The Effect Mechanism of N6-adenosine Methylation (m6A) in Melatonin Regulated LPS-induced Colon Inflammation.

Colon inflammation is characterized by disturbances in the intestinal microbiota and inflammation. Melatonin (Mel) can improve colon inflammation. However, the underlying mechanism remains unclear. Recent studies suggest that m6A methylation modification may play an important role in inflammatory responses. This study aimed to explore the effects of melatonin and LPS-mediated m6A methylation on colon inflammation. Our study found that melatonin inhibits M1 macrophages, activates M2 macrophages, inhibit the secretion of pro-inflammatory factors, maintain colon homeostasis and improves colon inflammation through MTNR1B. In addition, the increased methylation level of m6A is associated with the occurrence of colon inflammation, and melatonin can also reduce the level of colon methylation to improve colon inflammation. Among them, the main methylated protein METTL3 can be inhibited by melatonin through MTNR1B. In a word, melatonin regulates m6A methylation by improving abnormal METTL3 protein level to reshape the microflora and activate macrophages to improve colon inflammation, mainly through MTNR1B.

The Association between Dietary Iron Intake, SNP of the MTNR1B rs10830963, and Glucose Metabolism in Chinese Population.

Type 2 diabetes is associated with both dietary iron intake and single-nucleotide polymorphism (SNP) of intronic rs10830963 in melatonin receptor 1B (MTNR1B); however, it is unclear whether they interact. The aim of this study was to examine the associations between dietary iron intake, SNP of rs10830963, and glucose metabolism. Data were obtained from the Shanghai Diet and Health Survey (SDHS) during 2012-2018. Standardized questionnaires were carried out through face-to-face interviews. A 3-day 24 h dietary recall was used to evaluate dietary iron intake. Anthropometric and laboratory measurements were applied. Logistic regression and general line models were used to evaluate the association between dietary iron intake, SNP of the MTNR1B rs10830963, and glucose metabolism. In total, 2951 participants were included in this study. After adjusting for age, sex, region, years of education, physical activity level, intentional physical exercise, smoking status, alcohol use, and total energy, among G allele carriers, dietary iron intake was associated with a risk of elevated fasting glucose, higher fasting glucose, and higher HbA1c, while no significant results were observed among G allele non-carriers. The G allele of intronic rs10830963 in MTNR1B potentially exacerbated unfavorable glucose metabolism with the increasing dietary iron intake, and it was possibly a risk for glucose metabolism homeostasis in the Chinese population.

The Uterine Melatonergic Systems of AANAT and Melatonin Membrane Receptor 2 (MT2) Are Essential for Endometrial Receptivity and Early Implantation in Mice.

In the current study, using Aanat and Mt2 KO mice, we observed that the preservation of the melatonergic system is essential for successful early pregnancy in mice. We identified that aralkylamine N-acetyltransferase (AANAT), melatonin receptor 1A (MT1), and melatonin receptor 1B (MT2) were all expressed in the uterus. Due to the relatively weak expression of MT1 compared to AANAT and MT2, this study focused on AANAT and MT2. Aanat and Mt2 KO significantly reduced the early implantation sites and the abnormal morphology of the endometrium of the uterus. Mechanistical analysis indicated that the melatonergic system is the key player in the induction of the normal nidatory estrogen (E2) response for endometrial receptivity and functions by activating the STAT signaling pathway. Its deficiency impaired the interactions between the endometrium, the placenta, and the embryo. The reduction in melatonin production caused by Aanat KO and the impairment of signal transduction caused by Mt2 KO reduced the uterine MMP-2 and MMP-9 activity, resulting in a hyperproliferative endometrial epithelium. In addition, melatonergic system deficiency also increased the local immunoinflammatory reaction with elevated local proinflammatory cytokines leading to early abortion in the Mt2 KO mice compared to the WT mice. We believe that the novel data obtained from the mice might apply to other animals including humans. Further investigation into the interaction between the melatonergic system and reproductive effects in different species would be worthwhile.

The genomic response of human granulosa cells (KGN) to melatonin and specific agonists/antagonists to the melatonin receptors.

