Identification and functional analysis of SKA2 interaction with the glucocorticoid receptor

Venlafaxine exposure alters mitochondrial respiration and mitomiR abundance in zebrafish brains

Wastewater treatment plant (WWTP) effluent often releases pharmaceuticals like venlafaxine (a serotonin-norephinephrine reuptake inhibitor antidepressant) to freshwater ecosystems at levels causing adverse metabolic effects on fish. Changes to fish metabolism can be regulated by epigenetic mechanisms like microRNA (small RNA molecules that regulate mRNA translation), including regulating mitochondrial mRNAs. Nuclear-encoded microRNAs regulate mitochondrial gene expression in mammals, and have predicted effects in fish. We aimed to identify whether venlafaxine exposure changed mitochondrial respiration and resulted in differentially abundant mitochondrial microRNA (mitomiRs) in zebrafish brains. In vitro exposure of brain homogenate to below environmentally relevant concentrations of venlafaxine (<1 µg/L) caused a decrease in mitochondrial respiration, although this was not driven by changes to mitochondrial Complex I or II function. To identify whether these effects occur in vivo, zebrafish were exposed to 1 µg/L venlafaxine for 0, 1, 6, 12, 24, and 96 h. In vivo, venlafaxine exposure had no significant effects on brain mitochondrial respiration; however, select mitomiRs (dre-miR-301a-5p, dre-miR-301b-3p, and dre-miR-301c-3p) were also measured, because they were bioinformatically predicted to regulate mitochondrial cytochrome c oxidase subunit I (COI) abundance. These mitomiRs were differentially regulated based on venlafaxine exposure (with miR-301c-3p abundance differing during the day and miR-301b-3p being lower in exposed fish at night), and with respect to sex and time sampled. Overall, the results demonstrated that in vitro venlafaxine exposure to zebrafish brain caused a decrease in mitochondrial respiration, but these effects were not seen after acute in vivo exposure. Results may have differed because in vivo exposure allows for fish to mitigate effects through mechanisms that could include mitomiR regulation, and because fish were only acutely exposed. Environ Toxicol Chem 2024;43:1569-1582. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The role of SKA2 on affective disorder, post-traumatic stress disorder and suicide behavior: systematic review and in silico analysis

Genes involved in the hypothalamic-pituitary-adrenal axis may be a robust biomarker of psychiatric disorders. Genetic polymorphisms of the SKA2 gene are associated with several behavioral disorders. In this study, we embarked on a systematic search of all possible reports of genetic association with SKA2 and affective disorder, post-traumatic stress disorder, and suicide behavior; the functional consequences of nsSNPs were explored through computational tools with an in silico analysis. Eight eligible articles were included. Our study identified that SKA2 did not show association with risk of Major Depression Disorder. Epigenetic variation at SKA2 mediates vulnerability to Post-Traumatic Stress Disorder. Studies provide strong preliminary evidence that alterations at the SKA2 gene covary with types of suicide behavior, including suicidal ideation, attempts, and completions. Results from in silico analysis predicted that I22S, I22G, I78T, A15L, D18R, R25L, N42I, Y21S, K14I, K14L, and L60R were the most structurally and functionally significant nsSNPs in SKA2. Amino acid conservation analysis revealed that the amino acids were highly conserved and some dissimilarities of mutant type amino acids from wild-type amino acids such as charge, size, and hydrophobicity were observed. In the future, SKA2 gene have the potential to be evaluated as prognostic biomarkers for diagnosis and research.

The rs7208505 Polymorphism and Differential Expression of the SKA2 Gene in the Prefrontal Cortex of Suicide Victims from the Mexican Population

OBJECTIVE

The main aim of the current study was to investigate whether SKA2 gene expression in the postmortem brain of rs7208505 genotype are altered in suicide victims from a Mexican population.

METHODS

In this study, we report a genetic analysis of expression levels of the SKA2 gene in the prefrontal cortex of the postmortem brain of suicidal subjects (n = 22) compared to subjects who died of causes other than suicide (n = 22) in a Mexican population using RT-qPCR assays. Additionally, we genotyped the rs7208505 polymorphism in suicide victims (n = 98) and controls (n = 88) and we evaluate the association of genotypes for the SNP rs7208505 with expression level of SKA2.

RESULTS

The results showed that the expression of the SKA2 gene was significantly higher in suicide victims compared to control subjects (p = 0.044). Interestingly, we observed a greater proportion of allele A of the rs7208505 in suicide victims than controls. Even though there was no association between the SNP with suicide in the study population we found a significative association of the expression level from SKA2 with the allele A of the rs7208505 and suicide.

CONCLUSION

The evidence suggests that the expression of SKA2 in the prefrontal cortex may be a critical factor in the etiology of suicidal behavior.

SKA2 regulated hyperactive secretory autophagy drives neuroinflammation-induced neurodegeneration

High levels of proinflammatory cytokines induce neurotoxicity and catalyze inflammation-driven neurodegeneration, but the specific release mechanisms from microglia remain elusive. Here we show that secretory autophagy (SA), a non-lytic modality of autophagy for secretion of vesicular cargo, regulates neuroinflammation-mediated neurodegeneration via SKA2 and FKBP5 signaling. SKA2 inhibits SA-dependent IL-1β release by counteracting FKBP5 function. Hippocampal Ska2 knockdown in male mice hyperactivates SA resulting in neuroinflammation, subsequent neurodegeneration and complete hippocampal atrophy within six weeks. The hyperactivation of SA increases IL-1β release, contributing to an inflammatory feed-forward vicious cycle including NLRP3-inflammasome activation and Gasdermin D-mediated neurotoxicity, which ultimately drives neurodegeneration. Results from protein expression and co-immunoprecipitation analyses of male and female postmortem human brains demonstrate that SA is hyperactivated in Alzheimer's disease. Overall, our findings suggest that SKA2-regulated, hyperactive SA facilitates neuroinflammation and is linked to Alzheimer's disease, providing mechanistic insight into the biology of neuroinflammation.

Associations of altered leukocyte DDR1 promoter methylation and childhood trauma with bipolar disorder and suicidal behavior in euthymic patients

Altered DNA methylation (DNAm) patterns of discoidin domain receptor 1 (DDR1) have been found in the blood and brain of patients with schizophrenia (SCZ) and the brain of patients with bipolar disorder (BD). Childhood trauma (CT) is associated with changes in DNAm that in turn are related to suicidal behavior (SB) in patients with several psychiatric disorders. Here, using MassARRAY® technology, we studied 128 patients diagnosed with BD in remission and 141 healthy controls (HCs) to compare leukocyte DDR1 promoter DNAm patterns between patients and HCs and between patients with and without SB. Additionally, we investigated whether CT was associated with DDR1 DNAm and mediated SB. We found hypermethylation at DDR1 cg19215110 and cg23953820 sites and hypomethylation at cg14279856 and cg03270204 sites in patients with BD compared to HCs. Logistic regression models showed that hypermethylation of DDR1 cg23953820 but not cg19215110 and CT were risk factors for BD, while cg14279856 and cg03270204 hypomethylation were protective factors. In patients, CT was a risk factor for SB, but DDR1 DNAm, although associated with CT, did not mediate the association of CT with SB. This is the first study demonstrating altered leukocyte DDR1 promoter DNAm in euthymic patients with BD. We conclude that altered DDR1 DNAm may be related to immune and inflammatory mechanisms and could be a potential blood biomarker for the diagnosis and stratification of psychiatric patients.

Molecular Changes Associated with Suicide

Suicide is a serious global public health problem, with a worrying recent increase in suicide rates in both adolescent and adult populations. However, it is essential to recognize that suicide is preventable. A myriad of factors contributes to an individual's vulnerability to suicide. These factors include various potential causes, from psychiatric disorders to genetic and epigenetic alterations. These changes can induce dysfunctions in crucial systems such as the serotonergic, cannabinoid, and hypothalamic-pituitary-adrenal axes. In addition, early life experiences of abuse can profoundly impact an individual's ability to cope with stress, ultimately leading to changes in the inflammatory system, which is a significant risk factor for suicidal behavior. Thus, it is clear that suicidal behavior may result from a confluence of multiple factors. This review examines the primary risk factors associated with suicidal behavior, including psychiatric disorders, early life adversities, and epigenetic modifications. Our goal is to elucidate the molecular changes at the genetic, epigenetic, and molecular levels in the brains of individuals who have taken their own lives and in the plasma and peripheral mononuclear cells of suicide attempters and how these changes may serve as predisposing factors for suicidal tendencies.

