Luteinizing hormone/choriogonadotropin receptor

The luteinizing hormone/choriogonadotropin receptor (LHCGR), also lutropin/choriogonadotropin receptor (LCGR) or luteinizing hormone receptor (LHR), is a transmembrane receptor found predominantly in the ovary and testis, but also many extragonadal organs such as the uterus and breasts. The receptor interacts with both luteinizing hormone (LH) and chorionic gonadotropins (such as hCG in humans) and represents a G protein-coupled receptor (GPCR). Its activation is necessary for the hormonal functioning during reproduction.

LHCGR
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 7FIG, 7FIH, 7FII, 7FIJ
Identifiers
Aliases	LHCGR, HHG, LCGR, LGR2, LH/CG-R, LH/CGR, LHR, LHRHR, LSH-R, ULG5, Luteinizing hormone/choriogonadotropin receptor
External IDs	OMIM: 152790; MGI: 96783; HomoloGene: 37276; GeneCards: LHCGR; OMA:LHCGR - orthologs
Gene location (Human) Chr. Chromosome 2 (human) Band 2p16.3 Start 48,686,774 bp End 48,755,730 bp
Gene location (Mouse) Chr. Chromosome 17 (mouse) Band 17 E4|17 58.35 cM Start 89,023,909 bp End 89,099,418 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in testicle sural nerve gonad Achilles tendon left ovary epithelium of colon right ovary adipose tissue stromal cell of endometrium subcutaneous adipose tissue Top expressed in Gonadal ridge ovary basal plate spermatocyte testicle ventricular zone superior frontal gyrus rhombencephalon mesencephalon central gray substance of midbrain More reference expression data BioGPS More reference expression data
Gene ontology Molecular function G protein-coupled peptide receptor activity G protein-coupled receptor activity choriogonadotropin hormone binding signal transducer activity protein-hormone receptor activity choriogonadotropin hormone receptor activity follicle-stimulating hormone receptor activity luteinizing hormone receptor activity Cellular component integral component of membrane endosome membrane integral component of plasma membrane plasma membrane Biological process G protein-coupled receptor signaling pathway male gonad development male genitalia development cognition G protein-coupled receptor signaling pathway, coupled to cyclic nucleotide second messenger activation of adenylate cyclase activity positive regulation of inositol trisphosphate biosynthetic process hormone-mediated signaling pathway cellular response to gonadotropin stimulus signal transduction primary ovarian follicle growth phospholipase C-activating G protein-coupled receptor signaling pathway follicle-stimulating hormone signaling pathway regulation of osteoclast differentiation luteinizing hormone signaling pathway positive regulation of adenylate cyclase activity cellular response to luteinizing hormone stimulus adenylate cyclase-activating G protein-coupled receptor signaling pathway ovulation cycle process Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 3973 16867 Ensembl ENSG00000138039 ENSMUSG00000024107 UniProt P22888 P30730 RefSeq (mRNA) NM_000233 NM_013582 NM_001364898 RefSeq (protein) NP_000224 NP_038610 NP_001351827 Location (UCSC) Chr 2: 48.69 – 48.76 Mb Chr 17: 89.02 – 89.1 Mb PubMed search
Wikidata
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LHCGR gene

The gene for the LHCGR is found on chromosome 2 p21 in humans, close to the FSH receptor gene. It consists of 70 kbp (versus 54 kpb for the FSHR). The gene is similar to the gene for the FSH receptor and the TSH receptor.

Receptor structure

The LHCGR consists of 674 amino acids and has a molecular mass of about 85–95 kDA based on the extent of glycosylation.

Like other GPCRs, the LHCG receptor possess seven membrane-spanning domains or transmembrane helices. The extracellular domain of the receptor is heavily glycosylated. These transmembrane domains contain two highly conserved cysteine residues, which build disulfide bonds to stabilize the receptor structure. The transmembrane part is highly homologous with other members of the rhodopsin family of GPCRs. The C-terminal domain is intracellular and brief, rich in serine and threonine residues for possible phosphorylation.

Ligand binding and signal transduction

Upon binding of LH to the external part of the membrane spanning receptor, a transduction of the signal takes place. This process results in the activation of a heterotrimeric G protein. Binding of LH to the receptor shifts its conformation. The activated receptor promotes the binding of GTP to the G protein and its subsequent activation. After binding GTP, the G protein heterotrimer detaches from the receptor and disassembles. The alpha-subunit Gs binds adenylate cyclase and activates the cAMP system.

