A common polymorphism in serotonin receptor 1B mRNA moderates regulation by miR-96 and associates with aggressive human behaviors

5-HTP inhibits eosinophilia via intracellular endothelial 5-HTRs; SNPs in 5-HTRs associate with asthmatic lung function

Background

Previous research showed that 5-hydroxytryptophan (5HTP), a metabolic precursor of serotonin, reduces allergic lung inflammation by inhibiting eosinophil migration across endothelial monolayers.

Objective

It is unknown if serotonin receptors are involved in mediating this 5HTP function or if serotonin receptor (HTR) single nucleotide polymorphisms (SNPs) associate with lung function in humans.

Methods

Serotonin receptor subtypes were assessed by qPCR, western blot, confocal microscopy, pharmacological inhibitors and siRNA knockdown. HTR SNPs were assessed in two cohorts.

Results

Pharmacological inhibition or siRNA knockdown of the serotonin receptors HTR1A or HTR1B in endothelial cells abrogated the inhibitory effects of 5HTP on eosinophil transendothelial migration. In contrast, eosinophil transendothelial migration was not inhibited by siRNA knockdown of HTR1A or HTR1B in eosinophils. Surprisingly, these HTRs were intracellular in endothelial cells and an extracellular supplementation with serotonin did not inhibit eosinophil transendothelial migration. This is consistent with the inability of serotonin to cross membranes, the lack of selective serotonin reuptake receptors on endothelial cells, and the studies showing minimal impact of selective serotonin reuptake inhibitors on asthma. To extend our HTR studies to humans with asthma, we examined the CHIRAH and GALA cohorts for HTR SNPs that affect HTR function or are associated with behavior disorders. A polygenic index of SNPs in HTRs was associated with lower lung function in asthmatics.

Conclusions

Serotonin receptors mediate 5HTP inhibition of transendothelial migration and HTR SNPs associate with lower lung function. These results may serve to aid in design of novel interventions for allergic inflammation.

The potential role of miRNAs in the pathogenesis of schizophrenia - A focus on signaling pathways interplay

microRNAs (miRNAs) play a crucial role in brain growth and function. Hence, research on miRNA has the potential to reveal much about the etiology of neuropsychiatric diseases. Among these, schizophrenia (SZ) is a highly intricate and destructive neuropsychiatric ailment that has been thoroughly researched in the field of miRNA. Despite being a relatively recent area of study about miRNAs and SZ, this discipline has advanced enough to justify numerous reviews that summarize the findings from the past to the present. However, most reviews cannot cover all research, thus it is necessary to synthesize the large range of publications on this topic systematically and understandably. Consequently, this review aimed to provide evidence that miRNAs play a role in the pathophysiology and progression of SZ. They have also been investigated for their potential use as biomarkers and therapeutic targets.

A Functional Single Nucleotide Polymorphism in the 3' Untranslated Region of the Porcine JARID2 Gene Is Associated with Aggressive Behavior of Weaned Pigs after Mixing

In pig production, pigs often show more aggressive behavior after mixing, which adversely affects animal welfare and growth performance. The Jumonji and structural domain-rich AT interaction domain 2 (JARID2) gene plays an important role in neurodevelopment in mice and various psychiatric disorders in humans. The JARID2 gene may impact the aggressive behavior of pigs. By observing the behavior of 500 weaned pigs during the first 72 h after mixing, the ear tissue samples of the 12 most aggressive and 12 least aggressive pigs were selected for DNA resequencing based on the intensity of their aggressive behavior. Large group correlation analysis indicated that the rs3262221458 site located in the 3'-UTR region of the porcine JARID2 gene has a strong relationship with the aggressive behavior of weaned pigs. Pigs with the mutant TT genotype of rs3262221458 have more aggressive behavior than those pigs with the GG and GT genotypes. The dual luciferase assay indicated that the luciferase activity of the plasmids containing the G allele of rs326221458 was significantly less than that of plasmids containing the T allele of rs326221458 and control groups. The binding ability of miR-9828-3p to sequences containing the T allele was less than that of sequences containing the G allele. The overexpression of miR-9828-3p in porcine neuroglial cells (PNGCs) and PK15 cells significantly decreased the mRNA and protein levels of the JARID2 gene. In addition, miR-9828-3p inhibited the proliferation of PNGCs. After inhibiting miR-9828-3p, the mRNA and protein expression levels of JARID2 increased, and the proliferation of PNGCs showed an opposite trend to the cells that forced the expression of miR-9828-3p. In addition, interference with the JARID2 gene by siRNA can effectively inhibit the proliferation of PNGCs. In summary, we found that the rs326221458 locus regulates the expression of the JARID2 gene by affecting the binding of miR-9828-3p and the JARID2 gene, thereby affecting the aggressive behavior of weaned pigs after mixing.

Genetic Variants and Their Putative Effects on microRNA-Seed Sites: Characterization of the 3' Untranslated Region of Genes Associated with Temperament

The 3' untranslated region has an important role in gene regulation through microRNAs, and it has been estimated that microRNAs regulate up to 50% of coding genes in mammals. With the aim of allelic variant identification of 3' untranslated region microRNA seed sites, the 3' untranslated region was searched for seed sites of four temperament-associated genes (CACNG4, EXOC4, NRXN3, and SLC9A4). The microRNA seed sites were predicted in the four genes, and the CACNG4 gene had the greatest number with 12 predictions. To search for variants affecting the predicted microRNA seed sites, the four 3' untranslated regions were re-sequenced in a Brahman cattle population. Eleven single nucleotide polymorphisms were identified in the CACNG4, and eleven in the SLC9A4. Rs522648682:T>G of the CACNG4 gene was located at the predicted seed site for bta-miR-191. Rs522648682:T>G evidenced an association with both exit velocity (p = 0.0054) and temperament score (p = 0.0097). The genotype TT had a lower mean exit velocity (2.93 ± 0.4 m/s) compared with the TG and GG genotypes (3.91 ± 0.46 m/s and 3.67 ± 0.46 m/s, respectively). The allele associated with the temperamental phenotype antagonizes the seed site, disrupting the bta-miR-191 recognition. The G allele of CACNG4-rs522648682 has the potential to influence bovine temperament through a mechanism associated with unspecific recognition of bta-miR-191.

Serotonin Receptor Gene Polymorphisms Are Associated with Cerebrospinal Fluid, Genetic, and Neuropsychological Biomarkers of Alzheimer's Disease

A decrease in serotonergic transmission throughout the brain is among the earliest pathological changes in Alzheimer's disease (AD). Serotonergic receptors are also affected in AD. Polymorphisms in genes of serotonin (5HT) receptors have been mostly associated with behavioral and psychological symptoms of dementia (BPSD). In this study, we examined if AD patients carrying different genotypes in 5HTR1B rs13212041, 5HTR2A rs6313 (T102C), 5HTR2C rs3813929 (-759C/T), and 5HTR6 rs1805054 (C267T) polymorphisms have a higher risk of faster disease progression (assessed by neuropsychological testing), are more prone to develop AD-related pathology (reflected by levels of cerebrospinal fluid [CSF] AD biomarkers), or have an association with an apolipoprotein E (APOE) haplotype. This study included 115 patients with AD, 53 patients with mild cognitive impairment (MCI), and 2701 healthy controls. AD biomarkers were determined in the CSF of AD and MCI patients using enzyme-linked immunosorbent assays (ELISA), while polymorphisms were determined using either TaqMan SNP Genotyping Assays or Illumina genotyping platforms. We detected a significant decrease in the CSF amyloid β1-42 (Aβ1-42) and an increase in p-tau181/Aβ1-42 ratio in carriers of the T allele in the 5HTR2C rs3813929 (-759C/T) polymorphism. A significantly higher number of APOE ε4 allele carriers was observed among individuals carrying a TT genotype within the 5HTR2A T102C polymorphism, a C allele within the 5HTR1B rs13212041 polymorphism, and a T allele within the 5HTR6 rs1805054 (C267T) polymorphism. Additionally, individuals carrying the C allele within the 5HTR1B rs13212041 polymorphism were significantly more represented among AD patients and had poorer performances on the Rey-Osterrieth test. Carriers of the T allele within the 5HTR6 rs1805054 had poorer performances on the MMSE and ADAS-Cog. As all four analyzed polymorphisms of serotonin receptor genes showed an association with either genetic, CSF, or neuropsychological biomarkers of AD, they deserve further investigation as potential early genetic biomarkers of AD.