Decreased mononuclear cell NR3C1 SKA2 and FKPB5 expression levels among adult survivors of suicide bombing terror attacks in childhood are associated with the development of PTSD

Life threatening trauma and the development of PTSD during childhood, may each associate with transcriptional perturbation of immune cell glucocorticoid reactivity, yet their separable longer term contributions are less clear. The current study compared resting mononuclear cell gene expression levels of the nuclear receptor, subfamily 3, member 1 (NR3C1) coding the glucocorticoid receptor, its trans-activator spindle and kinetochore-associated protein 2 (SKA2), and its co-chaperon FKBP prolyl isomerase 5 (FKBP5), between a cohort of young adults first seen at the Hadassah Emergency Department (ED) after surviving a suicide bombing terror attack during childhood, and followed longitudinally over the years, and matched healthy controls not exposed to life threatening trauma. While significant reductions in mononuclear cell gene expression levels were observed among young adults for all three transcripts following early trauma exposure, the development of subsequent PTSD beyond trauma exposure, accounted for a small but significant portion of the variance in each of the three transcripts. Long-term perturbation in the expression of immune cell glucocorticoid response transcripts persists among young adults who develop PTSD following life threatening trauma exposure in childhood, denoting chronic dysregulation of immune stress reactivity.

SKA2 regulated hyperactive secretory autophagy drives neuroinflammation-induced neurodegeneration

High levels of proinflammatory cytokines induce neurotoxicity and catalyze inflammation-driven neurodegeneration, but the specific release mechanisms from microglia remain elusive. We demonstrate that secretory autophagy (SA), a non-lytic modality of autophagy for secretion of vesicular cargo, regulates neuroinflammation-mediated neurodegeneration via SKA2 and FKBP5 signaling. SKA2 inhibits SA-dependent IL-1β release by counteracting FKBP5 function. Hippocampal Ska2 knockdown in mice hyperactivates SA resulting in neuroinflammation, subsequent neurodegeneration and complete hippocampal atrophy within six weeks. The hyperactivation of SA increases IL-1β release, initiating an inflammatory feed-forward vicious cycle including NLRP3-inflammasome activation and Gasdermin D (GSDMD)-mediated neurotoxicity, which ultimately drives neurodegeneration. Results from protein expression and co-immunoprecipitation analyses of postmortem brains demonstrate that SA is hyperactivated in Alzheimer's disease. Overall, our findings suggest that SKA2-regulated, hyperactive SA facilitates neuroinflammation and is linked to Alzheimer's disease, providing new mechanistic insight into the biology of neuroinflammation.

DNA Methylation of Genes Involved in the HPA Axis in Presence of Suicide Behavior: A Systematic Review

DNA methylation in genes of the hypothalamic–pituitary–adrenal (HPA) axis has been associated with suicide behavior. Through a systematic review, we aimed to evaluate DNA methylation levels of the genes involved in the HPA pathway and their association with suicide behavior. A search of articles was performed using PubMed and Science Direct, EBSCO. The terms included were “DNA methylation”, “suicide”, “epigenetics”, “HPA axis” and “suicide behavior”. This systematic review was performed by the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statement. Six studies comprising 743 cases and 761 controls were included in this systematic review. The studies included individuals with suicide ideation, suicide attempts or completed suicide and childhood trauma, post-traumatic stress disorder (PTSD), or depression. One study reported hypermethylation in GR in childhood trauma, while two studies found hypermethylation of NR3C1 in childhood trauma and major depressive disorder (MDD). Only one study reported hypermethylation in BNDF in people with MDD. FKBP5 was found to be hypermethylated in people with MDD. Another study reported hypermethylation in CRHBP. SKA2 was reported to be hypermethylated in one study and another study found hypomethylated both in populations with PTSD. CRHR1 was found to be hypermethylated in people with MDD, and the last study found hypomethylation in CRH. Our result showed that patients with suicidal behavior showed a DNA methylation state of genes of the HPA axis in association with psychiatric comorbidity and with adverse events. Genes of the HPA axis could play a role in suicidal behavior associated with adverse events and pathologies. As a result, DNA methylation levels, proteins, and genes involved in the HPA axis could be considered for the search for biomarkers for the prevention of suicidal behavior in future studies.

SKA1 is overexpressed in laryngocarcinoma and modulates cell growth via P53 signaling pathway

Laryngocarcinoma is one of the most frequent malignancies occurring in the head and neck. The roles of spindle- and kinetochore-associated complex 1 (SKA1) in the malignant progression of several cancers have already been discussed. However, the precise significance and action's mechanism of SKA1 in laryngocarcinoma remain largely unknown. In this study, SKA1 was shown to be strongly expressed in laryngocarcinoma tissues and cells, and higher expression of SKA1 was associated with more severe tumor infiltration, larger tumor diameter, higher risk of lymphatic metastasis and later pathological stage. Additionally, loss-of-function assays in vitro suggested that SKA1 depletion caused a reduction in cell proliferation, migration, and colony formation as well as an increase in apoptosis. In animal experiments, tumors generated from AMC-HN-8 cells with SKA1 depletion exhibited declined tumor volume and weight. Similarly, the detection of Ki67 protein in xenograft tumor tissues reflected that knocking down SKA1 curbed tumor growth in vivo. Further exploration on downstream mechanism revealed that after treatment with Pifithrin-α, the suppression in proliferation level caused by SKA1 knockdown was reversed, while the increase of cell apoptosis was withdrawn; at the molecular level, Pifithrin-α treatment caused p-P53 and Bax diminished, while Bcl-2 ameliorated. In short, SKA1 promotes the development of laryngocarcinoma via activating the P53 signaling pathway.

Exposure to war and conflict: The individual and inherited epigenetic effects on health, with a focus on post-traumatic stress disorder

War and conflict are global phenomena, identified as stress-inducing triggers for epigenetic modifications. In this state-of-the-science narrative review based on systematic principles, we summarise existing data to explore the outcomes of these exposures especially in veterans and show that they may result in an increased likelihood of developing gastrointestinal, auditory, metabolic and circadian issues, as well as post-traumatic stress disorder (PTSD). We also note that, despite a potential "healthy soldier effect", both veterans and civilians with PTSD exhibit the altered DNA methylation status in hypothalamic-pituitary-adrenal (HPA) axis regulatory genes such as NR3C1. Genes associated with sleep (PAX8; LHX1) are seen to be differentially methylated in veterans. A limited number of studies also revealed hereditary effects of war exposure across groups: decreased cortisol levels and a heightened (sex-linked) mortality risk in offspring. Future large-scale studies further identifying the heritable risks of war, as well as any potential differences between military and civilian populations, would be valuable to inform future healthcare directives.

SKA2-mediated transcriptional downregulation of the key enzyme of CoQ10 biosynthesis PDSS2 in lung cancer cells

Lung cancer is the leading cause of cancer-associated mortality worldwide. SKA2 is a novel cancer-associated gene that plays critical roles in both cell cycle and tumorigenesis including lung cancer. However, the molecular mechanisms underlying its implication in lung cancer remains elusive. In this study, we first analyzed the gene expression profiling after SKA2 knockdown, and identified several candidate downstream target genes of SKA2, including PDSS2, the first key enzyme in CoQ₁₀ biosynthesis pathway. Further experiments verified that SKA2 remarkably repressed PDSS2 gene expression at both mRNA and protein levels. Luciferase reporter assay showed that SKA2 repressed PDSS2 promoter activity through its Sp1-binding sites. Co-immunoprecipitation assay demonstrated that SKA2 associated with Sp1. Functional analysis revealed that PDSS2 remarkably suppressed lung cancer cell growth and motility. Furthermore, SKA2-induced malignant features can be also significantly attenuated by PDSS2 overexpression. However, CoQ10 treatment showed no obvious effects on lung cancer cell growth and motility. Of note, PDSS2 mutants with no catalytic activity exhibited comparable inhibitory effects on the malignant features of lung cancer cells and could also abrogate SKA2-promoted malignant phenotypes in lung cancer cells, highly suggesting a non-enzymatic tumor-suppressing activity of PDSS2 in lung cancer cells. The levels of PDSS2 expression were significantly decreased in lung cancer samples, and lung cancer patients with high expression of SKA2 and low expression of PDSS2 displayed remarkable poor prognosis. Collectively, our results demonstrated that PDSS2 is a novel downstream target gene of SKA2 in lung cancer cells, and the SKA2-PDSS2 transcriptional regulatory axis functionally contributes to human lung cancer cell malignant phenotypes and prognosis.

