Project description:Identify mRNA targets of the RNA-binding protein HuR in vivo during Schwann cell development using RIP-chip analysis. IP protocol of endogenous mRNA-transfected HuR complexes was performed as described in Keene et al. (2006). In brief, 500 mg of whole-cell lysate obtained from a pool of NB or P5 sciatic nerves from C57BL6J mice were incubated with a suspension of Protein Sepharose beads (Sigma-Aldrich), pre-coated with 15 mg of either IgG1 (BD Pharmingen) or anti-HuR (Santa Cruz Biotechnology) antibodies. mRNAs were isolated using the phenol-chloroform method.
Project description:HuR is a regulator of mRNA turnover or translation of inflammatory genes through binding to adenylate-uridylate-rich elements (ARE) and related motifs present in the 3’untranslated region (UTR) of mRNAs. We aimed to identify HuR targets in the human airway epithelial cell line BEAS-2B challenged with TNFa plus IFNg, a strong stimulus for inflammatory epithelial responses. Ribonucleoprotein (RNP) complexes from resting and cytokine-treated cells were immunoprecipitated (IP) using anti-HuR and isotype-control antibody, and eluted mRNAs were reverse-transcribed and hybridized to an inflammatory-focused gene array. The chemokines CCL2, CCL8, CXCL1 and CXCL2 ranked highest among 27 signaling and inflammatory genes significantly enriched in the HuR RNP-IP from stimulated cells over the control IP. Among these, 20 displayed published HuR binding motifs. Association of HuR with the four endogenous chemokine mRNAs was validated by single-gene RNP-IP, and shown to be 3’UTR-dependent by biotin pull-down assay. Cytokine treatment increased mRNA stability only for CCL2 and CCL8, and transient silencing and overexpression of HuR affected only CCL2 and CCL8 expression in primary and transformed epithelial cells. Cytokine-induced CCL2 mRNA was predominantly cytoplasmic; conversely, CXCL1 mRNA remained mostly nuclear and unaffected, as CXCL2, by changes in HuR levels. Increase in cytoplasmic HuR and HuR target expression partially relied on the inhibition of AMP-dependent kinase, a negative regulator of HuR nucleocytoplasmic shuttling. We postulate that HuR critically regulates the epithelial response, by associating with multiple adenylate-uridylate-rich elements (ARE)-bearing, functionally related inflammatory transcripts. On the basis of genome-wide studies probing the relationship between RNA-binding proteins and the functional profile of their associated transcripts, we combined the specific HuR immunoprecipitation of RNPs and the genome-scale microarray to profile the target mRNAs of HuR in the human airway epithelial cell line BEAS-2B challenged with very strong inflammatory stimulation, TNFa plus IFNG. The array platform we used is the Human Autoimmune and Inflammatory Response Gene Array (SuperArray Bioscience, Frederick, MD). To validate the association of HuR and its target mRNAs, we planned to apply biotin pull-down assay. HuR overexpression and knockdown assays were also planned to further verify the association of HuR and its target mRNAs. Overall, we did three biological replicates for the IP array experiments, which include both IgG1 control IP and HuR IP arrays.
Project description:Elavl1/HuR is a ubiquitous and conserved RNA-binding protein that binds to a U-rich RNA motif that shuttles between nucleus and cytoplasm. In epithelia, the elevated expression of HuR assumingly promotes degeneration and cancer suggesting that its generic suppression may provide clinical benefits. In this study we focused on biological and clinical functions of HuR in intestinal epithelial cells and we presented evidence that changes in HuR levels induce polarized distortions in these cells to support different pathologic outcomes. Here we study the differentiality in mRNA abundance between Control mice and mice overexpressing Elavl1 (TgATF-HuR). Control and TgATF-HuR mice were treated with Dimethylhydrazine (DMH)/Dextran Sodium Sulphate (DSS) for 60 days and tumors where dissected from large intestines; those with sizes between 10-15mm2 were pooled to generate samples with 4 tumors/sample and snap frozen. Three samples per genotype were used either for RIP analyses or total RNA extraction. Isolated RNA was used for microarray or qRT-PCR analyses.
