Major depressive disorder-associated SIRT1 locus affects the risk for suicide in women after middle age

Investigating the relationship between DNA methylation, genetic variation, and suicide attempt in bipolar disorder

Individuals with bipolar disorder are at increased risk for suicide, and this can be influenced by a range of biological, clinical, and environmental risk factors. Biological components associated with suicide include DNA modifications that lead to changes in gene expression. Common genetic variation and DNA methylation changes are some of the most frequent types of DNA findings associated with an increased risk for suicidal behavior. Importantly, the interplay between genetic predisposition and DNA methylation patterns is becoming more prevalent in genetic studies. We hypothesized that DNA methylation patterns in specific loci already genetically associated with suicide would be altered in individuals with bipolar disorder and a history of suicide attempt. To test this hypothesis, we searched the literature to identify common genetic variants (N=34) previously associated with suicidal thoughts and behaviors in individuals with bipolar disorder. We then created a customized sequencing panel that covered our chosen genomic loci. We profiled DNA methylation patterns from blood samples collected from bipolar disorder participants with suicidal behavior (N=55) and without suicidal behavior (N=51). We identified seven differentially methylated CpG sites and five differentially methylated regions between the two groups. Additionally, we found that DNA methylation changes in MIF and CACNA1C were associated with lethality or number of suicide attempts. Finally, we identified three meQTLs in SIRT1 , IMPA2 , and INPP1 . This study illustrates that DNA methylation is altered in individuals with bipolar disorder and a history of suicide attempts in regions known to harbor suicide-related variants.

The role of polyunsaturated fatty acids in the neurobiology of major depressive disorder and suicide risk

Long-chain polyunsaturated fatty acids (LC-PUFAs) are obtained from diet or derived from essential shorter-chain fatty acids, and are crucial for brain development and functioning. Fundamentally, LC-PUFAs' neurobiological effects derive from their physicochemical characteristics, including length and double bond configuration, which differentiate LC-PUFA species and give rise to functional differences between n(omega)-3 and n-6 LC-PUFAs. LC-PUFA imbalances are implicated in psychiatric disorders, including major depression and suicide risk. Dietary intake and genetic variants in enzymes involved in biosynthesis of LC-PUFAs from shorter chain fatty acids influence LC-PUFA status. Domains impacted by LC-PUFAs include 1) cell signaling, 2) inflammation, and 3) bioenergetics. 1) As major constituents of lipid bilayers, LC-PUFAs are determinants of cell membrane properties of viscosity and order, affecting lipid rafts, which play a role in regulation of membrane-bound proteins involved in cell-cell signaling, including monoaminergic receptors and transporters. 2) The n-3:n-6 LC-PUFA balance profoundly influences inflammation. Generally, metabolic products of n-6 LC-PUFAs (eicosanoids) are pro-inflammatory, while those of n-3 LC-PUFAs (docosanoids) participate in the resolution of inflammation. Additionally, n-3 LC-PUFAs suppress microglial activation and the ensuing proinflammatory cascade. 3) N-3 LC-PUFAs in the inner mitochondrial membrane affect oxidative stress, suppressing production of and scavenging reactive oxygen species (ROS), with neuroprotective benefits. Until now, this wealth of knowledge about LC-PUFA biomechanisms has not been adequately tapped to develop translational studies of LC-PUFA clinical effects in humans. Future studies integrating neurobiological mechanisms with clinical outcomes may suggest ways to identify depressed individuals most likely to respond to n-3 LC-PUFA supplementation, and mechanistic research may generate new treatment strategies.

Personality traits as mediators in the association between SIRT1 rs12415800 polymorphism and depressive symptoms among Chinese college students

Background

Previous research has linked polymorphisms in the SIRT1 gene to depressive symptoms, particularly in Chinese individuals. However, it is not clear how personality traits may contribute to this association.

Methods

To explore the potential mediating effect of personality traits, we utilized a mediation model to examine the relationship between the SIRT1 rs12415800 polymorphism and depressive symptoms in 787 Chinese college students. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale, while personality traits were measured using the Big Five Inventory (BFI).

Results

Our analysis indicated a significant association between the SIRT1 rs12415800 polymorphism and depressive symptoms, with this relationship partially mediated by the personality traits of neuroticism and conscientiousness. Specifically, individuals who were heterozygous for the rs12415800 polymorphism and had higher levels of conscientiousness were less likely to experience depressive symptoms. Conversely, those who were homozygous for the rs12415800 polymorphism and had higher levels of neuroticism were more likely to experience depressive symptoms.