Targeted sequencing approach: Comprehensive analysis of DNA methylation and gene expression across blood and brain regions in suicide victims

OBJECTIVES

Epigenetic mechanisms are involved in regulation of many pathologies, including suicidal behaviour. However, the factors through which epigenetics affect suicidal behaviour are not fully understood.

METHODS

We analysed DNA methylation of eight neuropsychiatric genes (NR3C1, SLC6A4, HTR1A, TPH2, SKA2, MAOA, GABRA1, and NRIP3) in brain regions (hippocampus, insula, amygdala, Brodmann area 46) and blood of 25 male suicide victims and 28 male control subjects, using bisulphite next-generation sequencing.

RESULTS

Comparing mean methylation values, notable changes were observed in NR3C1 (insula p-value = 0.05), HTR1A (insula p-value < 0.001, blood p-value = 0.001), SKA2 (insula p-value = 0.03, blood p-value = 0.016), MAOA (blood p-value < 0.001), GABRA1 (insula p-value = 0.05, blood p-value = 0.024) and NRIP3 (hippocampus p-value = 0.001, insula p-value = 0.002, amygdala p-value = 0.014). Comparing methylation pattern between blood and brain, similarity was observed between blood and insula for HTR1A. Gene expression analysis in hippocampus revealed changes in expression of NR3C1 (p-value = 0.049), SLC6A4 (p-value = 0.017) and HTR1A (p-value = 0.053).

CONCLUSIONS

Results provide an insight into the altered state of DNA methylation in suicidal behaviour. Epigenetic differences could therefore affect suicidal behaviour in both previously known and in novel neuropsychiatric candidate genes.

Resting mononuclear cell NR3C1 and SKA2 expression levels predict blunted cortisol reactivity to combat training stress among elite army cadets exposed to childhood adversity

Childhood adversity (CA) may alter reactivity to stress throughout life, increasing risk for psychiatric and medical morbidity, yet long-term correlates of milder CA levels among high functioning healthy adolescents are less studied. The current study examined the prevalence and impact of CA exposure among a cohort of healthy motivated elite parachute unit volunteers, prospectively assessed at rest and at the height of an intensive combat-simulation exposure. We found significantly reduced gene expression levels in resting mononuclear cell nuclear receptor, subfamily 3, member 1 (NR3C1), and its transactivator spindle and kinetochore-associated protein 2 (SKA2), that predict blunted cortisol reactivity to combat-simulation stress among CA exposed adolescents. Long-term alterations in endocrine immune indices, subjective distress, and executive functions persist among healthy high functioning adolescents following milder CA exposure, and may promote resilience or vulnerability to later real-life combat exposure.

Association and Genetic Expression between Genes Involved in HPA Axis and Suicide Behavior: A Systematic Review

BACKGROUND

Suicide behavior (SB) has been highly associated with the response to stress and the hypothalamic-pituitary-adrenal (HPA) axis. The aim of this study was to summarize the results obtained in genetic studies that analyzed the HPA axis-stress pathway and SB through a systematic review.

METHODS

We performed an online search in PubMed, EBSCO, Web of Science, Scopus, and PsycoInfo databases up to May 2021. We followed the PRISMA guidelines for systematic reviews. We included case-control and expression studies that provided data on mRNA expression and single-nucleotide polymorphisms of genes associated with SB.

RESULTS

A total of 21,926 individuals participated across 41 studies (not repeats); 34 studies provided data on single-nucleotide polymorphisms in 21,284 participants and 11 studies reported data on mRNA expression in 1034 participants. Ten genes were identified: FKBP5, CRH, CRHBP, CRHR1, CRHR2, NR3C1, NR3C2, SKA2, MC2R, and POMC.

CONCLUSIONS

Our findings suggest that key stress pathway genes are significantly associated with SB and show potential as biomarkers for SB.

The Shift of HbF to HbA under Influence of SKA2 Gene; A Possible Link between Cortisol and Hematopoietic Maturation in Term and Preterm Newborns

BACKGROUND

We hypothesized that the SKA2 gene can convert hemoglobin F to A leading to the maturity of the hematopoietic system by glucocorticoid hormone; so, the present study aimed to investigate the health outcome of newborns by using the effect of SKA2 gene on hematopoietic maturation.

METHODS

At first, 142 samples were divided into term and preterm. After sampling from the umbilical cord blood, the expression of SKA2 genes and HbA and F were evaluated by quantitative RT-PCR. The blood gases were measured by Campact 3 device. Finally, the cortisol level was measured by ELISA method and HbA and F levels were investigated by capillary electrophoresis.

RESULTS

The blood gases and Apgar scores were more favorable in term newborns (P <0.001). Levels of protein/expression of HbF in newborns with Apgar score greater than 7 was lower than that of the newborns with Apgar score below 7 (P <0.001). Cortisol and HbA levels were considerably higher in term newborns compared to the preterm ones (P <0.001). In the preterm and term groups, SKA2 gene expression had a positive and significant relationship with cortisol and HbA levels as well as a negative relationship with the HbF level. In the preterm group, a positive and significant relationship was observed between the expression of SKA2 and HbF genes.

CONCLUSION

The results revealed that the SKA2 gene affected hematopoietic maturation in preterm and term newborns and the health outcome of newborns improved by increasing HbA level.

Mifepristone Treatment Promotes Testicular Leydig Cell Tumor Progression in Transgenic Mice

Simple Summary

Recently, the antiprogestin activity of selective progesterone receptor (PR) modulator mifepristone (MF) has proven unsuccessful as a potential anti-cancer agent in various clinical trials. Herein, we analyzed the effects of MF treatment on Leydig cell tumor (LCT) progression in a transgenic mouse model (inhibin-α promoter-driven SV40 T-antigen), as well as on the proliferation of two Leydig tumor cell lines. MF significantly stimulated the proliferation of LCT in vitro. Similarly, a 1-mo MF or P4 treatment stimulated LCT tumor growth in vivo. Only the abundant membrane Pgrmc1 expression was found in LCTs, but no other classical Pgr or nonclassical membrane PRs. Functional analysis showed that PGRMC1 is required for MF and P4 to stimulate the proliferation and invasiveness of LCTs. Our findings provide novel information that the use of MF as an anti-cancer agent should be considered with caution due to its potential PGRMC1 tumor-promoting pathway activation in cancers.

Abstract

The selective progesterone receptor modulator mifepristone (MF) may act as a potent antiproliferative agent in different steroid-dependent cancers due to its strong antagonistic effect on the nuclear progesterone receptor (PGR). Hereby, we analyzed the effects of MF treatment on Leydig cell tumor (LCT) progression in a transgenic mouse model (inhibin-α promoter-driven SV40 T-antigen), as well as on LCT (BLTK-1 and mLTC-1) cell proliferation. MF significantly stimulated the proliferation of LCT in vitro. Similarly, a 1-mo MF or P4 treatment stimulated LCT tumor growth in vivo. Traceable/absent classical Pgr or nonclassical membrane PRs α, β, γ and Pgrmc2, but abundant membrane Pgrmc1 expression, was found in LCTs. MF did not activate glucocorticoid or androgen receptors in LCTs. Functional analysis showed that PGRMC1 is required for MF and P4 to stimulate the proliferation and invasiveness of LCTs. Accordingly, MF and P4 induced PGRMC1 translocation into the nucleus and thereby stimulated the release of TGFβ1 in LCT cells. MF and P4 treatments upregulated Tgfbr1, Tgfbr2, and Alk1 expression and stimulated TGFβ1 release in LCT cells. Our findings provide novel mechanistic insights into the action of MF as a membrane PR agonist that promotes LCT growth through PGRMC1 and the alternative TGFβ1 signaling pathway.