Project description:Integrative regulatory mapping indicates that the RNA-binding protein HuR (ELAVL1) couples pre-mRNA processing and mRNA stability In this dataset, we employed two distinct experiments. 1) HuR RIP-chip to identify mRNA targets of HuR. 2) HuR knockdown to identify mRNAs whose expression are dependent on HuR. All 12 samples were normalized with PLIER using Affymetrix power tools. To identify RNA targets of HuR, HuR RIP samples were compared to Mock RIP samples. To identify RNA regulated by HuR, HuR knockdown samples were compared to mock knockdown samples.
Project description:Elavl1/HuR is a ubiquitous and conserved RNA-binding protein that binds to a U-rich RNA motif that shuttles between nucleus and cytoplasm. In epithelia, the elevated expression of HuR assumingly promotes degeneration and cancer suggesting that its generic suppression may provide clinical benefits. In this study we focused on biological and clinical functions of HuR in intestinal epithelial cells and we presented evidence that changes in HuR levels induce polarized distortions in these cells to support different pathologic outcomes. In this experiment we investigate Elavl1 targets via Elavl1 Immunopercipitation (RIP-chip) by arrays and compare relative to background. Control and TgATF-HuR mice were treated with Dimethylhydrazine (DMH)/Dextran Sodium Sulphate (DSS) for 60 days and tumors where dissected from large intestines; those with sizes between 10-15mm2 were pooled to generate samples with 4 tumors/sample and snap frozen. Three samples per genotype were used either for RIP analyses or total RNA extraction. Isolated RNA was used for microarray or qRT-PCR analyses.
Project description:The purpose of the study was to identify mRNA bound to HuR in the presence of doxorubicin in MCF7 cells. We collected cytoplasmic RNA from untreated and treated cells and detected differentially expressed genes (DEGs). We also coimmunoprecipitated HuR and IgG (as control) from doxorubicin treated cells. Comparison between HuR RIP and IgG RIP signals was used to discriminate specific mRNA bound to HuR. HuR coimmmunoprecipitated material was hybridized together with cytoplasmic mRNA of doxorubicin treated cells, enabling the fold enrichment calculation and the selection of mRNAs bound to HuR. Keywords: RIP-Chip, HuR, doxorubicin, MCF7, HuR consensus binding, post-transcriptional regulation. We subjected MCF7 cells to starvation for 24h and then we added doxorubicin at final concentration of 10 uM, profiling before and after 4 hours of treatment in biological quadruplicate (only on cytoplasmic mRNAs, as HuR was found in the cytoplasm). Differentially expressed genes, altered during the treatment, were identified. Data derived from HuR RIP-Chip and IgG RIP-Chip (in biological quadruplicate) allowed the identification of specific mRNAs bound to HuR. The comparison between HuR RIP-Chip and cytoplasmic extracts from doxorubicin treated cells (in biological triplicate) identified those genes that were more strictly bound to HuR independently from their expression levels.
