Abelson helper integration site-1 gene variants on major depressive disorder and bipolar disorder

Abelson Helper Integration Site 1 haplotypes and peripheral blood expression associates with lithium response and immunomodulation in bipolar patients

RATIONALE

In bipolar disorder (BD), immunological factors play a role in the pathogenesis and treatment of the illness. Studies showed the potential link between Abelson Helper Integration Site 1 (AHI1) protein, behavioural changes and innate immunity regulation. An immunomodulatory effect was suggested for lithium, a mood stabilizer used in BD treatment.

OBJECTIVES

We hypothesized that AHI1 may be an important mediator of lithium treatment response. Our study aimed to investigate whether the AHI1 haplotypes and expression associates with lithium treatment response in BD patients. We also examined whether AHI1 expression and lithium treatment correlate with innate inflammatory response genes.

RESULTS

We genotyped seven AHI1 single nucleotide polymorphisms in 97 euthymic BD patients and found that TG haplotype (rs7739635, rs9494332) was significantly associated with lithium response. We also showed significantly increased AHI1 expression in the blood of lithium responders compared to non-responders and BD patients compared to healthy controls (HC). We analyzed the expression of genes involved in the innate immune response and inflammatory response regulation (TLR4, CASP4, CASP5, NLRP3, IL1A, IL1B, IL6, IL10, IL18) in 21 lithium-treated BD patients, 20 BD patients treated with other mood stabilizer and 19 HC. We found significantly altered expression between BD patients and HC, but not between BD patients treated with different mood stabilizers.

CONCLUSIONS

Our study suggests the involvement of AHI1 in the lithium mode of action. Moreover, mood-stabilizing treatment associated with the innate immunity-related gene expression in BD patients and only the lithium-treated BD patients showed significantly elevated expression of anti-inflammatory IL10, suggesting lithium's immunomodulatory potential.

GR/Ahi1 regulates WDR68-DYRK1A binding and mediates cognitive impairment in prenatally stressed offspring

Accumulating research shows that prenatal exposure to maternal stress increases the risk of behavioral and mental health problems for offspring later in life. However, how prenatal stress affects offspring behavior remains unknown. Here, we found that prenatal stress (PNS) leads to reduced Ahi1, decreased synaptic plasticity and cognitive impairment in offspring. Mechanistically, Ahi1 and GR stabilize each other, inhibit GR nuclear translocation, promote Ahi1 and WDR68 binding, and inhibit DYRK1A and WDR68 binding. When Ahi1 deletion or prenatal stress leads to hyperactivity of the HPA axis, it promotes the release of GC, leading to GR nuclear translocation and Ahi1 degradation, which further inhibits the binding of Ahi1 and WDR68, and promotes the binding of DYRK1A and WDR68, leading to elevated DYRK1A, reduced synaptic plasticity, and cognitive impairment. Interestingly, we identified RU486, an antagonist of GR, which increased Ahi1/GR levels and improved cognitive impairment and synaptic plasticity in PNS offspring. Our study contributes to understanding the signaling mechanisms of prenatal stress-mediated cognitive impairment in offspring.

Depression compromises antiviral innate immunity via the AVP-AHI1-Tyk2 axis

Depression is a serious public-health issue. Recent reports have suggested higher susceptibility to viral infections in depressive patients. However, how depression affects antiviral innate immune signaling remains unknown. Here, we revealed a reduction in expression of Abelson helper integration site 1 (AHI1) in the peripheral blood mononuclear cells (PBMCs) and macrophages from the patients with major depressive disorder (MDD), which leads to attenuated antiviral immune response. We found that depression-related arginine vasopressin (AVP) induces reduction of AHI1 in macrophages. Further studies demonstrated that AHI1 is a critical stabilizer of basal type-I-interferon (IFN-I) signaling. Mechanistically, AHI1 recruits OTUD1 to deubiquitinate and stabilize Tyk2, while AHI1 reduction downregulates Tyk2 and IFN-I signaling activity in macrophages from both MDD patients and depression model mice. Interestingly, we identified a clinical analgesic meptazinol that effectively stimulates AHI1 expression, thus enhancing IFN-I antiviral defense in depression model mice. Our study promotes the understanding of the signaling mechanisms of depression-mediated antiviral immune dysfunction, and reveals meptazinol as an enhancer of antiviral innate immunity in depressive patients.

Ahi1 regulates serotonin production by the GR/ERβ/TPH2 pathway involving sexual differences in depressive behaviors

BACKGROUND

Depression is one of the most common psychiatric diseases. The monoamine transmitter theory suggests that neurotransmitters are involved in the mechanism of depression; however, the regulation on serotonin production is still unclear. We previously showed that Ahi1 knockout (KO) mice exhibited depression-like behavior accompanied by a significant decrease in brain serotonin.