HTR1B genotype and psychopathy: Main effect and interaction with paternal maltreatment

Psychopathy is a condition characterized by atypical emotions and socially maladaptive behavioral patterns. Among incarcerated people, psychopathy has been associated with higher rates of crimes, recidivism, and resistance to treatment. Many studies have indicated significant heritability of psychopathic traits, but little is known about the specific contribution of genes and their interaction with adverse experiences in life. Considering the primary role that serotonin plays in cognition and emotion, we investigated TPH2-rs4570625, 5-HTTLPR, MAOA-uVNTR, HTR1B-rs13212041 and HTR2A-rs6314 as risk factors for psychopathy in the largest sample of institutionalized individuals studied so far, consisting of 793 US White male incarcerated adults, and in a replication sample of 168 US White male incarcerated adolescents. In a subgroup of the adult sample, the interaction between genetics and parenting style, assessed by the Measure of Parental Style (MOPS) questionnaire, was also evaluated. The HTR1B-rs13212041-T/T genotype, as compared to HTR1B-rs13212041-C allele, predicted higher psychopathy scores in both the adult and the adolescent samples. The interaction between HTR1B-rs13212041-T/T genotype and paternal MOPS scores, investigated in a subgroup of the adult sample, was an even stronger predictor of higher levels of psychopathy than either the genetics or the environment taken individually. Overall, these data, obtained in two independent samples, shed new light on neurobiological correlates of psychopathy with promising implications both at a clinical and forensic level.

Identification of Functional Single Nucleotide Polymorphisms in the Porcine SLC6A4 Gene Associated with Aggressive Behavior in Weaned Pigs after Mixing

Variation in genes of the serotonergic system influence aggressive behavior by affecting serotonin levels in the central and cortical nervous system. SLC6A4 (serotonin transporter) is a master regulator of 5-HT signaling and involved in the regulation of aggressive behavior in humans and rodents. To identify potential functional single nucleotide polymorphisms (SNPs) for the porcine SLC6A4 gene associated with aggressive behavior, a total of 500 pigs (268 barrows and 232 gilts) were selected and mixed in 51 pens. Their behavior was recorded and observed for 72 h after mixing. Based on a composite aggressive score (CAS), the most aggressive and the least aggressive pigs within each pen were selected separately (a total of 204 pigs). Ear tissue was sampled to extract genomic DNA. Eight SNPs in the 5'-flanking region, coding region, and 3'-untranslated region (3'-UTR) of SLC6A4 were genotyped, of which 6 SNPs had significant differences (P < 0.05) in allele frequency between the most aggressive and least aggressive pigs. Luciferase activity was greater in plasmids of genotype GG than plasmids of genotype CC of rs345058216 (P < 0.01). Computational analysis nominated MAZ as putative transcription factor (TF) with higher probability to bind the SLC6A4 promoter at the SNP (rs345058216) site. Also, we demonstrated that MAZ overexpression modulates SLC6A4 promoter activity in allele-specific manner with an in vitro assay. In addition, we demonstrated that SLC6A4 was a direct target of miR-671-5p. The dual luciferase reporter gene assay and cell transfection were performed to examine the role of miR-671-5p in regulating SLC6A4 expression. The luciferase assays revealed that the SNP rs332335871 affects regulation of miR-671-5p in SLC6A4 expression. After overexpression of miR-671-5p in porcine primary neural cells, the SLC6A4 mRNA levels can be significantly reduced. In conclusion, we here found that miR-671-5p and MAZ mediated porcine SLC6A4 expression level, which provides the possible molecular mechanism of aggressive behavior.

Exploring Association Between Serotonin and Neurogenesis Related Genes in Obsessive-Compulsive Disorder in Chinese Han People: Promising Association Between DMRT2, miR-30a-5p, and Early-Onset Patients

Obsessive-compulsive disorder (OCD) is a deliberating disorder with complex genetic and environmental etiologies. Hypotheses about OCD mainly include dysregulated neurotransmitters, especially serotonin, and disturbed neurodevelopment. Single nucleotide polymorphism (SNP) association studies regarding OCD are often met with inconsistent results. However, stratification by age of onset may sometimes help to limit the heterogenicity of OCD patients. Therefore, we conducted a stratified SNP association study enrolling 636 patients and 612 healthy controls. Patients were stratified by age of onset as early-onset (EO-OCD) and late-onset (LO-OCD). Blood extracted from the patients was used to genotype 18 loci, including serotonin system genes, Slitrk1, Slitrk5, and DMRT2 and related miRNA genes. Logistic regression was used to compare allele and genotype frequencies of variants. A general linear model was used to evaluate the association between variants and trait anxiety. In our study, rs3824419 in DMRT2 was associated with EO-OCD, G allele was the risk allele. Rs2222722 in miR-30a-5p was associated with EO-OCD, with the C allele being the risk allele. Rs1000952 in HTR3D was found associated with trait anxiety in OCD patients. The significance disappeared after FDR correction. Our results supported neurodevelopment-related genes, DMRT2 and miR-30a-5p, to be related to EO-OCD. However, we cannot prove serotonin genes to be directly associated with EO-OCD. While an association between HTR3D and trait anxiety was discovered, comparisons based on biological or clinical traits may be helpful in future studies. As our detective powers were limited, more large-scale studies will be needed to confirm our conclusion.

Forensic Value of Genetic Variants Associated with Anti-Social Behavior

Insanity defense is sometimes invoked in criminal cases, and its demonstration is usually based on a multifactorial contribution of behavioural, clinical, and neurological elements. Neuroradiological evidence of structural alterations in cerebral areas that involve decision-making and moral reasoning is often accepted as a useful tool in these evaluations. On the other hand, the genetic predisposition to anti-social behavior is still controversial. In this paper, we describe two cases of violent crimes committed by young carriers of genetic variants associated with personality disorder; both the defendants claimed to be insane at the time of the crime. We discuss these cases and review the scientific literature regarding the relationship between legal incapacity/predisposition to criminal behavior and genetic mutations. In conclusion, despite some genetic variants being able to influence several cognitive processes (like moral judgement and impulse control), there is currently no evidence that carriers of these mutations are, per se, incapable of intentionally committing crimes.

The Association between 5-Hydroxytryptamine Receptor 1B rs13212041 Polymorphism and Trait Anxiety in Chinese Han College Subjects

Trait anxiety is a vulnerable personality factor for anxiety and depression. High levels of trait anxiety confer an elevated risk for the development of anxiety and other psychiatric disorders. There is evidence that 5-hydroxytryptamine receptor 1B (5-HT1B) gene polymorphisms play an important role in emotional disorders. Genotyping for four single-nucleotide polymorphisms (SNP) (rs11568817, rs130058, rs6297, and rs13212041) was conducted for 388 high trait anxious (HTA) individuals and 463 low traitanxious (LTA) individuals in Chinese Han college subjects. The results showed that the frequencies of the C-allele and TC + CC genotype of rs13212041 in the LTA individuals were higher than that in the HTA individuals (p = 0.025 and p = 0.014, respectively). Both the C-allele and TC + CC genotype were associated with trait anxiety decreasing (OR = 0.771 and OR = 0.71, respectively). Furthermore, different gene model analysis also showed that the C allele was a protective factor for trait anxiety in Chinese Han college subjects. These findings suggest that 5-HT1B rs13212014 may play a role in trait anxiety among China Han college subjects. The rs13212014 polymorphism may be involved in decreasing the risk of trait anxiety. These results also provide a novel insight into the molecular mechanism underlying trait anxiety.

Genetic variants in miRNAs differentially expressed during brain development and their relevance to psychiatric disorders susceptibility

OBJECTIVES

MicroRNAs (miRNAs) play an important regulatory role in the expression of genes involved in brain functions during development. Genetic variants in miRNA genes may impact their regulatory function and lead to psychiatric disorders. To evaluate the role of genetic variants in genes of miRNAs differentially expressed during neurodevelopment on autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), schizophrenia (SCZ), and major depressive disorder (MDD).

