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.

Sperm melatonin receptors, seminal plasma melatonin and semen freezability in goats.

Goat bucks are seasonal breeders that show variation in sperm quality, endogenous melatonin (MLT), and presumably in the expression of MLT receptors on the sperm throughout the year, which may modify sperm freezability. The aim of this study was to determine whether sperm freezability is associated with (i) endogenous melatonin levels in seminal plasma and (ii) the expression of sperm plasma membrane melatonin receptors (MT1, MT2). To evaluate this, spermatozoa from seven Saanen goat bucks were cryopreserved throughout the year in Mexico using a standard freezing protocol. Seminal plasma MLT concentrations were determined by ELISA and the expression and localization of MT1 and MT2 were detected by immunocytochemistry and confirmed by western blotting. The recovery rate of progressive motility after thawing was higher in spring than autumn and winter; in contrast, the F pattern (CTC assay) was higher in winter than in the other seasons. A proportional increase in the AR pattern (CTC assay) was smaller in winter than in the other seasons and the proportion of sperm showing high plasma membrane fluidity was higher in spring than in summer and autumn. The seminal plasma MLT concentrations showed no significant interseasonal differences. The MT1 receptor was immunolocalised at the apical region of the sperm head, while MT2 was mainly localised in the neck. The relative expression of MLT receptors showed significant differences between summer and winter for all bands, except at 75 kDa of MT2. In conclusion, there was an association between the relative expression of MT1 and MT2 receptors throughout the year and sperm freezability in goat bucks in México. Post-thaw sperm quality is enhanced in semen samples collected during breeding season.

Thirty-seven years of MT1 and MT2 melatonin receptor localization in the brain: Past and future challenges.

Identifying the target cells of a hormone is a key step in understanding its function. Once the molecular nature of the receptors for a hormone has been established, researchers can use several techniques to detect these receptors. Here I will review the different tools used over the years to localize melatonin receptors and the problems associated with each of these techniques. The radioligand 2-[125I] iodomelatonin was the first tool to allow localization of melatonin receptors on tissue sections. Once the MT1 and MT2 receptors were cloned, in situ hybridization could be used to detect the messenger RNA for these receptors. The deduced amino acid sequences for MT1 and MT2 receptors allowed the production of peptide immunogens to generate antibodies against the MT1 and MT2 receptors. Finally, transgenic reporters driven by the promoter elements of the MT1 and MT2 genes have been used to map the expression of MT1 and MT2 in the brain and the retina. Several issues have complicated the localization of melatonin receptors and the characterization of melatonin target cells over the last three decades. Melatonin receptors are expressed at low levels, leading to sensitivity issues for their detection. The second problem are specificity issues with antibodies directed against the MT1 and MT2 melatonin receptors. These receptors are G protein-coupled receptors and many antibodies directed against such receptors have been shown to present similar problems concerning their specificity. Despite these specificity problems which start to be seriously addressed by recent studies, antibodies will be important tools in the future to identify and phenotype melatonin target cells. However, we will have to be more stringent than previously when establishing their specificity. The results obtained by these antibodies will have to be confronted and be coherent with results obtained by other techniques.

MTNR 1B (rs10830963) Gene Polymorphism, but not MTNR 1A (rs2119882), Associated with Type 2 Diabetes Mellitus Risk in Saudi Arabia.

