SUMOylation promotes survival and integration of neural stem cell grafts in stroke
ABSTRACT: In this study we sought to determine the effect of overexpressing the SUMOylation E2 conjugase Ubc9 on the response of murine Neural Stem Cells (NSCs) to oxygen-glucose-deprivation and restoration of oxygen/glucose (OGD/ROG). We established stably-expandable lines of NSCs from the subventricular zones (SVZ) of adult wild-type mice (WT NSCs) and Ubc9-overexpressing mice (Ubc9 NSCs) and profiled their transcriptional changes in response to OGD/ROG as well as in response to differentiation.
Project description:miRNA microarray profiling of primary cortical neurons exposed to 4h oxygen and glucose deprivation (OGD) in vitro. RNA samples collected at 8h post-OGD terminaion. miRNAs were also profiled in mice exposed to 3- vessel occlusion model of stroke. RNA samples collected from contralateral (control) and ipsilateral (infarct) sides of the brain following 24h of reperfusion. Comparison of control and ischemic samples across 3 biological replicates for both in vitro and in vivo samples. In vitro cultures consisted of primary cortical neurons derived from E17 rat Wistar embryos. In vivo samples were obtained from C57bl/6 mice exposed to three-vessel occlusion.
Project description:The present study has used whole-rat genome microarray expression profiling to identify genes whose expression is significantly altered in hippocampal neuronal cultures submitted to oxygen and glucose deprivation (OGD), an established in vitro model for cerebral global ischemia that is suitable for investigations at the molecular level. To do so, total RNA was extracted from hippocampal neuronal cultures at an early (7h) and delayed (24h) time point after OGD, as well as from control neurons. Analysis of gene ontology showed that OGD followed by 7h or 24h of recovery induces changes in the expression levels of genes related with inflammation, response to oxidative stress, metabolism, apoptosis, synaptic proteins and ion channels and, importantly, genes that show different expression levels are mainly specific to one of the two time points of recovery analyzed. The expression levels of several genes were confirmed by qPCR and were in good agreement with the microarray data, showing that the combined use of the OGD model and the microarray technology can be a useful tool for the study molecular mechanisms contributing to the neuronal demise after transient global ischemia. Ischemia induced gene expression in primary hippocampal neuronal rat cultures was measured at 7 and 24 hours after exposure to Oxygen and Glucose deprivation (OGD). Three independent experiments were performed at each time (7 or 24 hours) as independent biological replicates.
Project description:Oxygen-glucose deprivation (OGD) is a cellular phenomenon consistently observed upon occurrence of ischemic stroke which eventually results in neuronal death. Neuronal cell death after ischemia takes place via two distinct processes, necrosis and apoptosis. Apoptosis, programmed cell death, is denoted by chromatin condensation, nuclear blebbing, cellular shrinkage, and DNA fragmentation. Unlike apoptosis, cellular swelling and lysis is suggestive of necrosis. However, these two processes are related not only to the severity but also to the duration of ischemia. Microarray analysis was carried out using 20 Illumina mouse Ref8V1.1 genechip arrays. The assignment of the arrays was as follows: Controls (n=5); exposure to OGD for 10min, 5h, 8h, 15h and 24 h (n=3 respectively).
Project description:The human immortalized brain endothelial cell line hCMEC/D3 is considered an in vitro model of the blood-brain-barrier. We aimed to characterize changes in the secretome of hCMEC/D3 subjected to oxygen and glucose deprivation (OGD) by SILAC, in order to identify new proteins involved in ischemia-triggered blood-brain-barrier disruption and test their potential as blood biomarkers for ischemic stroke diagnosis. After SILAC analysis, 19 proteins were found differentially secreted between OGD and normoxia/normoglycemia conditions (Fold Change>|1.4| and peptide count≥2). Protein folding and nucleic acid binding were the main molecular functions and epithelial adherens junctions and aldosterone signaling appeared as the main canonical pathways represented by OGD-secreted proteins. ANXA1, CLUS, IGFBP2, PRDX3, TIMP2 and COL1A2 were replicated by western blotting in 9 independent cell cultures. Five replicated proteins were analyzed in human serum samples of 38 ischemic stroke patients compared to 18 stroke-mimicking conditions and 18 healthy controls by ELISA. IGFBP2 showed increased blood levels when strokes were compared with stroke-mimicking patients (p<0.1). In conclusion, we characterized changes in the secretome of hCMEC/D3 after an ischemic insult and highlighted some candidates to become biomarkers for ischemic stroke diagnosis related to blood-brain-barrier disruption.
