Dataset Information

Meta-analysis of gene coexpression networks in the post-mortem prefrontal cortex of patients with schizophrenia and unaffected controls.

ABSTRACT:

Background

Gene expression profiling of the postmortem human brain is part of the effort to understand the neuropathological underpinnings of schizophrenia. Existing microarray studies have identified a large number of genes as candidates, but efforts to generate an integrated view of molecular and cellular changes underlying the illness are few. Here, we have applied a novel approach to combining coexpression data across seven postmortem human brain studies of schizophrenia.

Results

We generated separate coexpression networks for the control and schizophrenia prefrontal cortex and found that differences in global network properties were small. We analyzed gene coexpression relationships of previously identified differentially expressed 'schizophrenia genes'. Evaluation of network properties revealed differences for the up- and down-regulated 'schizophrenia genes', with clustering coefficient displaying particularly interesting trends. We identified modules of coexpressed genes in each network and characterized them according to disease association and cell type specificity. Functional enrichment analysis of modules in each network revealed that genes with altered expression in schizophrenia associate with modules representing biological processes such as oxidative phosphorylation, myelination, synaptic transmission and immune function. Although a immune-function enriched module was found in both networks, many of the genes in the modules were different. Specifically, a decrease in clustering of immune activation genes in the schizophrenia network was coupled with the loss of various astrocyte marker genes and the schizophrenia candidate genes.

Conclusion

Our novel network-based approach for evaluating gene coexpression provides results that converge with existing evidence from genetic and genomic studies to support an immunological link to the pathophysiology of schizophrenia.

SUBMITTER: Mistry M

PROVIDER: S-EPMC3849476 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature

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Publications

Meta-analysis of gene coexpression networks in the post-mortem prefrontal cortex of patients with schizophrenia and unaffected controls.

Mistry Meeta M Gillis Jesse J Pavlidis Paul P

BMC neuroscience 20130926

<h4>Background</h4>Gene expression profiling of the postmortem human brain is part of the effort to understand the neuropathological underpinnings of schizophrenia. Existing microarray studies have identified a large number of genes as candidates, but efforts to generate an integrated view of molecular and cellular changes underlying the illness are few. Here, we have applied a novel approach to combining coexpression data across seven postmortem human brain studies of schizophrenia.<h4>Results< ...[more]

PMID: 24070017

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Project description:BackgroundThe cortico-cerebellar-thalamic-cortical circuit has been implicated in the emergence of psychotic symptoms in schizophrenia (SZ). The kynurenine pathway (KP) has been linked to alterations in glutamatergic and monoaminergic neurotransmission and to SZ symptomatology through the production of the metabolites quinolinic acid (QA) and kynurenic acid (KYNA).MethodsThis work describes alterations in KP in the post-mortem prefrontal cortex (PFC) and cerebellum (CB) of 15 chronic SZ patients and 14 control subjects in PFC and 13 control subjects in CB using immunoblot for protein levels and ELISA for interleukins and QA and KYNA determinations. Monoamine metabolites were analysed by high-performance liquid chromatography and SZ symptomatology was assessed by Positive and Negative Syndrome Scale (PANSS). The association of KP with inflammatory mediators, monoamine metabolism and SZ symptomatology was explored.ResultsIn the PFC, the presence of the anti-inflammatory cytokine IL-10 together with IDO2 and KATII enzymes decreased in SZ, while TDO and KMO enzyme expression increased. A network interaction analysis showed that in the PFC IL-10 was coupled to the QA branch of the kynurenine pathway (TDO-KMO-QA), whereas IL-10 associated with KMO in CB. KYNA in the CB inversely correlated with negative and general PANSS psychopathology. Although there were no changes in monoamine metabolite content in the PFC in SZ, a network interaction analysis showed associations between dopamine and methoxyhydroxyphenylglycol degradation metabolite. Direct correlations were found between general PANSS psychopathology and the serotonin degradation metabolite, 5-hydroxyindoleacetic acid. Interestingly, KYNA in the CB inversely correlated with 5-hydroxyindoleacetic acid in the PFC.ConclusionsThus, this work found alterations in KP in two brain areas belonging to the cortico-cerebellar-thalamic-cortical circuit associated with SZ symptomatology, with a possible impact across areas in 5-HT degradation.

Project description:Altered levels of steroids have been reported in the brain, cerebral spinal fluid and plasma of patients with mood disorders. Neuroimaging studies have reported both functional and structural alterations in mood disorders, for instance in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC). In order to determine whether the endogenous production of steroids is altered in the ACC and DLPFC of patients with major depressive disorder (MDD) or bipolar disorder (BPD), quantitative real-time PCR was performed to detect mRNA expression level of key enzymes in the steroid biosynthetic pathways. In MDD, a significant decrease in mRNA level of cytochrome P450 17A1 (CYP17A1, synthesizing C19 ketosteroids) in the ACC and a significant increase in mRNA levels of hydroxysteroid sulfotransferase 2A1 [SULT2A1, catalyzing the sulfate conjugation of dehydroepiandrosterone (DHEA)] were observed in the DLPFC, suggesting alterations in DHEA and its sulfate metabolite DHEAS levels. Decreased intensity and distribution of CYP17A1 immunohistochemical staining was found in the ACC of MDD patients. Interestingly, there was a significant positive correlation between the mRNA levels of CYP17A1 and tyrosine-related kinase B (TrkB) full length isoform. In a unique post-mortem human brain slice culture paradigm, BDNF mRNA expression was found to be significantly increased following incubation with DHEA. Together, these data indicate a close relationship between DHEA and BDNF-TrkB pathways in depression. Furthermore, in the DLPFC, higher mRNA levels of 11β-hydroxysteroid dehydrogenase-1 (HSD11B1, reducing cortisone to the active hormone cortisol) and steroidogenic acute regulatory protein (STAR, facilitating the shuttle of cholesterol through the intermembrane space) were found in the MDD patients and BPD patients, respectively. In conclusion, this study suggests the presence of a disturbance in the endogenous synthesis of DHEA and DHEAS in mood disorders, which has a close relationship with BDNF-TrkB signaling.

Dataset Information

Meta-analysis of gene coexpression networks in the post-mortem prefrontal cortex of patients with schizophrenia and unaffected controls.

Background

Results

Conclusion

Publications

Meta-analysis of gene coexpression networks in the post-mortem prefrontal cortex of patients with schizophrenia and unaffected controls.

Similar Datasets

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