BACKGROUND: Disrupted circadian rhythm has been linked to the pathogenesis of type 2 diabetes mellitus (T2DM). Single nucleotide polymorphisms (SNPs) in melatonin receptors (MTNR), MTNR 1A rs2119882 (T>C) and MTNR 1B rs10830963 (C>G) may interfere with the normal function of melatonin and increase the risk of T2DM. This study investigated the prevalence of MTNR 1A rs2119882 (T>C) and MTNR 1B rs10830963 (C>G) SNPs and tested their association with T2DM in Saudi Arabian population. METHODS: A total of 459 Saudi Arabian participants from Jazan Province, Saudi Arabia, were selected and included 227 T2DM patients and 232 control subjects. DNA was extracted from all participants and genotyped for rs2119882 and rs10830963 SNPs using TaqMan technology. Genotype frequencies were determined for both SNPs, and logistic regression was fitted to test the association with T2DM. RESULTS: No association was found between MTNR 1A rs2119882 (T>C) SNP and T2DM (odds ratio (OR) = 0.69; 95% confidence interval (CI) = 0.44 - 1.08; p-value = 0.111). However, the MTNR 1B rs10830963 (C>G) SNP was significantly associated with T2DM (OR = 1.73; 95% CI = 1.18 - 2.55; p-value = 0.0065). Co-inheritance of the MTNR 1B rs10830963 G allele and MTNR 1A rs2119882 T allele further increased the risk of T2DM (OR = 2.80; 95% CI = 1.71 - 4.57; p-value < 0.0001). CONCLUSIONS: The minor G allele of the MTNR 1B rs10830963 SNP was significantly associated with T2DM in our population. This association further intensified with the presence of the T allele in MTNR 1A rs2119882 locus. This study sheds light on the importance of melatonin receptor polymorphisms as genetic candidates for the development of T2DM in Saudi Arabia.

Melatonin Alleviates Lipopolysaccharide-Induced Abnormal Pregnancy through MTNR1B Regulation of m6A.

Pregnancy is a highly intricate and delicate process, where inflammation during early stages may lead to pregnancy loss or defective implantation. Melatonin, primarily produced by the pineal gland, exerts several pharmacological effects. N6-methyladenosine (m6A) is the most prevalent mRNA modification in eukaryotes. This study aimed to investigate the association between melatonin and m6A during pregnancy and elucidate the underlying protective mechanism of melatonin. Melatonin was found to alleviate lipopolysaccharide (LPS)-induced reductions in the number of implantation sites. Additionally, it mitigated the activation of inflammation, autophagy, and apoptosis pathways, thereby protecting the pregnancy process in mice. The study also revealed that melatonin regulates uterine m6A methylation levels and counteracts abnormal changes in m6A modification of various genes following LPS stimulation. Furthermore, melatonin was shown to regulate m6A methylation through melatonin receptor 1B (MTNR1B) and subsequently modulate inflammation, autophagy, and apoptosis through m6A. In conclusion, our study demonstrates that melatonin protects pregnancy by influencing inflammation, autophagy, and apoptosis pathways in an m6A-dependent manner via MTNR1B. These findings provide valuable insights into the mechanisms underlying melatonin's protective effects during pregnancy and may have implications for potential therapeutic strategies in managing pregnancy-related complications.

MTNR1B genotype and effects of carbohydrate quantity and dietary glycaemic index on glycaemic response to an oral glucose load: the OmniCarb trial.

AIMS/HYPOTHESIS: A type 2 diabetes-risk-increasing variant, MTNR1B (melatonin receptor 1B) rs10830963, regulates the circadian function and may influence the variability in metabolic responses to dietary carbohydrates. We investigated whether the effects of carbohydrate quantity and dietary glycaemic index (GI) on glycaemic response during OGTTs varied by the risk G allele of MTNR1B-rs10830963. METHODS: This study included participants (n=150) of a randomised crossover-controlled feeding trial of four diets with high/low GI levels and high/low carbohydrate content for 5 weeks. The MTNR1B-rs10830963 (C/G) variant was genotyped. Glucose response during 2 h OGTT was measured at baseline and the end of each diet intervention. RESULTS: Among the four study diets, carrying the risk G allele (CG/GG vs CC genotype) of MTNR1B-rs10830963 was associated with the largest AUC of glucose during 2 h OGTT after consuming a high-carbohydrate/high-GI diet (ß 134.32 [SE 45.69] mmol/l × min; p=0.004). The risk G-allele carriers showed greater increment of glucose during 0-60 min (ß 1.26 [0.47] mmol/l; p=0.008) or 0-90 min (ß 1.10 [0.50] mmol/l; p=0.028) after the high-carbohydrate/high-GI diet intervention, but not after consuming the other three diets. At high carbohydrate content, reducing GI levels decreased 60 min post-OGTT glucose (mean -0.67 [95% CI: -1.18, -0.17] mmol/l) and the increment of glucose during 0-60 min (mean -1.00 [95% CI: -1.67, -0.33] mmol/l) and 0-90 min, particularly in the risk G-allele carriers (pinteraction <0.05 for all). CONCLUSIONS/INTERPRETATION: Our study shows that carrying the risk G allele of MTNR1B-rs10830963 is associated with greater glycaemic responses after consuming a diet with high carbohydrates and high GI levels. Reducing GI in a high-carbohydrate diet may decrease post-OGTT glucose concentrations among the risk G-allele carriers.

