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Differential expression of exosomal microRNAs in prefrontal cortices of schizophrenia and bipolar disorder patients.

ABSTRACT: Exosomes are cellular secretory vesicles containing microRNAs (miRNAs). Once secreted, exosomes are able to attach to recipient cells and release miRNAs potentially modulating the function of the recipient cell. We hypothesized that exosomal miRNA expression in brains of patients diagnosed with schizophrenia (SZ) and bipolar disorder (BD) might differ from controls, reflecting either disease-specific or common aberrations in SZ and BD patients. The sources of the analyzed samples included McLean 66 Cohort Collection (Harvard Brain Tissue Resource Center), BrainNet Europe II (BNE, a consortium of 18 brain banks across Europe) and Boston Medical Center (BMC). Exosomal miRNAs from frozen postmortem prefrontal cortices with well-preserved RNA were isolated and submitted to profiling by Luminex FLEXMAP 3D microfluidic device. Multiple statistical analyses of microarray data suggested that certain exosomal miRNAs were differentially expressed in SZ and BD subjects in comparison to controls. RT-PCR validation confirmed that two miRNAs, miR-497 in SZ samples and miR-29c in BD samples, have significantly increased expression when compared to control samples. These results warrant future studies to evaluate the potential of exosome-derived miRNAs to serve as biomarkers of SZ and BD.

SUBMITTER: Banigan MG

PROVIDER: S-EPMC3559697 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Differential expression of exosomal microRNAs in prefrontal cortices of schizophrenia and bipolar disorder patients.

Banigan Meredith G MG Kao Patricia F PF Kozubek James A JA Winslow Ashley R AR Medina Juan J Costa Joan J Schmitt Andrea A Schneider Anja A Cabral Howard H Cagsal-Getkin Ozge O Vanderburg Charles R CR Delalle Ivana I

PloS one 20130130 1

Exosomes are cellular secretory vesicles containing microRNAs (miRNAs). Once secreted, exosomes are able to attach to recipient cells and release miRNAs potentially modulating the function of the recipient cell. We hypothesized that exosomal miRNA expression in brains of patients diagnosed with schizophrenia (SZ) and bipolar disorder (BD) might differ from controls, reflecting either disease-specific or common aberrations in SZ and BD patients. The sources of the analyzed samples included McLean ...[more]

PMID: 23382797

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Project description:Because of the role played by miRNAs in post-transcriptional regulation of an array of genes, their impact in neuropsychiatric disease pathophysiology has increasingly been evident. In the present study, we assessed microRNA expression in prefrontal cortex (Brodmann area 10) of a well-characterized cohort of major depressed, bipolar, and schizophrenia subjects (obtained from Stanley Neuropathology Consortium; n = 15 in each group), using high throughput RT-PCR plates. Discrete miRNA alterations were observed in all disorders, as well as in suicide subjects (pooled across diagnostic categories) compared to all non-suicide subjects. The changes in the schizophrenia group were partially similar to those in the bipolar group, but distinct from changes in depression and suicide. Intriguingly, those miRNAs which were down-regulated in the schizophrenia group tended to be synaptically enriched, whereas up-regulated miRNAs tended not to be. To follow this up, we purified synaptosomes from pooled samples of the schizophrenia vs. control groups and subjected them to Illumina deep sequencing. There was a significant loss of small RNA expression in schizophrenia synaptosomes only for certain sequence lengths within the miRNA range. Moreover, 73 miRNAs were significantly down-regulated whereas only one was up-regulated. Strikingly, across all expressed miRNAs in synaptosomes, there was a significant inverse correlation between the fold-change of a given miRNA seen in schizophrenia and its synaptic enrichment ratio observed in controls. Thus, synaptic miRNAs tended to be down-regulated in schizophrenia, and the more highly synaptically enriched miRNAs tended to show greater down-regulation. These findings point to some deficit in miRNA biogenesis, transport, processing or turnover in schizophrenia that is selective for the synaptic compartment. A novel class of ncRNA-derived small RNAs, shown to be strongly induced during an early phase of learning in mouse, is also expressed in man, and at least one representative (SNORD85) was strongly down-regulated in schizophrenia synaptosomes.

Project description:Prior studies have demonstrated reduced dendritic spine density in the dorsolateral prefrontal cortex (DLPFC) in schizophrenia. However, it remains unclear how generalizable this finding is in schizophrenia and if it is seen in bipolar disorder, a historically distinct psychiatric condition.To assess whether spine loss is present in the DLPFC of individuals with schizophrenia and individuals with bipolar disorder.This study used postmortem human brain tissue from individuals with schizophrenia (n=14), individuals with bipolar disorder (n=9), and unaffected control participants (n=19). Tissue samples containing the DLPFC (Brodmann area 46) were Golgi-stained, and basilar dendrites of pyramidal cells in the deep half of layer III were reconstructed.The number of spines per dendrite, spine density, and dendrite length were compared across groups. We also assessed for the potential effects of clinical and demographic variables on dendritic parameters.The mean (SD) spine density was significantly reduced (ie, by 10.5%) in individuals with bipolar disorder (0.28 [0.04] spines/?m) compared with control participants (0.31 [0.05] spines/?m) (P=.02). In individuals with schizophrenia, the mean (SD) spine density was also reduced (by 6.5%; 0.29 [0.03] spines/?m) but just missed significance when compared with control participants (P=.06). There was a significant reduction in the mean (SD) number of spines per dendrite in both individuals with schizophrenia (72.8 [24.9] spines per dendrite) and individuals with bipolar disorder (68.9 [12.9] spines per dendrite) compared with controls (92.8 [31.1] spines per dendrite) (individuals with schizophrenia vs controls: 21.6% reduction [P=.003]; individuals with bipolar disorder vs controls: 25.8% reduction [P=.005]). In addition, both individuals with schizophrenia and individuals with bipolar disorder had a reduced mean (SD) dendrite length (246.5 [67.4] and 245.6 [29.8] ?m, respectively) compared with controls (301.8 [75.1] ?m) (individuals with schizophrenia vs controls: 18.3% reduction [P=.005]; individuals with bipolar disorder vs controls: 18.6% reduction [P=.005]).Dendritic spine loss in the DLPFC was seen in both individuals with schizophrenia and individuals with bipolar disorder, suggesting that the 2 disorders may share some common pathophysiological features.