Identification of Spindle and Kinetochore-Associated Family Genes as Therapeutic Targets and Prognostic Biomarkers in Pancreas Ductal Adenocarcinoma Microenvironment

Aim

The role of spindle and kinetochore-associated (SKA) genes in tumorigenesis and cancer progression has been widely studied. However, so far, the oncogenic involvement of SKA family genes in pancreatic cancer and their prognostic potential remain unknown.

Methods

Here, we carried out a meta-analysis of the differential expression of SKA genes in normal and tumor tissue. Univariate and multivariate survival analyses were done to evaluate the correlation between SKA family gene expression and pancreas ductal adenocarcinoma (PDAC) prognosis. Joint-effect and stratified survival analysis as well as nomogram analysis were used to estimate the prognostic value of genes. The underlying regulatory and biological mechanisms were identified by Gene set enrichment analysis. Interaction between SKA prognosis-related genes and immune cell infiltration was assessed using the Tumor Immune Estimation Resource tool.

Results

We find that SKA1-3 are highly expressed in PDAC tissues relative to non-cancer tissues. Survival analysis revealed that high expression of SKA1 and SKA3 independently indicate poor prognosis but they are not associated with relapse-free survival. The prognostic value of SKA1 and SKA3 was further confirmed by the nomogram, joint-effect, and stratified survival analysis. Analysis of underlying mechanisms reveals that these genes influence cancer-related signaling pathways, kinases, miRNA, and E2F family genes. Notably, prognosis-related genes are inversely correlated with several immune cells infiltrating levels.

Conclusion

We find that SKA1 and SKA3 expression correlates with prognosis and immune cell infiltration in PDAC, highlighting their potential as pancreatic cancer prognostic biomarkers.

Spindle and kinetochore-associated protein 2 facilitates the proliferation and invasion of hepatocellular carcinoma via the regulation of Wnt/β-catenin signaling

Recent studies have shown that spindle and kinetochore-associated protein 2 (SKA2) is dysregulated in multiple tumors and acts as a key regulator of tumor progression. However, whether SKA2 plays a role in hepatocellular carcinoma (HCC) has not been fully elucidated. The purpose of this study was to explore the expression, function and underlying molecular mechanism of SKA2 in HCC. We found that SKA2 was highly expressed in HCC tissues and cell lines. Knockdown of SKA2 caused marked reductions in the proliferative, colony-forming and invasive capacities of HCC cells, while SKA2 overexpression had opposite effects. Further experiments revealed that overexpression of SKA2 enhanced expression levels of phosphorylated glycogen synthase kinase-3β (GSK-3β) and active β-catenin in HCC cells. Moreover, SKA3 overexpression enhanced transcriptional activity mediated by Wnt/β-catenin signaling. Knockdown of SKA3 downregulated the activation of Wnt/β-catenin signaling, and the effect was significantly reversed by the inhibition of GSK-3β. Notably, inhibition of Wnt/β-catenin signaling markedly abrogated SKA2-mediated promotion effect on HCC proliferation and invasion. In addition, knockdown of SKA2 impeded tumor formation and growth in HCC cells in a nude mouse in vivo model. Overall, these findings indicate that SKA2 accelerates the progression of HCC through the upregulation of Wnt/β-catenin signaling. Our study highlights a potential role of SKA2 in HCC progression and suggests it as a possible target for HCC treatment.

The Correlation of SKA2 with Cortisol, IL-1β and Anxiety in Pregnant Women with the Risk of Preterm Delivery

OBJECTIVE

The association between preterm birth (PTB), Spindle and Kinetochore Associated Complex Subunit 2 gene (SKA2), cortisol and anxiety have been shown, but in this study, we aimed to clarify whether the expression of the SKA2 gene plays a role in interleukin1β (IL-1β) level since increasing level of IL-1β is linked with PTB.

METHODS

The case-control study was conducted on 49 and 51 women with preterm and term delivery, respectively. The score of anxiety was ranked according to the Spielberger state trait Anxiety Inventory. The concentration of cortisol and IL-1β was determined by the ELISA method. The expression of SKA2 gene was assessed by the quantitative real time real time polymerase chain reaction (qRT-PCR). The western blot analysis was also performed to confirm the expression of SKA2 at the levels of protein.

RESULTS

The results showed that the gene/protein expression of SKA2, the concentrations of cortisol and IL-1β were significantly higher in the preterm than the term group. In the preterm group, the expression of SKA2 was positively correlated to the other factors including cortisol, IL-1β, and the degree of anxiety.

CONCLUSION

Our findings suggest that the expression of SKA2 was correlated positively to the levels of cortisol, IL-1β and the rate of anxiety in women with PTB.

Suicide epigenetics, a review of recent progress

BACKGROUND

Suicide results in over 800,000 deaths every year, making it a major public health concern worldwide. It is highly complex, with genetic and environmental influences. Epigenetic mechanisms, including DNA methylation, miRNA, and histone modifications, could explain the complex interplay of environmental risk factors with genetic risk factors in the emergence of suicidal behavior.

METHODS

Here, we review the literature on suicide epigenetics over the past 10 years.

RESULTS

There has been significant progress in the field of suicide epigenetics, with emerging findings in the brain-derived neurotrophic factor and hypothalamic-pituitary-adrenal axis genes.

LIMITATIONS

Studying patient subgroups is needed in order to extract more comparable and reproducible epigenetic findings in suicide.

CONCLUSIONS

It is crucial to consider suicidal patients or suicide victims' distal and proximal past history e.g., early-life adversity and psychiatric disorder in epigenetic studies of suicidality.

The Role of Epigenetic Dysregulation in Suicidal Behaviors

Suicidal behaviors have been associated with both heritable genetic variables and environmental risk factors. Epigenetic processes, such as DNA methylation, have important roles in mediating the effects of the environment on behavior. Dysregulation of these processes has been observed in many psychiatric disorders, and evidence suggests that they may also be involved in suicidal behaviors. Herein, we have summarized candidate gene and epigenome-wide studies which have investigated DNA methylation in relation to suicidal behaviors, as well as discussed some of the limitations of the field to date.

SKA1 promotes malignant phenotype and progression of glioma via multiple signaling pathways

Background

Spindle and kinetochore associated protein 1 (SKA1) is a protein involved in chromosome congression and mitosis. It has been found to be upregulated and oncogenic in several human cancers. Herein, we investigated the precise role of SKA1 in the progression and malignant phenotype of human glioma.

Methods

Bioinformatic analysis was carried out based on the RNA-seq data and corresponding clinical data from GEO, TCGA and CGGA databases. Western blot was performed to analyze the expression of SKA1 in clinical samples and signaling pathway proteins in glioma cells, respectively. CCK8 assay, colony forming assay and EdU assay were performed to assess the cell viability. Cell migration and invasion assays were also performed. Moreover, xenograft model was established and the expression of SKA1 was assessed in the xenograft by immunohistochemistry.

Results

SKA1 expression is positively correlated with glioma grade and could be a promising biomarker for GBM. Moreover, overexpression of SKA1 may lead to poor prognosis in glioma. Downregulation of SKA1 attenuated cell viability, migration, and invasion in U251, U87, LN229 and T98 cells. Furthermore, GSEA analysis demonstrated that SKA1 was involved in the cell cycle, EMT pathway as well as Wnt/β-catenin signaling pathway, which were then confirmed with Western blot analysis.

Conclusion

SKA1 promotes malignant phenotype and progression of glioma via multiple pathways, including cell cycle, EMT, Wnt/β-catenin signaling pathway. Therefore, SKA1 could be a promising therapeutic target for the treatment of human gliomas.

Molecular mechanisms underlying mifepristone's agonistic action on ovarian cancer progression

Background

Recent clinical trials on ovarian cancer with mifepristone (MF) have failed, despite in vitro findings on its strong progesterone (P4) antagonist function.

Methods

Ovarian cancer human and murine cell lines, cultured high-grade human primary epithelial ovarian cancer (HG-hOEC) cells and their explants; as well as in vivo transgenic mice possessing ovarian cancer were used to assess the molecular mechanism underlying mifepristone (MF) agonistic actions in ovarian cancer progression.

