LGR protein do not respond to human glycoprotein hormones, these cells exhibited major increases in basal cAMP production in the absence of ligand stimulation, reaching levels comparable to those in cells expressing a constitutively activated mutant human LH receptor found in patients with familial male-limited precocious puberty. Analysis of cAMP production mediated by chimeric receptors further indicated that the ectodomain and TM region of the nematode LGR and human LH receptor are interchangeable and the TM region of the nematode LGR is responsible for constitutive receptor activation. Thus, the identification and characterization of the nematode receptor provides the basis for understanding the evolutionary relationship of diverse LGRs and for future analysis of mechanisms underlying the activation of glycoprotein hormone receptors and related LGRs.

scholarly journals Characterization of Two Fly LGR (Leucine-Rich Repeat-Containing, G Protein-Coupled Receptor) Proteins Homologous to Vertebrate Glycoprotein Hormone Receptors: Constitutive Activation of Wild-Type Fly LGR1 But Not LGR2 in Transfected Mammalian Cells**This study was supported by NIH Grant HD-23273. The GenBank submission number for fly LGR2 is AF274591.

Endocrinology ◽  
2000 ◽  
Vol 141 (11) ◽  
pp. 4081-4090 ◽  
Author(s):  
Shinya Nishi ◽  
Sheau Yu Hsu ◽  
Karen Zell ◽  
Aaron J. W. Hsueh
Keyword(s):  
G Protein ◽  
Hormone Receptors ◽  
Coupling Mechanism ◽  
Leucine Rich Repeat ◽  
G Protein Coupled Receptor ◽  
Glycoprotein Hormone ◽  
Glycoprotein Hormone Receptors ◽  
Signaling Mechanisms ◽  
G Protein Coupled

Abstract The receptors for lutropin (LH), FSH, and TSH belong to the large G protein-coupled receptor (GPCR) superfamily and are unique in having a large N-terminal extracellular (ecto-) domain important for interactions with the large glycoprotein hormone ligands. Recent studies indicated the evolution of a large family of the leucine-rich repeat-containing, G protein-coupled receptors (LGRs) with at least seven members in mammals. Based on the sequences of mammalian glycoprotein hormone receptors, we have identified a new LGR in Drosophila melanogaster and named it as fly LGR2 to distinguish it from the previously reported fly LH/FSH/TSH receptor (renamed as fly LGR1). Genomic analysis indicated the presence of 10 exons in fly LGR2 as compared with 16 exons in fly LGR1. The deduced fly LGR2 complementary DNA (cDNA) showed 43 and 64% similarity to the fly LGR1 in the ectodomain and transmembrane region, respectively. Comparison of 12 LGRs from diverse species indicated that these proteins can be divided into three subfamilies and fly LGR1 and LGR2 belong to different subfamilies. Potential signaling mechanisms were tested in human 293T cells overexpressing the fly receptors. Of interest, fly LGR1, but not LGR2, showed constitutive activity as reflected by elevated basal cAMP production in transfected cells. The basal activity of fly LGR1 was further augmented following point mutations of key residues in the intracellular loop 3 or transmembrane VI, similar to those found in patients with familial male precocious puberty. The present study reports the cloning of fly LGR2 and indicates that the G protein-coupling mechanism is conserved in fly LGR1 as compared with the mammalian glycoprotein hormone receptors. The characterization of fly receptors with features similar to mammalian glycoprotein hormone receptors allows a better understanding of the evolution of this unique group of GPCRs and future elucidation of their ligand signaling mechanisms.

scholarly journals Autoantibody and hormone activation of the thyrotropin G protein-coupled receptor

2022 ◽  
Author(s):  
Bryan Faust ◽  
Isha Singh ◽  
Kaihua Zhang ◽  
Nicholas Hoppe ◽  
Antonio F.M. Pinto ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
G Protein ◽  
Conformational Changes ◽  
Hormone Receptors ◽  
Transmembrane Domain ◽  
Extracellular Domain ◽  
Receptor Activation ◽  
Glycoprotein Hormone ◽  
Membrane Bilayer ◽  
G Protein Coupled