METHODS

The miRNAs were identified in the literature. Summary statistics from the most recent genome-wide association studies to date were used to evaluate the association between the selected polymorphisms and each disorder in a look-up approach. In a global analysis, we compared the standardised risk effect of variants in neurodevelopment-related miRNAs with those in the remaining miRNAs from miRBase.

RESULTS

The global analysis showed that variants in neurodevelopment-related miRNAs had higher risk effects compared to the other miRNAs for SCZ (p = 0.010) and ADHD (p = 0.001). MIR33B, MIR29B2, MIR29C, MIR137, and MIR135A1 were significantly associated with SCZ, while 55.9% of the miRNAs were at least nominally associated with one or more psychiatric disorders (p < 0.05).

CONCLUSIONS

Genetic variants in neurodevelopment-related miRNAs play an important role in the genetic susceptibility of psychiatric disorders, mainly SCZ and ADHD.

miR-96 Inhibits SV2C to Promote Depression-Like Behavior and Memory Disorders in Mice

Accumulating evidence continues to emphasize the role of microRNAs as significant contributors to depression-like behavior and memory disorders. The current study aimed to investigate the mechanism by which miR-96 influences depression-like behavior and memory deficit in mice. A depression-like behavior and memory disorder mouse model was initially established by means of intraperitoneal injection with lipopolysaccharide. Memory deficits in the mice were evaluated using the Novel Object Recognition Test and Morris water maze experiments, whereas the Sucrose Preference Experiment and forced swimming experiments were performed to identify depression-like behavior in mice. The levels of tumor necrosis factor-α, malondialdehyde, superoxide dismutase, glutathione, and the monoamine transmitters 5-hydroxytryptamine and dopamine were subsequently detected in the serum. Reverse transcription-quantitative polymerase chain reaction and Western blot analysis evaluated the expression of miR-96 and SV2C expression in the CA1 hippocampal region of the mice. Finally, the relationship of miR-96 and SV2C was verified by dual-luciferase reporter gene assay. Our data indicated that the expression of miR-96 was increased, whereas that of SV2C was decreased in the CA1 region of mice exhibiting depression-like behavior and memory impairment. When miR-96 was downregulated or SV2C was overexpressed via intra-cerebroventricular injection with a miR-96 antagonist (miR-96 antagomir) or overexpression of SV2C vector, the Novel Object Recognition Test and sucrose preference index were increased, whereas the escape latency, the number of water maze platform crossings, and the immobility time of the mice were decreased. The serum levels of tumor necrosis factor-α, interleukin-1β, and malondialdehyde in the mouse CA1 region of mice were reduced, whereas the levels of superoxide dismutase and glutathione were elevated after the downregulation of miR-96 or overexpression of SV2C. Collectively, our study demonstrates that miR-96 negatively regulates the expression of SV2C, which consequently leads to depression-like behavior and memory impairment in mice. Our findings highlight the potential of miR-96-targeted therapeutics.

The neurobiology of human aggressive behavior: Neuroimaging, genetic, and neurochemical aspects

In modern societies, there is a strive to improve the quality of life related to risk of crimes which inevitably requires a better understanding of brain determinants and mediators of aggression. Neurobiology provides powerful tools to achieve this end. Pre-clinical and clinical studies show that changes in regional volumes, metabolism-function and connectivity within specific neural networks are related to aggression. Subregions of prefrontal cortex, insula, amygdala, basal ganglia and hippocampus play a major role within these circuits and have been consistently implicated in biology of aggression. Genetic variations in proteins regulating the synthesis, degradation, and transport of serotonin and dopamine as well as their signal transduction have been found to mediate behavioral variability observed in aggression. Gene-gene and gene-environment interactions represent additional important risk factors for aggressiveness. Considering the social burden of pathological forms of aggression, more basic and translational studies should be conducted to accelerate applications to clinical practice, justice courts, and policy making.

Effects of miR-143 and its target receptor 5-HT2B on agonistic behavior in the Chinese mitten crab (Eriocheir sinensis)

Chinese mitten crab (Eriocheir sinensis) as a commercially important species is widely cultured in China. However, E. sinensis is prone to agonistic behavior, which causes physical damage and wastes energy resources, negatively impacting their growth and survival. Therefore, understanding the regulatory mechanisms that underlie the switching of such behavior is essential for ensuring the efficient and cost-effective aquaculture of E. sinensis. The 5-HT2B receptor is a key downstream target of serotonin (5-HT), which is involved in regulating animal behavior. In this study, the full-length sequence of 5-HT2B gene was cloned. The total length of the 5-HT2B gene was found to be 3127 bp with a 236 bp 5′-UTR (untranslated region), a 779 bp 3′-UTR, and a 2112 bp open reading frame encoding 703 amino acids. Phylogenetic tree analysis revealed that the 5-HT2B amino acid sequence of E. sinensis is highly conserved with that of Cancer borealis. Using in vitro co-culture and luciferase assays, the miR-143 targets the 5-HT2B 3′-UTR and inhibits 5-HT2B expression was confirmed. Furthermore, RT-qPCR and Western blotting analyses revealed that the miR-143 mimic significantly inhibits 5-HT2B mRNA and protein expression. However, injection of miR-143 did not decrease agonistic behavior, indicating that 5-HT2B is not involved in the regulation of such behavior in E. sinensis.

Modeling endophenotypes of suicidal behavior in animals

Suicide is a major public health concern. One of the common contributors to the increased risk for suicide is the genetic constitution of individuals, which determines certain endophenotypic traits used as quantifiable measure of neurobiological functions. Therefore, a logical deconstruction of the originating endophenotypes associated with suicidal risk could provide a better understanding of this complex disorder. In this regard, non-human animals can be a useful resource to test endophenotypes of suicidal behavior and the neurobiology underlying these endophenotypes. In this review, we have focused on the neurobiological abnormalities, primarily genetic and epigenetic abnormalities, associated with suicidal behavior and the scope of their modeling in animals. This can substantially advance the current understanding of suicidal behavior manifested with certain trait-based endophenotypes and may provide an opportunity to test novel hypotheses as well as aid in the development of treatment opportunities and risk assessment.

Functional polymorphisms and transcriptional analysis in the 5' region of the human serotonin receptor 1B gene (HTR1B) and their associations with psychiatric disorders

BACKGROUND

The 5-hydroxytryptamine 1B receptor (5-HT1B) plays an essential role in the serotonin (5-HT) system and is widely involved in a variety of brain activities. HTR1B is the gene encoding 5-HT1B. Genome-wide association studies have shown that HTR1B polymorphisms are closely related to multiple mental and behavioral disorders; however, the functional mechanisms underlying these associations are unknown. This study investigated the effect of several HTR1B haplotypes on regulation of gene expression in vitro and the functional sequences in the 5' regulatory region of HTR1B to determine their potential association with mental and behavioral disorders.

METHODS

Six haplotypes consisting of rs4140535, rs1778258, rs17273700, rs1228814, rs11568817, and rs130058 and several truncated fragments of the 5' regulatory region of HTR1B were transfected into SK-N-SH and HEK-293 cells. The relative fluorescence intensities of the different haplotypes and truncated fragments were detected using a dual-luciferase reporter assay system.

RESULTS

Compared to the major haplotype T-G-T-C-T-A, the relative fluorescence intensities of haplotypes C-A-T-C-T-A, C-G-T-C-T-A, C-G-C-A-G-T, and C-G-T-A-T-A were significantly lower, and that of haplotype C-G-C-A-G-A was significantly higher. Furthermore, the effects of the rs4140535T allele, the rs17273700C-rs11568817G linkage combination, and the rs1228814A allele made their relative fluorescence intensities significantly higher than their counterparts at each locus. Conversely, the rs1778258A and rs130058T alleles decreased the relative fluorescence intensities. In addition, we found that regions from - 1587 to - 1371 bp (TSS, + 1), - 1149 to - 894 bp, - 39 to + 130 bp, + 130 to + 341 bp, and + 341 to + 505 bp upregulated gene expression. In contrast, regions - 603 to - 316 bp and + 130 to + 341 bp downregulated gene expression. Region + 341 to + 505 bp played a decisive role in gene transcription.