Findings

Herein, we show that ovarian cancer cells express traceable/no nuclear P4 receptor (PGR), but abundantly P4 receptor membrane component 1 (PGRMC1). MF significantly stimulated ovarian cancer cell migration, proliferation and growth in vivo, and the translocation of PGRMC1 into the nucleus of cancer cells; the effects inhibited by PGRMC1 inhibitor. The beneficial antitumor effect of high-doses MF could not be achieved in human cancer tissue, and the low tissue concentrations achieved with the therapeutic doses only promoted the growth of ovarian cancers.

Interpretation

Our results indicate that treatment of ovarian cancer with MF and P4 may induce similar adverse agonistic effects in the absence of classical nuclear PGRs in ovarian cancer. The blockage of PGRMC1 activity may provide a novel treatment strategy for ovarian cancer.

Fund

This work was supported by grants from the National Science Centre, Poland (2013/09/N/NZ5/01831 to DP-T; 2012/05/B/NZ5/01867 to MC), Academy of Finland (254366 to NAR), Moikoinen Cancer Research Foundation (to NAR) and EU PARP Cluster grant (UDA-POIG.05.01.00-005/12-00/NCREMFP to SW).

PRR11 and SKA2 gene pair is overexpressed and regulated by p53 in breast cancer

Our previous study found that two novel cancer-related genes, PRR11 and SKA2, constituted a classic gene pair that was regulated by p53 and NF-Y in lung cancer. However, their role and regulatory mechanism in breast cancer remain elusive. In this study, we found that the expression levels of PRR11 and SKA2 were upregulated and have a negative prognotic value in breast cancer. Loss-of-function experiments showed that RNAi-mediated knockdown of PRR11 and/or SKA2 inhibited proliferation, migration, and invasion of breast cancer cells. Mechanistic experiments revealed that knockdown of PRR11 and/or SKA2 caused dysregulation of several downstream genes, including CDK6, TPM3, and USP12, etc. Luciferase reporter assays demonstrated that wild type p53 significantly repressed the PRR11-SKA2 bidirectional promoter activity, but not NF-Y. Interestingly, NF-Y was only essential for and correlated with the expression of PRR11, but not SKA2. Consistently, adriamycin-induced (ADR) activation of endogenous p53 also caused significant repression of the PRR11 and SKA2 gene pair expression. Notably, breast cancer patients with lower expression levels of either PRR11 or SKA2, along with wild type p53, exhibited better disease-free survival compared to others with p53 mutations and/or higher expression levels of either PRR11 or SKA2. Collectively, our study indicates that the PRR11 and SKA2 transcription unit might be an oncogenic contributor and might serve as a novel diagnostic and therapeutic target in breast cancer.

SKA2 gene - A novel biomarker for latent anxiety and preterm birth prediction

BACKGROUND

There is a relationship between preterm birth (PTB) and anxiety. Spindle and Kinetochore Associated Complex Subunit 2 (SKA2) gene polymorphism (NC_000017.11: g.59110368 G > A) has also been associated with the development of anxiety. The current study was designed to evaluate the relationship between SKA2 gene SNP (NC_000017.11: g.59110368 G > A) with the occurrence of anxiety and PTB which might be considered a predictive biomarker for the prediction of preterm delivery.

METHODS

SKA2 gene (SNP rs7208505) genotyping was performed in 300 women with term birth (TB) and 293 women with PTB using PCR-RFLP method and then followed by DNA sequencing. Cortisol level was analyzed with ELISA method and the presence of anxiety was detected using Spielberg Inventory.

RESULTS

The AA genotype of SKA2 gene significantly increased the risk of PTB compared to the GG genotype by 9.6 fold ([CI] 4.5-20.2, P < 0.001) according to codominant model. Also, the frequency of A allele was significantly higher in PTB group (χ2 = 20.4, df = 1, P < 0.001) in comparison with the control group that increased the risk of PTB by 1.703 fold ([CI] 1.39-2.23, P < 0.001). Women with higher cortisol level with average 343.7 ± 3 nmol/L had AA genotype, while, the concentrations of cortisol in women with AG, and GG genotypes were 244.2 ± 3.1 nmol/L and 192.6 ± 2.5 nmol/L, respectively (P < 0.001). The score of apparent and latent anxiety in women with the AA genotype was higher compared to the AG and GG genotypes and also this score in women with the AG genotype was higher than the GG genotypes (P < 0.001). The history of preterm delivery was higher in women with the AA genotype (42.1%) in comparison with the GG (14.9%) and AG (22%) genotypes (P < 0.05).

CONCLUSION

The results of the current study suggest that prognosis of women with the AA genotype are more susceptible to be spontaneous preterm birth. Therefore, the A allele of SKA2 gene (NC_000017.11:g.59110368 G > A) could be as a predictive biomarker for the risk of PTB.

SKA1 induces de novo MTX-resistance in osteosarcoma through inhibiting FPGS transcription

De novo methotrexate (MTX)-resistance, whose underlying mechanism remains largely unknown, usually leads to very poor prognosis in patients with osteosarcoma (OS). In this study, we established the de novo MTX-resistant OS cell line SF-86 and identified the candidate gene spindle and kinetochore associated complex subunit 1 (SKA1) as potentially related to de novo MTX-resistance. Analysis of a cohort of 95 OS patients demonstrated that SKA1 overexpression significantly correlated with de novo MTX-resistance and poor 5-year survival. Mechanistically, SKA1 overexpression lead to a downregulation of folylpoly-γ-glutamate synthetase (FPGS), a key enzyme that converts MTX into its active form, MTX-PG. We further demonstrated that SKA1 interacts with DNA-directed RNA polymerase II subunit RPB3. ChIP analysis revealed that RPB3 binds the promoter region of the FPGS gene and triggers FPGS transcription upon MTX treatment in SW1353, a MTX-sensitive OS cell line lacking endogenous SKA1 expression. On the contrary, this process is blocked in SF-86 cells due to the formation of an inhibitory SKA1-RPB3 complex. Furthermore, downregulation of SKA1 levels restores MTX sensitivity in SF-86. Collectively, our study has established the de novo MTX-resistant cell line SF-86 and identified SKA1 as a novel regulator of FPGS, playing a key role in the development of de novo MTX-resistance in OS.

DNA methylation correlates of PTSD: Recent findings and technical challenges

There is increasing evidence that epigenetic factors play a critical role in posttraumatic stress disorder (PTSD), by mediating the impact of environmental exposures to trauma on the regulation of gene expression. DNA methylation is one epigenetic process that has been highly studied in PTSD. This review will begin by providing an overview of DNA methylation (DNAm) methods, and will then highlight two major biological systems that have been identified in the epigenetic regulation in PTSD: (a) the immune system and (b) the stress response system. In addition to candidate gene approaches, we will review novel strategies to study epigenome-wide PTSD-related effects, including epigenome-wide algorithms that distill information from many loci into a single summary score (e.g., measures of "epigenetic age" which have been associated with PTSD). This review will also cover recent epigenome wide association studies (EWAS) of PTSD, and biological pathway models used to identify gene sets enriched in PTSD. Finally, we address technical and methodological advances and challenges to the field, and highlight exciting directions for future research.

SKA2/FAM33A: A novel gene implicated in cell cycle, tumorigenesis, and psychiatric disorders

SKA2 (spindle and KT associated 2), also referred to as FAM33A (family with sequence similarity 33, member A), is a recently identified gene involved in cell cycle regulation, and growing evidence is implicating its roles in tumorigenesis and psychiatric disorders. It has been demonstrated that SKA2, along with its coworkers SKA1 and SKA3, constitutes the SKA complex which plays a critical role in the maintenance of the metaphase plate and/or spindle checkpoint silencing during mitosis. SKA2 is over-expressed both in cancer cell lines and clinical samples including small cell lung cancer and breast cancer, whereas downregulation of SKA2 is associated with depression and suicidal ideation. The expression of SKA2 is regulated by transcription factors including NF-κΒ and CREB, miRNAs as well as DNA methylation. In this review, we provide an overview of studies that reveal SKA2 gene and protein characteristics as well as physiological function, with a special focus on its transcription regulatory mechanisms, and also provide a summary regarding the translational opportunity of the SKA2 gene as a clinical biomarker for cancers and psychiatric disorders.