Project description:Migroglia cells were exposed to oxygen-glucose deprivation (OGD) for 3 h. The mRNA was isolated and the expression profiles of OGD-activated cells were compared with the profiles of resting cells. Overall design: Two samples were analysed. mRNAs that were differentially expressed (increased or decreased in expression by ≥1.5-fold) between the OGD-activated and resting cells were identified.
Project description:Oxygen and glucose metabolism plays a pivotal role in many (patho)physiological conditions. In particular, oxygen and glucose deprivation (OGD) occurs during ischemia and stroke, resulting in extensive tissue injury and cell death. We applied time-resolved ribosome profiling technique to assess early events at the level of gene expression in rat pheochromocytoma PC12 cells during short-term OGD. Most substantial alterations in transcripts levels and their translation were seen to occur in the first 20 minutes of OGD. The rapid adaptation of translation apparatus to OGD is global and involves altered elongation and initiation rates. We also observed salient and reproducible alterations in ribosome densities of individual mRNAs such as increased translation of particular upstream Open Reading Frames (uORFs); induced site-specific arrests of the ribosomes and synthesis of extended protein isoforms. Ribosome profiling (with mRNA-seq sequencing) was carried out at 0,20,40 and 60 minutes of OGD. Two biological replicates were used.
Project description:Migroglia cells were exposed to oxygen-glucose deprivation (OGD) for 3 h. The miRNA was isolated and the expression profiles of OGD-activated cells were compared with the profiles of resting cells. Two samples were analysed. miRNAs that were differentially expressed (increased or decreased in expression by ≥1.5-fold) between theOGD-activated and resting cells were identified.
Project description:Background: cancer cells rely on glycolysis as main ATP source (Warbürg effect). Tumor-initiating cells (TICs) are the fraction of cells that give raise and repopulate tumors. TICs are exposed to prolonged periods of oxygen and glucose deprivation (OGD), as they live in a hypoxic niche and they withstand prolonged lack of blood vessels during initial tumorigenesis or metastasis formation (avascular phase). Warbürg effect is energetically inefficient; we hypothesize that TICs might have differential metabolic features. Tumor eradication requires killing TICS; finding such features would have therapeutic implications. Methodology/principal findings: 106 MDA-MB-231 breast-cancer cells (hereafter Wt) were exposed for 5 weeks to 0.2% oxygen and 0.1g/l glucose, recovering 9 clones. Both flow-cytometry (50-fold enrichment in the CD24-/CD44+/CD133+ population) and xenografts in NOD/SCID mice using 100 cells (75% vs. 16% engraftment) suggest that OGD-resistant clones are true TICs (hereafter “TIC clones”). TIC clones showed a 30-fold higher replication and viability (BRDU incorporation, colony assay) than Wt. When exposed to OGD, ATP-production dropped 5-fold in WT, but was maintained in TIC clones by increasing 5-fold the fatty acid and oxygen consumption. These properties were explained by lack of upregulation of HIF-1 alpha and PDK1, as well as an increase in ATP-synthase. Analysis with metabolic inhibitors (2-deoxyglucose, antimycin-A) confirmed glycolysis and mitochondrial respiration as main routes of metabolism for Wt and TIC clones respectively. Metabolomics revealed that glutamine catabolism generated the NADPH required to quench reactive oxygen species generated during mitochondrial respiration in TIC clones. Glutamine deprivation or mitochondrial blockers were able to abrogate the viability of TIC clones. Conclusions/significance: the TIC-fraction of a cancer cell population withstands prolonged OGD by switching from the Warbürg effect to mitochondrial respiration. Targeting this metabolic feature abrogates the survival of TICs. Overall design: Mitochondrial metabolism in cancer-stem cells.
Project description:Oxygen-glucose deprivation (OGD) is a cellular phenomenon consistently observed upon occurrence of ischemic stroke which eventually results in neuronal death. Neuronal cell death after ischemia takes place via two distinct processes, necrosis and apoptosis. Apoptosis, programmed cell death, is denoted by chromatin condensation, nuclear blebbing, cellular shrinkage, and DNA fragmentation. Unlike apoptosis, cellular swelling and lysis is suggestive of necrosis. However, these two processes are related not only to the severity but also to the duration of ischemia. Overall design: Microarray analysis was carried out using 20 Illumina mouse Ref8V1.1 genechip arrays. The assignment of the arrays was as follows: Controls (n=5); exposure to OGD for 10min, 5h, 8h, 15h and 24 h (n=3 respectively).