Melatonin is a known modulator of follicle development; it acts through several molecular cascades via binding to its two specific receptors MT1 and MT2. Even though it is believed that melatonin can modulate granulosa cell (GC) functions, there is still limited knowledge of how it can act in human GC through MT1 and MT2 and which one is more implicated in the effects of melatonin on the metabolic processes in the dominant follicle. To better characterize the roles of these receptors on the effects of melatonin on follicular development, human granulosa-like tumor cells (KGN) were treated with specific melatonin receptor agonists and antagonists, and gene expression was analyzed with RNA-seq technology. Following appropriate normalization and the application of a fold change cut-off of 1.5 (FC 1.5, p ≤ 0.05) for each treatment, lists of the principal differentially expressed genes (DEGs) are generated. Analysis of major upstream regulators suggested that the MT1 receptor may be involved in the melatonin antiproliferative effect by reprogramming the metabolism of human GC by activating the PKB signaling pathway. Our data suggest that melatonin may act complementary through both MT1 and MT2 receptors to modulate human GC steroidogenesis, proliferation, and differentiation. However, MT2 receptors may be the ones implicated in transducing the effects of melatonin on the prevention of GC luteinization and follicle atresia at the antral follicular stage through stimulating the PKA pathway.

The role of MTNR1B polymorphism on circadian rhythm-related cancer: A UK Biobank cohort study.

A common G risk allele in the melatonin receptor 1B (MTNR1B, rs10830963) gene has been associated with altered melatonin signaling and secretion. Given that melatonin possesses anticancerogenic properties, we hypothesized that breast and prostate cancer risks vary by rs10830963 genotype. A total of 216 702 participants from the UK Biobank without cancer at baseline (aged 56.4 ± 8.0 years, 50.79% female) were included. Multivariable Cox regression adjusting for known risk factors for breast or prostate cancer was used to estimate the independent effects of the rs10830963 SNP and chronotype on cancer risk. Over a median follow-up of 8 years, 2367 (2.15% of women) incidences of breast cancer and 2866 (2.69% of men) incidences of prostate cancer were documented in females and males, respectively. rs10830963 genotype is not associated with cancer risk independently (female Ptrend  = .103, male Ptrend  = .281). A late chronotype is associated with breast cancer risk in females (Ptrend  = .014), but not prostate cancer risk in males (Ptrend  = .915). Further stratification analysis revealed that the rs10830963 genotype is associated with a breast cancer risk in females with moderate evening chronotype (Ptrend  = .001) and late chronotype is associated with breast cancer risk in females who carry rs10830963 G risk allele (Ptrend  = .015). Our study suggests that having a late chronotype might increase the risk of breast cancer among females, while the effect of MTNR1B rs10830963 genotype on breast cancer risk is mediated by chronotype.

Night Shift Work, MTNR1B rs10830963 Polymorphism, and Prostate Cancer Risk: Findings from a Prospective, Population-Based Study.

BACKGROUND: The association between night shift work and prostate cancer is controversial. Evidence shows that genetic and environmental factors both contribute to the development of prostate cancer. It is well known that melatonin plays a protective role in prostate cancer. Melatonin receptor 1B gene (MTNR1B) rs10830963 influences the dynamics of melatonin secretion, and night shift work, which disrupts our internal circadian rhythms, also dysregulates the production of melatonin. Therefore, we aimed to examine the interaction between night shift work and rs10830963 polymorphism on prostate cancer. METHODS: This is a prospective cohort study based on UK Biobank that included 133,416 employed male participants. Exposures included night shift work and rs10830963 polymorphism. The primary outcome was the incidence of prostate cancer. Cox regression analysis was used to estimate the association of night shift work and MTNR1B rs10830963 with prostate cancer. RESULTS: A significant interaction was found between night shift work and MTNR1B rs10830963 on the incidence of prostate cancer (P = 0.009). Among non-night shift workers, rs10830963 polymorphism was not significantly associated with the risk of prostate cancer. Among night shift workers, compared with CC carriers, GC carriers had a significantly lower risk of prostate cancer [HR: 0.69; 95% confidence interval (CI): 0.51-0.93], and similar associations were more evident for GG carriers (HR: 0.33; 95% CI: 0.15-0.75). CONCLUSIONS: Compared with MTNR1B rs10830963 CC, carrying allele G may reduce the risk of prostate cancer when exposed to night shift work. IMPACT: These results suggest that rs10830963 G carriers may have a lower risk of prostate cancer when taking night shifts.

Structural basis of the ligand binding and signaling mechanism of melatonin receptors.

