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Lithium-responsive neurological pathway (kitam-affy-droso-427260)

ABSTRACT: Lithium has been used for more than 50 years as the primary therapy for bipolar affective disorder (BPD) and is highly effective in its treatment. However, the molecular and cellular mechanisms underlying the lithium’s therapeutic action still remains elusive. The goal of the proposed study is to identify genes involved in the lithium-responsive neurological pathway using the fruit fly as a model organism. Based on the fact that the fundamental molecular and cellular mechanisms are well conserved between the fruit fly and vertebrates, the outcomes of this project are expected to lead to the recognition of uncharacterized players or processes responsible for the lithium action in the vertebrates, which would open up the future possibility to develop novel and improved therapies for BPD. The proposed gene-profiling experiment is designed to identify candidate genes and genetic pathways involved in the lithium-responsive biological process. Specific aims of this project are; 1) identify genes whose expression levels are significantly different between the wild type and Shu, 2) identify genes whose expression levels are enhanced or suppressed after lithium treatment, and 3) identify genes whose expression is differentially regulated in the wild type and Shu after lithium treatment. We expect that the genes identified through the proposed microarray analysis will provide important clues for elucidating the molecular and cellular processes responsible for the lithium action. A Drosophila mutant Shudderer (Shu) exhibits various neurological phenotypes, including hyperactivity, uncoordinated movements, and sporadically occurring jerks. Interestingly, many of these phenotypes are greatly suppressed by lithium with the internal concentrations used for treatment of human BPD patients. In addition, Shu mutant is more resistant to the toxic effects of lithium than the wild type strain. These data have led us to the hypothesis that the biological process responsive to lithium is affected in the Shu mutant. We expect that we will be able to identify genes and genetic pathways involved in the lithium-responsive process by comparing the gene expression profiles between the wild type and the Shu mutant with or without lithium treatment. Newly eclosed Canton-S (wild type) and Shu mutant females will be placed in vials containing fly food with or without 50mM LiCl. They will be cultured at 25oC with 65% humidity for 5 days. Three groups of fifty flies (150 flies in total) will be collected for each experimental condition (i.e., genotype and lithium treatment) and frozen on dry ice. The head will be separated and total RNA will be extracted from each group using the TRIzol Reagent (Life Technologies) followed by an RNeasy (Qiagen) cleanup step and a DNase I digestion step. The RNA will be resuspended in DEPC-treated water and the absorbance will be checked at 260 and 280 nm for determination of sample purity and concentration. The GeneChip Drosophila Genome 2.0 Arrays will be used to quantify the levels of transcripts in each sample. The total number of samples will be 4 (2 genotypes and 2 treatments) X 3 (triplicate) = 12. Keywords: dose response

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE8330 | GEO | 2007/06/30

SECONDARY ACCESSION(S): PRJNA101323

REPOSITORIES: GEO

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Project description:Lithium has been used for more than 50 years as the primary therapy for bipolar affective disorder (BPD) and is highly effective in its treatment. However, the molecular and cellular mechanisms underlying the lithiumâs therapeutic action still remains elusive. The goal of the proposed study is to identify genes involved in the lithium-responsive neurological pathway using the fruit fly as a model organism. Based on the fact that the fundamental molecular and cellular mechanisms are well conserved between the fruit fly and vertebrates, the outcomes of this project are expected to lead to the recognition of uncharacterized players or processes responsible for the lithium action in the vertebrates, which would open up the future possibility to develop novel and improved therapies for BPD. The proposed gene-profiling experiment is designed to identify candidate genes and genetic pathways involved in the lithium-responsive biological process. Specific aims of this project are; 1) identify genes whose expression levels are significantly different between the wild type and Shu, 2) identify genes whose expression levels are enhanced or suppressed after lithium treatment, and 3) identify genes whose expression is differentially regulated in the wild type and Shu after lithium treatment. We expect that the genes identified through the proposed microarray analysis will provide important clues for elucidating the molecular and cellular processes responsible for the lithium action. A Drosophila mutant Shudderer (Shu) exhibits various neurological phenotypes, including hyperactivity, uncoordinated movements, and sporadically occurring jerks. Interestingly, many of these phenotypes are greatly suppressed by lithium with the internal concentrations used for treatment of human BPD patients. In addition, Shu mutant is more resistant to the toxic effects of lithium than the wild type strain. These data have led us to the hypothesis that the biological process responsive to lithium is affected in the Shu mutant. We expect that we will be able to identify genes and genetic pathways involved in the lithium-responsive process by comparing the gene expression profiles between the wild type and the Shu mutant with or without lithium treatment. Newly eclosed Canton-S (wild type) and Shu mutant females will be placed in vials containing fly food with or without 50mM LiCl. They will be cultured at 25oC with 65% humidity for 5 days. Three groups of fifty flies (150 flies in total) will be collected for each experimental condition (i.e., genotype and lithium treatment) and frozen on dry ice. The head will be separated and total RNA will be extracted from each group using the TRIzol Reagent (Life Technologies) followed by an RNeasy (Qiagen) cleanup step and a DNase I digestion step. The RNA will be resuspended in DEPC-treated water and the absorbance will be checked at 260 and 280 nm for determination of sample purity and concentration. The GeneChip Drosophila Genome 2.0 Arrays will be used to quantify the levels of transcripts in each sample. The total number of samples will be 4 (2 genotypes and 2 treatments) X 3 (triplicate) = 12.

Project description:Bipolar disorder (BPD) is a debilitating heritable psychiatric disorder. Contemporary models for the manic pole of BPD have primarily utilized either single locus transgenics or treatment with psychostimulants. Our lab recently characterized a mouse strain, termed Madison (MSN), which naturally displays a manic phenotype, exhibiting elevated locomotor activity, increased sexual behavior, and higher forced swimming relative to control strains. Lithium chloride and olanzapine treatments attenuate this phenotype. In this study, we replicated our locomotor activity experiment, showing that MSN mice display generationally-stable mania relative to their outbred ancestral strain, hsd:ICR (ICR). We then performed a gene expression microarray experiment to compare hippocampus of MSN and ICR mice. We found dysregulation of multiple transcripts whose human orthologs are associated with BPD and other psychiatric disorders including schizophrenia and ADHD, including: Epor, Smarca4, Cmklr1, Cat, Tac1, Npsr1, Fhit, and P2rx7. RT-qPCR confirmed dysregulation for all of seven transcripts tested. Using a network analysis, we found dysregulation of a gene system related to chromatin packaging, a result convergent with recent human findings on BPD. Using a novel genomic enrichment algorithm, we found enrichment in genome regions homologous to human loci implicated in BPD in replicated linkage studies including homologs of human cytobands 1p36, 3p14, 3q29, 6p21-22, 12q24, 16q24, and 17q25. Our findings suggest that MSN mice represent a polygenic model for the manic pole of BPD showing much of the genetic systems complexity of the corresponding human disorder. Further, the high degree of convergence between our findings and the human literature on BPD brings up novel questions about evolution by analogy in mammalian genomes. In total, 12 total RNA samples were used for microarray analysis: 6 samples from Madison mice and 6 samples from ICR outbred mice. All samples were biological replicates.

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Lithium-responsive neurological pathway (kitam-affy-droso-427260)

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