Thyroid hormones are vital to growth and metabolism. Thyroid hormone synthesis is controlled by thyrotropin (TSH), which acts at the thyrotropin receptor (TSHR). Autoantibodies that activate the TSHR pathologically increase thyroid hormones in Graves' disease. How autoantibodies mimic TSH function remains unclear. We determined cryogenic-electron microscopy structures of active and inactive TSHR. In inactive TSHR, the extracellular domain lies close to the membrane bilayer. TSH selects an upright conformation of the extracellular domain due to steric clashes between a conserved hormone glycan and the membrane bilayer. An activating autoantibody selects a similar upright conformation of the extracellular domain. Conformational changes in the extracellular domain are transduced to the seven transmembrane domain via a conserved hinge domain, a tethered peptide agonist, and a phospholipid that binds within the seven transmembrane domain. Rotation of the TSHR ECD relative to the membrane bilayer is sufficient for receptor activation, revealing a shared mechanism for other glycoprotein hormone receptors that may also extend to G protein-coupled receptors with large extracellular domains.

scholarly journals Trans-Activation of Mutant Follicle-Stimulating Hormone Receptors Selectively Generates Only One of Two Hormone Signals

2004 ◽  
Vol 18 (4) ◽  
pp. 968-978 ◽  
Author(s):  
Inhae Ji ◽  
ChangWoo Lee ◽  
MyoungKun Jeoung ◽  
YongBum Koo ◽  
Gail A. Sievert ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
G Protein ◽  
Hormone Receptors ◽  
Transmembrane Domain ◽  
Signal Generation ◽  
Lh Receptor ◽  
Glycosyl Phosphatidylinositol ◽  
Mutant Receptors ◽  
G Protein Coupled ◽  
Hormone Signals

Abstract Previously, we reported that a liganded LH receptor (LHR) is capable of activating itself (cis-activation) and other nonliganded LHRs to induce cAMP (trans-activation). Trans-activation of the LHR raises two crucial questions. Is trans-activation unique to LHR or common to other G protein-coupled receptors? Does trans-activation stimulate phospholipase Cβ as it does adenylyl cyclase? To address these questions, two types of novel FSH receptors (FSHRs) were constructed, one defective in hormone binding and the other defective in signal generation. The FSHR, a G protein-coupled receptor, comprises two major domains, the N-terminal extracellular exodomain that binds the hormone and the membrane-associated endodomain that generates the hormone signals. For signal defective receptors, the exodomain was attached to glycosyl phosphatidylinositol (ExoGPI) or the transmembrane domain of CD8 immune receptor (ExoCD). ExoGPI and ExoCD can trans-activate another nonliganded FSH. Surprisingly, the trans-activation generates a signal to activate either adenylyl cyclase or phospholipase Cβ, but not both. These results indicate that trans-activation in these mutant receptors is selective and limited in signal generation, thus providing new approaches to investigating the generation of different hormone signals and a novel means to selectively generate a particular hormone signal. Our data also suggest that the FSHR’s exodomain could not trans-activate LHR.

scholarly journals Lutropins appear to contact two independent sites in the extracellular domain of their receptors

1998 ◽  
Vol 335 (3) ◽  
pp. 611-617 ◽  
Author(s):  
Michael P. BERNARD ◽  
Rebecca V. MYERS ◽  
William R. MOYLE
Keyword(s):  
Hormone Receptors ◽  
Extracellular Domain ◽  
Leucine Rich Repeat ◽  
Terminal Portion ◽  
Glycoprotein Hormone ◽  
Extracellular Domains ◽  
Affinity Ligand ◽  
Glycoprotein Hormone Receptors ◽  
Contact Residues ◽  
High Affinity Ligand