Melatonin receptors (MT1 and MT2 in humans) are family A G protein-coupled receptors that respond to the neurohormone melatonin to regulate circadian rhythm and sleep. Numerous efforts have been made to develop drugs targeting melatonin receptors for the treatment of insomnia, circadian rhythm disorder, and cancer. However, designing subtype-selective melatonergic drugs remains challenging. Here, we report the cryo-EM structures of the MT1-Gi signaling complex with 2-iodomelatonin and ramelteon and the MT2-Gi signaling complex with ramelteon. These structures, together with the reported functional data, reveal that although MT1 and MT2 possess highly similar orthosteric ligand-binding pockets, they also display distinctive features that could be targeted to design subtype-selective drugs. The unique structural motifs in MT1 and MT2 mediate structural rearrangements with a particularly wide opening on the cytoplasmic side. Gi is engaged in the receptor core shared by MT1 and MT2 and presents a conformation deviating from those in other Gi complexes. Together, our results provide new clues for designing melatonergic drugs and further insights into understanding the G protein coupling mechanism.

No association between a common type 2 diabetes risk gene variant in the melatonin receptor gene (MTNR1B) and mortality among type 2 diabetes patients.

The minor G risk allele in the common melatonin receptor gene (MTNR1B, rs10830963) has been associated with an increased risk of myocardial infarction among patients with type 2 diabetes (T2D). Furthermore, activating the melatonin receptor 1B through melatonin has been shown to promote cell proliferation, which could be hypothesized to increase cancer risk. Cardiovascular disease (CVD) and cancer are common causes of death among patients with T2D. Using data from 14 736  patients with T2D who participated in the UK Biobank investigation, we hypothesized an additive effect of the G risk allele on all-cause mortality, CVD mortality, and cancer mortality. As shown by Cox regression adjusted for confounders such as age, glucose-lowering medication, and socioeconomic status, no significant trend between the number of G risk alleles and mortality outcomes was found during the follow-up period of 11.1 years. Our negative findings do not speak against the role of this gene variant in the development of T2D, as repeatedly shown by previous large-scale studies. Instead, they may suggest that rs10830963 is less relevant for mortality risk in patients with T2D.

Interaction between rs10830962 polymorphism in MTNR1B and lifestyle intervention on maternal and neonatal outcomes: secondary analyses of the DALI lifestyle randomized controlled trial.

BACKGROUND: Interactions between polymorphisms of the melatonin receptor 1B (MTNR1B) gene and lifestyle intervention for gestational diabetes have been described. Whether these are specific for physical activity or the healthy eating intervention is unknown. OBJECTIVES: The aim was to assess the interaction between MTNR1B rs10830962 and rs10830963 polymorphisms and lifestyle interventions during pregnancy. METHODS: Women with a BMI (in kg/m2) of ≥29 (n = 436) received counseling on healthy eating (HE), physical activity (PA), or both. The control group received usual care. This secondary analysis had a factorial design with comparison of HE compared with no HE and PA compared with no PA. Maternal outcomes at 24-28 wk were gestational weight gain (GWG), maternal fasting glucose, insulin, insulin resistance (HOMA-IR), disposition index, and development of GDM. Neonatal outcomes were cord blood leptin and C-peptide and estimated neonatal fat percentage. The interaction between receiving either the HE or PA intervention and genotypes of both rs10830962 and rs10830963 was assessed using multilevel regression analysis. RESULTS: GDM risk was increased in women homozygous for the G allele of rs10830962 (OR: 2.60; 95% CI: 1.34, 5.06) or rs10830963 (OR: 2.83; 95% CI: 1.24, 6.47). Significant interactions between rs10830962 and interventions were found: in women homozygous for the G allele but not in the other genotypes, the PA intervention reduced maternal fasting insulin (ß: -0.16; 95% CI: -0.33, 0.02; P = 0.08) and HOMA-IR (ß: -0.17; 95% CI: -0.35, 0.01; P = 0.06), and reduced cord blood leptin (ß: -0.84; 95% CI: -1.42, -0.25; P = 0.01) and C-peptide (ß: -0.62; 95% CI: -1.07, -0.17; P = 0.01). In heterozygous women, the HE intervention had no effect, whereas in women homozygous for the C allele, HE intervention reduced GWG (ß: -1.6 kg; 95% CI: -2.4, -0.8 kg). No interactions were found. CONCLUSIONS: In women homozygous for the risk allele of MTNR1B rs10830962, GDM risk was increased and PA intervention might be more beneficial than HE intervention for reducing maternal insulin resistance, cord blood C-peptide, and cord blood leptin.

MTNR1B polymorphisms with CDKN2A and MGMT methylation status are associated with poor prognosis of colorectal cancer in Taiwan.