It is believed that a receptor molecule exists in a conformational equilibrium between active and inactive states. The binding of LH (or CG) to the receptor shifts the equilibrium towards the active form of the receptor. For a cell to respond to LH only a small percentage (≈1%) of receptor sites need to be activated.

Phosphorylation by cAMP-dependent protein kinases

Cyclic AMP-dependent protein kinases (protein kinase A) are activated by the signal cascade originated by the activation of the G protein Gs by the LHCG-receptor. Activated Gs binds the enzyme adenylate cyclase and this leads to the production of cyclic AMP (cAMP). Cyclin AMP-dependent protein kinases are present as tetramers with two regulatory subunits and two catalytic subunits. Upon binding of cAMP to the regulatory subunits, the catalytic units are released and initiate the phosphorylation of proteins leading to the physiologic action. Cyclic AMP is degraded by phosphodiesterase and release 5’AMP. One of the targets of protein kinase A is the Cyclic AMP Response Element Binding Protein, CREB, which binds DNA in the cell nucleus via direct interactions with specific DNA sequences called cyclic AMP response elements (CRE); this process results in the activation or inactivation of gene transcription.

The signal is amplified by the involvement of cAMP and the resulting phosphorylation. The process is modified by prostaglandins. Other cellular regulators that participate are the intracellular calcium concentration regulated by phospholipase C activation, nitric oxide, and other growth factors.

Other pathways of signaling exist for the LHCGR.

Action

Luteinizing hormone up-regulates cholesterol side chain cleaving enzyme in sensitive tissues, the first step of all human steroidogenesis.

The LHCG receptor's main function is the regulation of steroidogenesis. This is accomplished by increasing the intracellular levels of the enzyme cholesterol side chain cleaving enzyme, a member of the cytochrome P450 family. This leads to increased conversion of cholesterol into androgen precursors required to make many steroid hormones, including testosterone and estrogens.

Ovary

In the ovary, the LHCG receptor is necessary for follicular maturation and ovulation, as well as luteal function. Its expression requires appropriate hormonal stimulation by FSH and estradiol. The LHCGR is present on granulosa cells, theca cells, luteal cells, and interstitial cells The LCGR is restimulated by increasing levels of chorionic gonadotropins in case a pregnancy is developing. In turn, luteal function is prolonged and the endocrine milieu is supportive of the nascent pregnancy.

Testis

In the male the LHCGR has been identified on the Leydig cells that are critical for testosterone production, and support spermatogenesis.

Normal LHCGR functioning is critical for male fetal development, as the fetal Leydig cells produce androstenedione which is converted to testosterone in fetal Sertoli cells to induce masculinization.

Extragonadal

LHCGR have been found in many types of extragonadal tissues, and the physiologic role of some has remained largely unexplored. Thus receptors have been found in the uterus, sperm, seminal vesicles, prostate, skin, breast, adrenals, thyroid, neural retina, neuroendocrine cells, and (rat) brain.

Receptor regulation

The seven transmembrane α-helix structure of a G protein-coupled receptor such as LHCGR

Upregulation

Upregulation refers to the increase in the number of receptor sites on the membrane. Estrogen and FSH upregulate LHCGR sites in preparation for ovulation. After ovulation, the luteinized ovary maintains LHCGR s that allow activation in case there is an implantation. Upregulation in males requires gene transcription to synthesize LH receptors within the cell cytoplasm. Some reasons as to why downregulated LH receptors are not upregulated are: lack of gene transcription, lack of RNA to protein conversion and lack of cell membrane targeted shipments from Golgi.

Desensitization

The LHCGRs become desensitized when exposed to LH for some time. A key reaction of this downregulation is the phosphorylation of the intracellular (or cytoplasmic) receptor domain by protein kinases. This process uncouples Gs protein from the LHCGR.

Downregulation

Downregulation refers to the decrease in the number of receptor molecules. This is usually the result of receptor endocytosis. In this process, the bound LCGR-hormone complex binds arrestin and concentrates in clathrin coated pits. Clathrin coated pits recruit dynamin and pinch off from the cell surface, becoming clathrin-coated vesicles. Clathrin-coated vesicles are processed into endosomes, some of which are recycled to the cell surface while others are targeted to lysosomes. Receptors targeted to lysosomes are degraded. Use of long-acting agonists will downregulate the receptor population by promoting their endocytosis.