MTNR1B gene variations and high pre-pregnancy BMI increase gestational diabetes mellitus risk in Chinese women.

AIM: To investigate the association of melatonin receptor 1B (MTNR1B) gene variations and pre-pregnancy body mass index (BMI) with gestational diabetes mellitus (GDM). MATERIALS AND METHOD: In this study, 1566 Chinese Han pregnant women were enrolled and multiple genetic models were used to evaluate the association between MTNR1B gene polymorphisms and the risk of GDM. The clinical value of pre-pregnancy BMI in predicting GDM was analyzed and evaluated using receiver operating characteristic (ROC) curves. Several methods of analysis were used to examine the impact of gene-gene and gene-BMI interactions on the incidence of GDM influence. RESULTS: For the MTNR1B gene, rs1387153 (C > T), rs10830962 (C > G), rs4753426 (T > C), and rs10830963 (C > G) are all risk mutations associated with the susceptibility of GDM. The ROC curve analysis indicated that the BMI demonstrated an area under the curve (AUC) of 0.595. Alongside, the sensitivity and specificity stood at 0.676 and 0.474 respectively. The maximum Joden index was found to be 0.150, with a corresponding critical BMI value of 20.5691 kg/m2. Interaction analysis revealed that gene-gene and gene-BMI interactions had no significant effect on GDM occurrence. CONCLUSION: MTNR1B genetic variations confers the risk to GDM in Chinese women. Furthermore, the high pre-pregnancy BMI (≥20.5691 kg/m2) significantly increases the risk of GDM in Chinese women.

Melatonin MT1 receptors as a target for the psychopharmacology of bipolar disorder: A translational study.

The treatment of bipolar disorder (BD) still remains a challenge. Melatonin (MLT), acting through its two receptors MT1 and MT2, plays a key role in regulating circadian rhythms which are dysfunctional in BD. Using a translational approach, we examined the implication and potential of MT1 receptors in the pathophysiology and psychopharmacology of BD. We employed a murine model of the manic phase of BD (Clock mutant (ClockΔ19) mice) to study the activation of MT1 receptors by UCM871, a selective partial agonist, in behavioral pharmacology tests and in-vivo electrophysiology. We then performed a high-resolution Nuclear Magnetic Resonance study on isolated membranes to characterize the molecular mechanism of interaction of UCM871. Finally, in a cohort of BD patients, we investigated the link between clinical measures of BD and genetic variants located in the MT1 receptor and CLOCK genes. We demonstrated that: 1) UCM871 can revert behavioral and electrophysiological abnormalities of ClockΔ19 mice; 2) UCM871 promotes the activation state of MT1 receptors; 3) there is a significant association between the number of severe manic episodes and MLT levels, depending on the genetic configuration of the MT1 rs2165666 variant. Overall, this work lends support to the potentiality of MT1 receptors as target for the treatment of BD.

Relationship Between Genetic Variant Of OXTR (Rs53576) And MTNR1B (Rs1387153) And Symptoms Of Psychological Stress In Females With Gestational Diabetes Mellitus.