Human chorionic gonadotropin (hCG) and bovine lutropin (bLH), a hormone chemically more similar to most mammalian lutropins than hCG, interact with the extracellular domains of their gonadal lutropin receptors (LHRs). These portions of the rat and human LHRs are 85% identical and both receptors bind hCG with high, albeit not identical, affinity. However, at least 1000-fold more bLH is required to inhibit binding of radiolabelled hCG to the human LHR than to the rat LHR, a phenomenon that proved useful for identifying regions of the extracellular domain that contact lutropins. Previous studies using truncated receptors and lutropin/follitropin receptor chimaeras localized most, if not all, high-affinity ligand contacts to the N-terminal three-fifths of the rat LHR extracellular domain. We report here that 10-fold more bLH was needed to inhibit binding of labelled hCG to rat/human LHR chimaeras containing the N-terminal three-fifths of the human LHR extracellular domain than to the rat LHR. Unexpectedly, 100-fold more bLH was required to inhibit binding of labelled hCG to chimaeras containing the C-terminal one-fifth of the human LHR extracellular domain than to the rat LHR. The ability of the C-terminal portion of the human LHR extracellular domain to inhibit bLH binding suggests this region of the receptor also contacts the ligand even though it is not needed for ligand binding. The extracellular domains of all the glycoprotein hormone receptors are thought to be horseshoe-shaped, a consequence of their leucine-rich repeat motifs. Portions of the ligand that become located within the cavity created by the concave surface of the horseshoe would have the opportunity to contact residues in the C-terminal portion of the extracellular domain. Changes to the ligand or receptor that influence this interaction would be expected to alter binding and confound efforts to identify residues in key ligand–receptor contacts.

scholarly journals Autologous Biological Response Modification of the Gonadotropin Receptor

2001 ◽  
Vol 276 (15) ◽  
pp. 12410-12419 ◽  
Author(s):  
Smita D. Mahale ◽  
John Cavanagh ◽  
Anja Schmidt ◽  
Robert MacColl ◽  
James A. Dias
Keyword(s):  
Secondary Structure ◽  
Hormone Receptors ◽  
Biological Response ◽  
Cd Spectroscopy ◽  
Intrinsic Activity ◽  
Activation Process ◽  
Leucine Rich Repeat ◽  
Glycoprotein Hormone ◽  
Guanine Nucleotide Binding Protein ◽  
Glycoprotein Hormone Receptors

It is generally held with respect to heterotrimeric guanine nucleotide binding protein-coupled receptors that binding of ligand stabilizes a conformation of receptor that activates adenylyl cyclase. It is not formally appreciated if, in the case of G-protein-coupled receptors with large extracellular domains (ECDs), ECDs directly participate in the activation process. The large ECD of the glycoprotein hormone receptors (GPHRs) is 350 amino acids in length, composed of seven leucine-rich repeat domains, and necessary and sufficient for high affinity binding of the glycoprotein hormones. Peptide challenge experiments to identify regions in the follicle-stimulating hormone (FSH) receptor (FSHR) ECD that could bind its cognate ligand identified only a single synthetic peptide corresponding to residues 221–252, which replicated a leucine-rich repeat domain of the FSHR ECD and which had intrinsic activity. This peptide inhibited human FSH binding to the human FSHR (hFSHR) and also inhibited human FSH-induced signal transduction in Y-1 cells expressing recombinant hFSHR. The hFSHR-(221–252) domain was not accessible to anti-peptide antibody probes, suggesting that this domain resides at an interface between the hFSHR ECD and transmembrane domains. CD spectroscopy of the peptide in dodecyl phosphocholine micelles showed an increase in the ordered structure of the peptide. CD and NMR spectroscopies of the peptide in trifluoroethanol confirmed that hFSHR-(221–252) has the propensity to form ordered secondary structure. Importantly and consistent with the foregoing results, dodecyl phosphocholine induced a significant increase in the ordered secondary structure of the purified hFSHR ECD as well. These data provide biophysical evidence of the influence of environment on GPHR ECD subdomain secondary structure and identify a specific activation domain that can autologously modify GPHR activity.

