Structural characterization of the carbohydrates of the rat ovarian luteinizing hormone/chorionic gonadotropin receptor.
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ABSTRACT:
SUBMITTER: Petaja-Repo UE
PROVIDER: S-EPMC1137948 | biostudies-other | 1994 Mar
REPOSITORIES: biostudies-other
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Project description:Polycystic ovaries and irregular menstruation/anovulation are important diagnostic criteria along with hyperandrogenism as per the Androgen Excess Society-2006 criteria for polycystic ovarian syndrome (PCOS). In the etiopathogenesis of PCOS, one of the candidate genes causing ovarian failure is the luteinizing hormone (LH) chorionic gonadotropin hormone receptor (LHCGR). Our aim was to study the association of LHCGR polymorphism (rs2293275) with PCOS in our study population.Genetic case-control study from multiple gynecological centers from Hyderabad, a cosmopolitan city in South India. The study involved 204 women with PCOS and 204 healthy, sex-, and age-matched controls. Anthropometric and biochemical profiles were taken in a well-designed pro forma. Isolation of deoxyribonucleic acid (DNA) and genotype analysis were done for the entire study population using the polymerase chain reaction-restriction fragment length polymorphism method followed by 12% polyacrylamide gel electrophoresis.In this study, we have demonstrated an association between LHCGR (rs2293275) polymorphism and PCOS. The frequency of the G allele was 0.60 in PCOS and 0.49 in controls (odds ratio [OR] 1.531, confidence interval [CI] 1.16-2.01, and p-value=0.0026), which indicates that the G allele is associated with PCOS in our population. The GG genotype conferred a significant risk of developing PCOS (OR 3.36, CI 1.96-5.75, and p-value<0.0001). We found a significant association of the GG allele with body-mass index, waist to hip ratio, insulin resistance, LH, and LH/follicle-stimulating hormone (FSH) ratio in PCOS when compared with controls. The AA allele showed high basal FSH levels.This study suggests that LHCGR (rs2293275) polymorphism is associated with PCOS and could be used as a relevant molecular marker to identify women with the risk of developing PCOS in our population and may provide an understanding about the etiology of PCOS.
| S-EPMC4361359 | biostudies-literature
Project description:The aim of this study was to determine the relationship between a purported luteinizing hormone/chorionic gonadotropin (LHCGR) high function polymorphism (rs4539842/insLQ) and outcome to controlled ovarian hyperstimulation (COH).This was a prospective study of 172 patients undergoing COH at the Fertility and IVF Center at GWU. DNA was isolated from blood samples and a region encompassing the insLQ polymorphism was sequenced. We also investigated a polymorphism (rs4073366 G?>?C) that was 142 bp from insLQ. The association of the insLQ and rs4073366 alleles and outcome to COH (number of mature follicles, estradiol level on day of human chorionic gonadotropin (hCG) administration, the number of eggs retrieved and ovarian hyperstimulation syndrome (OHSS)) was determined.Increasing age and higher day 3 (basal) FSH levels were significantly associated with poorer response to COH. We found that both insLQ and rs4073366 were in linkage disequilibrium (LD) and no patients were homozygous for both recessive alleles (insLQ/insLQ; C/C). The insLQ variant was not significantly associated with any of the main outcomes to COH. Carrier status for the rs4073366 C variant was associated (P?=?0.033) with an increased risk (OR 2.95, 95% CI?=?1.09-7.96) of developing OHSS.While age and day 3 FSH levels were predictive of outcome, we found no association between insLQ and patient response to COH. Interestingly, rs4073366 C variant carrier status was associated with OHSS risk. To the best of our knowledge, this is the first report suggesting that LHCGR genetic variation might function in patient risk for OHSS.
