Maoa and Maob polymorphisms and personality traits in suicide attempters and healthy controls: a preliminary study

Impact of genetic variants within serotonin turnover enzymes on human cerebral monoamine oxidase A in vivo

Variants within the monoamine oxidase A (MAO-A, MAOA) and tryptophan hydroxylase 2 (TPH2) genes, the main enzymes in cerebral serotonin (5-HT) turnover, affect risk for depression. Depressed cohorts show increased cerebral MAO-A in positron emission tomography (PET) studies. TPH2 polymorphisms might also influence brain MAO-A because availability of substrates (i.e. monoamine concentrations) were shown to affect MAO-A levels. We assessed the effect of MAOA (rs1137070, rs2064070, rs6323) and TPH2 (rs1386494, rs4570625) variants associated with risk for depression and related clinical phenomena on global MAO-A distribution volume (VT) using [11C]harmine PET in 51 participants (21 individuals with seasonal affective disorder (SAD) and 30 healthy individuals (HI)). Statistical analyses comprised general linear models with global MAO-A VT as dependent variable, genotype as independent variable and age, sex, group (individuals with SAD, HI) and season as covariates. rs1386494 genotype significantly affected global MAO-A VT after correction for age, group and sex (p < 0.05, corr.), with CC homozygotes showing 26% higher MAO-A levels. The role of rs1386494 on TPH2 function or expression is poorly understood. Our results suggest rs1386494 might have an effect on either, assuming that TPH2 and MAO-A levels are linked by their common product/substrate, 5-HT. Alternatively, rs1386494 might influence MAO-A levels via another mechanism, such as co-inheritance of other genetic variants. Our results provide insight into how genetic variants within serotonin turnover translate to the cerebral serotonin system. Clinicaltrials.gov Identifier: NCT02582398. EUDAMED Number: CIV-AT-13-01-009583.

Interactions of Carbohydrate Intake and Physical Activity with Regulatory Genes Affecting Glycaemia: A Food4Me Study Analysis

INTRODUCTION

Carbohydrate intake and physical activity are related to glucose homeostasis, both being influenced by individual genetic makeup. However, the interactions between these 2 factors, as affected by genetics, on glycaemia have been scarcely reported.

OBJECTIVE

We focused on analysing the interplay between carbohydrate intake and physical activity levels on blood glucose, taking into account a genetic risk score (GRS), based on SNPs related to glucose/energy metabolism.

METHODS

A total of 1,271 individuals from the Food4Me cohort, who completed the nutritional intervention, were evaluated at baseline. We collected dietary information by using an online-validated food frequency questionnaire, a questionnaire on physical activity, blood biochemistry by analysis of dried blood spots, and by analysis of selected SNPs. Fifteen out of 31 SNPs, with recognized participation in carbohydrate/energy metabolism, were included in the component analyses. The GRS included risk alleles involved in the control of glycaemia or energy-yielding processes.

RESULTS

Data concerning anthropometric, clinical, metabolic, dietary intake, physical activity, and genetics related to blood glucose levels showed expected trends in European individuals of comparable sex and age, being categorized by lifestyle, BMI, and energy/carbohydrate intakes, in this Food4Me population. Blood glucose was inversely associated with physical activity level (β = -0.041, p = 0.013) and positively correlated with the GRS values (β = 0.015, p = 0.047). Interestingly, an interaction affecting glycaemia, concerning physical activity level with carbohydrate intake, was found (β = -0.060, p = 0.033), which also significantly depended on the genetic background (GRS).

CONCLUSIONS

The relationships of carbohydrate intake and physical activity are important in understanding glucose homeostasis, where a role for the genetic background should be ascribed.

