Unknown,Transcriptomics,Genomics,Proteomics

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Transcriptional analysis of apoptotic cerebellar granule neurons following rescue by Gip, Sp, Pacap and Igf1

ABSTRACT: Primary cultures of Cerebellar Granule Neurons (CGNs) have been extensively utilized to examine the signal transduction mechanisms underlying neuronal apoptosis. We conducted whole-genome expression profiling to decipher the transcriptional program controlling the apoptotic/survival switch in cerebellar granule neurons (CGNs) following the induction of apoptosis by serum and potassium deprivation and their rescue by gastric inhibitory polypeptide (Gip), substance p (Sp), insulin-like growth factor-1 (Igf1) or pituitary adenylyl cyclase-activating polypeptide (Pacap). Our results reveal the transcriptional changes intersecting neuronal apoptosis and survival and form the basis for further functional analyses and pharmacological exploitation to identify neuroprotective drugs. After six days âin vitroâ (DIV), extracellular KCl of CGNs was shifted from 25 to 5 mM for neuronal apoptotic death induction. After two washes with serum-free BME containing 5 mM KCl, neurons were incubated with the same medium for 6 h (K5), while control neurons were incubated with serum free medium supplemented with 25 mM KCl (K25). K5 neurons were also treated with a maximal effective dose of Gip, Sp, Igf1 and Pacap. Four biological replicates (derived from the same litter) for each of the experimental conditions (K25, K5, K5 + Gip; K25, K5, K5 + Sp; K25, K5, K5 + Igf1; K25, K5, K5 + Pacap) were analyzed.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Sebastiano Cavallaro

PROVIDER: E-GEOD-67788 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:The bovine chromaffin cell (BCC) is a unique modelM-bM-^@M-^Ta highly homogeneous and accessible neuroendocrine cellM-bM-^@M-^Tin which to study gene regulation through first messenger-initiated signaling pathways that are specific to post-mitotic cells. BCCs were treated with tumor necrosis factor (TNF) or pituitary adenylate cyclase activating polypeptide (PACAP), two critical regulators of neural cell transcriptional programming during inflammation that act on TNFR2 and PAC1 receptors, respectively, in post-mitotic neuroendocrine cells. Transcripts which were significantly up regulated by either or both first messenger were identified from microarray analysis using two bovine oligonucleotide arrays (Affymetrix and Agilent) followed by statistical analysis with Partek Genomic suite. Microarray data were combined from the two arrays using qRT-PCR sampling validation, and the first-messenger transcriptome derived from TNF and PACAP signaling were compared. More than 90 percent of the genes up regulated either by TNF or PACAP were specific to a single first messenger. BioBase suite, DIRE and Opossum were used to identify common promoter/enhancer response elements that control the expression of TNF- or PACAP-stimulated genes. Bioinformatic analysis revealed that distinct groups of transcription factors control the expression of genes up regulated by either TNF or PACAP . Most of the genes up regulated by TNF contained response elements for members of the Rel transcription factor family, suggesting TNF-TNFR2 signaling mainly through the NF-kB signaling pathway. On the other hand, the PACAP regulated genes showed no enrichment for any single response element, containing instead response elements for combinations of transcription factors allowing activation through multiple signaling pathways, including cAMP, calcium and ERK, in neuroendocrine cells. Pharmacological strategies for mimicking neuroprotection by either PACAP or TNF in the context of CNS injury or degeneration in disease might focus on individual downstream gene activation pathways to achieve greater specificity in vivo. For our analysis we have used both Affymetrix and Agilent arrays to identify the genes that are regulated up or down by neuropeptide PACAP and TNF-alpha. On Affyemetrix platform we performed technical repeats with 3 arrays with untreated samples, 3 arrays with samples from PACAP treatment, and 3 array with samples from TNF-alpha treatment. On the Agilent platform we performed technical repeats with 3 arrays for each treatment hybridizing Cy3-labelled RNA from untreated samples and Cy5-labelled RNA from either TNF-alpha or PACAP treated samples.