| S-EPMC3727944 | biostudies-literature
Project description:The contribution of the carbohydrate moiety of the rat ovarian luteinizing-hormone (LH)/chorionic-gonadotropin (CG) receptor to ligand-binding specificity and signal transduction was investigated by using glycosidases. Purified membranes from pseudo-pregnant rat ovaries were treated with neuraminidase or peptide N-glycosidase F, to remove terminal sialic acids and N-linked oligosaccharides of the receptor, respectively. Ligand blotting and densitometric scanning of the autoradiograms showed that 90-95% of the receptors were deglycosylated, and that desialylation was virtually complete. Neither the desialylated nor the deglycosylated receptors were able to bind human follicle-stimulating hormone or bovine thyroid-stimulating hormone, as revealed by competition binding experiments. The 50% effective dose of hCG for adenylate cyclase activation, as determined by measuring the formation of cyclic [32P]AMP from [alpha-32P]ATP for 15 min at 30 degrees C, was similar in the control and deglycosylated membranes: 10.2 +/- 3.3 nM and 12.2 +/- 3.8 nM respectively. The same was true for the time course of the basal, hCG- and forskolin-stimulated enzyme activity. In addition, removal of oligosaccharides from the receptor did not restore the ability of desialylated hCG, nor of the deglycosylated hormone, to stimulate adenylate cyclase. In conclusion, the carbohydrate moiety of the native membrane-inserted rat ovarian LH/CG receptor does not contribute to the ligand-binding specificity, and it is not required for the functional coupling of the occupied receptor and the adenylate cyclase system. These functions are associated with the polypeptide portion of the receptor.
| S-EPMC1134190 | biostudies-other
Project description:Prostate cancer (PCa) cells become castrate-resistant after initial tumor regression following castration-based lowering of testosterone (T). De-novo intra-tumoral steroid synthesis is a suggested biological mechanism of castration resistant PCa, but the regulators are unknown. Testicular T production is controlled by the luteinizing hormone/choriogonadotropin receptor (LHCGR). To elucidate the influence of LHCGR on PCa development the presence and effects of LHCGR in PCa and whether LHCGR in serum holds prognostic information in PCa patients is investigated. LHCGR expression was investigated by RT-PCR, WB, IHC, qPCR in PCa cell lines and prostatic tissue. Steroid production was measured in media from cell lines with LC-MS/MS and expression of steroidogenic enzymes with qPCR. Serum LHCGR (sLHCGR) was measured with ELISA in PCa patients (N = 157). Presence of LHCGR was established in prostatic tissue and PCa cell lines. Cell proliferation increased by 1.29-fold in LNCaP (P = 0.007) and 1.33-fold in PC-3 cells (P = 0.0007), when stimulated by luteinizing hormone. Choriogonadotropin stimulation decreased proliferation 0.93-fold in DU145 cells (P = 0.05), but none of the treatments altered steroid metabolite secretion. Low sLHCGR concentration was associated with a higher risk of biochemical failure after radical prostatectomy (HR = 3.05, P = 0.06) and castration resistance (HR = 6.92, P = 0.004) compared to high sLHCGR concentration. LHCGR is expressed in PCa and may exert a growth regulatory role in PCa derived cell lines. A potential prognostic role of sLHCGR for determining recurrence risk in PCa patients is found in this pilot study but needs verification in larger cohorts.
| S-EPMC7470326 | biostudies-literature
Project description:The aim of this study was to develop a scoring system of the immunohistochemical (IHC) expression of luteinizing hormone/human chorionic gonadotropin receptor (LHCG-R) in endometrial cancer (EC) patients. Nonconsecutive hysterectomy specimens containing EC collected from April 2013 to October 2015 were selected. Hematoxylin-eosin stained sections from each case were reviewed and representative sections from each tumor were selected. IHC staining was performed for the detection of LHCG-R. The percentage of stained cells and the staining intensity were assessed in order to develop an immunohistochemical score. Moreover, we examined the correlation of the score with grading and lymphovascular space invasion (LVSI). There was a statistically significant positive correlation between grading and IHC scoring (p = 0.01) and a statistically significant positive correlation between LVSI and IHC score (p < 0.01). In conclusion, we suggest that the immunohistochemical score presented here could be used as a marker of bad prognosis of EC patients. Nevertheless, further studies are needed in order to validate it. The study was registered in the Careggi Hospital public trials registry with the following number: 2013/0011391.