Objective: To assess the association of oxytocin receptor (rs53576) and melatonin hormone receptor 1B (rs1387153) gene single nucleotide polymorphisms with psychological symptoms in women with gestational diabetes mellitus. METHODS: The case-control study was conducted from May 1 to June 1, 2022, at the Department of Physiology, University of Karachi, in collaboration with the Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, and the Department of Obstetrics and Gynaecology, Jinnah Postgraduate Medical Centre, Karachi. Fifty gestational diabetic pregnant women and ninety healthy pregnant women were recruited. Sanger sequencing was performed to assess the genotypic frequency and polymorphic variation of all subjects. Perceived stress scale and diabetes-related distress scale were used to assess the stress levels. Data was analysed using SPSS 23. RESULTS: Of the 140 subjects, 90 (64.3%) were controls with mean age 24.96±4.35 years, and 50 (35.7%) were cases with mean age 28.78±5.25 (p<0.05). Mean body weight and mean gestational age were not significantly different between the groups (p>0.05). Melatonin hormone receptor 1B rs1387153 frequency was significantly different between the groups (p<0.05). Among the cases, a significant mean difference for regimen distress scores between AA and GG was observed for oxytocin receptor rs53576 (p=0.04). A significant mean difference in sum of PSS, diabetes-related stress, total diabetes- related stress and emotional distress was noted between CC and TT genotypes for melatonin hormone receptor 1B rs1387153 (p=0.001). Conclusion: MTNR1B rs1387153 genotypes were associated with perceived stress, diabetes-related stress, diabetic distress, and emotional burden, while OXTR rs53576 genotypes were associated with regimen distress in GDM women.

MTNR1B rs1387153 Polymorphism and Risk of Gestational Diabetes Mellitus: Meta-Analysis and Trial Sequential Analysis.

BACKGROUND: Published data on the association between the MTNR1B rs1387153 polymorphism and gestational diabetes mellitus (GDM) risk are controversial. OBJECTIVE: A meta-analysis was performed to assess whether the polymorphism of MTNR1B rs1387153 is associated with GDM risk. METHOD: Medline, Embase, China National Knowledge Infrastructure, and Chinese Biomedicine Databases were searched to identify eligible studies. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for MTNR1B rs1387153 polymorphism and GDM were appropriately derived from fixed-effects or random effects models. RESULTS: A total of 8 studies were enrolled in this meta-analysis. The pooled analyses revealed that MTNR1B rs1387153 polymorphism significantly increased the risk of GDM in all models (allele contrast (C vs. T): OR, 0.78; 95% CI, 0.73-0.83; homozygote (CC vs. TT): OR, 0.61; 95% CI, 0.53-0.69; heterozygote (CT vs. TT): OR, 0.78; 95% CI, 0.69-0.89; dominant model (CC + CT vs. TT): OR, 0.71; 95% CI, 0.63-0.80; recessive model (CC vs. CT + TT): OR, 0.73; 95% CI, 0.67-0.81). Further subgroup analyses by ethnicity of participants yielded similar positive results. CONCLUSIONS: Present meta-analysis reveals that MTNR1B rs1387153 variant may serve as genetic biomarkers of GDM.

Myocardial Infarction Susceptibility and the MTNR1B Polymorphisms.

Melatonin is a circadian hormone with antioxidant properties that protects against myocardial ischemia-reperfusion injury. Genetic variations of the melatonin receptor 1B gene (MTNR1B) play an important role in the development of type 2 diabetes, a risk factor for cardiovascular diseases. Accordingly, MTNR1B polymorphisms are crucial in numerous disorders of the cardiovascular system. Therefore, the aim of the present study was to investigate a possible association of MTNR1B polymorphisms with chronotype and susceptibility to myocardial infarction. The present case-control study included 199 patients with myocardial infarction (MI) (57% men) and 198 control participants (52% men) without previous cardiovascular diseases who underwent genotyping for the MTNR1B polymorphisms rs10830963, rs1387153, and rs4753426 from peripheral blood samples. Chronotype was determined using the Morningness-Eveningness Questionnaire (MEQ). As estimated by the chi-square test, no significant association was found in the distribution of alleles and genotypes between myocardial infarction patients and controls. In addition, there was no association between MTNR1B polymorphisms and chronotype in MI patients. As some previous studies have shown, the present negative results do not exclude the role of the MTNR1B polymorphisms studied in the development of myocardial infarction. Rather, they may indicate that MTNR1B polymorphisms are a minor risk factor for myocardial infarction.