CONCLUSIONS

HTR1B 5' regulatory region polymorphisms have regulatory effects on gene expression and potential correlate with several pathology and physiology conditions. This study suggests that a crucial sequence for transcription is located in region + 341 ~ + 505 bp. Regions - 1587 to - 1371 bp, - 1149 to - 894 bp, - 603 to - 316 bp, - 39 to + 130 bp, and + 130 to + 341 bp contain functional sequences that can promote or suppress the HTR1B gene expression.

Early Life Stress and the Onset of Obesity: Proof of MicroRNAs' Involvement Through Modulation of Serotonin and Dopamine Systems' Homeostasis

Healthy persons hold a very complex system for controlling energy homeostasis. The system functions on the interconnected way between the nutritional, endocrine, neural, and epigenetic regulation, which includes the microRNAs (miRNAs). Currently, it is well accepted that experiences of early life stress (ELS) carry modification of the central control of feeding behavior, one of the factors controlling energy homeostasis. Recently, studies give us a clue on the modulation of eating behavior, which is one of the main factors associated with the development of obesity. This clue connected the neural control through the serotonin (5HT) and dopamine (DA) systems with the fine regulation of miRNAs. The first pieces of evidence highlight the presence of the miR-16 in the regulation of the serotonin transporter (SERT) as well as the receptors 1a (5HT1A) and 2a (5HT2A). On the other hand, miR-504 is related to the dopamine receptor D2 (DRD2). As our knowledge advance, we expected to discover other important pathways for the regulation of the energy homeostasis. As both neurotransmission systems and miRNAs seem to be sensible to ELS, the aim of this review is to bring new insight about the involvement of miRNAs with a central role in the control of eating behavior focusing on the influences of ELS and regulation of neurotransmission systems.

Effects of HTR1B 3' region polymorphisms and functional regions on gene expression regulation

Background

The HTR1B gene encodes the 5-hydroxytryptamine (5-HT1B) receptor, which is involved in a variety of brain activities and mental disorders. The regulatory effects of non-coding regions on genomic DNA are one of many reasons for the cause of genetic-related diseases. Post-transcriptional regulation that depends on the function of 3′ regulatory regions plays a particularly important role. This study investigated the effects, on reporter gene expression, of several haplotypes of the HTR1B gene (rs6297, rs3827804, rs140792648, rs9361234, rs76194807, rs58138557, and rs13212041) and truncated fragments in order to analyze the function of the 3′ region of HTR1B.

Results

We found that the haplotype, A-G-Del-C-T-Ins-A, enhanced the expression level compared to the main haplotype; A-G-Del-C-G-Ins-A; G-G-Del-C-G-Ins-G decreased the expression level. Two alleles, rs76194807T and rs6297G, exhibited different relative luciferase intensities compared to their counterparts at each locus. We also found that + 2440 ~ + 2769 bp and + 1953 ~ + 2311 bp regions both had negative effects on gene expression.

Conclusions

The 3′ region of HTR1B has a regulatory effect on gene expression, which is likely closely associated with the interpretation of HTR1B-related disorders. In addition, the HTR1B 3′ region includes several effector binding sites that induce an inhibitory effect on gene expression.

Identification and Integrated Analysis of MicroRNA and mRNA Expression Profiles During Agonistic Behavior in Chinese Mitten Crab (Eriocheir sinensis) Using a Deep Sequencing Approach

As a commercially important species, the Chinese mitten crab (Eriocheir sinensis) has been cultured for a long time in China. Agonistic behavior often causes limb disability and requires much energy, which is harmful to the growth and survival of crabs. In this paper, we divided crabs into a control group (control, no treatment) and an experimental group (fight, agonistic behavior after 1 h) and then collected the thoracic ganglia (TG) to extract RNA. Subsequently, we first used a deep sequencing approach to examine the transcripts of microRNAs (miRNAs) and messenger RNAs (mRNAs) in E. sinensis displaying agonistic behavior. According to the results, we found 29 significant differentially expressed miRNAs (DEMs) and 116 significant differentially expressed unigenes (DEGs). The DEMs esi-miR-199a-5p, esi-let-7d, esi-miR-200a, and esi-miR-200b might participate in the regulation of agonistic behavior by mediating neuroregulation and energy metabolism. Focusing on the transcripts of the mRNAs, the renin–angiotensin system (RAS) Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway might be involved in the regulation of agonistic behavior through glucose metabolism as this pathway was significantly enriched with DEGs. Besides, an integrated analysis of the miRNA and mRNA profiles revealed that the retinoid X receptor (RXR) was also involved in visual signal transduction, which was important for agonistic behavior. In addition, four vital agonistic behavior-related metabolic pathways, including the cAMP signaling, MAPK, protein digestion and absorption, and fatty acid metabolism pathways, were significantly enriched with the predicted target unigenes. In conclusion, the findings of this study might provide important insight enhancing our understanding of the underlying molecular mechanisms of agonistic behavior in E. sinensis.

A functional SNP in MIR124-1, a brain expressed miRNA gene, is associated with aggressiveness in a Colombian sample

Background:

Interpersonal violence and suicide are among the main causes of mortality and morbidity around the world. In several developing countries, such as Colombia, they are among the first five entities of public health concern. Aggressiveness is an important endophenotype for aggression and suicidal behavior, having a heritability of around 50%. Exploration of classical candidate genes, involved in serotoninergic and dopaminergic neurotransmission, has identified few consistent risk factors for aggressiveness. miRNAs are a novel class of molecules with a growing role in normal neural function and neuropsychiatric disorders; of special interest, miR-124 is a brain-specific miRNA that is key for neuronal plasticity. We evaluated the hypothesis that a functional polymorphism in MIR124-1 gene might be associated with aggressiveness in a Colombian sample.

Methods:

The Spanish adaptation of the refined version of the Aggression Questionnaire and the abbreviated Barratt Impulsiveness Scale were applied to 170 young subjects. The functional SNP in MIR124-1 (rs531564) was genotyped by a TaqMan assay.

Results:

We found a significant association between the MIR124-1 and aggressiveness in our sample, with G/G carriers having lower scores (P = 0.01). This association seemed to be specific for aggressiveness, as it was not significant for impulsiveness.

Conclusions:

We showed for the first time the association of a functional polymorphism in MIR124-1 and aggressiveness. Known targets of miR-124 (such as BDNF and DRD4 genes) could explain the effect of this miRNA on behavior. A future analysis of additional novel functional polymorphisms in other brain expressed miRNAs could be useful for a deeper understanding of aggression in humans.

HTR1A, HTR1B, HTR2A, HTR2C and HTR6 Gene Polymorphisms and Extrapyramidal Side Effects in Haloperidol-Treated Patients with Schizophrenia

Schizophrenia is a serious, chronic psychiatric disorder requiring lifelong treatment. Extrapyramidal side effects (EPS) are common adverse reactions to antipsychotic medications. In addition to the dopaminergic system, serotonergic mechanisms, including serotonin (5-HT) receptors, might be involved in EPS development. This study aimed to examine molecular associations of HTR1A, HTR1B, HTR2A, HTR2C and HTR6 gene polymorphisms with acute EPS in 229 male schizophrenia patients, following two weeks of haloperidol monotherapy. The Simpson-Angus Rating Scale for Extrapyramidal Side Effects (SAS), Barnes Akathisia Rating Scale (BARS) and Extrapyramidal Symptom Rating Scale (ESRS) were used to evaluate EPS severity. Genotyping was performed using real-time PCR, following extraction of blood DNA. Significant acute EPS appeared in 48.03% of schizophrenia patients. For the rs13212041 HTR1B gene polymorphism, affecting microRNA regulation of HTR1B gene expression, a higher frequency of TT carriers was found among haloperidol-treated patients with akathisia when compared to the group without akathisia symptoms. In comparison to C-allele carriers, patients carrying the TT genotype had higher akathisia severity, as determined by the SAS, BARS and ESRS scales. These molecular findings suggest potential involvement of 5-HT_1B receptors in akathisia development following haloperidol treatment, as well as possible epigenetic mechanisms of serotonergic modulation associated with antipsychotic-induced EPS.