Conclusion

Our results suggest that personality traits, particularly neuroticism and conscientiousness, may play a critical role in the association between the SIRT1 rs12415800 polymorphism and depressive symptoms among Chinese college students. These findings highlight the importance of considering both genetic factors and personality traits when exploring the etiology of depressive symptoms in this population.

Effects of Histone Modification in Major Depressive Disorder

Major depressive disorder (MDD) is a disease associated with many factors; specifically, environmental, genetic, psychological, and biological factors play critical roles. Recent studies have demonstrated that histone modification may occur in the human brain in response to severely stressful events, resulting in transcriptional changes and the development of MDD. In this review, we discuss five different histone modifications, histone methylation, histone acetylation, histone phosphorylation, histone crotonylation and histone β-hydroxybutyrylation, and their relationships with MDD. The utility of histone deacetylase (HDAC) inhibitors (HDACis) for MDD treatment is also discussed. As a large number of MDD patients in China have been treated with traditional Chineses medicine (TCM), we also discuss some TCM therapies, such as Xiaoyaosan (XYS), and their effects on histone modification. In summary, targeting histone modification may be a new strategy for elucidating the mechanism of MDD and a new direction for MDD treatment.

Interaction between Sirtuin 1 (SIRT1) polymorphisms and childhood maltreatment on aggression risk in Chinese male adolescents

BACKGROUND

Aggressive behavior is a highly prevalent and serious public health problem among adolescents. However, the etiology and pathogenesis of aggressive behavior remain unclear. Childhood maltreatment is an acknowledged factor for aggressive behavior. SIRT1 is closely related to the occurrence and development of psychiatric disorders. We aimed to reveal the interactive effect between SIRT1 and childhood maltreatment on aggressive behavior among Chinese adolescents.

METHODS

Aggressive behavior and childhood maltreatment were evaluated by the Buss and Warren's Aggression Questionnaire (BWAQ) and short form Childhood Trauma Questionnaire (CTQ-SF), respectively. This study comprised 436 aggression cases and 435 controls. Four SIRT1 tagSNPs were selected for genotyping. Interaction between SIRT1 and childhood maltreatment was estimated by logistic regression models.

RESULTS

Individuals carrying SIRT1 rs4746720 minor allele and TAAC haplotype derived from SIRT1 variants was associated with reduced aggression risk when childhood maltreatment occurred (all P < 0.01). An antagonistic additive interaction between SIRT1 rs4746720 and childhood maltreatment on aggressive behavior (S = 0.421; 95%CI: 0.234 to 0.758) was further testified. No main effect of the SIRT1 SNPs or the haplotype block was observed (all P > 0.05).

LIMITATIONS

Since participants were only males, our findings were unable to be directly extended to females. Cross-sectional design, self-reported measurements and limited sample size were adopted.

CONCLUSION

This study provides the first evidence of SIRT1 × childhood maltreatment interaction on aggressive behavior in male adolescents. The minor allele of SIRT1 rs4746720 presents a protective effect on combination with childhood maltreatment on the risk of aggressive behavior.

Relationship between SIRT1 gene and adolescent depressive disorder with nonsuicidal self-injury behavior: Based on gene methylation and mRNA expression

OBJECTIVE

The incidence of non-suicidal self-injury (NSSI) behavior in adolescents is increasing year by year. Patients with a history of both depression and NSSI behavior tend to be at greater risk for suicide. At present, the mechanism of adolescent depressive disorder with NSSI behavior is not clear and still in research and exploration. The expression of the Silent Information Regulator 2 Related Enzyme 1 (SIRT1) gene is closely related to the level of serotonin in molecular mechanisms, and may be closely related to the occurrence and development of depressive disorder. This study aimed to explore the relationship between the SIRT1 gene and NSSI behaviors in adolescents with depressive disorder.

METHODS

A total of 15 adolescent depressed patients with NSSI behavior and 15 healthy controls were enrolled in the study. Bisulfite Sequencing PCR (BSP) was used to test the methylation level of SIRT1 gene promoter region of the participants. The real-time fluorescent quantitative PCR was conducted to measure the mRNA expression level of SIRT1 gene.

