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Hippocampal Gene Expression Profile of Mitogen Stress activated Kinase 1 (MSK1) null mice.

ABSTRACT: Analysis of alterations in the hippocampus transcriptome caused by deletion of Mitogen Stress activated Kinase 1 (MSK1). MAPK signaling has been implicated in a wide range of neuronal processes, including development, plasticity and viability. One of the principal downstream targets of both the ERK/MAPK pathway and the p38 MAPK pathway is Mitogen Stress activated Kinase 1 (MSK1). Here, we sought to understand the role that MSK1 plays in neuroprotection against excitotoxic stimulation in the hippocampus. To this end, we utilized a MSK1 null mouse line, cell viability assays and array-based profiling approaches. Here we show that MSK1 is broadly expressed within the major neuronal cell layers of the hippocampus and that status epilepticus (SE) drives acute induction of MSK1 activation. In response to the SE paradigm, MSK1 KO mice exhibited a striking increase in vulnerability to pilocarpine-evoked cell death within the CA1 and CA3 cell layers. Further, cultured MSK1 null neurons exhibited a heighted level of NMDA-evoked excitotoxicity relative to WT neurons, as assessed using the LDH assay. Given these findings, we examined the hippocampal transcriptional profile of MSK1 null mice. Affymetrix array profiling revealed that with MSK1 deletion a total of 115 genes showed significant changes (> 1.25-fold) in expression. Notably, functional analysis indicated that a subset of these genes contribute to neuroprotective signaling networks. Together, these data provide important new insights into the mechanism by which the MAPK/MSK1 signaling cassette confers neuroprotection against excitotoxic insults. Approaches designed to upregulate or mimic the functional effects of MSK1 may prove beneficial against an array of degenerative processes resulting from excitotoxic insults. MAPK signaling has been implicated in a wide range of neuronal processes, including development, plasticity and viability. One of the principal downstream targets of both the ERK/MAPK pathway and the p38 MAPK pathway is Mitogen Stress activated Kinase 1 (MSK1). Here, we sought to understand the role that MSK1 plays in neuroprotection against excitotoxic stimulation in the hippocampus. To this end, we utilized a MSK1 null mouse line, cell viability assays and array-based profiling approaches. Here we show that MSK1 is broadly expressed within the major neuronal cell layers of the hippocampus and that status epilepticus (SE) drives acute induction of MSK1 activation. In response to the SE paradigm, MSK1 KO mice exhibited a striking increase in vulnerability to pilocarpine-evoked cell death within the CA1 and CA3 cell layers. Further, cultured MSK1 null neurons exhibited a heighted level of NMDA-evoked excitotoxicity relative to WT neurons, as assessed using the LDH assay. Given these findings, we examined the hippocampal transcriptional profile of MSK1 null mice. Affymetrix array profiling revealed that with MSK1 deletion a total of 115 genes showed significant changes (> 1.25-fold) in expression. Notably, functional analysis indicated that a subset of these genes contribute to neuroprotective signaling networks. Together, these data provide important new insights into the mechanism by which the MAPK/MSK1 signaling cassette confers neuroprotection against excitotoxic insults. Approaches designed to upregulate or mimic the functional effects of MSK1 may prove beneficial against an array of degenerative processes resulting from excitotoxic insults.

ORGANISM(S): Mus musculus

PROVIDER: GSE98751 | GEO | 2017/10/31

SECONDARY ACCESSION(S): PRJNA386112

REPOSITORIES: GEO

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Project description:Status epilepticus (SE) is a life-threatening condition that can give rise to a number of neurological disorders, including learning deficits, depression, and epilepsy. Many of the effects of SE appear to be mediated by alterations in gene expression. To gain deeper insight into how SE affects the transcriptome, we employed the pilocarpine SE model in mice and Illumina-based high-throughput sequencing to characterize alterations in gene expression from the induction of SE, to the development of spontaneous seizure activity. While some genes were upregulated over the entire course of the pathological progression, each of the three sequenced time points (12-hour, 10-days and 6-weeks post-SE) had a largely unique transcriptional profile. Hence, genes that regulate synaptic physiology and transcription were most prominently altered at 12-hours post-SE; at 10-days post-SE, marked changes in metabolic and homeostatic gene expression were detected; at 6-weeks, substantial changes in the expression of cell excitability and morphogenesis genes were detected. At the level of cell signaling, KEGG analysis revealed dynamic changes within the MAPK pathways, as well as in CREB-associated gene expression. Notably, the inducible expression of several noncoding transcripts was also detected. These findings offer potential new insights into the cellular events that shape SE-evoked pathology. cDNA from two animals was pooled into two independent biological replicates for each timepoint (ie. two sets of two animals per experimental group: control, 12 hours, 10 days, 6 weeks). Samples were sequenced using a Genome Analyzer II (GAII) at a concentration of 10pM in each lane. Base-calling was conducted with the standard Illumina Analysis Pipeline 1.0 (Firescrest-Bustard). Eight FASTQ sequence files (sequencing reads plus quality information) were generated and mapped to the mouse genome (UCSC mm9) using the Bowtie algorithm with default settings. A C++ program was used to count the number of uniquely mapped reads within exons of Ref-Seq genes (UCSC Genome Browser mm9 annotation).