scholarly journals FSH and TSH binding to their respective receptors: similarities, differences and implication for glycoprotein hormone specificity

2008 ◽  
Vol 41 (3) ◽  
pp. 145-164 ◽  
Author(s):  
R Núñez Miguel ◽  
J Sanders ◽  
D Y Chirgadze ◽  
T L Blundell ◽  
J Furmaniak ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Binding Affinity ◽  
Binding Specificity ◽  
Receptor Activation ◽  
Activation Process ◽  
Leucine Rich Repeat ◽  
Glycoprotein Hormone ◽  
Repeat Domain ◽  
Leucine Rich Repeats ◽  
Hormone Specificity

The crystal structures of the leucine-rich repeat domain (LRD) of the FSH receptor (FSHR) in complex with FSH and the TSH receptor (TSHR) LRD in complex with the thyroid-stimulating autoantibody (M22) provide opportunities to assess the molecular basis of the specificity of glycoprotein hormone–receptor binding. A comparative model of the TSH–TSHR complex was built using the two solved crystal structures and verified using studies on receptor affinity and activation. Analysis of the FSH–FSHR and TSH–TSHR complexes allowed identification of receptor residues that may be important in hormone-binding specificity. These residues are in leucine-rich repeats at the two ends of the FSHR and the TSHR LRD structures but not in their central repeats. Interactions in the interfaces are consistent with a higher FSH-binding affinity for the FSHR compared with the binding affinity of TSH for the TSHR. The higher binding affinity of porcine (p)TSH and bovine (b)TSH for human (h)TSHR compared with hTSH appears not to be dependent on interactions with the TSHR LRD as none of the residues that differ among hTSH, pTSH or bTSH interact with the LRD. This suggests that TSHs are likely to interact with other parts of the receptors in addition to the LRD with these non-LRD interactions being responsible for affinity differences. Analysis of interactions in the FSH–FSHR and TSH–TSHR complexes suggests that the α-chains of both hormones tend to be involved in the receptor activation process while the β-chains are more involved in defining binding specificity.

scholarly journals The Cloned Equine Thyrotropin Receptor Is Hypersensitive to Human Chorionic Gonadotropin; Identification of Three Residues in the Extracellular Domain Involved in Ligand Specificity

Endocrinology ◽  
2008 ◽  
Vol 149 (10) ◽  
pp. 5088-5096 ◽  
Author(s):  
Julien Royer ◽  
Anne Lefevre-Minisini ◽  
Gianluigi Caltabiano ◽  
Thierry Lacombe ◽  
Yves Malthiery ◽  
...  
Keyword(s):  
Chorionic Gonadotropin ◽  
Hormone Receptors ◽  
Functional Characterization ◽  
Targeted Mutagenesis ◽  
Ligand Specificity ◽  
Glycoprotein Hormone ◽  
Glycoprotein Hormone Receptors ◽  
Leucine Rich Repeats ◽  
Hormone Specificity

The receptors for TSH, LH/chorionic gonadotropin (CG), and FSH belong to the same subfamily of G protein-coupled receptors. The specificity of recognition of their cognate hormone involves a limited number of residues in the leucine-rich repeats present in the N-terminal ectodomain of the receptor. It is admitted that receptors of this subfamily coevoluted with their respective ligands. The secretion of CG is restricted to gestation of primates and Equidae. We hypothesized that, facing the challenge of a new hormone, the glycoprotein hormone receptors would have evolved differently in Equidae and human so that distinct residues are involved in hormone specificity. In particular, it is known that equine CG has a dual (FSH and LH) activity when administered to other species. In the present work, we cloned and characterized functionally the equine TSH receptor (TSHR), which shares 89% homology with the human TSHR. The equine TSHR is not responsive to equine CG but is more sensitive to human CG than the human TSHR. Three residues, at positions 60, 229, and 235 of the ectodomain, are responsible for this difference in sensitivity as shown by modelization and targeted mutagenesis, followed by in vitro functional characterization. The phylogenetic approach is a suitable approach to identify determinants of specificity of receptors.

