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ABSTRACT: Chen H, Wang N, Zhao X, Ross CA, O'Shea KS, McInnis MG. Gene expression alterations in bipolar disorder postmortem brains. Bipolar Disord 2013: 00: 000-000. © 2013 John Wiley & Sons A/S.Published by Blackwell Publishing Ltd. Objectives: Bipolar disorder (BD) is a mental illness of unknown neuropathology and has several genetic associations. Antipsychotics are effective for the treatment of acute mania, psychosis, or mixed states in individuals with BD. We aimed to identify gene transcripts differentially expressed in postmortem brains from antipsychotics-exposed individuals with BD (hereafter the 'exposed' group), non-exposed individuals with BD (hereafter the 'non-exposed' group), and controls. Methods: We quantified the abundance of gene transcripts in postmortem brains from seven exposed individuals, seven non-exposed individuals, and 12 controls with the Affymetrix U133P2 GeneChip microarrays and technologies. We applied a q-value of ≤0.005 to identify statistically significant transcripts with mean abundance differences between the exposed, non-exposed and control groups. Results: We identified 2191 unique genes with significantly altered expression levels in non-exposed brains compared to those in the control and exposed groups. The expression levels of these genes were not significantly different between exposed brains and controls, suggesting a normalization effect of antipsychotics on the expression of these genes. Gene ontology (GO) enrichment analysis showed significant (Bonferroni p ≤ 0.05) clustering of subgroups of the 2191 genes under many GO terms; notably, the protein products of genes enriched are critical to the function of synapses, affecting, for example, intracellular trafficking and synaptic vesicle biogenesis, transport, release and recycling, as well as organization and stabilization of the node of Ranvier. Conclusions: These results support a hypothesis of synaptic and intercellular communication impairment in BD. The apparent normalization of expression patterns with exposure to antipsychotic medication may represent a physiological process that relates both to etiology and improvement patterns of the disorder.
Bipolar Disorders 01/2013; · 5.29 Impact Factor
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ABSTRACT: Lithium is an effective treatment for Bipolar Disorder (BD) and significantly reduces suicide risk, though the molecular basis of lithium's effectiveness is not well understood. We seek to improve our understanding of this effectiveness by posing hypotheses based on new experimental data as well as published data, testing these hypotheses in silico, and posing new hypotheses for validation in future studies. We initially hypothesized a gene-by-environment interaction where lithium, acting as an environmental influence, impacts signal transduction pathways leading to differential expression of genes important in the etiology of BD mania.
Using microarray and rt-QPCR assays, we identified candidate genes that are differentially expressed with lithium treatment. We used a systems biology approach to identify interactions among these candidate genes and develop a network of genes that interact with the differentially expressed candidates. Notably, we also identified cocaine as having a potential influence on the network, consistent with the observed high rate of comorbidity for BD and cocaine abuse. The resulting network represents a novel hypothesis on how multiple genetic influences on bipolar disorder are impacted by both lithium treatment and cocaine use. Testing this network for association with BD and related phenotypes, we find that it is significantly over-represented for genes that participate in signal transduction, consistent with our hypothesized-gene-by environment interaction. In addition, it models related pharmacogenomic, psychiatric, and chemical dependence phenotypes.
We offer a network model of gene-by-environment interaction associated with lithium's effectiveness in treating BD mania, as well as the observed high rate of comorbidity of BD and cocaine abuse. We identified drug targets within this network that represent immediate candidates for therapeutic drug testing. Posing novel hypotheses for validation in future work, we prioritized SNPs near genes in the network based on functional annotation. We also developed a "concept signature" for the genes in the network and identified additional candidate genes that may influence the system because they are significantly associated with the signature.
BMC Systems Biology 01/2010; 4:158. · 3.15 Impact Factor
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ABSTRACT: Lithium (Li) is commonly used in the treatment of bipolar disorder (BD). However, the molecular mechanism of its action is not completely understood. MicroRNAs (miRNAs), a class of small RNA species are recognized as important regulators in post-transcription gene expression. To explore the role of miRNAs in Li's action, we quantitatively analysed the expression patterns of 13 miRNAs in 20 lymphoblastoid cell lines (LCLs) with or without Li treatment in culture. Using paired t statistics in the analysis, we identified significant changes in seven of the 13 miRNAs tested in LCLs sampled at treatment day 4 (p<0.05). Four of the seven significant miRNAs, miR-34a, miR-152, miR-155, and miR-221 consistently changed expression in the same LCLs at a longer treatment time-point, day 16 (Bonferroni p<0.05). Interestingly, miR-221 and miR-34a also changed expression in rat hippocampus in response to Li treatment (Zhou et al. 2008), although in the opposite direction. We focused on the predicted target mRNAs of miR-221 and miR-34a, and identified 29 and ten targets that were strongly and inversely correlated to expression with the two miRNAs, respectively. Our results suggest that miRNAs are excellent candidates for the study of the molecular basis of Li's treatment action in cell systems such as lymphocytes given limited access to the human brain.
The International Journal of Neuropsychopharmacology 04/2009; 12(7):975-81. · 4.58 Impact Factor
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ABSTRACT: MicroRNAs (miRNA) are endogenous tissue-specific short RNAs that regulate gene expression. Discriminating each let-7 family member expression is especially important due to let-7's abundance and connection with development and cancer. However, short lengths (22 nt) and similarities between multiple sequences have prevented identification of individual members. Here, we present ProDeG, a computational algorithm which designs imperfectly matched sequences (previously yielding only noise levels in microarray experiments) for genome-wide microarray "signal" probes to discriminate single nucleotide differences and to improve probe qualities. Our probes for the entire let-7 family are both homogeneous and specific, verified using microarray signals from fluorescent dye-tagged oligonucleotides corresponding to the let-7 family, demonstrating the power of our algorithm. In addition, false let-7c signals from conventional perfectly-matched probes were identified in lymphoblastoid cell-line samples through comparison with our probe-set signals, raising concerns about false let-7 family signals in conventional microarray platform.
Nucleic Acids Research 04/2008; 36(5):e27. · 8.03 Impact Factor
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ABSTRACT: The disruption of the disrupted-in-schizophrenia (DISC1) gene segregates with major mental illnesses in a Scottish family. Association of DISC1 with schizophrenia has been reported in several ethnic groups, and now recently with mood disorder.
A family-based association study of DISC1 and bipolar disorder (BP) in 57 bipolar pedigrees was conducted. Then, we examined possible association of bipolar disorder with DISC1 mRNA expression in human lymphoblasts. We also studied the correlation of several clinical features with the levels of DISC1 mRNA expression.
Haplotype analysis identified one haplotype (HP1) that was overtransmitted to the BP phenotype (p = .01) and a second haplotype that was undertransmitted (HP2). There was a gender influence in the transmission distortion, with overtransmission of HP1 to affected females (p = .004). A significant decrease in DISC1 mRNA expression was observed in lymphoblasts from affected HP1 group compared to those from unaffected subjects with the HP2 (p = .006). Further, a higher number of manic symptoms correlated with lower levels of DISC1 expression (p = .008).
These results suggest that decreased mRNA levels of DISC1 expression, associating with the risk haplotype, may be implicated in the pathophysiology of bipolar disorder.
Biological Psychiatry 12/2006; 60(9):929-35. · 8.28 Impact Factor