Project description:Purpose: to evaluate changes in the transcriptome of hippocampal cells during the course of epileptogenesis, from the early events post status epilepticus (SE) to the onset of recurrent spontaneous seizures. Experimental Design: Gene expression profiling was analyzed in hippocampi of rats subjected to the pilocarpine model of epilepsy at different times during the course of epileptogenesis: 3 days post-SE (3D), 7 days post-SE (7D), and immediately (up to 12h) after the first spontaneous seizure (Chronic). All three pilocarpine subgroups had a corresponding age-matched control group (saline-treated rats), from which normal hippocampi samples were obtained at the same experimental time points. Independent microarray hybridizations were carried out for each sample (n = 5, per experimental group) with oligonucleotide microarrays covering 34,000 transcripts representing most of the known and predictive genes of the rat genome (CodeLink™ Rat Whole Genome Bioarrays, GE Healthcare), following the manufacturer’s protocol. Results: differential expression of almost 1,400 genes was detected during the course of epileptogenesis, from the early events post status epilepticus (SE) to the onset of recurrent spontaneous seizures. Most of these genes are novel and displayed an up-regulation after SE. Noteworthy, a group of 128 genes functioning in neurogenesis, apoptosis, immune response, and intracellular signal transduction was found consistently hyper-expressed throughout epileptogenesis, indicating stable molecular alterations within the hippocampus. Those include modulation of the MAPK, Jak-STAT, PI3K, TGF-beta, and mTOR signaling pathways. Differential expression of genes from the p38 MAPK pathway, mediating inflammation and neurogenesis, was also confirmed by real-time PCR. These findings reveal dynamic molecular changes occurring in the hippocampus that may serve as a starting point for the generation of new hypothesis regarding the underlying mechanisms of epilepsy and for the designing of alternative therapeutic strategies. Keywords: gene expression changes during epileptogenesis.

Project description:Purpose: to evaluate changes in the transcriptome of hippocampal cells during the course of epileptogenesis, from the early events post status epilepticus (SE) to the onset of recurrent spontaneous seizures. Experimental Design: Gene expression profiling was analyzed in hippocampi of rats subjected to the pilocarpine model of epilepsy at different times during the course of epileptogenesis: 3 days post-SE (3D), 7 days post-SE (7D), and immediately (up to 12h) after the first spontaneous seizure (Chronic). All three pilocarpine subgroups had a corresponding age-matched control group (saline-treated rats), from which normal hippocampi samples were obtained at the same experimental time points. Independent microarray hybridizations were carried out for each sample (n = 5, per experimental group) with oligonucleotide microarrays covering 34,000 transcripts representing most of the known and predictive genes of the rat genome (CodeLinkâ¢ Rat Whole Genome Bioarrays, GE Healthcare), following the manufacturerâs protocol. Results: differential expression of almost 1,400 genes was detected during the course of epileptogenesis, from the early events post status epilepticus (SE) to the onset of recurrent spontaneous seizures. Most of these genes are novel and displayed an up-regulation after SE. Noteworthy, a group of 128 genes functioning in neurogenesis, apoptosis, immune response, and intracellular signal transduction was found consistently hyper-expressed throughout epileptogenesis, indicating stable molecular alterations within the hippocampus. Those include modulation of the MAPK, Jak-STAT, PI3K, TGF-beta, and mTOR signaling pathways. Differential expression of genes from the p38 MAPK pathway, mediating inflammation and neurogenesis, was also confirmed by real-time PCR. These findings reveal dynamic molecular changes occurring in the hippocampus that may serve as a starting point for the generation of new hypothesis regarding the underlying mechanisms of epilepsy and for the designing of alternative therapeutic strategies. Keywords: gene expression changes during epileptogenesis. We performed a genome wide analysis of genes differentially expressed during epileptogenesis. Virtually, all possible changes in the rat transcriptome were monitored at distinct time points corresponding to the latent to chronic phase transition of the pilocarpine model of epilepsy, which is probably the most extensively studied chemically inductive model of TLE. Genes identified as being differentially expressed were classified based on their respective biological functions to envisage processes and pathways likely implicated in epileptogenesis, as well as their possible value as targets for therapy. Results were expressed as fold variation, and genes displaying greater than 2-fold changes in transcript abundance and p<0.01 were selected.

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Hippocampal Gene Expression Profile of Mitogen Stress activated Kinase 1 (MSK1) null mice.

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