SKA2 mediates invasion and metastasis in human breast cancer via EMT

Spindle and kinetochore‑associated protein 2 (SKA2) is essential for regulating the progression of mitosis. In recent years, SKA2 upregulation has been detected in various human malignancies and the role of SKA2 in tumorigenesis has received increasing attention. However, the expression and functional significance of SKA2 in breast cancer are not completely understood. To study the effects of SKA2 on breast cancer, the expression levels of SKA2 in breast cancer tissues and cell lines were evaluated by western blotting, reverse transcription‑quantitative polymerase chain reaction and immunohistochemical staining. The results demonstrated that SKA2 expression was increased in breast cancer tissues and cells, and SKA2 overexpression was associated with clinical stage and lymph node metastasis. Functional investigations revealed that SKA2 knockdown in breast cancer cells significantly reduced migration and invasion, and resulted in the decreased expression levels of matrix metalloproteinase (MMP)2 and MMP9. Furthermore, the typical microtubule arrangement was altered in SKA2 small interfering RNA (siSKA2)‑transfected cells. Reduced levels of SKA2 also downregulated the expression of epithelial‑mesenchymal transition proteins, including fibronectin, N‑cadherin and vimentin, whereas there were no alterations in the protein expression levels of E‑cadherin. Conversely, upregulation of SKA2 decreased the expression levels of E‑cadherin, and increased N‑cadherin, fibronectin and vimentin levels. Notably, it was demonstrated that E‑cadherin was translocated from the cytoplasm to the nucleus in siSKA2‑transfected cells. These results demonstrated that SKA2 may be associated with breast cancer metastasis, and siSKA2 inhibited the invasion and metastasis of breast cancer via translocation of E‑cadherin from the cytoplasm to the nucleus.

Neurotransmitter, Peptide, and Steroid Hormone Abnormalities in PTSD: Biological Endophenotypes Relevant to Treatment

PURPOSE OF REVIEW

This review summarizes neurotransmitter, peptide, and other neurohormone abnormalities associated with posttraumatic stress disorder (PTSD) and relevant to development of precision medicine therapeutics for PTSD.

RECENT FINDINGS

As the number of molecular abnormalities associated with PTSD across a variety of subpopulations continues to grow, it becomes clear that no single abnormality characterizes all individuals with PTSD. Instead, individually variable points of molecular dysfunction occur within several different stress-responsive systems that interact to produce the clinical PTSD phenotype. Future work should focus on critical interactions among the systems that influence PTSD risk, severity, chronicity, comorbidity, and response to treatment. Effort also should be directed toward development of clinical procedures by which points of molecular dysfunction within these systems can be identified in individual patients. Some molecular abnormalities are more common than others and may serve as subpopulation biological endophenotypes for targeting of currently available and novel treatments.

Anti-tumor roles of both strands of the miR-455 duplex: their targets SKA1 and SKA3 are involved in the pathogenesis of renal cell carcinoma

Recent studies revealed that some passenger strands of miRNAs acted as anti-tumor or oncogenic miRNAs in cancer cells. In this study, we focused on miR-455-5p (the passenger strand) and miR-455-3p (the guide strand) based on microRNA (miRNA) expression signatures of cancer cells. Both miR-455-5p and miR-455-3p were downregulated in renal cell carcinoma (RCC) tissues and low expression of these miRNAs was significantly associated with poor prognosis. Cancer cell proliferation, migration and invasive abilities were significantly inhibited by ectopic expression of miR-455-5p and miR-455-3p. To identify their oncogenic targets, we applied a combination of genome-wide gene expression and in silico miRNA database analyses. We focused on spindle and kinetochore-associated proteins, SKA1 and SKA3 and demonstrated direct regulation of SKA1 by miR-455-5p and SKA3 by miR-455-3p in RCC cells. Our present data demonstrated overexpression of SKA3 in RCC clinical specimens. Moreover, the study showed that the miR-455-3p/SKA3 axis contributed to cancer cell aggressiveness. Analytic strategies based on anti-tumor miRNAs, including passenger strands of miRNAs, are effective approaches for the elucidation of the molecular pathogenesis of RCC.

MiR-520d-3p antitumor activity in human breast cancer via post-transcriptional regulation of spindle and kinetochore associated 2 expression

MicroRNAs (miRNAs) play an important role in human tumorigenesis as oncogenes or tumor suppressors by directly binding to the 3'-untranslated region of their target mRNAs. MiR-520d-3p has been reported as a tumor suppressor gene in ovarian cancer and gastric cancer, while the function of miR-520d-3p in human breast cancers is still uninvolved. In this study, we initially identified that the expression of miR-520d-3p was significantly reduced in breast cancer specimens and cell lines. The restoration of miR-520d-3p expression not only reduced breast cancer cell viability by causing the accumulation of G2 phase and cell apoptosis, but also inhibited tumorigenicity in vivo. In addition, as a critical target of miR-520d-3p, the activity of spindle and kinetochore associated 2 (SKA2) was greatly inhibited by miR-520d-3p, and overexpression of miR-520d-3p decreased the expression of SKA2. SKA2 downregulation suppressed cell viability, whereas restoration of SKA2 expression significantly reversed the inhibitory effects of miR-520d-3p antitumor activity. Furthermore, SKA2 was frequently overexpressed in clinical specimens and cell lines, and the expression levels were statistically inversely correlated with miR-520d-3p expression. In conclusion, our data demonstrated that miR-520d-3p antitumor activity is achieved by targeting the SKA2 in human breast cancer cells, suggesting that miR-520d-3p may be a potential target molecule for the therapy.

Understanding the Neuroepigenetic Constituents of Suicide Brain

Stressful life incidents often cause a predisposition for developing mental disorders such as major depressive disorder (MDD). Impaired neurocognitive and neuro-vegetative functions of the central nervous system are the hallmarks of this mental illness. Blunted responses from emotionally salient regions of the brain including cortex, hippocampus, and amygdala have been associated with MDD-related behavioral changes. Moreover, improper signal processing and neuronal atrophy were held responsible for the overall dysfunctionality of these vulnerable regions in the MDD brain. The prevalence of genetic susceptibility along with adverse environmental stimuli often makes the situation worse for MDD patients, leading to an increased risk of suicidal behavior and eventually death by suicide. Despite considerable efforts to understand the complex neurobiology associated with MDD and suicidal behavior, their pathological determinants remain mostly elusive. Recent research, however, has shown that epigenetic perturbations have a formidable impact on the etiopathogenesis of MDD. Understanding the neuroepigenetic nature of this mental disorder may provide opportunities to devise more effective treatment strategies. Moreover, this can potentially lead to identifying predictive biomarkers associated with suicide risk. The present chapter critically reviews studies pertaining to epigenetic signatures of MDD and suicide brain.

The stress response HPA-axis hormone, glucocorticoid, reduces cellular SKA complex gene expression

The Spindle- and Kinetochore-Associated (SKA) complex has been proven to be involved in many human mental behavioral disorders. Glucocorticoid, a hypothalamic-pituitary-adrenal (HPA) axis hormone, is a critical mediator of stress response in neurons. However, the underlying mechanisms of glucocorticoid's effects on human neuronal cells remain unclear. This study demonstrates that increased extracellular glucocorticoid levels significantly reduce neuronal cell SKA complex genes' expression levels, followed by altered neuronal cell viability and neurite development. The results suggest that the abnormality of this HPA-axis hormone could impact the neuronal cell functions through the alternation of SKA complex functions, which might induce cell death.