| S-EPMC5902075 | biostudies-literature
Project description:(1) The human luteinizing hormone (LH)/chorionic gonadotropin (hCG) receptor (LHCGR) discriminates its two hormone ligands and differs from the murine receptor (Lhr) in amino acid residues potentially involved in qualitative discerning of LH and hCG. The latter gonadotropin is absent in rodents. The aim of the study is to identify LHCGR residues involved in hCG/LH discrimination. (2) Eight LHCGR cDNAs were developed, carrying "murinizing" mutations on aminoacidic residues assumed to interact specifically with LH, hCG, or both. HEK293 cells expressing a mutant or the wild type receptor were treated with LH or hCG and the kinetics of cyclic adenosine monophosphate (cAMP) and phosphorylated extracellular signal-regulated kinases 1/2 (pERK1/2) activation was analyzed by bioluminescence resonance energy transfer (BRET). (3) Mutations falling within the receptor leucine reach repeat 9 and 10 (LRR9 and LRR10; K225S +T226I and R247T), of the large extracellular binding domain, are linked to loss of hormone-specific induced cAMP increase, as well as hCG-specific pERK1/2 activation, leading to a Lhr-like modulation of the LHCGR-mediated intracellular signaling pattern. These results support the hypothesis that LHCGR LRR domain is the interaction site of the hormone β-L2 loop, which differs between LH and hCG, and might be fundamental for inducing gonadotropin-specific signals. (4) Taken together, these data identify LHCGR key residues likely evolved in the human to discriminate LH/hCG specific binding.
| S-EPMC7794846 | biostudies-literature
Project description:Male pseudohermaphroditism, or Leydig cell hypoplasia (LCH), is an autosomal recessive disorder in individuals with a 46,XY karyotype, characterized by a predominantly female phenotype, a blind-ending vagina, absence of breast development, primary amenorrhea, and the presence of testicular structures. It is caused by mutations in the luteinizing hormone/chorionic gonadotropin receptor gene (LHCGR), which impair either LH/CG binding or signal transduction. However, molecular analysis has revealed that the LHCGR is apparently normal in about 50% of patients with the full clinical phenotype of LCH. We therefore searched the LHCGR for novel genomic elements causative for LCH.In the present study we have identified a novel, primate-specific bona fide exon (exon 6A) within the LHCGR gene. It displays composite characteristics of an internal/terminal exon and possesses stop codons triggering nonsense-mediated mRNA decay (NMD) in LHCGR. Transcripts including exon 6A are physiologically highly expressed in human testes and granulosa cells, and result in an intracellular, truncated LHCGR protein of 209 amino acids. We sequenced exon 6A in 16 patients with unexplained LCH and detected mutations in three patients. Functional studies revealed a dramatic increase in the expression of the mutated internal exon 6A transcripts, indicating aberrant NMD. These altered ratios of LHCGR transcripts result in the generation of predominantly nonfunctional LHCGR isoforms, thereby preventing proper expression and functioning.The identification and characterization of this novel exon not only identifies a new regulatory element within the genomic organization of LHCGR, but also points toward a complex network of receptor regulation, including events at the transcriptional level. These findings add to the molecular diagnostic tools for LCH and extend our understanding of the endocrine regulation of sexual differentiation.
| S-EPMC2323302 | biostudies-literature
Project description:Segmental duplicons (>1 kb) of high sequence similarity (>90%) covering >5% of the human genome are characterized by complex sequence variation. Apart from a few well-characterized regions (MHC, beta-globin), the diversity and linkage disequilibrium (LD) patterns of duplicons and the role of gene conversion in shaping them have been poorly studied. To shed light on these issues, we have re-sequenced the human Luteinizing Hormone/Chorionic Gonadotropin beta (LHB/CGB) cluster (19q13.32) of three population samples (Estonians, Mandenka, and Han). The LHB/CGB cluster consists of seven duplicated genes critical in human reproduction. In the LHB/CGB region, high sequence diversity, concentration of gene-conversion acceptor sites, and strong LD colocalize with peripheral genes, whereas central loci are characterized by lower variation, gene-conversion donor activity, and breakdown of LD between close markers. The data highlight an important role of gene conversion in spreading polymorphisms among duplicon copies and generating LD around them. The directionality of gene-conversion events seems to be determined by the localization of a predicted recombination "hotspot" and "warm spot" in the vicinity of the most active acceptor genes at the periphery of the cluster. The data suggest that enriched crossover activity in direct and inverted segmental repeats is in accordance with the formation of palindromic secondary structures promoting double-strand breaks rather than fixed DNA sequence motifs. Also, this first detailed coverage of sequence diversity and structure of the LHB/CGB gene cluster will pave the way for studying the identified polymorphisms as well as potential genomic rearrangements in association with an individual's reproductive success.