Monoamino Oxidase A Gene Single-Nucleotide Polymorphisms and Methylation Status and the Risk of Violent Suicide Attempts in Affective Disorder Patients

Background: When investigating the neurobiology of suicidal behavior, Monoamino Oxidase A (MAOA) is one of the prime suspects to consider. Interestingly, MAOA dysregulation has also been associated with violent behavior in previous publications. In the present study, we aimed to establish an association between polymorphisms of the MAOA gene and methylation status of the MAOA gene Exon I, and suicide attempts with violent methods in a sample of affective disorder patients. Methods: Eight hundred fourteen Caucasian affective disorder patients were assessed at the Department of Psychiatry and Psychotherapy of the Medical University Vienna, the Karl Landsteiner University for Health and Science and Zentren für seelische Gesundheit, BBRZ-Med Leopoldau. An assemblage of psychiatric interviews was performed (e.g., SCAN, HAMD, SBQ-R, CTQ) and DNA samples of peripheral blood cells were collected for Sequenom MassARRAY® iPLEX Gold genotyping and Multiplexed and Sensitive DNA Methylation Testing. Results: Female affective disorder patients with a history of violent suicide attempt were found to have a significantly increased frequency of the AA genotype in the rs5906957 single nucleotide polymorphism (p = 0.003). Furthermore, the MAOA gene exon I promoter region showed significantly decreased methylation in female violent suicide attempter(s) as opposed to female affective disorder patients who had no history of suicide attempt or no history of suicide attempt with violent method. Limitations: The small sample size hampers to reveal small genetic effects as to be expected in psychiatric disorders. Conclusions: This study offers promising findings about associations between the MAOA gene and violent suicide especially in women.

miR-522 facilitates the prosperities of endometrial carcinoma cells by directly binding to monoamine oxidase B

It is well known that microRNAs (miRNAs) are crucial regulatory factors in tumorigenesis, as tumor suppressors or cancer-promoting factors. However, the study of endometrial carcinoma relevance in miR-522 is rare, indicating an undefined molecular mechanism for its role. Therefore, we performed this study to examine the role of miR-522 on the biological behaviors of endometrial carcinoma. In this work, we found that miR-522 was highly expressed in endometrial carcinoma and negatively regulated monoamine oxidase B (MAOB) expression. They also have the opposite effect on prognosis of endometrial carcinoma patients. More importantly, miR-522 could decreased MAOB expression by binding to MAOB with a putative site, thereby promoting cell proliferation, migration, and invasion through in vitro functional analyses, including MTT assay, wound-healing and transwell invasion experiments. Upregulation of MAOB rescued the impacts of miR-522 mimic on cell behaviors. In conclusion, our observations demonstrated that miR-522 accelerated the progression of endometrial carcinoma by inhibiting MAOB, which might lead to a novel therapeutic therapy for endometrial carcinoma.

Single nucleotide polymorphisms, variable number tandem repeats and allele influence on serotonergic enzyme modulators for aggressive and suicidal behaviors: A review

The serotonergic system plays key regulatory roles in cognition and emotion. Several lines of evidence suggest that genetic variation is associated with aggressive and suicidal behaviors. Genetic studies have largely focused on three types of variations: single nucleotide polymorphisms (SNPs), variable number tandem repeats (VNTRs), and alleles. 95 published papers (49 papers for aggression and 46 for suicide) were reviewed to summarize the impact of SNPs, VNTRs, and alleles of tryptophan hydroxylase (TPH, the rate-limiting enzyme in serotonin [5-HT] synthesis), 5-HT transporter (5-HTT), serotonergic receptors, monoamine oxidase (an enzyme that catalyzes 5-HT degradation) on aggression and suicidal behaviors. These study samples include healthy controls, psychiatric disease patients, and animal models. This article mainly reviews studies on the relationship between 5-HT transmissions and genetic variations involved in aggression (particularly impulsive aggression) or suicide in people with different ethnicities and psychiatric disorders. We found that most SNPs, VNTRs, and alleles exerted influences on aggression or suicide. Only A128C in TPH1, A138G in 5-HT2A, and L type in the VNTR of monoamine oxidase A (MAOA) affected both aggression and suicide. The associations between some genetic variations and aggression/suicide may be influenced by gender, age, ethnicity, psychiatric disease, and even parenting or prenatal stress. These findings may help clarify how genetic and environmental factors influence the development of aggressive and suicidal behaviors.