Upregulation of acetylcholinesterase caused by downregulation of microRNA-132 is responsible for the development of dementia after ischemic stroke

MicroRNA-132 (miR-132) has been shown to participate in many diseases. This study aimed to understand the correlation between the level of miR-132 and the severity of dementia post-ischemic stroke. An online tool (www.mirdb.org) was used to find the miR-132 binding site in acetylcholinesterase (ACHE) 3'-untranslated region (UTR), followed by a luciferase reporter assay to validate ACHE as a miR-132 target. A similar relationship between miR-132 and ACHE was also established in cerebrospinal fluid samples collected from human subjects. A negative correlation was established between ACHE and miR-132 by measuring the relative luciferase activity. Meanwhile, Western blot analysis and real-time polymerase chain reaction were also conducted to compare the levels of ACHE messenger RNA and protein between two groups (dementia positive, n = 26 and dementia negative, n = 26) or among cells treated with miR-132 mimics, ACHE small interfering RNA, and miR-132 inhibitors. As shown in the results, miR-132 can reduce the expression of ACHE. Further experiments were also carried out to study the effect of miR-132 and ACHE on cell viability and apoptosis, and the results demonstrated that miR-132 enhanced cell viability while suppressing apoptosis. In addition, ACHE reduced cell viability while promoting apoptosis. miR-132 targeted ACHE and suppressed its expression. Additionally, miR-132 and ACHE have been shown to affect the cell viability and apoptosis in the central nervous system.

hsa-miR-3177-5p and hsa-miR-3178 Inhibit 5-HT1A Expression by Binding the 3'-UTR Region in vitro

Abnormal expression of the 5-HT1A receptor, which is encoded by the HTR1A gene, leads to susceptibilities to neuropsychiatric disorders such as depression, anxiety, and schizophrenia. miRNAs regulate gene expression by recognizing the 3'-UTR region of mRNA. This study evaluated the miRNAs that might identify and subsequently determine the regulatory mechanism of HTR1A gene. Using the HEK-293, U87, SK-N-SH and SH-SY5Y cell lines, we determined the functional sequence of the 3'-UTR region of the HTR1A gene and predicted miRNA binding. Dual luciferase reporter assay and Western Blot were used to confirm the effect of miRNA mimics and inhibitors on endogenous 5-HT1A receptors. In all cell lines, gene expression of the -17 bp to +443 bp fragment containing the complete sequence of the 3'-UTR region was significantly decreased, although mRNA quantification was not different. The +375 bp to +443 bp sequence, which exhibited the most significant change in relative chemiluminescence intensity, was recognized by hsa-miR-3177-5p and hsa-miR-3178. In HEK-293 and U87 cells, hsa-miR-3177-5p significantly inhibited the 5-HT1A receptor expression, while a hsa-miR-3178 inhibitor up-regulated HTR1A gene expression in SK-N-SH and SH-SY5Y cells. By constructing the pmirGLO-vector with the mutated HTR1A gene, we further confirmed that hsa-miR-3177-5p recognized the HTR1A gene tgtacaca at +377 bp to +384 bp, and the +392 bp to +399 bp fragment cgcgccca was identified by hsa-miR-3178. hsa-miR-3177-5p and hsa-miR-3178 had significant inhibitory effects on expression of the HTR1A gene and 5-HT1A receptor and may directly participate in the development of neuropsychiatric diseases.

The association between HTR1B gene rs13212041 polymorphism and onset of alcohol abuse

BACKGROUND

Alcohol dependence displays a wide variety of clinical phenotypes. Various typology classifications of alcoholism include age of onset of alcohol abuse as one of the major phenotypic features. Serotonergic changes have been associated with alcoholism, while serotonin receptors type 1B (5-HT1B) play an important role in regulating serotonergic neurotransmission. The rs13212041 polymorphism modulates the expression of HTR1B gene coding for 5-HT1B receptor. This study examined the association of platelet serotonin (5-HT) and HTR1B gene with the onset of alcohol abuse in alcohol-dependent subjects.

MATERIALS AND METHODS

Determination of platelet 5-HT concentration and genotyping of rs13212041 HTR1B gene polymorphism were performed in 613 alcohol-dependent patients, subdivided according to early/late onset (before/after 25 years of age) of alcohol abuse.

RESULTS

Alcohol-dependent individuals with CC genotype were more frequent in the group with early onset of alcohol abuse compared to carriers of T allele. Besides HTR1B genotype, age and gender, but not platelet 5-HT, were major variables associated with the onset of alcohol abuse. Platelet 5-HT concentration was not significantly different between patients with early and late onset of alcohol abuse, or patients carrying various HTR1B genotypes. Although we observed no influence of co-variables such as age, gender, or somatic and psychiatric comorbidities, platelet 5-HT concentration was significantly affected by smoking.

CONCLUSION

These findings support potential involvement of 5-HT1B receptors in the onset of alcohol abuse and development of alcohol dependence. Additionally, the results of our study emphasize the importance of controlling for smoking status, as one of the significant confounding factors influencing platelet 5-HT concentration.

Polymorphisms in the human serotonin receptor 1B (HTR1B) gene are associated with schizophrenia: a case control study

BACKGROUND

Schizophrenia is associated with multiple neurotransmitter disorders, including serotonin (5-hydroxytryptamine, 5-HT). The neuromodulatory action of serotonin on brain function largely depends on the action of specific subtypes of serotonin receptors. The serotonin receptor 1B (HTR1B) gene has been proposed to play putative roles in the development of multiple emotional and psychiatric disorders.

METHODS

To study the relationship of HTR1B polymorphisms and schizophrenia, gene information was drawn from a cohort of 310 schizophrenic patients (152 men and 158 women) and 313 healthy controls (153 men and 160 women) of northern Han Chinese descent. The χ2 test was used to compare allele and genotype distributions between case and control groups. The haplotype and linkage equilibrium were also assessed in two group comparisons.

RESULTS

We detected 14 SNPs. Male patients were observed to have higher frequencies of the A-allele and AA+AG genotype at rs1778258 than female patients (p = 0.012 and p = 0.015, respectively). Both the A-allele and AA+AG genotype were associated with schizophrenia risk (OR = 1.986 and OR = 2.061, respectively), although the statistical significance of the genotype was lost after Bonferroni correction. Linkage analysis showed that rs17273700, rs11568817, rs9361234 and rs58138557 polymorphisms exhibit strong linkage disequilibrium (LD). In addition, schizophrenic patients show stronger linkage between 11,568,817 and rs130058 than healthy controls.

CONCLUSIONS

HTR1B polymorphisms are associated with schizophrenia in the northern Han Chinese population, which provides an etiological reference for schizophrenia.

Dysregulation and functional roles of miR-183-96-182 cluster in cancer cell proliferation, invasion and metastasis

Previous studies have reported aberrant expression of the miR-183-96-182 cluster in a variety of tumors, which indicates its' diagnostic or prognostic value. However, a key characteristic of the miR-183-96-182 cluster is its varied expression levels, and pleomorphic functional roles in different tumors or under different conditions. In most tumor types, the cluster is highly expressed and promotes tumorigenesis, cancer progression and metastasis; yet tumor suppressive effects have also been reported in some tumors. In the present study, we discuss the upstream regulators and the downstream target genes of miR-183-96-182 cluster, and highlight the dysregulation and functional roles of this cluster in various tumor cells. Newer insights summarized in this review will help readers understand the different facets of the miR-183-96-182 cluster in cancer development and progression.

Alcohol Intoxication Moderates the Association between a Polygenic Risk Score and Unprovoked Intimate Partner Aggression

Despite evidence that genetic variation contributes to aggression, few studies have examined how genetic variation contributes to IPA specifically. In the current study, 69 couples from a Midwestern university completed self-report measures of IPA, childhood trauma exposure, and hazardous alcohol use, and were randomly assigned to consume either a placebo or alcohol beverage before participating in an analogue aggression task against their partner. Genetic risk (i.e., association with lower transcriptional efficiency) for aggression was measured with a polygenic risk score (PRS) created from four polymorphisms (HTR1B rs13212041, HTR2B rs6437000, 5-HTTLPR, and MAOA uVNTR). Among individuals with a low PRS, individuals who consumed alcohol (BrAC = 0.07%) showed greater unprovoked IPA than individuals who consumed a placebo. Findings contribute to our limited understanding regarding the etiology of IPA and suggest that individuals who have increased transcriptional activity in certain serotonin system genes may be at higher risk of IPA when intoxicated.