Project description:RNA-binding proteins coordinate the fates of multiple RNAs, but the principles underlying these global interactions remain poorly understood. We elucidated regulatory mechanisms of the RNA-binding protein HuR, by integrating data from diverse high-throughput targeting technologies, specifically PAR-CLIP, RIP-chip, and whole-transcript expression profiling. The number of binding sites per transcript, degree of HuR-association, and degree of HuR-dependent RNA stabilization were positively correlated. Pre-mRNA and mature mRNA containing both intronic and 3' UTR binding sites were more highly stabilized than transcripts with only 3' UTR or only intronic binding sites, suggesting that HuR couples pre-mRNA processing with mature mRNA stability. We also observed HuR-dependent splicing changes and substantial binding of HuR in poly-pyrimidine tracts of pre-mRNAs. Comparison of the spatial patterns surrounding HuR and miRNA binding sites provided functional evidence for HuR-dependent antagonism of proximal miRNA-mediated repression. We conclude that HuR coordinates gene expression outcomes at multiple interconnected steps of RNA processing. HuR (ELAVL1) PAR-CLIP
Project description:HuR promotes myogenesis by stabilizing MyoD, Myogenin and p21 mRNAs during the fusion step of muscle cells to form myotubes. Here we show that HuR, via a novel mRNA destabilizing activity, promotes the early steps of myogenesis by reducing the expression of the cell cycle promoter nucleophosmin (NPM). Depletion of HuR stabilizes the NPM mRNA, increases NPM protein levels and inhibits myogenesis, while its overexpression elicits the opposite effects. NPM mRNA destabilization involves the association of HuR with the decay factor KSRP as well as the ribonuclease PARN and the exosome complex. The C-terminus of HuR mediates the formation of the HuR-KSRP complex and is sufficient for maintaining a low level of the NPM mRNA as well as promoting the commitment of muscle cells to myogenesis. We therefore propose a model whereby the downregulation of the NPM mRNA, mediated by the HuR/KSRP complex and its associated ribonucleases, is required for proper myogenesis. RNA was extracted from C2C12 treated with siRNA against HuR and compared to control siRNA
Project description:Analysis of RNA immunoprecipitation of HuR, a RNA binding protein (RBP), in breast cancer cell lines. This approach, utilizing RNA immunoprecipitation hybridized to microarray (RIP-Chip), provides global identification of putative endogenous mRNA targets of different RBPs. HuR is an RBP that binds to the AU-rich (ARE) regions of labile mRNAs, such as proto-oncogenes, facilitating their translation into protein. HuR has been shown to play a role in cancer progression and elevated levels of cytoplasmic HuR directly correlate with increased invasiveness and poor prognosis for many cancers, including those of the breast. We used HuR RIP-Chip as a comprehensive and systematic method to survey breast cancer target genes in both MCF-7 (estrogen receptor positive, ER+) and MDA-MB-231 (estrogen receptor negative, ER-) breast cancer cell lines. We identified unique subsets of HuR associated mRNAs found individually or in both cell types. Two novel HuR targets, CD-9 and CALM-2, were identified and validated by quantitative RT-PCR and biotin pulldown analysis. Our findings reveal that the differential regulation of these two cancer-related genes by HuR was contingent upon the cellular environment. RNA immunoprecipitation of the HuR RNA binding protein by 3A2 antibody and IgG (control) from two human breast cancer cell lines, MCF-7 and MDA-MB-231 .
Project description:Upon muscle injury the high mobility group box 1 (HMGB1) protein is up-regulated and secreted to initiate reparative responses. Here we show that HMGB1 controls myogenesis both in vitro and in vivo, during development and after adult muscle injury. HMGB1 expression in muscle cells is regulated at the translational level: the miRNA miR-1192 inhibits HMGB1 translation and the RNA-binding protein HuR promotes it. HuR binds to a cis-element, HuRBS, located in the 3'UTR of the HMGB1 transcript, and at the same time miR-1192 is recruited to an adjacent seed element. The binding of HuR to the HuRBS prevents the recruitment of Argonaute 2 (Ago2), overriding miR-1192-mediated translation inhibition. Depleting HuR reduces myoblast fusion and silencing miR-1192 re-establishes the fusion potential of HuR-depleted cells. We propose that HuR promotes the commitment of myoblasts to myogenesis by enhancing the translation of HMGB1 and suppressing the translation inhibition mediated by miR-1192. RNA content was extracted following immunoprecipitation of HuR using a monoclonal antibody (3A2) and the levels of mRNA were compared to an IgG control in order to determine which transcripts were enriched in the HuR ribonucleoprotein complex.