Unknown,Transcriptomics,Genomics,Proteomics

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Transcriptional profiling of dentate granule cells in 4 rat epilepsy models

ABSTRACT: Global expression profiling of epileptogenesis has been confounded by variability across laboratories, epilepsy models, tissue sampled and experimental platforms, with the result that very few genes demonstrate consistent expression changes. The present study minimizes these confounds by combining Affymetrix microarray datasets from seven laboratories, using three status epilepticus (SE) models of epilepsy in rats (pilocarpine, kainate, self-sustained SE or SSSE) and the rat kindling model. Total RNA was harvested from laser-captured dentate granule cells from 6 rats at three times during the early-to-mid latent phase that precedes epilepsy symptoms in the SE models (1, 3 and 10 days after SE), or 24 hr after the first stage 2, stage 4 and stage 5 seizure in the kindling model. Each epilepsy model was studied in two independent laboratories except SSSE. The initial goals of this study were to a) identify model-independent transcriptional changes in dentate granule cells that could point to novel intervention targets for epileptogenesis, b) characterize the basal transcriptional profile of dentate granule cells, and c) identify genes that have highly variable expression. Each experimental group consists of 6 rats (biological replicates) from one laboratory at a single time point, except for the SSSE group (6 at day 1 after SSSE, 5 controls and at day 3 after SSSE, 4 at day 10). Thus granule cells were harvested from 164 rats.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Winnie Liang

PROVIDER: E-GEOD-47752 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Neurodegenerative brain disorders become more common in the aged. Most of these disorders are associated with or caused by selective death of certain neuronal subpopulations. The mechanisms underlying the differential vulnerability of certain neuronal populations are still largely unexplored and few neuroprotective treatments are available to date. Elucidation of these mechanisms may lead to a greater understanding of the pathogenesis and treatment of neurodegenerative diseases. Moreover, preconditioning by a short seizure confers neuroprotection following a subsequent prolonged seizure. Our goal is to identify pathways that confer vulnerability and resistance to neurotoxic conditions by comparing the basal and preconditioned gene expression profiles of three differentially vulnerable hippocampal neuron populations. Hippocampal CA1 and CA3 pyramidal neurons are highly susceptible to seizures and ischemia, whereas dentate gyrus granule cells are relatively resistant. A brief preconditioning seizure confers protection to the pyramidal cells. We will first determine gene expression profiles of untreated rat CA1 and CA3 pyramidal cells, and dentate granule cells, using laser capture microscopy to obtain region-specific neuronal mRNA. We will then determine the effect of a brief preconditioning seizure, which is neuroprotective in CA1 and CA3, on these expression profiles. We hypothesize that common molecular mechanisms exist in neurons that determine their susceptibility to seizure-induced injury. Intrinsic differences in gene expression exist between hippocampal glutamatergic CA1 and CA3 pyramidal neurons, on the one hand, and dentate granule cells on the other, which contribute to the greater susceptibility of pyramidal neurons to degeneration in experimental stroke and epilepsy. We specifically hypothesize that differences in basal energy metabolism genes may confer differential susceptibility to neurodegeneration produced by seizures and ischemia. Anesthetized animals will be sacrificed by decapitation, and frozen 10 micron sections will be lightly stained with cresyl violet to identify cell layers in the hippocampus. Approximately 1000 neurons from each of the three cell layers will be isolated by LCM. Poly-A RNA will be amplified using a modified Eberwine protocol. The quality of our aRNA will be evaluated by quantitative RT-PCR of GluR6 and KA2 mRNA levels before we send the samples to the Center for labeling and hybridization to Affymetrix rat 230A arrays. We will provide a one-round amplification cDNA product to the center for labeling and hybridization. This protocol is identical to a previously approved study by Jim Greene in our laboratory.

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Transcriptional profiling of dentate granule cells in 4 rat epilepsy models

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