Evidence of sexual dimorphism of HTR1B gene on major adult ADHD comorbidities

Attention-deficit/hyperactivity disorder (ADHD) is a very common psychiatric disorder across the life cycle and frequently presents comorbidities. Since ADHD is highly heritable, several studies have focused in the underlying genetic factors involved in its etiology. One of the major challenges in this search is the phenotypic heterogeneity, which could be partly attributable to the sexual dimorphism frequently seen in psychiatric disorders. Taking into account the well-known sexual dimorphic effect observed in serotonergic system characteristics, we differentially tested the influence of HTR1B SNPs (rs11568817, rs130058, rs6296 and rs13212041) on ADHD susceptibility and on its major comorbidities according to sex. The sample comprised 564 adults with ADHD diagnosed according to DSM-IV criteria and 635 controls. There was no association of any HTR1B SNPs tested in relation to ADHD susceptibility. As for the comorbidities evaluated, after correction for multiple tests, significant associations were observed for both rs11568817 and rs130058 with substance use disorders (P_corr = 0.009 and P_corr = 0.018, respectively) and for rs11568817 with nicotine dependence (P_corr = 0.025) in men with ADHD. In women with ADHD, the same rs11568817 was associated with generalized anxiety disorder (P_corr = 0.031). The observed effects of rs11568817 G allele presence conferring risk to either substance use disorders or generalized anxiety disorder according to sex, suggest an overall scenario where a higher transcriptional activity of HTR1B, resulting from the presence of this allele, is related to externalizing behaviors in men and internalizing behaviors in women. These results are consistent with and expand previous evidence of sexual dimorphism of the serotoninergic system.

Serotonergic activation during courtship and aggression in the brown anole, Anolis sagrei

The role of serotonin (5-hydroxytryptamine, 5-HT) in social behavior regulation is not fully understood. While 5-HT release in nuclei of the social behavior network has generally been associated with inhibition of aggressive behavior across multiple classes of vertebrates, less is known about its effects on sexual, especially non-copulatory courtship display behaviors. Furthermore, most research has examined effects at 5-HT release sites, while studies examining the behavioral relevance of source cell populations have generated contradictory findings. This study utilized immunohistochemistry to examine the colocalization of 5-HT with Fos, an immediate early gene product and marker of neural activity, in the raphe and superior reticular nuclei of male brown anoles (Anolis sagrei) exposed to either aggression, courtship, or control social interactions. Supporting previous research, copulation was associated with a decrease in 5-HT activity, while a novel link between 5-HT activity and latency to non-copulatory courtship was also found. Within the aggression group, intensity and frequency of behavior were both associated with decreased 5-HT activity. An effect of social context was also seen, with anoles exposed to either courtship or aggression encounters showing decreased 5-HT activity in certain raphe and superior reticular nuclei populations compared to controls. Interestingly, context effects and behavioral effects were seen at separate brain nuclei, suggesting the presence of separate systems with distinct functional roles.

Genetic and Modeling Approaches Reveal Distinct Components of Impulsive Behavior

Impulsivity is an endophenotype found in many psychiatric disorders including substance use disorders, pathological gambling, and attention deficit hyperactivity disorder. Two behavioral features often considered in impulsive behavior are behavioral inhibition (impulsive action) and delayed gratification (impulsive choice). However, the extent to which these behavioral constructs represent distinct facets of behavior with discrete biological bases is unclear. To test the hypothesis that impulsive action and impulsive choice represent statistically independent behavioral constructs in mice, we collected behavioral measures of impulsivity in a single cohort of mice using well-validated operant behavioral paradigms. Mice with manipulation of serotonin 1B receptor (5-HT_1BR) expression were included as a model of disordered impulsivity. A factor analysis was used to characterize correlations between the measures of impulsivity and to identify covariates. Using two approaches, we dissociated impulsive action from impulsive choice. First, the absence of 5-HT_1BRs caused increased impulsive action, but not impulsive choice. Second, based on an exploratory factor analysis, a two-factor model described the data well, with measures of impulsive action and choice separating into two independent factors. A multiple-indicator multiple-causes analysis showed that 5-HT_1BR expression and sex were significant covariates of impulsivity. Males displayed increased impulsivity in both dimensions, whereas 5-HT_1BR expression was a predictor of increased impulsive action only. These data support the conclusion that impulsive action and impulsive choice are distinct behavioral phenotypes with dissociable biological influences that can be modeled in mice. Our work may help inform better classification, diagnosis, and treatment of psychiatric disorders, which present with disordered impulsivity.

Animal models to improve our understanding and treatment of suicidal behavior

Worldwide, suicide is a leading cause of death. Although a sizable proportion of deaths by suicide may be preventable, it is well documented that despite major governmental and international investments in research, education and clinical practice suicide rates have not diminished and are even increasing among several at-risk populations. Although nonhuman animals do not engage in suicidal behavior amenable to translational studies, we argue that animal model systems are necessary to investigate candidate endophenotypes of suicidal behavior and the neurobiology underlying these endophenotypes. Animal models are similarly a critical resource to help delineate treatment targets and pharmacological means to improve our ability to manage the risk of suicide. In particular, certain pathophysiological pathways to suicidal behavior, including stress and hypothalamic-pituitary-adrenal axis dysfunction, neurotransmitter system abnormalities, endocrine and neuroimmune changes, aggression, impulsivity and decision-making deficits, as well as the role of critical interactions between genetic and epigenetic factors, development and environmental risk factors can be modeled in laboratory animals. We broadly describe human biological findings, as well as protective effects of medications such as lithium, clozapine, and ketamine associated with modifying risk of engaging in suicidal behavior that are readily translatable to animal models. Endophenotypes of suicidal behavior, studied in animal models, are further useful for moving observed associations with harmful environmental factors (for example, childhood adversity, mechanical trauma aeroallergens, pathogens, inflammation triggers) from association to causation, and developing preventative strategies. Further study in animals will contribute to a more informed, comprehensive, accelerated and ultimately impactful suicide research portfolio.

SNPs in microRNA target sites and their potential role in human disease

In the post-genomic era, the goal of personalized medicine is to determine the correlation between genotype and phenotype. Developing high-throughput genotyping technologies such as genome-wide association studies (GWAS) and the 1000 Genomes Project (http://www.internationalgenome.org/about/#1000G_PROJECT) has dramatically enhanced our ability to map where changes in the genome occur on a population level by identifying millions of single nucleotide polymorphisms (SNPs). Polymorphisms, particularly those within the coding regions of proteins and at splice junctions, have received the most attention, but it is also now clear that polymorphisms in the non-coding regions are important. In these non-coding regions, the enhancer and promoter regions have received the most attention, whereas the 3'-UTR regions have until recently been overlooked. In this review, we examine how SNPs affect microRNA-binding sites in these regions, and how mRNA stability changes can lead to disease pathogenesis.

Two SNAP-25 genetic variants in the binding site of multiple microRNAs and susceptibility of ADHD: A meta-analysis

The aim of this meta-analysis is to assess the associations between two most widely investigated polymorphisms (rs3746544 and rs1051312) in the 3'UTR of the SNAP-25 gene and susceptibility of ADHD. Two investigators selected related studies and assessed methodological quality independently. Six studies were included in this meta-analysis for a total of 715 cases and 655 controls. There is no apparent association between rs3746544 polymorphisms and risk of ADHD. However, subgroup analysis based on ethnicity demonstrated a strong association between rs3746544 polymorphism and ADHD in the subset of Asian participants, but not among Caucasians. Compared to the T allele, the allele G was associated with a significantly decreased risk of developing ADHD in the Asian population (odds ratio (OR) = 0.70, 95% confidence interval (CI) = 0.52-0.95, p = 0.02). The association between the TT genotype and ADHD risk was also significantly increased as compared to G/T (OR = 1.56, 95% CI = 1.00-2.44, p = 0.05) and the dominant genetic model (GG + GT vs. TT: OR = 1.51, 95% CI = 1.07-2.13, p = 0.02). For the rs1051312 SNP, being homozygous for the minor allele (C/C) was associated with a 3.66 higher odds of ADHD as compared to cases homozygous for the major allele (T/T) (95% CI = 1.64-8.13, p = 0.001), and 3.57 higher odds as compared to heterozygous (C/T) carriers (95% CI = 2.01-12.90, p < 0.001). Our results suggest that the polymorphisms rs3746544 and rs1051312 may increase the odds of developing ADHD. Additional studies are needed to confirm these findings.