Association of rotating night shift work, CLOCK, MTNR1A, MTNR1B genes polymorphisms and their interactions with type 2 diabetes among steelworkers: a case-control study.

BACKGROUND: The purpose of this study is to investigate the association of rotating night shift work, CLOCK, MTNR1A, MTNR1B genes polymorphisms and their interactions with type 2 diabetes among steelworkers. METHODS: A case-control study was conducted in the Tangsteel company in Tangshan, China. The sample sizes of the case group and control group were 251 and 451, respectively. The logistic regression, log-linear model and generalized multifactor dimensionality (GMDR) method were used to investigate the interaction between circadian clock gene, melatonin receptor genes and rotating night shift work on type 2 diabetes among steelworkers. Relative excess risk due to interaction (RERI) and attributable proportions (AP) were used to evaluate additive interactions. RESULTS: Rotating night shift work, current shift status, duration of night shifts, and average frequency of night shifts were associated with an increased risk of type 2 diabetes after adjustment for confounders. Rs1387153 variants in MTNR1B was found to be associated with an increased risk of type 2 diabetes, which was not found between MTNR1A gene rs2119882 locus, CLOCK gene rs1801260 locus and the risk of type 2 diabetes. The association between rotating night shift work and risk of type 2 diabetes appeared to be modified by MTNR1B gene rs1387153 locus (RERI = 0.98, (95% CI, 0.40-1.55); AP = 0.60, (95% CI, 0.07-1.12)). The interaction between MTNR1A gene rs2119882 locus and CLOCK gene rs1801260 locus was associated with the risk of type 2 diabetes (RERI = 1.07, (95% CI, 0.23-1.91); AP = 0.77, (95% CI, 0.36-1.17)). The complex interaction of the MTNR1A-MTNR1B-CLOCK-rotating night shift work model based on the GMDR methods may increase the risk of type 2 diabetes (P = 0.011). CONCLUSIONS: Rotating night shift work and rs1387153 variants in MTNR1B were associated with an increased risk of type 2 diabetes among steelworkers. The complex interaction of MTNR1A-MTNR1B-CLOCK-rotating night shift work may increase the risk of type 2 diabetes.

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.

Molecular Mechanisms of the Melatonin Receptor Pathway Linking Circadian Rhythm to Type 2 Diabetes Mellitus.

Night-shift work and sleep disorders are associated with type 2 diabetes (T2DM), and circadian rhythm disruption is intrinsically involved. Studies have identified several signaling pathways that separately link two melatonin receptors (MT1 and MT2) to insulin secretion and T2DM occurrence, but a comprehensive explanation of the molecular mechanism to elucidate the association between these receptors to T2DM, reasonably and precisely, has been lacking. This review thoroughly explicates the signaling system, which consists of four important pathways, linking melatonin receptors MT1 or MT2 to insulin secretion. Then, the association of the circadian rhythm with MTNR1B transcription is extensively expounded. Finally, a concrete molecular and evolutionary mechanism underlying the macroscopic association between the circadian rhythm and T2DM is established. This review provides new insights into the pathology, treatment, and prevention of T2DM.

The melatonin receptor 1B gene links circadian rhythms and type 2 diabetes mellitus: an evolutionary story.