Project description:BackgroundNeuregulin 1 (NRG1) is a key candidate susceptibility gene for both schizophrenia (SCZ) and bipolar disorder (BPD). The function of the NRG1 transmembrane proteins is regulated by cleavage. Alteration of membrane bound-NRG1 cleavage has been previously shown to be associated with behavioral impairments in mouse models lacking expression of NRG1-cleavage enzymes such as BACE1 and gamma secretase. We sought to determine whether alterations in NRG1 cleavage and associated enzymes occur in patients with SCZ and BPD.Methodology/principal findingsUsing human postmortem brain, we evaluated protein expression of NRG1 cleavage products and enzymes that cleave at the external (BACE1, ADAM17, ADAM19) and internal (PS1-gamma secretase) sides of the cell membrane. We used three different cohorts (Controls, SCZ and BPD) and two distinct brain regions: BA9-prefrontal cortex (Controls (n = 6), SCZ (n = 6) and BPD (n = 6)) and hippocampus (Controls (n = 5), SCZ (n = 6) and BPD (n = 6)). In BA9, the ratio of the NRG1 N-terminal fragment relative to full length was significantly upregulated in the SCZ cohort (Bonferroni test, p = 0.011). ADAM17 was negatively correlated with full length NRG1 levels in the SCZ cohort (r = -0.926, p = 0.008). In the hippocampus we found significantly lower levels of a soluble 50 kDa NRG1 fragment in the two affected groups compared the control cohort (Bonferroni test, p = 0.0018). We also examined the relationship of specific symptomatology criteria with measures of NRG1 cleavage using the Bipolar Inventory of Signs and Symptoms Scale (BISS) and the Montgomery Åsberg Depression Rating Scale (MADRS). Our results showed a positive correlation between ADAM19 and psychosis (r = 0.595 p = 0.019); PS1 and mania (r = 0.535, p = 0.040); PS1 and depression (r = 0.567, p = 0.027) in BA9, and BACE1 with anxiety (r = 0.608, p = 0.03) in the hippocampus.Conclusion/significanceOur preliminary findings suggest region-specific alterations in NRG1 cleavage in SCZ and BPD patients. These changes may be associated with specific symptoms in these psychiatric disorders.

Project description:Dorsolateral prefrontal cortex (DLPFC) and temporal pole (TP) are brain regions that display abnormalities in bipolar disorder (BD) patients. DNA methylation - an epigenetic mechanism both heritable and sensitive to the environment - may be involved in the pathophysiology of BD. To study BD-associated DNA methylomic differences in these brain regions, we extracted genomic DNA from the postmortem tissues of Brodmann Area (BA) 9 (DLPFC) and BA38 (TP) gray matter from 20 BD, ten major depression (MDD), and ten control age-and-sex-matched subjects. Genome-wide methylation levels were measured using the 850 K Illumina MethylationEPIC BeadChip. We detected striking differences between cortical regions, with greater numbers of between-brain-region differentially methylated positions (DMPs; i.e., CpG sites) in all groups, most pronounced in the BD group, and with substantial overlap across groups. The genes of DMPs common to both BD and MDD (hypothetically associated with their common features such as depression) and those distinct to BD (hypothetically associated with BD-specific features such as mania) were enriched in pathways involved in neurodevelopment including axon guidance. Pathways enriched only in the BD-MDD shared list pointed to GABAergic dysregulation, while those enriched in the BD-only list suggested glutamatergic dysregulation and greater impact on synaptogenesis and synaptic plasticity. We further detected group-specific between-brain-region gene expression differences in ODC1, CALY, GALNT2, and GABRD, which contained significant between-brain-region DMPs. In each brain region, no significant DMPs or differentially methylated regions (DMRs) were found between diagnostic groups. In summary, the methylation differences between DLPFC and TP may provide molecular targets for further investigations of genetic and environmental vulnerabilities associated with both unique and common features of various mood disorders and suggest directions of future development of individualized treatment strategies.

Dataset Information

Differential expression of exosomal microRNAs in prefrontal cortices of schizophrenia and bipolar disorder patients.

Publications

Differential expression of exosomal microRNAs in prefrontal cortices of schizophrenia and bipolar disorder patients.

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