Regulation of the serotonin transporter in the pathogenesis of irritable bowel syndrome

Serotonin (5-HT) and the serotonin transporter (SERT) have earned a tremendous amount of attention regarding the pathogenesis of irritable bowel syndrome (IBS). Considering that enteric 5-HT is responsible for the secretion, motility and perception of the bowel, the involvement of altered enteric 5-HT metabolism in the pathogenesis of IBS has been elucidated. Higher 5-HT availability is commonly associated with depressed SERT mRNA in patients with IBS compared with healthy controls. The expression difference of SERT between IBS patients and healthy controls might suggest that SERT plays an essential role in IBS pathogenesis, and SERT was expected to be a novel therapeutic target for IBS. Progress in this area has begun to illuminate the complex regulatory mechanisms of SERT in the etiology of IBS. In this article, current insights regarding the regulation of SERT in IBS are provided, including aspects of SERT gene polymorphisms, microRNAs, immunity and inflammation, gut microbiota, growth factors, among others. Potential SERT-directed therapies for IBS are also described. The potential regulators of SERT are of clinical importance and are important for better understanding IBS pathophysiology and therapeutic strategies.

The neurobiological basis of human aggression: A review on genetic and epigenetic mechanisms

Aggression is an evolutionary conserved behavior present in most species including humans. Inadequate aggression can lead to long-term detrimental personal and societal effects. Here, we differentiate between proactive and reactive forms of aggression and review the genetic determinants of it. Heritability estimates of aggression in general vary between studies due to differing assessment instruments for aggressive behavior (AB) as well as age and gender of study participants. In addition, especially non-shared environmental factors shape AB. Current hypotheses suggest that environmental effects such as early life stress or chronic psychosocial risk factors (e.g., maltreatment) and variation in genes related to neuroendocrine, dopaminergic as well as serotonergic systems increase the risk to develop AB. In this review, we summarize the current knowledge of the genetics of human aggression based on twin studies, genetic association studies, animal models, and epigenetic analyses with the aim to differentiate between mechanisms associated with proactive or reactive aggression. We hypothesize that from a genetic perspective, the aminergic systems are likely to regulate both reactive and proactive aggression, whereas the endocrine pathways seem to be more involved in regulation of reactive aggression through modulation of impulsivity. Epigenetic studies on aggression have associated non-genetic risk factors with modifications of the stress response and the immune system. Finally, we point to the urgent need for further genome-wide analyses and the integration of genetic and epigenetic information to understand individual differences in reactive and proactive AB. © 2015 Wiley Periodicals, Inc.

Aggressive behavior in humans: Genes and pathways identified through association studies

Aggressive behavior has both genetic and environmental components. Many association studies have been performed to identify genetic factors underlying aggressive behaviors in humans. In this review we summarize the previous work performed in this field, considering both candidate gene (CGAS) and genome-wide association studies (GWAS), excluding those performed in samples where the primary diagnosis is a psychiatric or neurological disorder other than an aggression-related phenotype. Subsequently, we have studied the enrichment of pathways and functions in GWAS data. The results of our searches show that most CGAS have identified associations with genes involved in dopaminergic and serotonergic neurotransmission and in hormone regulation. On the other hand, GWAS have not yet identified genome-wide significant associations, but top nominal findings are related to several signaling pathways, such as axon guidance or estrogen receptor signaling, and also to neurodevelopmental processes and synaptic plasticity. Future studies should use larger samples, homogeneous phenotypes and standardized measurements to identify genes that underlie aggressive behaviors in humans. © 2016 Wiley Periodicals, Inc.

Intensified vmPFC surveillance over PTSS under perturbed microRNA-608/AChE interaction

Trauma causes variable risk of posttraumatic stress symptoms (PTSS) owing to yet-unknown genome-neuronal interactions. Here, we report co-intensified amygdala and ventromedial prefrontal cortex (vmPFC) emotional responses that may overcome PTSS in individuals with the single-nucleotide polymorphism (SNP) rs17228616 in the acetylcholinesterase (AChE) gene. We have recently shown that in individuals with the minor rs17228616 allele, this SNP interrupts AChE suppression by microRNA (miRNA)-608, leading to cortical elevation of brain AChE and reduced cortisol and the miRNA-608 target GABAergic modulator CDC42, all stress-associated. To examine whether this SNP has effects on PTSS and threat-related brain circuits, we exposed 76 healthy Israel Defense Forces soldiers who experienced chronic military stress to a functional magnetic resonance imaging task of emotional and neutral visual stimuli. Minor allele individuals predictably reacted to emotional stimuli by hyperactivated amygdala, a hallmark of PTSS and a predisposing factor of posttraumatic stress disorder (PTSD). Despite this, minor allele individuals showed no difference in PTSS levels. Mediation analyses indicated that the potentiated amygdala reactivity in minor allele soldiers promoted enhanced vmPFC recruitment that was associated with their limited PTSS. Furthermore, we found interrelated expression levels of several miRNA-608 targets including CD44, CDC42 and interleukin 6 in human amygdala samples (N=7). Our findings suggest that miRNA-608/AChE interaction is involved in the threat circuitry and PTSS and support a model where greater vmPFC regulatory activity compensates for amygdala hyperactivation in minor allele individuals to neutralize their PTSS susceptibility.

Pathogenetic and therapeutic applications of microRNAs in major depressive disorder

As a class of noncoding RNAs, microRNAs (miRNAs) regulate gene expression by inhibiting translation of messenger RNAs. These miRNAs have been shown to play a critical role in higher brain functioning and actively participate in synaptic plasticity. Pre-clinical evidence demonstrates that expression of miRNAs is differentially altered during stress. On the other hand, depressed individuals show marked changes in miRNA expression in brain. MiRNAs are also target of antidepressants and electroconvulsive therapy. Moreover, these miRNAs are present in circulating blood and can be easily detected. Profiling of miRNAs in blood plasma/serum provides evidence that determination of miRNAs in blood can be used as possible diagnostic and therapeutic tool. In this review article, these aspects are critically reviewed and the role of miRNAs in possible etiopathogenesis and therapeutic implications in the context of major depressive disorder is discussed.

Genetics of aggressive behavior: An overview

The Research Domain Criteria (RDoC) address three types of aggression: frustrative non-reward, defensive aggression and offensive/proactive aggression. This review sought to present the evidence for genetic underpinnings of aggression and to determine to what degree prior studies have examined phenotypes that fit into the RDoC framework. Although the constructs of defensive and offensive aggression have been widely used in the animal genetics literature, the human literature is mostly agnostic with regard to all the RDoC constructs. We know from twin studies that about half the variance in behavior may be explained by genetic risk factors. This is true for both dimensional, trait-like, measures of aggression and categorical definitions of psychopathology. The non-shared environment seems to have a moderate influence with the effects of shared environment being unclear. Human molecular genetic studies of aggression are in an early stage. The most promising candidates are in the dopaminergic and serotonergic systems along with hormonal regulators. Genome-wide association studies have not yet achieved genome-wide significance, but current samples are too small to detect variants having the small effects one would expect for a complex disorder. The strongest molecular evidence for a genetic basis for aggression comes from animal models comparing aggressive and non-aggressive strains or documenting the effects of gene knockouts. Although we have learned much from these prior studies, future studies should improve the measurement of aggression by using a systematic method of measurement such as that proposed by the RDoC initiative.

Upregulation of microRNA-96 and its oncogenic functions by targeting CDKN1A in bladder cancer

Background

Genome-wide miRNA expression profile has identified microRNA (miR)-96 as one of upregulated miRNAs in clinical bladder cancer (BC) tissues compared to normal bladder tissues. The aim of this study was to confirm the expression pattern of miR-96 in BC tissues and to investigate its involvement in carcinogenesis.