Disturbed circadian rhythms have been a risk factor for type 2 diabetes mellitus (T2DM). Melatonin is the major chronobiotic hormone regulating both circadian rhythm and glucose homeostasis. The rs10830963 (G allele) of the melatonin receptor 1B (MTNR1B) gene has the strongest genetic associations with T2DM according to several genome-wide association studies. The MTNR1B rs10830963 G allele is also associated with disturbed circadian phenotypes and altered melatonin secretion, both factors that can elevate the risk of diabetes. Furthermore, evolutionary studies implied the presence of selection pressure and ethnic diversity in MTNR1B, which was consistent with the "thrifty gene" hypothesis in T2DM. The rs10830963 G risk allele is associated with delayed melatonin secretion onset in dim-light and prolonged duration of peak melatonin. This delayed melatonin secretion may help human ancestors adapt to famine or food shortages during long nights and early mornings and avoid nocturnal hypoglycemia but confers susceptibility to T2DM due to adequate energy intake in modern society. We provide new insight into the role of MTNR1B variants in T2DM via disturbed circadian rhythms from the perspective of the "thrifty gene" hypothesis; these data indicate a novel target for the prevention and treatment of susceptible populations with the thrifty genotype.

MTNR1A and MTNR1B Gene Variants of the Melatonin Receptor and Arterial Stiffness in Persons without Arterial Hypertension.

A comparative analysis of vascular stiffness indices and the results of blood test was carried out in 85 healthy donors aged 19-64 years, carriers of polymorphic variants of type 1 and type 2 melatonin receptor genes. The associations of polymorphic markers of type 1 MTNR1A (rs34532313) and type 2 MTNR1B (rs10830963) melatonin receptor genes with parameters of vascular stiffness and blood parameters in healthy patients were studied. Genotyping was performed using allele-specific PCR. In all patients, 24-h BP monitoring with assessment of arterial stiffness was performed. Allele C homozygotes of MTNR1A differed significantly from carriers of the major T allele by elevated triglyceride, LDL, and fibrinogen levels. The major allele C of the rs10830963 polymorphic variant of the MTNR1B gene is associated with elevated LDL and triglycerides, as well as with individual differences in the elastic properties of the vascular wall in the examined subjects.

Role of melatonin receptor 1B gene polymorphism and its effect on the regulation of glucose transport in gestational diabetes mellitus.

Melatonin receptor 1B (MT2, encoded by the MTNR1B gene), a high-affinity receptor for melatonin, is associated with glucose homeostasis including glucose uptake and transport. The rs10830963 variant in the MTNR1B gene is linked to glucose metabolism disorders including gestational diabetes mellitus (GDM); however, the relationship between MT2-mediated melatonin signaling and a high birth weight of GDM infants from maternal glucose abnormality remains poorly understood. This article aims to investigate the relationship between rs10830963 variants and GDM development, as well as the effects of MT2 receptor on glucose uptake and transport in trophoblasts. TaqMan-MGB (minor groove binder) probe quantitative real-time polymerase chain reaction (qPCR) assays were used for rs10930963 genotyping. MT2 expression in the placenta of GDM and normal pregnant women was detected by immunofluorescence, western blot, and qPCR. The relationship between MT2 and glucose transporters (GLUTs) or peroxisome proliferator-activated receptor γ (PPARγ) was established by western blot, and glucose consumption of trophoblasts was measured by a glucose assay kit. The results showed that the genotype and allele frequencies of rs10830963 were significantly different between GDM and normal pregnant women (P<0.05). The fasting, 1-h and 2-h plasma glucose levels of G-allele carriers were significantly higher than those of C-allele carriers (P<0.05). Besides, the protein and messenger RNA (mRNA) expression of MT2 in the placenta of GDM was significantly higher than that of normal pregnant women (P<0.05). Melatonin could stimulate glucose uptake and GLUT4 and PPARγ protein expression in trophoblasts, which could be attenuated by MT2 receptor knockdown. In conclusion, the rs10830963 variant was associated with an increased risk of GDM. The MT2 receptor is essential for melatonin to raise glucose uptake and transport, which may be mediated by PPARγ.

Hypomethylation in MTNR1B: a novel epigenetic marker for atherosclerosis profiling using stenosis radiophenotype and blood inflammatory cells.