BACKGROUND: Identifying novel colorectal cancer (CRC) prognostic biomarkers is crucial to helping clinicians make appropriate therapy decisions. Melatonin plays a major role in managing the circadian rhythm and exerts oncostatic effects on different kinds of tumours. AIM: To explore the relationship between MTNR1B single-nucleotide polymorphism (SNPs) combined with gene hypermethylation and CRC prognosis. METHODS: A total of 94 CRC tumour tissues were investigated. Genotyping for the four MTNR1B SNPs (rs1387153, rs2166706, rs10830963, and rs1447352) was performed using multiplex polymerase chain reaction. The relationships between the MTNR1B SNPs and CRC 5-year overall survival (OS) was assessed by calculating hazard ratios with 95%CIs. RESULTS: All SNPs (rs1387153, rs2166706, rs10830963, and rs1447352) were correlated with decreased 5-year OS. In stratified analysis, rs1387153, rs10830963, and rs1447352 risk genotype combined with CDKN2A and MGMT methylation status were associated with 5-year OS. A strong cumulative effect of the four polymorphisms on CRC prognosis was observed. Four haplotypes of MTNR1B SNPs were also associated with the 5-year OS. MTNR1B SNPs combined with CDKN2A and MGMT gene methylation status could be used to predict shorter CRC survival. CONCLUSION: The novel genetic biomarkers combined with epigenetic biomarkers may be predictive tool for CRC prognosis and thus could be used to individualise treatment for patients with CRC.

Melatonin modulates swine luteal and adipose stromal cell functions.

Based on our previous study in follicles, the first aim of this work was to evaluate the effect of melatonin in the swine corpus luteum (CL). Luteal cells were exposed to 10 and 20pg mL-1 melatonin. We evaluated the effect on proliferation (bromo-deoxy-uridine uptake), steroidogenesis (progesterone) and redox status by means of Griess test (nitric oxide production), WST-1 test (superoxide anion generation) and FRAP test (non-enzymatic antioxidant power). The results showed a significant increase in antioxidant power, as well as a reduction in the other parameters analysed. These data and the expression of MT2 observed in luteal cells allow us to hypothesise a physiological role of melatonin in the regulation of CL functionality. The reproductive function is dependent on energy reserves stored in adipose tissue. Therefore, we sought to verify the effect of melatonin on adipose stromal cells (ASCs). MT2 receptor expression was detected in ASCs and the presence of gene markers (PPARγ and leptin) before and after adipogenic differentiation was verified. The differentiation was significantly inhibited by melatonin, as well as cell viability. In conclusion, present results suggest that melatonin exerts a potential inhibitory action on luteal function and adipogenesis, possibly mediated by MT2.

MT1 and MT2 melatonin receptors play opposite roles in brain cancer progression.

Primary brain tumors remain among the deadliest of all cancers. Glioma grade IV (glioblastoma), the most common and malignant type of brain cancer, is associated with a 5-year survival rate of < 5%. Melatonin has been widely reported as an anticancer molecule, and we have recently demonstrated that the ability of gliomas to synthesize and accumulate this indolamine in the surrounding microenvironment negatively correlates with tumor malignancy. However, our understanding of the specific effects mediated through the activation of melatonin membrane receptors remains limited. Thus, here we investigated the specific roles of MT1 and MT2 in gliomas and medulloblastomas. Using the MT2 antagonist DH97, we showed that MT1 activation has a negative impact on the proliferation of human glioma and medulloblastoma cell lines, while MT2 activation has an opposite effect. Accordingly, gliomas have a decreased mRNA expression of MT1 (also known as MTNR1A) and an increased mRNA expression of MT2 (also known as MTNR1B) compared to the normal brain cortex. The MT1/MT2 expression ratio negatively correlates with the expression of cell cycle-related genes and is a positive prognostic factor in gliomas. Notably, we showed that functional selective drugs that simultaneously activate MT1 and inhibit MT2 exert robust anti-tumor effects in vitro and in vivo, downregulating the expression of cell cycle and energy metabolism genes in glioma stem-like cells. Overall, we provided the first evidence regarding the differential roles of MT1 and MT2 in brain tumor progression, highlighting their relevance as druggable targets. KEY MESSAGES: • MT1 impairs while MT2 promotes the proliferation of glioma and medulloblastoma cell lines. • Gliomas have a decreased expression of MT1 and an increased expression of MT2 compared to normal brain cortex. • Tumors with a high MT1/MT2 expression ratio have significantly better survival rates. • Functional selective drugs that simultaneously activate MT1 and inhibit MT2 downregulate the expression of cell cycle and energy metabolism genes in glioma stem-like cells and exert robust anti-tumor effects in vivo.