Methods

Quantitative real-time PCR was performed to detect the expression levels of miR-96 in 60 BC and 40 normal control tissues. Bioinformatics prediction combined with luciferase reporter assay were used to verify whether the cyclin-dependent kinase inhibitor CDKN1A was a potential target gene of miR-96. Cell counting kit-8 and apoptosis assays were further performed to evaluate the effects of miR-96-CDKN1A axis on cell proliferation and apoptosis of BC cell lines.

Results

We validated that miR-96 was significantly increased in both human BC tissues and cell lines. According to the data of miRTarBase, CDKN1A might be a candidate target gene of miR-96. In addition, luciferase reporter and Western blot assays respectively demonstrated that miR-96 could bind to the putative seed region in CDKN1A mRNA 3′UTR, and significantly reduce the expression level of CDKN1A protein. Moreover, we found that the inhibition of miR-96 expression remarkably decreased cell proliferation and promoted cell apoptosis of BC cell lines, which was consistent with the findings observed following the introduction of CDKN1A cDNA without 3′UTR restored miR-96.

Conclusions

Our data reveal that miR-96 may function as an onco-miRNA in BC. Upregulation of miR-96 may contribute to aggressive malignancy partly through suppressing CDKN1A protein expression in BC cells.

A Sex-Specific MicroRNA-96/5-Hydroxytryptamine 1B Axis Influences Development of Pulmonary Hypertension

RATIONALE

Females are predisposed to pulmonary arterial hypertension (PAH); evidence suggests that serotonin, mutations in the bone morphogenetic protein receptor (BMPR) II gene, and estrogens influence development of PAH. The 5-hydroxytryptamine 1B receptor (5-HT1BR) mediates human pulmonary artery smooth muscle cell (hPASMC) proliferation.

OBJECTIVES

We aimed to determine whether selected microRNAs (miRNAs) expressed in PASMCs are influenced by sex, BMPR-II mutations, and estrogens, and contribute to PASMC proliferation in PAH.

METHODS

Expression levels of miRNAs targeting genes related to PAH, estrogen, and serotonin were determined by quantitative RT-PCR in hPASMCs and mouse PASMCs harboring a heterozygous mutation in BMPR-II (BMPR-II(R899X+/-) PASMCs). miRNA-96 targets 5-HT1BR and was selected for further investigation. miRNA target validation was confirmed by luciferase reporter assay. Precursor miRNA-96 was transfected into hPASMCs to examine effects on proliferation and 5-HT1BR expression. The effect of a miRNA-96 mimic on the development of hypoxic pulmonary hypertension in mice was also assessed.

MEASUREMENTS AND MAIN RESULTS

miRNA-96 expression was reduced in BMPR-II(R899X+/-) PASMCs from female mice and hPASMCs from female patients with PAH; this was associated with increased 5-HT1BR expression and serotonin-mediated proliferation. 5-HT1BR was validated as a target for miRNA-96. Transfection of precursor miRNA-96 into hPASMCs reduced 5-HT1BR expression and inhibited serotonin-induced proliferation. Restoration of miRNA-96 expression in pulmonary arteries in vivo via administration of an miRNA-96 mimic reduced the development of hypoxia-induced pulmonary hypertension in the mouse.

CONCLUSIONS

Increased 5-HT1BR expression may be a consequence of decreased miRNA-96 expression in female patient PASMCs, and this may contribute to the development of PAH.

Susceptibility loci for heroin and cocaine addiction in the serotonergic and adrenergic pathways in populations of different ancestry

BACKGROUND

Drug addiction is influenced by genetic factors.

AIM

To determine if genetic variants in the serotonergic and adrenergic pathways are associated with heroin and/or cocaine addiction.

SUBJECTS & METHODS

The study examined 140 polymorphisms in 19 genes in 1855 subjects with predominantly European or African ancestries.

RESULTS

A total of 38 polymorphisms (13 genes) showed nominal associations, including novel associations in S100A10 (p11) and SLC18A2 (VMAT2). The association of HTR3B SNP rs11606194 with heroin addiction in the European ancestry subgroup remained significant after correction for multiple testing (p(corrected) = 0.04).

CONCLUSION

The study strengthens our previous findings of association of polymorphisms in HTR3A, HTR3B and ADRA1A. The study suggests partial overlap in genetic susceptibility between populations of different ancestry and between heroin and cocaine addiction.

The microRNA-183 cluster: the family that plays together stays together

The microRNA (miR)183 cluster, which is comprised of miRs-183, -96 and -182, is also a miR family with sequence homology. Despite the strong similarity in the sequences of these miRs, minute differences in their seed sequences result in both overlapping and distinct messenger RNA targets, which are often within the same pathway. These miRs have tightly synchronized expression during development and are required for maturation of sensory organs. In comparison to their defined role in normal development, the miR-183 family is frequently highly expressed in a variety of non-sensory diseases, including cancer, neurological and auto-immune disorders. Here, we discuss the conservation of the miR-183 cluster and the functional role of this miR family in normal development and diseases. We also describe the regulation of vital cellular pathways by coordinated expression of these miR siblings. This comprehensive review sheds light on the likely reasons why the genomic organization and seeming redundancy of the miR-183 family cluster was conserved through 600 million years of evolution.

The neurobiology of aggression and violence

Aggression and violence represent a significant public health concern and a clinical challenge for the mental healthcare provider. A great deal has been revealed regarding the neurobiology of violence and aggression, and an integration of this body of knowledge will ultimately serve to advance clinical diagnostics and therapeutic interventions. We will review here the latest findings regarding the neurobiology of aggression and violence. First, we will introduce the construct of aggression, with a focus on issues related to its heterogeneity, as well as the importance of refining the aggression phenotype in order to reduce pathophysiologic variability. Next we will examine the neuroanatomy of aggression and violence, focusing on regional volumes, functional studies, and interregional connectivity. Significant emphasis will be on the amygdala, as well as amygdala-frontal circuitry. Then we will turn our attention to the neurochemistry and molecular genetics of aggression and violence, examining the extensive findings on the serotonergic system, as well as the growing literature on the dopaminergic and vasopressinergic systems. We will also address the contribution of steroid hormones, namely, cortisol and testosterone. Finally, we will summarize these findings with a focus on reconciling inconsistencies and potential clinical implications; and, then we will suggest areas of focus for future directions in the field.

MicroRNA hsa-miR-4717-5p regulates RGS2 and may be a risk factor for anxiety-related traits

Regulator of G-protein Signaling 2 (RGS2) is a key regulator of G-protein-coupled signaling pathways involved in fear and anxiety. Data from rodent models and genetic analysis of anxiety-related traits and disorders in humans suggest down-regulation of RGS2 expression to be a risk factor for anxiety. Here we investigated, whether genetic variation in microRNAs mediating posttranscriptional down-regulation of RGS2 may be a risk factor for anxiety as well. 75 microRNAs predicted to regulate RGS2 were identified by four bioinformatic algorithms and validated experimentally by luciferase reporter gene assays. Specificity was confirmed for six microRNAs (hsa-miR-1271-5p, hsa-miR-22-3p, hsa-miR-3591-3p, hsa-miR-377-3p, hsa-miR-4717-5p, hsa-miR-96-5p) by disrupting their seed sequence at the 3' untranslated region of RGS2. Hsa-miR-4717-5p showed the most robust effect on RGS2 and regulated two other candidate genes of anxiety disorders (CNR1 and IKBKE) as well. Two SNPs (rs150925, rs161427) within and 1,000 bp upstream of the hostgene of hsa-miR-4717-5p (MIR4717) show a minor allele frequency greater than 0.05. Both were in high linkage disequilibrium (r(2) = 1, D' = 1) and both major (G) alleles showed a trend for association with panic disorder with comorbid agoraphobia in one of two patient/control samples (combined n(patients) = 497). Dimensional anxiety traits, as described by Anxiety Sensitivity Index (ASI) and Agoraphobic Cognitions Questionnaire (ACQ) were significantly higher among carriers of both major (G) alleles in a combined patient/control sample (n(combined) = 831). Taken together, data indicate that MIR4717 regulates human RGS2 and contributes to the genetic risk towards anxiety-related traits.