METHODS

In the present study, western blot, gene knockdown, immunofluorescence, dual-luciferase reporter assay, and rescue assay were used to detect changes in the Ahi1/GR/ERβ/TPH2 pathway in the brains of male stressed mice and male Ahi1 KO mice to explain the pathogenesis of depression-like behaviors. In addition, E2 levels in the blood and brain of male and female mice were measured to investigate the effect on the ERβ/TPH2 pathway and to reveal the mechanisms for the phenomenon of gender differences in depression-like behaviors.

RESULTS

We found that the serotonin-producing pathway-the ERβ/TPH2 pathway was inhibited in male stressed mice and male Ahi1 KO mice. We further demonstrated that glucocorticoid receptor (GR) as a transcription factor bound to the promoter of ERβ that contains glucocorticoid response elements and inhibited the transcription of ERβ. Our recent study had indicated that Ahi1 regulates the nuclear translocation of GR upon stress, thus proposing the Ahi1/GR/ERβ/TPH2 pathway for serotonin production. Interestingly, female Ahi1 KO mice did not exhibit depressive behaviors, indicating sexual differences in depressive behaviors compared with male mice. Furthermore, we found that serum 17β-estradiol (E2) level was not changed in male and female mice; however, brain E2 level significantly decreased in male but not female Ahi1 KO mice. Further, ERβ agonist LY-500307 increased TPH2 expression and 5-HT production. Therefore, both Ahi1 and E2 regulate the ERβ/TPH2 pathway and involve sexual differences in brain serotonin production and depressive behaviors.

CONCLUSIONS

In conclusion, although it is unclear how Ahi1 controls E2 secretion in the brain, our findings demonstrate that Ahi1 regulates serotonin production by the GR/ERβ/TPH2 pathway in the brain and possibly involves the regulation on sex differences in depressive behaviors. Video Abstract.

Ahi1 regulates the nuclear translocation of glucocorticoid receptor to modulate stress response

Stress activates the nuclear translocation of glucocorticoid receptors (GR) to trigger gene expression. Abnormal GR levels can alter the stress responses in animals and therapeutic effects of antidepressants. Here, we reported that stress-mediated nuclear translocation of GR reduced Ahi1 in the stressed cells and mouse brains. Ahi1 interacts with GR to stabilize each other in the cytoplasm. Importantly, Ahi1 deficiency promotes the degradation of GR in the cytoplasm and reduced the nuclear translocation of GR in response to stress. Genetic depletion of Ahi1 in mice caused hyposensitivity to antidepressants under the stress condition. These findings suggest that AHI1 is an important regulator of GR level and may serve as a therapeutic target for stress-related disorders.

Effect of chronic unpredictable stress on mice with developmental under-expression of the Ahi1 gene: behavioral manifestations and neurobiological correlates

The Abelson helper integration site 1 (Ahi1) gene plays a pivotal role in brain development and is associated with genetic susceptibility to schizophrenia, and other neuropsychiatric disorders. Translational research in genetically modified mice may reveal the neurobiological mechanisms of such associations. Previous studies of mice heterozygous for Ahi1 knockout (Ahi1+/-) revealed an attenuated anxiety response on various relevant paradigms, in the context of a normal glucocorticoid response to caffeine and pentylenetetrazole. Resting-state fMRI showed decreased amygdalar connectivity with various limbic brain regions and altered network topology. However, it was not clear from previous studies whether stress-hyporesponsiveness reflected resilience or, conversely, a cognitive-emotional deficit. The present studies were designed to investigate the response of Ahi1+/- mice to chronic unpredictable stress (CUS) applied over 9 weeks. Wild type (Ahi1+/+) mice were significantly affected by CUS, manifesting decreased sucrose preference (p < 0.05); reduced anxiety on the elevated plus maze and light dark box and decreased thigmotaxis in the open field (p < 0.01 0.05); decreased hyperthermic response to acute stress (p < 0.05); attenuated contextual fear conditioning (p < 0.01) and increased neurogenesis (p < 0.05). In contrast, Ahi1+/- mice were indifferent to the effects of CUS assessed with the same parameters. Our findings suggest that Ahi1 under-expression during neurodevelopment, as manifested by Ahi1+/- mice, renders these mice stress hyporesponsive. Ahi1 deficiency during development may attenuate the perception and/or integration of environmental stressors as a result of impaired corticolimbic connectivity or aberrant functional wiring. These neural mechanisms may provide initial clues as to the role Ahi1 in schizophrenia and other neuropsychiatric disorders.