Comparative analyses of site-directed mutagenesis of human melatonin MTNR1A and MTNR1B receptors using a yeast fluorescent biosensor.

Melatonin is an indoleamine neurohormone made by the pineal gland. Its receptors, MTNR1A and MTNR1B, are members of the G-protein-coupled receptor (GPCR) family and are involved in sleep, circadian rhythm, and mood disorders, and in the inhibition of cancer growth. These receptors, therefore, represent significant molecular targets for insomnia, circadian sleep disorders, and cancer. The yeast Saccharomyces cerevisiae is an attractive host for assaying agonistic activity for human GPCR. We previously constructed a GPCR-based biosensor employing a high-sensitivity yeast strain that incorporated both a chimeric yeast-human Gα protein and a bright fluorescent reporter gene (ZsGreen). Similar approaches have been used for simple and convenient measurements of various GPCR activities. In the current study, we constructed a fluorescence-based yeast biosensor for monitoring the signaling activation of human melatonin receptors. We used this system to analyze point mutations, including previously unreported mutations of the consensus sequences of MTNR1A and MTNR1B melatonin receptors and compared their effects. Most mutations in the consensus sequences significantly affected the signaling capacities of both receptors, but several mutations showed differences between these subtype receptors. Thus, this yeast biosensor holds promise for revealing the functions of melatonin receptors.

A circadian rhythm-related MTNR1B genetic variant (rs10830963) modulates glucose metabolism and insulin resistance after body weight loss secondary to biliopancreatic diversion surgery.

INTRODUCTION: Objective: the rs10830963 SNP of the MTNR1B gene may be related with biochemical changes after weight loss induced by caloric restriction. We investigated the role of this SNP on biochemical parameters after biliopancreatic diversion (BPD) surgery in morbid obese subjects. Patients and methods: one hundred and fifty-four patients with morbid obesity, without diabetes mellitus type 2, were enrolled. Their biochemical and anthropometric parameters were recorded before the procedure and after one, two, and three years of follow-up. All subjects were genotyped (rs10830963) at baseline. Results: the decrease in fasting insulin levels seen after the first year (delta: -3.9 ± 1.2 mIU/L vs. -1.8 ± 1.1 mIU/L; p = 0.03), the second year (delta: -5.0 ± 0.3 mIU/L vs. -2.3 ± 0.2 mIU/L; p = 0.01) and the third year (delta: -5.1 ± 1.9 mIU/L vs. -2.8 ± 1.1 mIU/L; p = 0.02) was higher in non-G-allele carriers than in G-allele carriers. Additionally, the improvement of HOMA-IR levels at year one (delta: -0.7 ± 0.2 mIU/L vs. -0.2 ± 0.2 mIU/L; p = 0.03), year two (delta: -1.0 ± 0.3 mIU/L vs. -0.5 ± 0.2 mIU/L; p = 0.01) and year three (delta: -1.2 ± 0.3 mIU/L vs. -0.4 ± 0.2 mIU/L; p = 0.03) was also higher in non-G-allele carriers than in G-allele carriers. Finally, basal glucose levels after the first year (delta: -10.1 ± 2.4 mg/dL vs. -3.6 ± 1.8 mg/dL; p = 0.02), the second year (delta: -16.0 ± 2.3 mg/dL vs. -8.4 ± 2.2 mg/dL; p = 0.01) and the third year (delta: -17.4 ± 3.1 mg/dL vs. -8.8 ± 2.9 mg/dL; p = 0.03) were higher in non-G-allele carriers than in G-allele carriers, too. Improvements seen in comorbidities were similar in both genotype groups. Conclusion: our study showed an association of the rs10830963 MTNR1B polymorphism after massive weight loss with lower glucose response, insulin resistance, and fasting insulin levels in G-allele carriers.