BACKGROUND: Changes in gene-specific promoter methylation may result from aging and environmental influences. Atherosclerosis is associated with aging and environmental effects. Thus, promoter methylation profiling may be used as an epigenetic tool to evaluate the impact of aging and the environment on atherosclerosis development. However, gene-specific methylation changes are currently inadequate epigenetic markers for predicting atherosclerosis and cardiovascular disease pathogenesis. RESULTS: We profiled and validated changes in gene-specific promoter methylation associated with atherosclerosis using stenosis radiophenotypes of cranial vessels and blood inflammatory cells rather than direct sampling of atherosclerotic plaques. First, we profiled gene-specific promoter methylation changes using digital restriction enzyme analysis of methylation (DREAM) sequencing in peripheral blood mononuclear cells from eight samples each of cranial vessels with and without severe-stenosis radiophenotypes. Using DREAM sequencing profiling, 11 tags were detected in the promoter regions of the ACVR1C, ADCK5, EFNA2, ENOSF1, GLS2, KNDC1, MTNR1B, PACSIN3, PAX8-AS1, TLDC1, and ZNF7 genes. Using methylation evaluation, we found that EFNA2, ENOSF1, GLS2, KNDC1, MTNR1B, PAX8-AS1, and TLDC1 showed > 5% promoter methylation in non-plaque intima, atherosclerotic vascular tissues, and buffy coats. Using logistic regression analysis, we identified hypomethylation of MTNR1B as an independent variable for the stenosis radiophenotype prediction model by combining it with traditional atherosclerosis risk factors including age, hypertension history, and increases in creatinine, lipoprotein (a), and homocysteine. We performed fivefold cross-validation of the prediction model using 384 patients with ischemic stroke (50 [13%] no-stenosis and 334 [87%] > 1 stenosis radiophenotype). For the cross-validation, the training dataset included 70% of the dataset. The prediction model showed an accuracy of 0.887, specificity to predict stenosis radiophenotype of 0.940, sensitivity to predict no-stenosis radiophenotype of 0.533, and area under receiver operating characteristic curve of 0.877 to predict stenosis radiophenotype from the test dataset including 30% of the dataset. CONCLUSIONS: We identified and validated MTNR1B hypomethylation as an epigenetic marker to predict cranial vessel atherosclerosis using stenosis radiophenotypes and blood inflammatory cells rather than direct atherosclerotic plaque sampling.

Role of melatonin receptor 1B gene polymorphism and its effect on the regulation of glucose transport in gestational diabetes mellitus / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Melatonin receptor 1B (MT2, encoded by the MTNR1B gene), a high-affinity receptor for melatonin, is associated with glucose homeostasis including glucose uptake and transport. The rs10830963 variant in the MTNR1B gene is linked to glucose metabolism disorders including gestational diabetes mellitus (GDM); however, the relationship between MT2-mediated melatonin signaling and a high birth weight of GDM infants from maternal glucose abnormality remains poorly understood. This article aims to investigate the relationship between rs10830963 variants and GDM development, as well as the effects of MT2 receptor on glucose uptake and transport in trophoblasts. TaqMan-MGB (minor groove binder) probe quantitative real-time polymerase chain reaction (qPCR) assays were used for rs10930963 genotyping. MT2 expression in the placenta of GDM and normal pregnant women was detected by immunofluorescence, western blot, and qPCR. The relationship between MT2 and glucose transporters (GLUTs) or peroxisome proliferator-activated receptor γ (PPARγ) was established by western blot, and glucose consumption of trophoblasts was measured by a glucose assay kit. The results showed that the genotype and allele frequencies of rs10830963 were significantly different between GDM and normal pregnant women (P<0.05). The fasting, 1-h and 2-h plasma glucose levels of G-allele carriers were significantly higher than those of C-allele carriers (P<0.05). Besides, the protein and messenger RNA (mRNA) expression of MT2 in the placenta of GDM was significantly higher than that of normal pregnant women (P<0.05). Melatonin could stimulate glucose uptake and GLUT4 and PPARγ protein expression in trophoblasts, which could be attenuated by MT2 receptor knockdown. In conclusion, the rs10830963 variant was associated with an increased risk of GDM. The MT2 receptor is essential for melatonin to raise glucose uptake and transport, which may be mediated by PPARγ.