Project description:The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is considered to be a potential therapeutic agent for prevention of cerebral ischemia. Ischemia is a most common cause of death after heart attack and cancer causing major negative social and economic consequences. - This study was designed to investigate the effect of PACAP38 injection intracerebroventrically in a mouse model of permanent middle cerebral artery occlusion (PMCAO) along with corresponding sham control that used 0.9% saline injection. Ischemic and non-ischemic brain tissues were sampled at 6 and 24 hours post-treatment. - Following behavioral analyses to confirm whether the ischemia has occurred, we investigated the genome-wide changes in gene and protein expresison using DNA microarray chip (4x44K, Agilent) and one-/two-dimensional gel electrophoresis (1-/2-DGE) coupled with matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), respectively. - Our results revealed numerous changes in the transcriptome of ischemic (ipsilateral) hemisphere treated with PACAP38 over the saline-injected SHAM control hemisphere. In parallel, 2-DGE analysis revealed a highly expressed protein spot in the ischemic region that was identified as dihydropyrimidinase-related protein 2 (DPYL2). The DPYL2, also known as Crmp2, is a marker for the activated neuronal defense mechanisms, and interestingly, PACAP strongly suppresed this induction. - This study provides the first inventory of PACAP influenced gene and protein targets in ischemic hemisphere, and provides new targets for thereaupetic interventions. The PMCAO model mice were generated as described previously. Briefly, the mice were anesthetized with 4% sevoflurane (induction) and 2% sevoflurane (maintenance) in a 30% O2 and 70% N2O gas mixture via a face mask. An incision was then made in the cervical skin followed by opening of the salivary gland, and the right common carotid artery was visualized. A midline cervical incision was made to expose the external carotid artery. The intraluminal filament technique was used, to generate the PMCAO model. - The PACAP38 (1 M-BM-5l containing 1 pmol) or 1 M-BM-5l of saline (0.9% NaCl) was injected intracerebroventrically, immediately after PMCAO. PACAP38 (Peptide Institute Inc., Osaka, Japan; supplier temperature was -20M-BM-:C and was stored at -80M-BM-:C) was dissolved in, and diluted M-CM-^W10 times with 0.9% NaCl just before use. - In the sham control animals, following exposure of the external carotid artery, the wound was sutured. The PACAP38 or saline was injected intracerebroventrically in the same concentrations as above. After injections, the animals were returned to their cages. - A total of eight groups were prepared: four groups of three, seven, four and five mice in the PMCAO plus PACAP38 and PMCAO plus saline cohorts at 6 and 24 h after operation, respectively, and five mice each in the control (sham) plus PACAP and saline groups at 6 and 24 h after operation, respectively. - We used three mice each in PMCAO groups that exhibited neurological grades G1 and G2 and three mice each at random in sham groups for the subsequent downstream analysis. Six or 24 hours post-injection of PACAP38 or saline, the mice were removed from their cages, decapitated, and their brains carefully removed on ice. The left (contralateral) and right (ipsilateral; ischemic) hemispheres were dissected and placed in 2 mL Eppendorf tubes, which were then quickly immersed in liquid nitrogen before being stored in -80M-BM-:C prior to further analysis. - For analysis of gene components, the tissues were ground to a very fine powder with liquid nitrogen, used for total RNA extraction, quantity and quality check, followed by cDNA synthesis, and RT-PCR. A mouse 4 x 44K whole genome oligo DNA microarray chip (G4122F, Agilent Technologies, Palo Alto, CA, USA) was used for global gene expression analysis using the ipsilateral (ischemic) hemisphere. Briefly, total RNA (900 ng; 300 ng each replicate pooled together) was labeled with either Cy3 or Cy5 dye using an Agilent Low RNA Input Fluorescent Linear Amplification Kit (Agilent). Fluorescently labeled targets of control (sham) as well as treated (PMCAO) samples with PACAP38 or without PACAP38 (saline) were hybridized to the same microarray slide with 60-mer probes. - Here, we compared the PMCAO plus PACAP38 injected mice to PMCAO plus saline, i.e. the ipsilateral brain region of the PMCAO mice was compared with the same right hemisphere of the control mice. Similarly, Sham control plus PACAP38 injected mice to Sham control plus saline were analyzed to identify only the PACAP38 influenced genes. A flip labeling (dye-swap or reverse labeling with Cy3 and Cy5 dyes) procedure was followed to nullify the dye bias associated with unequal incorporation of the two Cy dyes into cDNA.

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Transcriptional analysis of apoptotic cerebellar granule neurons following rescue by Gip, Sp, Pacap and Igf1

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