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No-glucose, hypoxic or ischemic (ODG) treatment of pericytes

ABSTRACT: Brain pericytes are important to maintain vascular integrity of the neurovascular unit under both, physiological and ischemic conditions. Ischemic stroke is known to induce an inflammatory and hypoxic response due to the lack of oxygen and glucose in the brain tissue. How this early response to ischemia is molecularly regulated in pericytes is largely unknown but may be of importance for future therapeutic targets .Here we evaluate the transcriptional responses in in vitro cultured human brain pericytes after oxygen and/or glucose deprivation. Hypoxia has been widely known to stabilise the transcription factor hypoxia inducible factor 1-alpha (HIF1alpha) and mediate the induction of hypoxic transcriptional programs after ischemia. However, we find that the transcription factors Jun Proto-Oncogene (c-JUN), Nuclear Factor Of Kappa Light Polypeptide Gene Enhancer In B-Cells (NFkappaB) and signal transducer and activator of transcription 3 (STAT3) bind genes regulated after 2 hours of omitted glucose and oxygen before HIF1alpha. Potent HIF1alpha responses require 6 hours of hypoxia to substantiate transcriptional regulation comparable to either c-JUN or STAT3. We show that STAT3 and c-JUN are regulating their bound genes before HIF1alpha after 2 hours of hypoxia or omitted glucose and oxygen, suggesting that HIF1alpha is not the initiating trans-acting factor in the response of pericytes to ischemia.

ORGANISM(S): Homo sapiens

PROVIDER: GSE109233 | GEO | 2018/03/08

REPOSITORIES: GEO

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Project description:The high rates of mortality associated with epithelial ovarian cancer (EOC) are a direct consequence of its metastatic nature. Metastasis is dependent on many factors, among which activation of angiogenesis is most significant. Angiogenesis is, in turn, contingent upon the cellular response to hypoxia within the tumor microenvironment. Hypoxia-inducible factor 1 (HIF1) is a transcription factor composed of HIF1alpha and HIF1beta subunits and is the master regulator of the hypoxic response. It is therefore a critical mediator of tumor angiogenesis and metastasis. Regulation of HIF1 is primarily at the level of protein. In normoxia, the HIF1alpha subunit is hydroxylated via an oxygen- and iron-dependent mechanism and targeted for destruction. In hypoxia, low oxygen levels preclude hydroxylation and HIF1alpha is stabilized, allowing for its association with constitutively expressed HIF1beta to form bioactive HIF1. We have identified a novel mechanism of HIF1alpha regulation in EOC cells that involves microRNAs (miRs), ~22 nucleotide, non-coding RNA molecules that repress translation of target mRNAs by binding their 3’ untranslated regions (UTRs). Using microarray and qPCR analysis, we found that levels of miR-199a-1, a miR that is predicted in silico to target the HIF1alpha 3’ UTR, were reduced under hypoxia in EOC cells. We further demonstrated that miR-199a-1 directly targets the HIF1alpha 3’ UTR and overexpression of miR-199a-1 suppresses HIF1alpha protein levels and HIF1-driven gene expression. Moreover, cells stably overexpressing miR-199a-1 exhibit marked defects in migratory ability. These data were corroborated by our in vivo findings, which demonstrated that overexpression of miR-199a-1 causes significant reductions in tumor vessel density and tumor burden in nude mice. These findings provide insight into non-canonical, miR- and iron-based mechanisms of HIF1 regulation that may have important implications in the progression of EOC. miRNA expression analysis of A2780 epithelial ovarian cancer cells by microarrays

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No-glucose, hypoxic or ischemic (ODG) treatment of pericytes

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