Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Perturbation of placental endocrine function by endoplasmic reticulum stress leads to maladaptation of maternal hepatic glucose metabolism

ABSTRACT: To investigate whether ER stress underpins the secretion of mis-glycosylated glycoproteins by trophoblast, we treated trophoblast-like BeWo cells with the ER stress inducer thapsigargin (Tg), an inhibitor specific for sarco/endoplasmic reticulum Ca2+-ATPase.

INSTRUMENT(S): Illumina HiSeq 2000

ORGANISM(S): Homo sapiens

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PROVIDER: E-MTAB-10943 | biostudies-arrayexpress |

SECONDARY ACCESSION(S): ERP131881

REPOSITORIES: biostudies-arrayexpress

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Project description:Inadequate extracellular conditions can adversely affect the environment of the ER and impinge on the maturation of nascent proteins. The resultant accumulation of unfolded proteins activates a signal transduction pathway, known as the unfolded protein response, which serves primarily to protect the cell during stress and helps restore homeostasis to the ER. Microarray analysis of the unfolded protein response in a human medulloblastoma cell line treated with thapsigargin revealed that, in addition to known targets, a large number of proangiogenic factors were up-regulated. Real-time PCR analyses confirmed that four of these factors, VEGF, FGF2, angiogenin and IL-8, were transcriptionally up-regulated in multiple cell lines by various ER stress inducers. Our studies on VEGF regulation revealed that XBP-1(S), a UPR-inducible transcription factor, bound to two regions on the VEGF promoter, and analysis of XBP-1 null mouse embryonic fibroblasts revealed that it contributes to VEGF expression in response to ER stress. ATF4, another UPR-inducible transcription factor, also binds to the VEGF gene, although its contribution to VEGF transcription appeared to be fairly modest. We also found that VEGF mRNA stability is increased in response to UPR activation, via activation of the AMP and p38MAP kinases, demonstrating that increased mRNA levels occur at two regulatory points. In keeping with the mRNA levels, we found that VEGF protein is secreted at levels as high as or higher than that achieved in response to hypoxia. Our results indicate that the UPR plays a significant role in inducing positive regulators of angiogenesis. It also regulates VEGF expression at multiple levels and is likely to have widespread implications for promoting angiogenesis in response to normal physiological cues as well as in pathological conditions like cancer. We used microarrays to perform genome wide expression analysis in Daoy medulloblastoma cells to identify gene profiles that change in response to thapsigargin treatment which causes induction of the unfolded protein response.

Project description:The accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) results in the condition called âER stressâ which induces the unfolded protein response (UPR) which is a complex cellular process that includes changes in expression of many genes. Failure to restore homeostasis in the ER is associated with human diseases. To identify the underlying changes in gene expression in response to ER stress, we induced ER stress in human B-cells and then measured gene expression at 10 time-points. We followed up those results by studying cells from 60 unrelated people. We rediscovered genes that were known to play a role in ER stress response and uncovered several thousand genes that are not known to be involved. Two of these are VLDLR and INHBE which showed significant increase in expression following ER stress in B-cells and in primary fibroblasts. To study the links between unfolded protein response and disease susceptibility, we identified ER stress responsive genes that are associated with human diseases and assessed individual differences in ER stress response. Many of the UPR genes are associated with Mendelian disorders such as Wolfram syndrome and complex human diseases including amyotrophic lateral sclerosis and diabetes. Data from two independent samples showed extensive individual variability in ER stress response. Additional analyses with monozygotic twins revealed significant correlations within twin pairs in their responses to ER stress thus showing evidence for heritable variation among individuals. These results have implications for basic understanding of ER function and its role in disease susceptibility. Keywords: array-based gene expression We measured gene expression levels in immortalized B cells from members of 60 unrelated CEPH-Utah grandparents. Each individual was treated for 8 hours with either DMSO or with 4 ug/ml of tunicamycin. Gene expression was measured to identify tunicamycin-responsive genes. To assess whether there is a genetic component to the individual variation in gene expression response to ER stress, we used microarrays to measure expression of genes in 26 monozygotic twin pairs treated with either DMSO or 500 nM thapsigargin for 4 hours.

Project description:Dendritic cells (DCs) are a special class of leukocytes able to activate both innate and adaptive immune responses. They interact with microbes through germline-encoded pattern-recognition receptors (PRRs), which recognize molecular patterns expressed by various microorganisms. Upon antigen binding, PRRs instruct DCs for the appropriate priming of natural killer cells, followed by specific T-cell responses. Once completed the effector phase, DCs reach the terminal differentiation stage and eventually die by apoptosis. We have observed that following lipopolysaccharide (LPS)-stimulation the initiation of the apoptotic pathway in DCs is due the activation of NFAT proteins. Indeed, LPS induces Src-family kinase and phospholipase C (PLC)Î³2 activation, influx of extracellular Ca2+ and calcineurin-dependent nuclear NFAT translocation. The initiation of this pathway is independent of TLR4 engagement, and dependent exclusively on CD14. According with this observation CD14-deficient DCs do not die following LPS stimulation. Nevertheless, CD14-deficient DC death following LPS activation can be restored by co-stimulating DCs with LPS and thapsigargin. Thapsigargin empties the intracellular calcium stores by blocking calcium pumping into the sarcoplasmic and endoplasmic reticulum and thereby activates plasma membrane calcium channels. This, in turn, allows an influx of calcium into the cytosol and NFAT activation. To identify the NFAT controlled apoptosis genes in LPS activated DCs we have performed a kinetic microarray analysis (0, 48 and 60 h) in conditions allowing or inhibiting NFAT activation. Four genes have been selected: Nur77, Gadd45g, Ddit3/Gadd153/Chop-10 and Tia1. To identify apoptosis genes selectively modulated by NFAT, a comparative kinetic (time points 0, 48 and 60 h) microarray analysis was performed in the following conditions: 1) wild type bone marrow derived DCs (wtBMDCs) stimulated with LPS; 2) CD14-deficient BMDCs stimulated with LPS; 3) wtBMDCs stimulated with LPS in presence of thapsigargin; 4) CD14-deficient BMDCs stimulated with LPS in presence of thapsigargin.

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Perturbation of placental endocrine function by endoplasmic reticulum stress leads to maladaptation of maternal hepatic glucose metabolism

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