scholarly journals Cis- and Trans-Activation of Hormone Receptors: the LH Receptor

2002 ◽  
Vol 16 (6) ◽  
pp. 1299-1308 ◽  
Author(s):  
Inhae Ji ◽  
ChangWoo Lee ◽  
YongSang Song ◽  
P. Michael Conn ◽  
Tae H. Ji
Keyword(s):  
Adenylyl Cyclase ◽  
Hormone Receptors ◽  
Transmembrane Domain ◽  
Wide Spectrum ◽  
Receptor Activation ◽  
Inherited Disorders ◽  
Glycoprotein Hormone ◽  
Lh Receptor ◽  
Amino Terminal ◽  
Gpcr Activation

Abstract G protein-coupled receptors (GPCRs) accommodate a wide spectrum of activators from ions to glycoprotein hormones. The mechanism of activation for this large and clinically important family of receptors is poorly understood. Although initially thought to function as monomers, there is a growing body of evidence that GPCR dimers form, and in some cases that these dimers are essential for signal transduction. Here we describe a novel mechanism of intermolecular GPCR activation, which we refer to as trans-activation, in the LH receptor, a GPCR that does not form stable dimers. The LH receptor consists of a 350-amino acid amino-terminal domain, which is responsible for high-affinity binding to human CG, followed by seven-transmembrane domains and connecting loops. This seven-transmembrane domain bundle transmits the signal from the extracellular amino terminus to intracellular G proteins and adenylyl cyclase. Here, we show that binding of hormone to one receptor can activate adenylyl cyclase through its transmembrane bundle, intramolecular activation (cis-activation), as well as trans-activation through the transmembrane bundle of an adjacent receptor, without forming a stable receptor dimer. Coexpression of a mutant receptor defective in hormone binding and another mutant defective in signal generation rescues hormone-activated cAMP production. Our observations provide new insights into the mechanism of receptor activation mechanisms and have implications for the treatment of inherited disorders of glycoprotein hormone receptors.

scholarly journals Glycoprotein G-protein Coupled Receptors in Disease: Luteinizing Hormone Receptors and Follicle Stimulating Hormone Receptors

Diseases ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 35
Author(s):  
Duaa Althumairy ◽  
Xiaoping Zhang ◽  
Nicholas Baez ◽  
George Barisas ◽  
Deborah A. Roess ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
G Protein ◽  
Hormone Receptors ◽  
Follicle Stimulating Hormone ◽  
G Protein Coupled Receptors ◽  
Human Beings ◽  
Glycoprotein Hormone ◽  
Luteinizing Hormone Receptors ◽  
G Protein Coupled ◽  
Stimulating Hormone

Signal transduction by luteinizing hormone receptors (LHRs) and follicle-stimulating hormone receptors (FSHRs) is essential for the successful reproduction of human beings. Both receptors and the thyroid-stimulating hormone receptor are members of a subset of G-protein coupled receptors (GPCRs) described as the glycoprotein hormone receptors. Their ligands, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and a structurally related hormone produced in pregnancy, human chorionic gonadotropin (hCG), are large protein hormones that are extensively glycosylated. Although the primary physiologic functions of these receptors are in ovarian function and maintenance of pregnancy in human females and spermatogenesis in males, there are reports of LHRs or FSHRs involvement in disease processes both in the reproductive system and elsewhere. In this review, we evaluate the aggregation state of the structure of actively signaling LHRs or FSHRs, their functions in reproduction as well as summarizing disease processes related to receptor mutations affecting receptor function or expression in reproductive and non-reproductive tissues. We will also present novel strategies for either increasing or reducing the activity of LHRs signaling. Such approaches to modify signaling by glycoprotein receptors may prove advantageous in treating diseases relating to LHRs or FSHRs function in addition to furthering the identification of new strategies for modulating GPCR signaling.

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