INTRODUCCIÓN: Objetivo: la variante SNP rs10830963 del gen MTNR1B podría estar relacionada con cambios bioquímicos tras la pérdida de peso inducida por una restricción calórica. El objetivo de este trabajo es evaluar el papel de este SNP en los parámetros bioquímicos después de la cirugía de derivación biliopancreática (DBP). Pacientes y métodos: se reclutaron un total de 154 pacientes con obesidad mórbida sin diabetes mellitus de tipo 2. La valoración bioquímica y antropométrica se realizó antes de la intervención y tras 1, 2 y 3 años de seguimiento. Todos los sujetos fueron genotipados (rs10830963) en el momento basal. Resultados: la disminución de los niveles de insulina en ayunas después del primer año (delta: -3,9 ± 1,2 mUI/L vs. -1,8 ± 1,1 mUI/L; p = 0,03), el segundo año (delta: -5,0 ± 0,3 mUI/L vs. -2,3 ± 0,2 mUI/L; p = 0,01) y el tercer año (delta: -5,1 ± 1,9 mUI/L vs. -2,8 ± 1,1 mUI/L; p = 0,02) fueron mayores en los no portadores del alelo G que en los portadores. Además, la mejora de los niveles de HOMA-IR en el primer año (delta: -0,7 ± 0,2 mUI/L ± -0,2 ± 0,2 mUI/L; p = 0,03), segundo año (delta: -1,0 ± 0,3 mUI/L vs. -0,5 ± 0,2 mUI/L; p = 0,01) y en el tercer año (delta: -1,2 ± 0,3 mUI/L vs. -0,4 ± 0,2 mUI/L; p = 0,03) también fueron mayores en los no portadores del alelo G. Finalmente, los niveles basales de glucosa después del primer año (delta: -10,1 ± 2,4 mg/dL vs. -3,6 ± 1,8 mg/dL; p = 0,02), el segundo año (delta: -16,0 ± 2,3 mg/dL vs. ­ 8,4 ± 2,2 mg/dL; p = 0,01) y el tercer año (delta: -17,4 ± 3,1 mg/dL vs. -8,8 ± 2,9 mg/dL; p = 0.03) fueron mayores en los no portadores del alelo G. Las comorbilidades mejoraron en ambos genotipos de manera similar. Conclusión: nuestro estudio mostró una asociación del polimorfismo rs10830963 MTNR1B tras una pérdida de peso posquirúrgica con una menor respuesta de los niveles de glucosa, resistencia a la insulina e insulina en ayunas en portadores del alelo G.

Molecular basis defining the selectivity of substituted isoquinolinones for the melatonin MT2 receptor.

Melatonin MT1 and MT2 receptors represent attractive drug targets for the treatment of various disorders. However, the high conservation of the melatonin binding pocket has hindered the development of subtype-selective compounds. By leveraging on the recently resolved crystal structures of MT1 and MT2 receptors, this study aims to elucidate the structural basis of MT2-selectivity of a panel of isoquinolinone derivatives. Molecular modelling and ligand docking approaches were employed to predict residues involved in forming interactions with the MT2-selective isoquinolinones. Seven conserved residues (Asn175, His208, Trp264, Asn268, Gly271, Tyr294 and Tyr298) were selected as targets for site-directed mutagenesis. Ca2+ mobilization, cAMP inhibition, phosphorylation of extracellular signal-regulated kinase, and ligand binding assays were performed to functionally characterize the receptor mutants in transfected CHO cells. Unlike melatonin, isoquinolinones bearing a 3-methoxybenzyloxyl substituent were unaffected by alanine substitution at His208 of MT2. Although alanine substitutions at Tyr294 or Tyr298 reduced the potency of melatonin and some isoquinolinones on MT2, similar mutations on MT1 allowed five hitherto ineffective isoquinolinones to act as agonists. An isoquinolinone antagonist bearing a 4-methoxybenzyloxyl moiety turned into an agonist at MT2 mutants with alanine substitutions at His208, Tyr294 or Tyr298. A subset of residues is apparently involved in forming a hydrophobic binding cavity to confer selectivity upon the aromatic substituent of isoquinolinone compounds. Two conserved tyrosine residues on transmembrane helix 7 may confer ligand selectivity at MT1 and MT2 receptors, while a conserved histidine on transmembrane helix 5 is apparently involved in receptor activation.

Association between melatonin receptor gene polymorphisms and polycystic ovarian syndrome: a systematic review and meta-analysis.