| S-EPMC1310641 | biostudies-literature
Project description:LH triggers the biosynthesis of androgens in the theca-interstitial (T-I) cells of ovary through the activation of a cAMP-dependent pathway. We have previously shown that LH/human chorionic gonadotropin (hCG) activates mammalian target of rapamycin complex 1 (mTORC1) signaling network, leading to cell proliferation. In the present study, we provide evidence that the LH/hCG-mediated activation of the mTORC1 signaling cascade is involved in the regulation of steroidogenic enzymes in androgen biosynthesis. Treatment with LH/hCG increased the expression of downstream targets of mTORC1, ribosomal protein S6 kinase 1, and eukaryotic initiation factor 4E as well as steroidogenic enzymes. LH/hCG-mediated stimulation of the steroidogenic enzyme mRNA was blocked by the mTORC1 inhibitor, rapamycin. This inhibitory effect was selective because rapamycin failed to block hCG-mediated increase in the expression of Star mRNA levels. Furthermore, pharmacological targeting of mTORC1 with rapamycin also blocked LH/hCG- or forskolin-induced expression of cAMP response element-binding protein (CREB) and steroidogenic enzymes (P450 side-chain cleavage enzyme, 3?-hydroxysteroid dehydrogenase type 1, and 17?-hydroxylase/17,20 lyase) but produced no effect on steroidogenic acute regulatory protein levels. These results were further confirmed by demonstrating that the knockdown of mTOR using small interfering RNA selectively abrogated the LH/hCG-induced increase in steroidogenic enzyme expression, without affecting steroidogenic acute regulatory protein expression. LH/hCG-stimulated androgen production was also blocked by rapamycin. Furthermore, the pharmacological inhibition of mTORC1 or ribosomal protein S6 kinase 1 signaling prevented the LH/hCG-induced phosphorylation of CREB. Chromatin immunoprecipitation assays revealed the association of CREB with the proximal promoter of the Cyp17a1 gene in response to hCG, and this association was reduced by rapamycin treatment. Taken together, our findings show for the first time that LH/hCG-mediated activation of androgen biosynthesis is regulated by the mTORC1 signaling pathway in T-I cells.
| S-EPMC3458224 | biostudies-literature
Project description:BackgroundIn higher primates, during non-pregnant cycles, it is indisputable that circulating LH is essential for maintenance of corpus luteum (CL) function. On the other hand, during pregnancy, CL function gets rescued by the LH analogue, chorionic gonadotropin (CG). The molecular mechanisms involved in the control of luteal function during spontaneous luteolysis and rescue processes are not completely understood. Emerging evidence suggests that LH/CGR activation triggers proliferation and transformation of target cells by various signaling molecules as evident from studies demonstrating participation of Src family of tyrosine kinases (SFKs) and MAP kinases in hCG-mediated actions in Leydig cells. Since circulating LH concentration does not vary during luteal regression, it was hypothesized that decreased responsiveness of luteal cells to LH might occur due to changes in LH/CGR expression dynamics, modulation of SFKs or interference with steroid biosynthesis.MethodsSince, maintenance of structure and function of CL is dependent on the presence of functional LH/CGR its expression dynamics as well as mRNA and protein expressions of SFKs were determined throughout the luteal phase. Employing well characterized luteolysis and CL rescue animal models, activities of SFKs, cAMP phosphodiesterase (cAMP-PDE) and expression of SR-B1 (a membrane receptor associated with trafficking of cholesterol ester) were examined. Also, studies were carried out to investigate the mechanisms responsible for decline in progesterone biosynthesis in CL during the latter part of the non-pregnant cycle.Results and discussionThe decreased responsiveness of CL to LH during late luteal phase could not be accounted for by changes in LH/CGR mRNA levels, its transcript variants or protein. Results obtained employing model systems depicting different functional states of CL revealed increased activity of SFKs [pSrc (Y-416)] and PDE as well as decreased expression of SR-B1 correlating with initiation of spontaneous luteolysis. However, CG, by virtue of its heroic efforts, perhaps by inhibition of SFKs and PDE activation, prevents CL from undergoing regression during pregnancy.ConclusionsThe results indicated participation of activated Src and increased activity of cAMP-PDE in the control of luteal function in vivo. That the exogenous hCG treatment caused decreased activation of Src and cAMP-PDE activity with increased circulating progesterone might explain the transient CL rescue that occurs during early pregnancy.
| S-EPMC3353251 | biostudies-literature