Genetic variant in CACNA1C is associated with PTSD in traumatized police officers

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder that may develop after a traumatic event. Here we aimed to identify epigenetic and genetic loci associated with PTSD. We included 73 traumatized police officers with extreme phenotypes regarding symptom severity despite similar trauma history: n = 34 had PTSD and n = 39 had minimal PTSD symptoms. Epigenetic and genetic profiles were based on the Illumina HumanMethylation450 BeadChip. We searched for differentially methylated probes (DMPs) and differentially methylated regions (DMRs). For genetic associations we analyzed the CpG-SNPs present on the array. We detected no genome-wide significant DMPs and we did not replicate previously reported DMPs associated with PTSD. However, GSE analysis of the top 100 DMPs showed enrichment of three genes involved in the dopaminergic neurogenesis pathway. Furthermore, we observed a suggestive association of one relatively large DMR between patients and controls, which was located at the PAX8 gene and previously associated with other psychiatric disorders. Finally, we validated five PTSD-associated CpG-SNPs identified with the array using sanger sequencing. We subsequently replicated the association of one common SNP (rs1990322) in the CACNA1C locus with PTSD in an independent cohort of traumatized children. The CACNA1C locus was previously associated with other psychiatric disorders, but not yet with PTSD. Thus, despite the small sample size, inclusion of extreme symptom severity phenotypes in a highly homogenous traumatized cohort enabled detection of epigenetic and genetic loci associated with PTSD. Moreover, here we showed that genetically confounded 450K probes are informative for genetic association analysis.

Long non-coding RNA SPRY4-IT1 promotes the proliferation and invasion of U251 cells through upregulation of SKA2

The long non-coding RNA SPRY4-intronic transcript 1 (SPRY4-IT1) has been shown to promote the progression of cancer; however, the role of SPRY4-IT1 in glioma remains unclear. The present study demonstrated that SPRY4-IT1 expression was markedly increased in glioma tissues and cells compared with normal brain tissues, whereas knockdown of SPRY4-IT1 inhibited cell proliferation, migration, and invasion in U251 cells. Spindle and kinetochore associated complex subunit 2 (SKA2) was found to be a target of SPRY4-IT1 and was downregulated by SPRY4-IT1-knockdown. Additionally, SPRY4-IT1 expression was positively correlated with SKA2 in glioma tissues. To the best of our knowledge, the present study provides the first demonstration that SKA2 may have an oncogenic role in U251 cells. These results indicate that SPRY4-IT1 may serve a notable role in the molecular etiology of glioma and represents a potential target in glioma therapy.

Epigenetic modification of miR-141 regulates SKA2 by an endogenous 'sponge' HOTAIR in glioma

Aberrant expression of miR-141 has recently implicated in the occurrence and development of various types of malignant tumors. However whether the involvement of miR-141 in the pathogenesis of glioma remains unknown. Here, we showed that miR-141 was markedly downregulated in glioma tissues and cell lines compared with normal brain tissues, and its expression correlated with the pathological grading. Enforced expression of miR-141 in glioma cells significantly inhibited cell proliferation, migration and invasion, whereas knockdown of miR-141 exerted opposite effect. Mechanistic investigations revealed that HOTAIR might act as an endogenous 'sponge' of miR-141, thereby regulating the derepression of SKA2. Further, we explored the molecular mechanism by which miR-141 expression was regulated, and found that the miR-141 promoter was hypermethylated and that promoter methylation of miR-141 was mediated by DNMT1 in glioma cells. Finally, both overexpression of miR-141 and knockdown of HOTAIR in a mouse model of human glioma resulted in significant reduction of tumor growth in vivo. Collectively, these results suggest that epigenetic modification of miR-141 and the interaction of ceRNA regulatory network will provide a new approach for therapeutics against glioma.

Cyclic AMP responsive element-binding protein promotes renal cell carcinoma proliferation probably via the expression of spindle and kinetochore-associated protein 2

Emerging evidence shows that the aberrantly expressed cyclic AMP responsive element-binding protein (CREB) is associated with tumor development and progression in several cancers. Spindle and kinetochore-associated protein 2 (SKA2) is essential for regulating the progress of mitosis. In this study, we evaluate in vitro and in vivo the functional relationship between CREB and SKA2 in renal cell carcinoma (RCC). Suppressing and replenishing CREB levels were used to manipulate SKA2 expression, observing the effects on RCC cell lines. Computational prediction and ChIP assay identified that CREB targeted ska2 by binding its CRE sequence in the human genome. Overexpression of CREB reversed the inhibited cell growth following siSKA2 treatment, and reduced the number of cells holding in mitosis. Decreased expression of CREB suppressed RCC cell growth and xenograft tumor formation, accompanied by reduced expression of SKA2. In RCC tumor samples from patients, mRNA for SKA2 were plotted near those of CREB in each sample, with significantly increased immunohistochemical staining of higher SKA2 and CREB in the higher TNM stages. The study adds evidence that CREB, a tumor oncogene, promotes RCC proliferation. It probably achieves this by increasing SKA2 expression.

Neuropathology of suicide: recent findings and future directions

Suicide is a major public health concern and a leading cause of death in most societies. Suicidal behaviour is complex and heterogeneous, likely resulting from several causes. It associates with multiple factors, including psychopathology, personality traits, early-life adversity and stressful life events, among others. Over the past decades, studies in fields ranging from neuroanatomy, genetics and molecular psychiatry have led to a model whereby behavioural dysregulation, including suicidal behaviour (SB), develops as a function of biological adaptations in key brain systems. More recently, the unravelling of the unique epigenetic processes that occur in the brain has opened promising avenues in suicide research. The present review explores the various facets of the current knowledge on suicidality and discusses how the rapidly evolving field of neurobehavioural epigenetics may fuel our ability to understand, and potentially prevent, SB.

Epigenome-wide association of PTSD from heterogeneous cohorts with a common multi-site analysis pipeline

Compelling evidence suggests that epigenetic mechanisms such as DNA methylation play a role in stress regulation and in the etiologic basis of stress related disorders such as Post traumatic Stress Disorder (PTSD). Here we describe the purpose and methods of an international consortium that was developed to study the role of epigenetics in PTSD. Inspired by the approach used in the Psychiatric Genomics Consortium, we brought together investigators representing seven cohorts with a collective sample size of N = 1147 that included detailed information on trauma exposure, PTSD symptoms, and genome-wide DNA methylation data. The objective of this consortium is to increase the analytical sample size by pooling data and combining expertise so that DNA methylation patterns associated with PTSD can be identified. Several quality control and analytical pipelines were evaluated for their control of genomic inflation and technical artifacts with a joint analysis procedure established to derive comparable data over the cohorts for meta-analysis. We propose methods to deal with ancestry population stratification and type I error inflation and discuss the advantages and disadvantages of applying robust error estimates. To evaluate our pipeline, we report results from an epigenome-wide association study (EWAS) of age, which is a well-characterized phenotype with known epigenetic associations. Overall, while EWAS are highly complex and subject to similar challenges as genome-wide association studies (GWAS), we demonstrate that an epigenetic meta-analysis with a relatively modest sample size can be well-powered to identify epigenetic associations. Our pipeline can be used as a framework for consortium efforts for EWAS.

Targeting mitotic pathways for endocrine-related cancer therapeutics

A colossal amount of basic research over the past few decades has provided unprecedented insights into the highly complex process of cell division. There is an ever-expanding catalog of proteins that orchestrate, participate and coordinate in the exquisite processes of spindle formation, chromosome dynamics and the formation and regulation of kinetochore microtubule attachments. Use of classical microtubule poisons has still been widely and often successfully used to combat a variety of cancers, but their non-selective interference in other crucial physiologic processes necessitate the identification of novel druggable components specific to the cell cycle/division pathway. Considering cell cycle deregulation, unscheduled proliferation, genomic instability and chromosomal instability as a hallmark of tumor cells, there lies an enormous untapped terrain that needs to be unearthed before a drug can pave its way from bench to bedside. This review attempts to systematically summarize the advances made in this context so far with an emphasis on endocrine-related cancers and the avenues for future progress to target mitotic mechanisms in an effort to combat these dreadful cancers.

Understanding epigenetic architecture of suicide neurobiology: A critical perspective

Current understanding of environmental cross-talk with genetic makeup is found to be mediated through an epigenetic interface which is associated with prominent reversible and heritable changes at gene expression level. Recent emergence of epigenetic modulation in shaping the genetic information has become a key regulatory factor in answering the underlying complexities associated with several mental disorders. A comprehensive understanding of the pertinent changes in the epigenetic makeup of suicide phenotype exhibits a characteristic signature with the possibility of using it as a biomarker to help predict the risk factors associated with suicide. Within the scope of this current review, the most sought after epigenetic changes of DNA methylation and histone modification are thoroughly scrutinized to understand their close functional association with the broad spectrum of suicide phenotype.