BACKGROUND: Polycystic ovarian syndrome (PCOS) is a kind of common gynecological endocrine disorder. And the mutations of melatonin receptor (MTNR) genes are related to the occurrence of PCOS. But previous researches have shown opposite results. So, the object of our systematic review and meta-analysis is to investigate the relationship between MTNR 1A/B polymorphisms and PCOS. METHODS: PubMed, Embase, Ovid, the Cochrane Library, Web of Science and three Chinese databases (VIP, CNKI and Wanfang) were used to retrieve eligible articles published between January 1980 and February 2020. And we used the odds ratio (OR) and its 95% confidence interval (CI) to investigate the strength of the association by six genetic models, allelic, codominant (homozygous and heterozygous), dominant, recessive and superdominant models. Review Manager 5.3, IBM SPSS statistics 25 and Stata MP 16.0 software were used to do this meta-analysis. RESULTS: Our meta-analysis involved 2553 PCOS patients and 3152 controls, for two single nucleotide polymorphisms (rs10830963 C> G in MTNR1B and rs2119882 T> C in MTNR1A) and significant associations were found in some genetic models of these single nucleotide polymorphisms (SNPs). For rs10830963, strongly significant was found in the heterozygote model (GC vs. CC, P=0.02). Additionally, a slight trend was detected in the allelic (G vs. C), homozygote (GG vs. CC) and dominant (GG+GC vs. CC) model of rs10830963 (P=0.05). And after further sensitivity analysis, a study with high heterogeneity was removed. In the allelic (P=0.000), homozygote (P=0.001), dominant (P=0.000) and recessive (GG vs. GC+CC, P=0.001) model, strong associations between rs10830963 and PCOS were found. Moreover, for rs2119882, five genetic models, allelic (C vs. T, P=0.000), codominant (the homozygote (CC vs. TT, P=0.000) and heterozygote model (CT vs. TT, P=0.02), dominant (CC + CT vs. TT, P=0.03) and recessive model (CC vs. CT + TT, P=0.000) showed significant statistical associations with PCOS. CONCLUSION: MTNR1B rs10830963 and MTNR1B rs2119882 polymorphisms are associated with PCOS risk. However, the above conclusions still require being confirmed by much larger multi-ethnic studies.

Genetic polymorphisms and vincristine-induced peripheral neuropathy in patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone therapy.

Vincristine (VCR)-induced peripheral neuropathy (VIPN) is a common and life-long toxicity in lymphoma patients receiving current standard chemotherapy. The association between VIPN and genetic polymorphisms is largely unknown in adult lymphoma patients. To examine the possible relationship between known genetic polymorphisms in patients with pediatric acute lymphoblastic leukemia and incidence of VIPN in adult patients with B cell lymphoma, we examined CEP72 rs924607, ETAA1 rs17032980, MTNR1B rs12786200, CYP3A5 rs776746, rs7963521, and rs1045644 genetic polymorphisms in samples from 56 adult patients with B-cell lymphoma who received rituximab, cyclophosphamide, doxorubicin, VCR, and prednisone (R-CHOP) chemotherapy. Mutation analysis was performed by direct sequencing. The median age was 65 years (range 30-79). The median cumulative dose of VCR was 12 mg (range 2-16). VIPN was documented in 42 patients (75%), and 9 (16%) had grade 2-4 VIPN. Age, impaired glucose tolerance, number of cycles of R-CHOP, and VCR cumulative dose were not associated with incidence of VIPN. There was no association between the incidence of grade 2-4 or any grade VIPN and these six genetic polymorphisms. These results indicate that CEP72, MTNR1B, ETAA1, CYP3A5, rs7963521, and rs1045644 genetic polymorphisms are not associated with VIPN in patients with B-cell lymphoma who received R-CHOP.

Dietary-fat effect of the rs10830963 polymorphism in MTNR1B on insulin resistance in response to 3 months weight-loss diets. / Efecto del polimorfismo rs10830963 MTNR1B y la composición de grasa de la dieta en la resistencia a la insulina tras la pérdida de peso durante 3 meses.