Modulators

Antibodies to LHCGR can interfere with LHCGR activity.

LHCGR antagonists and agonists

In 2019, the discovery of potent, and selective antagonists of the Luteinizing Hormone Receptor (BAY-298 and BAY-899) were reported which were able to reduce sex hormone levels in vivo. The latter fulfils the quality criteria for a 'Donated Chemical Probe' as defined by the Structural Genomics Consortium.

A series of thienopyr(im)idine-based compounds leading to optimized Org 43553 were described as the first Luteinizing Hormone Receptor agonists.

LHCGR abnormalities

Loss-of-function mutations in females can lead to infertility. In 46, XY individuals severe inactivation can cause male pseudohermaphroditism, as fetal Leydig cells during may not respond and thus interfere with masculinization. Less severe inactivation can result in hypospadias or a micropenis.

History

Alfred G. Gilman and Martin Rodbell received the 1994 Nobel Prize in Medicine and Physiology for the discovery of the G Protein System.

Interactions

Luteinizing hormone/choriogonadotropin receptor has been shown to interact with GIPC1.

Further reading

• Ji TH, Ryu KS, Gilchrist R, Ji I (1997). "Interaction, signal generation, signal divergence, and signal transduction of LH/CG and the receptor". Recent Progress in Hormone Research. 52: 431–53, discussion 454. PMID 9238862.
• Dufau ML (1998). "The luteinizing hormone receptor". Annual Review of Physiology. 60: 461–496. doi:10.1146/annurev.physiol.60.1.461. PMID 9558473.
• Ascoli M, Fanelli F, Segaloff DL (April 2002). "The lutropin/choriogonadotropin receptor, a 2002 perspective". Endocrine Reviews. 23 (2): 141–174. doi:10.1210/edrv.23.2.0462. PMID 11943741.
• Amsterdam A, Hanoch T, Dantes A, Tajima K, Strauss JF, Seger R (February 2002). "Mechanisms of gonadotropin desensitization". Molecular and Cellular Endocrinology. 187 (1–2): 69–74. doi:10.1016/S0303-7207(01)00701-8. PMID 11988313. S2CID 23625847.
• Fanelli F, Puett D (August 2002). "Structural aspects of luteinizing hormone receptor: information from molecular modeling and mutagenesis". Endocrine. 18 (3): 285–293. doi:10.1385/ENDO:18:3:285. PMID 12450321. S2CID 24739956.
• Latronico AC, Segaloff DL (January 2007). "Insights learned from L457(3.43)R, an activating mutant of the human lutropin receptor". Molecular and Cellular Endocrinology. 260–262: 287–293. doi:10.1016/j.mce.2005.11.053. PMC 1785107. PMID 17055147.
• Nagayama Y, Russo D, Wadsworth HL, Chazenbalk GD, Rapoport B (August 1991). "Eleven amino acids (Lys-201 to Lys-211) and 9 amino acids (Gly-222 to Leu-230) in the human thyrotropin receptor are involved in ligand binding". The Journal of Biological Chemistry. 266 (23): 14926–14930. doi:10.1016/S0021-9258(18)98566-2. PMID 1651314.
• Jia XC, Oikawa M, Bo M, Tanaka T, Ny T, Boime I, et al. (June 1991). "Expression of human luteinizing hormone (LH) receptor: interaction with LH and chorionic gonadotropin from human but not equine, rat, and ovine species". Molecular Endocrinology. 5 (6): 759–768. doi:10.1210/mend-5-6-759. PMID 1922095.
• Minegishi T, Nakamura K, Takakura Y, Miyamoto K, Hasegawa Y, Ibuki Y, et al. (November 1990). "Cloning and sequencing of human LH/hCG receptor cDNA". Biochemical and Biophysical Research Communications. 172 (3): 1049–1054. doi:10.1016/0006-291X(90)91552-4. PMID 2244890.
• Rousseau-Merck MF, Misrahi M, Atger M, Loosfelt H, Milgrom E, Berger R (1991). "Localization of the human luteinizing hormone/choriogonadotropin receptor gene (LHCGR) to chromosome 2p21". Cytogenetics and Cell Genetics. 54 (1–2): 77–79. doi:10.1159/000132962. PMID 2249480.