RESULTS

Our study found that the methylation level of SIRT1 gene promoter region at cytosine-guanine dinucleotide 5 (CpG5) site in depression group was higher than that of control group. Compared with that of control group, the plasma concentration of Sirt1 protein significantly decreased in depression group.

CONCLUSION

Our study investigated the methylation level and the mRNA expression of SIRT1 gene in adolescent depressive patients with NSSI behavior. The study points towards finding an in vivo molecular marker for those adolescent patients.

The Molecular Basis of Depression: Implications of Sex-Related Differences in Epigenetic Regulation

Major depressive disorder (MDD) is a leading cause of disability worldwide. Although the etiology and pathophysiology of MDD remain poorly understood, aberrant neuroplasticity mediated by the epigenetic dysregulation of gene expression within the brain, which may occur due to genetic and environmental factors, may increase the risk of this disorder. Evidence has also been reported for sex-related differences in the pathophysiology of MDD, with female patients showing a greater severity of symptoms, higher degree of functional impairment, and more atypical depressive symptoms. Males and females also differ in their responsiveness to antidepressants. These clinical findings suggest that sex-dependent molecular and neural mechanisms may underlie the development of depression and the actions of antidepressant medications. This review discusses recent advances regarding the role of epigenetics in stress and depression. The first section presents a brief introduction of the basic mechanisms of epigenetic regulation, including histone modifications, DNA methylation, and non-coding RNAs. The second section reviews their contributions to neural plasticity, the risk of depression, and resilience against depression, with a particular focus on epigenetic modulators that have causal relationships with stress and depression in both clinical and animal studies. The third section highlights studies exploring sex-dependent epigenetic alterations associated with susceptibility to stress and depression. Finally, we discuss future directions to understand the etiology and pathophysiology of MDD, which would contribute to optimized and personalized therapy.

SIRT1 and SIRT2 Modulators: Potential Anti-Inflammatory Treatment for Depression?

Depression is a psychiatric disorder that has a significant health burden on patients and their families. Unfortunately, the current antidepressant medications that mainly target monoamine neurotransmitters have limited efficacy. Recent evidence has indicated that neuroinflammation participates in the genesis and development of depression, and interacts with other factors involved in depression. Therefore, exploring effective anti-inflammatory medications could be beneficial for the development of new treatment options for depression. Sirtuins are a unique class of nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylases, which have seven members that can affect multiple downstream targets by deacetylation activity. Among these seven members, SIRT1 and SIRT2 have been shown to participate in the pathophysiology of inflammation in numerous studies. Thus, in this short article, we review the association of SIRT1 and SIRT2 activity and depression, and evidence of the effects of SIRT1 and SIRT2 modulators on inflammation in vitro and depressive-like behaviours in vivo.

Understanding the Complex of Suicide in Depression: from Research to Clinics

OBJECTIVE

Amongst psychiatric disorders, major depressive disorder (MDD) is the most prevalent, by affecting approximately 15-17% of the population and showing a high suicide risk rate equivalent to around 15%. The present comprehensive overview aims at evaluating main research studies in the field of MDD at suicide risk, by proposing as well as a schematic suicide risk stratification and useful flow-chart for planning suicide preventive and therapeutic interventions for clinicians.

METHODS

A broad and comprehensive overview has been here conducted by using PubMed/Medline, combining the search strategy of free text terms and exploded MESH headings for the topics of 'Major Depressive Disorder' and 'Suicide' as following: ((suicide [Title/Abstract]) AND (major depressive disorder [Title/Abstract])). All articles published in English through May 31, 2019 were summarized in a comprehensive way.

RESULTS

Despite possible pathophysiological factors which may explain the complexity of suicide in MDD, scientific evidence supposed the synergic role of genetics, exogenous and endogenous stressors (i.e., interpersonal, professional, financial, as well as psychiatric disorders), epigenetic, the hypothalamic-pituitary-adrenal stress-response system, the involvement of the monoaminergic neurotransmitter systems, particularly the serotonergic ones, the lipid profile, neuro-immunological biomarkers, the Brain-derived neurotrophic factor and other neuromodulators.

CONCLUSION

The present overview reported that suicide is a highly complex and multifaceted phenomenon in which a large plethora of mechanisms could be variable implicated, particularly amongst MDD subjects. Beyond these consideration, modern psychiatry needs a better interpretation of suicide risk with a more careful assessment of suicide risk stratification and planning of clinical and treatment interventions.