Tyrosine hydroxylase down-regulation after loss of Abelson helper integration site 1 (AHI1) promotes depression via the circadian clock pathway in mice

Abelson helper integration site 1 (AHI1) is associated with several neuropsychiatric and brain developmental disorders, such as schizophrenia, depression, autism, and Joubert syndrome. Ahi1 deficiency in mice leads to behaviors typical of depression. However, the mechanisms by which AHI1 regulates behavior remain to be elucidated. Here, we found that down-regulation of expression of the rate-limiting enzyme in dopamine biosynthesis, tyrosine hydroxylase (TH), in the midbrains of Ahi1-knockout (KO) mice is responsible for Ahi1-deficiency-mediated depressive symptoms. We also found that Rev-Erbα, a TH transcriptional repressor and circadian regulator, is up-regulated in the Ahi1-KO mouse midbrains and Ahi1-knockdown Neuro-2a cells. Moreover, brain and muscle Arnt-like protein 1 (BMAL1), the Rev-Erbα transcriptional regulator, is also increased in the Ahi1-KO mouse midbrains and Ahi1-knockdown cells. Our results further revealed that AHI1 decreases BMAL1/Rev-Erbα expression by interacting with and repressing retinoic acid receptor-related orphan receptor α, a nuclear receptor and transcriptional regulator of circadian genes. Of note, Bmal1 deficiency reversed the reduction in TH expression induced by Ahi1 deficiency. Moreover, microinfusion of the Rev-Erbα inhibitor SR8278 into the ventral midbrain of Ahi1-KO mice significantly increased TH expression in the ventral tegmental area and improved their depressive symptoms. These findings provide a mechanistic explanation for a link between AHI1-related behaviors and the circadian clock pathway, indicating an involvement of circadian regulatory proteins in AHI1-regulated mood and behavior.

The multiple sclerosis risk allele within the AHI1 gene is associated with relapses in children and adults

BACKGROUND

While common variant non-HLA (human leukocyte antigen) alleles have been associated with MS risk, their role in disease course is less clear. We sought to determine whether established multiple sclerosis (MS) genetic susceptibility factors are associated with relapse rate in children and an independent cohort of adults with MS.

METHODS

Genotyping was performed for 182 children with MS or clinically isolated syndrome with high risk for MS from two Pediatric MS Centers. They were prospectively followed for relapses. Fifty-two non-HLA MS susceptibility single nucleotide polymorphisms (SNPs) were evaluated for association with relapse rate. Cox regression models were adjusted for sex, genetic ancestry, disease-modifying therapy (DMT), 25-OH vitamin D level and HLA-DRB1*15:01/03 status. Investigation of pediatric subject SNP results was performed using a second cohort of 141 adult MS subjects of Northern European ancestry from the Southern Tasmanian Multiple Sclerosis Longitudinal Study.

RESULTS

For pediatric subjects, 408 relapses were captured over 622 patient-years of follow-up. Four non-HLA risk SNPs (rs11154801, rs650258, rs12212193, rs2303759) were associated with relapses (p < 0.01) in the pediatric subjects. After adjustment for genetic ancestry, sex, age, vitamin D level, DMT use and HLA-DRB1*15 status, having two copies of the MS risk allele within AHI1 (rs11154801) was associated with increased relapses among children (HR = 1.75,95%CI = 1.18-2.48, p = 0.006) and this result was also observed among adults (HR = 1.81,95%CI = 1.05-3.03, p = 0.026).

CONCLUSIONS

Our results suggest that the MS genetic risk variant within the gene AHI1 may contribute to disease course in addition to disease susceptibility.

Alterations in the expression of a neurodevelopmental gene exert long-lasting effects on cognitive-emotional phenotypes and functional brain networks: translational evidence from the stress-resilient Ahi1 knockout mouse

Many psychiatric disorders are highly heritable and may represent the clinical outcome of early aberrations in the formation of neural networks. The placement of brain connectivity as an 'intermediate phenotype' renders it an attractive target for exploring its interaction with genomics and behavior. Given the complexity of genetic make up and phenotypic heterogeneity in humans, translational studies are indicated. Recently, we demonstrated that a mouse model with heterozygous knockout of the key neurodevelopmental gene Ahi1 displays a consistent stress-resilient phenotype. Extending these data, the current research describes our multi-faceted effort to link early variations in Ahi1 expression with long-term consequences for functional brain networks and cognitive-emotional phenotypes. By combining behavioral paradigms with graph-based analysis of whole-brain functional networks, and then cross-validating the data with robust neuroinformatic data sets, our research suggests that physiological variation in gene expression during neurodevelopment is eventually translated into a continuum of global network metrics that serve as intermediate phenotypes. Within this framework, we suggest that organization of functional brain networks may result, in part, from an adaptive trade-off between efficiency and resilience, ultimately culminating in a phenotypic diversity that encompasses dimensions such as emotional regulation and cognitive function.