BACKGROUND & AIMS: The risk allele (G) of rs10830963 in the melatonin receptor 1 B (MTNR1B) gene presents an association with obesity. We study the effect of this SNP on cardiovascular risk factors and weight loss secondary to 2hypocaloric diets. METHODS: 361 obese subjects were randomly allocated during 3 months (Diet M - high monounsaturated fat hypocaloric diet vs. Diet P - high polyunsaturated fat hypocaloric diet). Anthropometric parameters, fasting blood glucose, C-reactive protein (CRP), insulin concentration, insulin resistance (HOMA-IR), lipid profile and adipocytokines levels were measured. Genotype of MTNR1B gene polymorphism (rs10830963) was evaluated. RESULTS: All anthropometric parameters, systolic blood pressure and leptin levels decreased in all subjects after both diets. This improvement of anthropometric parameters was higher in non G allele carriers than G allele carriers. After dietary intervention with Diet M, (CC vs. CG + GG); total cholesterol (delta: -10.4 ± 2.1mg/dl vs. -6.4 ± 1.2mg/dl: P <.05), LDL-cholesterol (delta:-7.1 ± 0.9mg/dl vs. -2.8 ± 0.8mg/dl: P <.05), insulin (delta:-3.0 ± 0.8 UI/L vs. -2.0 ± 1.0 UI/L: P<.05) and HOMA-IR (delta:-3.4 ± 1.0 units vs. -2.9 ± 0.9 units: P<.05) improved in no G allele carriers. After Diet P, in the group of subjects without G allele CC, insulin levels (delta: -2.9 ± 1.0 UI/L vs. -0.6 ± 0.2 UI/L: P <.05) and HOMA-IR (delta (CC vs. CG + GG): -0.8 ± 0.2 units vs. -0.4 ± 0.3 units: P <.05) decreased, too. CONCLUSIONS: Our study detected a relationship of rs10830963 MTNR1B SNP with body weight loss and insulin resistance modification induced by 2different hypocaloric. Only monounsaturated enriched hypocaloric diet and in no-G allele carriers showed a significant effect on lipoproteins.

Melatonin induces progesterone production in human granulosa-lutein cells through upregulation of StAR expression.

Steroidogenic acute regulatory protein (StAR) mediates the rate-limiting step in ovarian steroidogenesis and progesterone (P4) synthesis. Melatonin and its receptors are expressed in human granulosa cells, and have been shown to influence basal P4 production. However, previous studies addressing the regulation of StAR expression by melatonin and its impact on P4 secretion yielded contradictory results. Here, we demonstrate that melatonin upregulates StAR expression in primary cultures of human granulosa-lutein (hGL) cells obtained from women undergoing in vitro fertilization (IVF). Using pharmacological inhibitors, we show that the stimulatory effect of melatonin on StAR expression is mediated via both MT1 and MT2 melatonin receptors. Melatonin exposure activates the PI3K/AKT signaling pathway and its inhibition attenuates the stimulatory effect of melatonin on StAR expression. Moreover, siRNA-mediated knockdown of StAR abolishes melatonin-induced P4 production. Importantly, clinical analyses demonstrate that melatonin levels in human follicular fluid are positively correlated with P4 levels in serum. By illustrating the potential physiological role of melatonin in the regulation of StAR expression and P4 production in hGL cells, our results may serve to improve current strategies used to treat clinical infertility.

Melatonin Receptor 1ß Gene Polymorphism rs10830963, Serum Melatonin, TNF-α, IL-6, IL-1ß, in Egyptian Patients with Systemic Lupus Erythematosus.

Systemic lupus erythematosus (SLE) is a complex autoimmune disease affecting all organ systems due to alterations of both innate and adaptive immune systems. Given the importance of several factors that may be incriminated in deregulation of immune system in SLE, we aimed to study MTNR1ß gene polymorphisms rs10830963 C/G, serum levels of melatonin and pro-inflammatory cytokines; TNF-α, IL-6, and IL-1ß in SLE patients and the correlation of these parameters to SLE disease activity and damage index at time of study. Subjects were subdivided into 2 groups: group I: 40 SLE patients attending Alexandria main university hospital and outpatient clinic, and group II: 40 control cases of apparently healthy individuals matched for age and sex. For all cases, MTNR1ß gene polymorphism rs10830963 was analyzed by quantitative RT-PCR, serum levels of melatonin, TNF-α, IL-6 and IL-1ß were detected by ELISA. Activity index (SLEDAI) and damage index (SLEDDI) were assessed in SLE patients. MTNR1ß gene polymorphism rs10830963 genotype in SLE patients showed that 50% had GG, 35% CG and 15% CC. The control group had significantly lower ratios, 5% had GG, 15% CG and 80% CC (P < 0.001). Serum melatonin level was decreased in SLE patients (P < 0.001). Serum levels of TNF-α, IL-6, and IL-1ß were increased in SLE patients compared to controls (P < 0.001, P < 0.001, P < 0.001 respectively). There was no correlation between serum melatonin level, TNF-α, IL-6, and IL-1ß with SLEDAI or SLEDDI. In conclusion, MTNR1ß gene polymorphism rs10830963 G allele may contribute in SLE pathogenesis. Inflammatory cytokines; TNF-α, IL-6, IL-1ß may have role in SLE disease manifestations. Targeting immunoregulators as melatonin and proinflammatory cytokines in SLE treatment strategy can be a promising way to SLE cure.