Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcriptional and post-transcriptional regulation of VEGF by the unfolded protein response

ABSTRACT: 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.

ORGANISM(S): Homo sapiens

SUBMITTER: Geoffrey Neale

PROVIDER: E-GEOD-21979 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Transcriptional and post-transcriptional regulation of proangiogenic factors by the unfolded protein response.

Pereira Ethel R ER Liao Nan N Neale Geoff A GA Hendershot Linda M LM

PloS one 20100902 9

<h4>Background</h4>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.<h4>Principal findings</h4>Microarray analysis of the unfolded protein response in a human medulloblastoma cell line trea ...[more]

PMID: 20824063

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Project description:INS1-EGFP-L10a stable cell lines were induced with Doxycycline (Dox) for 24 hours, then either untreated or treated for 30 minutes with 1uM Thapsigargin to induce ER stress. Total RNA was purified with Trizol, and RIP RNA samples were extracted by immunoaffinity purification using an EGFP antibody We aimed to determine which genes are enriched under ER stress at the polyribosomal level. To do this we compared expression profiles of Total RNA with and without ER stress, and Immunoaffinity purified RNA (RIP) with and without ER stress. Microarray results of INS-1 EGFP-L10a cells either untreated or treated with 1uM Thapsigargin (Tg) in triplicate. Both Total RNA and RNA isolated from ribosomal Immunoprecipitation (RIP) When unfolded proteins accumulate to irremediably high levels within the endoplasmic reticulum (ER), intracellular signaling pathways called the unfolded protein response (UPR) become hyperactivated to cause programmed cell death. We discovered that thioredoxin-interacting protein (TXNIP) is a critical node in this M-bM-^@M-^\Terminal UPRM-bM-^@M-^]. TXNIP becomes rapidly induced by hyperactivated IRE1a, an ER bifunctional kinase/endoribonuclease (RNase). IRE1a controls TXNIP mRNA stability by reducing levels of a TXNIP destabilizing micro-RNA, miR-17. In turn, elevated TXNIP protein activates the NLRP3 inflammasome, causing Caspase-1 cleavage and interleukin 1b (IL-1b) secretion. Txnip gene deletion reduces pancreatic b-cell death during ER stress, and suppresses diabetes caused by proinsulin misfolding in the Akita mouse. Finally, small molecule IRE1a RNase inhibitors suppress TXNIP production to block IL-1b secretion. In summary, the IRE1a-TXNIP pathway is used in the terminal UPR to promote sterile inflammation and programmed cell death, and may be targeted to develop new treatments for degenerative diseases driven by ER stress. There are 12 samples total all in INS-1 EGFP L10a cells- 3 untreated total RNA (reference sample), 3 treated with 1uM Tg 30 min total RNA, 3 untreated RIP RNA (reference sample), 3 treated with 1uM for 30 min RIP RNA

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.

Dataset Information

Transcriptional and post-transcriptional regulation of VEGF by the unfolded protein response

Publications

Transcriptional and post-transcriptional regulation of proangiogenic factors by the unfolded protein response.

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