Primary Cilia as a Possible Link between Left-Right Asymmetry and Neurodevelopmental Diseases

Cilia have multiple functions in the development of the entire organism, and participate in the development and functioning of the central nervous system. In the last decade, studies have shown that they are implicated in the development of the visceral left-right asymmetry in different vertebrates. At the same time, some neuropsychiatric disorders, such as schizophrenia, autism, bipolar disorder, and dyslexia, are known to be associated with lateralization failure. In this review, we consider possible links in the mechanisms of determination of visceral asymmetry and brain lateralization, through cilia. We review the functions of seven genes associated with both cilia, and with neurodevelopmental diseases, keeping in mind their possible role in the establishment of the left-right brain asymmetry.

A cis-eQTL in AHI1 confers risk to schizophrenia in European populations

Schizophrenia is a devastating mental disorder, with heritability as high as 80%. Although genome-wide association studies have identified multiple promising risk variants of schizophrenia, they could only explain a small portion of the disease heritability, and other variants with low to moderate effect remain to be identified. Abelson helper integration site 1 (AHI1) is highly expressed in mammals throughout the developing brain, with lower expression continuing into adulthood. Besides, previous evidence suggested that AHI1 expression was changed in schizophrenia patients. Furthermore, association signal between AHI1 variants and schizophrenia has been reported in several European samples. In the present study, we first analyzed two expression quantitative trait loci (eQTL) datasets in healthy individuals and investigated the associations of eQTL of AHI1 with schizophrenia in independent European samples. We observed that a cis-eQTL of AHI1, rs11154801, showed significant association with AHI1 expression in both datasets (P<5E-05). Genetic evidence exhibited that rs11154801 was significantly associated with schizophrenia risk in both the discovery sample (9394 cases and 12462 controls, P=0.046, OR=0.958, 95% CI=0.918-0.999) and the replication sample (3240 cases and 14786 controls, P=0.024, OR=0.949, 95% CI=0.870-0.990). When the discovery and replication samples were pooled together, this association was further strengthened (P=0.004, OR=0.949, 95% CI=0.916-0.983). These results suggested that AHI1 is likely a risk gene for schizophrenia, at least in European populations.

Low-Level Laser Irradiation Improves Depression-Like Behaviors in Mice

Major depressive disorder (MDD) is one of the leading forms of psychiatric disorders, characterized by aversion to mobility, neurotransmitter deficiency, and energy metabolic decline. Low-level laser therapy (LLLT) has been investigated in a variety of neurodegenerative disorders associated with mitochondrial dysfunction and functional impairments. The goal of this study was to examine the effect of LLLT on depression-like behaviors and to explore the potential mechanism by detecting mitochondrial function following LLLT. Depression models in space restriction mice and Abelson helper integration site-1 (Ahi1) knockout (KO) mice were employed in this work. Our results revealed that LLLT effectively improved depression-like behaviors, in the two depression mice models, by decreasing immobility duration in behavioral despair tests. In addition, ATP biosynthesis and the level of mitochondrial complex IV expression and activity were significantly elevated in prefrontal cortex (PFC) following LLLT. Intriguingly, LLLT has no effects on ATP content and mitochondrial complex I-IV levels in other tested brain regions, hippocampus and hypothalamus. As a whole, these findings shed light on a novel strategy of transcranial LLLT on depression improvement by ameliorating neurotransmitter abnormalities and promoting mitochondrial function in PFC. The present work provides concrete groundwork for further investigation of LLLT for depression treatment.

The influence of AHI1 variants on the diagnosis and treatment outcome in schizophrenia

The present study aimed to explore whether four single nucleotide polymorphisms (SNPs) within the AHI1 gene could be associated with schizophrenia (SCZ) and whether they could predict the clinical outcomes in SCZ patients treated with antipsychotics. Four hundred twenty-six (426) in-patients with SCZ and 345 controls were genotyped for four AHI1 SNPs (rs11154801, rs7750586, rs9647635 and rs9321501). Baseline and clinical measures for SCZ patients were assessed through the Positive and Negative Syndrome Scale (PANSS). Allelic and genotypic frequencies in SCZ subjects were compared with those of controls using the χ² statistics. The repeated-measure ANOVA was used for the assessment of treatment outcomes measured by PANSS changes. The case-control analysis did not show any difference in the genotypic distribution of the SNPs, while in the allelic analysis, a weak association was found between the rs9647635 A allele and SCZ. Furthermore, in the haplotype analysis, three haplotypes resulted in being associated with SCZ. On the other hand, two SNPs (rs7750586 and rs9647635) were associated with clinical improvement of negative symptoms in the allelic analysis, although in the genotypic analysis, only trends of association were found for the same SNPs. Our findings suggest a possible influence of AHI1 variants on SCZ susceptibility and antipsychotic response, particularly concerning negative symptomatology. Subsequent well-designed studies would be mandatory to confirm our results due to the methodological shortcomings of the present study.