Discovery and replication of a peripheral tissue DNA methylation biosignature to augment a suicide prediction model

Background

Suicide is the second leading cause of death among adolescents in the USA, and rates are rising. Methods to identify individuals at risk are essential for implementing prevention strategies, and the development of a biomarker can potentially improve prediction of suicidal behaviors. Prediction of our previously reported SKA2 biomarker for suicide and PTSD is substantially improved by questionnaires assessing perceived stress or anxiety and is therefore reliant on psychological assessment. However, such stress-related states may also leave a biosignature that could equally improve suicide prediction. In genome-wide DNA methylation data, we observed significant overlap between waking cortisol-associated and suicide-associated DNA methylation in blood and the brain, respectively.

Results

Using a custom bioinformatic brain to blood discovery algorithm, we derived a DNA methylation biosignature that interacts with SKA2 methylation to improve the prediction of suicidal ideation in our existing suicide prediction model across both blood and saliva data sets. This biosignature was independently validated in the Grady Trauma Project cohort and interacted with HPA axis metrics in the same cohort. The biosignature showed a relationship with immune status by its correlation with myeloid-derived cell proportions in all data sets and with IL-6 measures in a prospective postpartum depression cohort. Three probes showed significant correlations with the biosignature: cg08469255 (DDR1), cg22029879 (ARHGEF10), and cg24437859 (SHP1), of which SHP1 methylation correlated with immune measures.

Conclusions

We conclude that this biosignature interacts with SKA2 methylation to improve suicide prediction and may represent a biological state of immune and HPA axis modulation that mediates suicidal behavior.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-016-0279-1) contains supplementary material, which is available to authorized users.

The Expression of the Suicide-Associated Gene SKA2 Is Decreased in the Prefrontal Cortex of Suicide Victims but Not of Nonsuicidal Patients

BACKGROUND

Recent study of genome-wide DNA methylation profiling in the postmortem brain of suicidal and nonsuicidal subjects found that gene expression of spindle and kinetochore associated complex subunit 2 (SKA2) is decreased in the postmortem brain of suicide victims compared with nonsuicidal, nonpsychiatric control subjects.

METHODS

To determine if decreased SKA2 is specific to suicide and independent of diagnosis, we determined gene and protein expression of SKA2 in the prefrontal cortex obtained from suicide victims (n= 52), nonsuicidal psychiatric subjects (n= 27), and normal controls (n= 24). We determined gene expression by quantitative PCR technique and protein expression by Western blot. The postmortem brain samples were obtained from the Maryland Psychiatric Research Center.

RESULTS

We found that protein and gene expression of SKA2 was significantly reduced in the prefrontal cortex of suicide victims compared with normal control subjects and nonsuicidal patients. We also found that SKA2 protein and gene expression in depressed suicide victims, schizophrenic suicide victims, and suicide victims with substance abuse and/or conduct disorders was significantly decreased compared with normal control subjects and also with nonsuicidal depressed or schizophrenic subjects.

CONCLUSIONS

This study shows that decreased gene and protein expression of SKA2 observed in the prefrontal cortex of suicide victims is specific to suicide, which was not observed in the brain of nonsuicidal patients. It also indicates reduced SKA2 expression in suicide is independent of psychiatric diagnosis, since it is observed in all diagnostic groups studied. Therefore, SKA2 may be a potential biomarker for suicide.

GLUCOCORTICOID RECEPTOR-RELATED GENES: GENOTYPE AND BRAIN GENE EXPRESSION RELATIONSHIPS TO SUICIDE AND MAJOR DEPRESSIVE DISORDER

INTRODUCTION

We tested the relationship between genotype, gene expression and suicidal behavior and major depressive disorder (MDD) in live subjects and postmortem samples for three genes, associated with the hypothalamic-pituitary-adrenal axis, suicidal behavior, and MDD; FK506-binding protein 5 (FKBP5), Spindle and kinetochore-associated protein 2 (SKA2), and Glucocorticoid Receptor (NR3C1).

MATERIALS AND METHODS

Single-nucleotide polymorphisms (SNPs) and haplotypes were tested for association with suicidal behavior and MDD in a live (N = 277) and a postmortem sample (N = 209). RNA-seq was used to examine gene and isoform-level brain expression postmortem (Brodmann Area 9; N = 59). Expression quantitative trait loci (eQTL) relationships were examined using a public database (UK Brain Expression Consortium).

RESULTS

We identified a haplotype within the FKBP5 gene, present in 47% of the live subjects, which was associated with increased risk of suicide attempt (OR = 1.58, t = 6.03, P = .014). Six SNPs on this gene, three SNPs on SKA2, and one near NR3C1 showed before-adjustment association with attempted suicide, and two SNPs of SKA2 with suicide death, but none stayed significant after adjustment for multiple testing. Only the SKA2 SNPs were related to expression in the prefrontal cortex (pFCTX). One NR3C1 transcript had lower expression in suicide relative to nonsuicide sudden death cases (b = -0.48, SE = 0.12, t = -4.02, adjusted P = .004).

CONCLUSION

We have identified an association of FKBP5 haplotype with risk of suicide attempt and found an association between suicide and altered NR3C1 gene expression in the pFCTX. Our findings further implicate hypothalamic pituitary axis dysfunction in suicidal behavior.

Neuroimaging genetic approaches to Posttraumatic Stress Disorder

Neuroimaging genetic studies that associate genetic and epigenetic variation with neural activity or structure provide an opportunity to link genes to psychiatric disorders, often before psychopathology is discernable in behavior. Here we review neuroimaging genetics studies with participants who have Posttraumatic Stress Disorder (PTSD). Results show that genes related to the physiological stress response (e.g., glucocorticoid receptor and activity, neuroendocrine release), learning and memory (e.g., plasticity), mood, and pain perception are tied to neural intermediate phenotypes associated with PTSD. These genes are associated with and sometimes predict neural structure and function in areas involved in attention, executive function, memory, decision-making, emotion regulation, salience of potential threats, and pain perception. Evidence suggests these risk polymorphisms and neural intermediate phenotypes are vulnerabilities toward developing PTSD in the aftermath of trauma, or vulnerabilities toward particular symptoms once PTSD has developed. Work distinguishing between the re-experiencing and dissociative sub-types of PTSD, and examining other PTSD symptom clusters in addition to the re-experiencing and hyperarousal symptoms, will further clarify neurobiological mechanisms and inconsistent findings. Furthermore, an exciting possibility is that genetic associations with PTSD may eventually be understood through differential intermediate phenotypes of neural circuit structure and function, possibly underlying the different symptom clusters seen within PTSD.

SKA2 Methylation is Involved in Cortisol Stress Reactivity and Predicts the Development of Post-Traumatic Stress Disorder (PTSD) After Military Deployment

Genomic variation in the SKA2 gene has recently been identified as a promising suicide biomarker. In light of its role in glucocorticoid receptor transactivation, we investigated whether SKA2 DNA methylation influences cortisol stress reactivity and is involved in the development of post-traumatic stress disorder (PTSD). Increased SKA2 methylation was significantly associated with lower cortisol stress reactivity in 85 healthy individuals exposed to the Trier Social Stress Test (B=-173.40, t=-2.324, p-value=0.023). Next, we observed that longitudinal decreases in SKA2 methylation after deployment were associated with the emergence of post-deployment PTSD symptoms in a Dutch military cohort (N=93; B=-0.054, t=-3.706, p-value=3.66 × 10(-4)). In contrast, exposure to traumatic stress during deployment by itself resulted in longitudinal increases in SKA2 methylation (B=0.037, t=4.173, p-value=6.98 × 10(-5)). Using pre-deployment SKA2 methylation levels and childhood trauma exposure, we found that the previously published suicide prediction rule significantly predicted post-deployment PTSD symptoms (AUC=0.66, 95% CI: 0.53-0.79) with an optimal sensitivity of 0.81 and specificity of 0.91. Permutation analysis using random methylation loci supported these findings. Together, these data establish the importance of SKA2 for cortisol stress responsivity and the development of PTSD and provide further evidence that SKA2 is a promising biomarker for stress-related disorders including PTSD.