• Xie YB, Wang H, Segaloff DL (December 1990). "Extracellular domain of lutropin/choriogonadotropin receptor expressed in transfected cells binds choriogonadotropin with high affinity". The Journal of Biological Chemistry. 265 (35): 21411–21414. doi:10.1016/S0021-9258(18)45750-X. PMID 2254302.
• Frazier AL, Robbins LS, Stork PJ, Sprengel R, Segaloff DL, Cone RD (August 1990). "Isolation of TSH and LH/CG receptor cDNAs from human thyroid: regulation by tissue specific splicing". Molecular Endocrinology. 4 (8): 1264–1276. doi:10.1210/mend-4-8-1264. hdl:21.11116/0000-0000-7844-D. PMID 2293030.
• Keutmann HT, Charlesworth MC, Mason KA, Ostrea T, Johnson L, Ryan RJ (April 1987). "A receptor-binding region in human choriogonadotropin/lutropin beta subunit". Proceedings of the National Academy of Sciences of the United States of America. 84 (7): 2038–2042. Bibcode:1987PNAS...84.2038K. doi:10.1073/pnas.84.7.2038. PMC 304579. PMID 3470775.
• Jiang X, Dreano M, Buckler DR, Cheng S, Ythier A, Wu H, et al. (December 1995). "Structural predictions for the ligand-binding region of glycoprotein hormone receptors and the nature of hormone-receptor interactions". Structure. 3 (12): 1341–1353. doi:10.1016/S0969-2126(01)00272-6. PMID 8747461.
• Atger M, Misrahi M, Sar S, Le Flem L, Dessen P, Milgrom E (June 1995). "Structure of the human luteinizing hormone-choriogonadotropin receptor gene: unusual promoter and 5' non-coding regions". Molecular and Cellular Endocrinology. 111 (2): 113–123. doi:10.1016/0303-7207(95)03557-N. PMID 7556872. S2CID 25479294.
• Latronico AC, Anasti J, Arnhold IJ, Mendonça BB, Domenice S, Albano MC, et al. (August 1995). "A novel mutation of the luteinizing hormone receptor gene causing male gonadotropin-independent precocious puberty". The Journal of Clinical Endocrinology and Metabolism. 80 (8): 2490–2494. doi:10.1210/jcem.80.8.7629248. PMID 7629248.
• Shenker A, Laue L, Kosugi S, Merendino JJ, Minegishi T, Cutler GB (October 1993). "A constitutively activating mutation of the luteinizing hormone receptor in familial male precocious puberty". Nature. 365 (6447): 652–654. Bibcode:1993Natur.365..652S. doi:10.1038/365652a0. PMID 7692306. S2CID 4307732.
• Yano K, Saji M, Hidaka A, Moriya N, Okuno A, Kohn LD, et al. (April 1995). "A new constitutively activating point mutation in the luteinizing hormone/choriogonadotropin receptor gene in cases of male-limited precocious puberty". The Journal of Clinical Endocrinology and Metabolism. 80 (4): 1162–1168. doi:10.1210/jcem.80.4.7714085. PMID 7714085.
• Kremer H, Kraaij R, Toledo SP, Post M, Fridman JB, Hayashida CY, et al. (February 1995). "Male pseudohermaphroditism due to a homozygous missense mutation of the luteinizing hormone receptor gene". Nature Genetics. 9 (2): 160–164. doi:10.1038/ng0295-160. hdl:2066/20602. PMID 7719343. S2CID 8678536.
• Kosugi S, Van Dop C, Geffner ME, Rabl W, Carel JC, Chaussain JL, et al. (February 1995). "Characterization of heterogeneous mutations causing constitutive activation of the luteinizing hormone receptor in familial male precocious puberty". Human Molecular Genetics. 4 (2): 183–188. doi:10.1093/hmg/4.2.183. PMID 7757065.
• Kremer H, Mariman E, Otten BJ, Moll GW, Stoelinga GB, Wit JM, et al. (November 1993). "Cosegregation of missense mutations of the luteinizing hormone receptor gene with familial male-limited precocious puberty". Human Molecular Genetics. 2 (11): 1779–1783. doi:10.1093/hmg/2.11.1779. PMID 8281137.

External links

• "Glycoprotein Hormone Receptors: LH". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2021-01-18. Retrieved 2006-07-20.
• GRIS: Glycoprotein-hormone Receptor Information System
• LH-hCG+Receptors at the U.S. National Library of Medicine Medical Subject Headings (MeSH)