Project description:Accumulating evidence highlights the role of long non-coding RNAs (lncRNA) in cellular homeostasis, and their dysregulation in disease settings. Most lncRNAs function by interacting with proteins or protein complexes. While several orthogonal methods have been developed to identify these proteins, each method has its inherent strengths and limitations. Here, we combine two RNA-centric methods ChIRP-MS and RNA-BioID to obtain a comprehensive list of proteins that interact with the well-known lncRNA HOTAIR. Overexpression of HOTAIR has been associated with a metastasis-promoting phenotype in various cancers. Although HOTAIR is known to bind with PRC2 and LSD1 protein complexes, an unbiased and comprehensive method to map its interactome has not yet been performed. Both ChIRP-MS and RNA-BioID data sets show an association of HOTAIR with mitoribosomes, suggesting HOTAIR has functions independent of its (post-)transcriptional mode-of-action.
Project description:RNA pull-down assay.<br>For the recombinant protein pull-down assays, 50 M-5g of recombinant His-tag TcRBP40 protein were bound to 100 uL of Ni-NTA resin (Qiagen) overnight at 4M-0C. 100 M-5g of total RNA from epimastigotes were incubated with the bound protein in 500 M-5l EMSA buffer at 4M-0C for 2 h, in the presence of Heparine and Spermidine as competitors. Bounded and supernatant samples were separated. The bound sample was washed with the same buffer three times, soft-mixing for 10 min each. After washing, RNA present in the bound and supernatantM- fractions were purified.<br><br>RNA purification and amplification:<br><br>RNA was extracted using the RNeasy mini kit (Qiagen). Linearly amplified RNA (aRNA) was generated with the MessageAmpM-^YII aRNA Amplification kit (Ambion), according to the manufacturerM-^Rs manual.<br><br>Microarray analysis:<br>The microarray was constructed with 70-mer oligonucleotides. Due to the hybrid and repetitive nature of the sequenced T. cruzi strain, all coding regions (CDS) identified in the genome (version 3) were retrieved and clustered by the BLASTClust program, using parameters of 40% coverage and 75% identity. For probe design, it was used ArrayOligoSelector software (v. 3.8.1), with a parameter of 50% G+C content. Was obtained 10,359 probes for the longest T. cruzi CDS of each cluster, 393 probes corresponded to the genes of an external group (Cryptosporidium hominis) and 64 spots contained only spotting solution (SSC 3x), given 10,816 spots in total. These oligonucleotides were spotted from a 50 M-5M solution onto poly-L-lysine coated slides and cross-linked with 600 mJ UV. Each probe corresponding to the T. cruzi genes was identified according to the T. cruzi Genome Consortium annotation (www.genedb.org). We compared bound and unbound mRNA, extracted from two independent pull-down assays, in a dye-swap design including four slides. <br>Microarray images were analyzed by Spot software (Spot). The Limma package (Smyth GK, 2004) was used for background correction by the normexp method, intra-slide normalization by the printtiploess method and inter-slide normalization by the quantile method. The results for the two intra-slide probe replicates were then averaged. The pull-down results were averaged, and probes displaying more than a two-fold difference between the bound and unbound fractions were selected, at FDR 1%.
Project description:Neuroblastoma (NB) is an embryonal tumor with various clinical presentations and behaviors. Several genomic alterations has been well-studied in NB, among which genomic amplification of MYCN oncogene, is a strong prognostic biomarker with worsens outcome. Long noncoding RNAs (lncRNAs), constitute major proportion of the cellular transcripts with no coding capacity. One of their function is to guide transcription factors to the target genes and facilitate gene expression. However, relative contribution of lncRNA and MYCN to the advanced NB has remained unclear. Herein, by applying a network-based integrative analysis on MYCN amplified and MYCN nonamplified lncRNA expression profile from both RNA-seq and microarray platform, we identified lncRNA, SNHG1 to be differentially expressed and strongly correlated with MYCN in MYCN-amplified NB. The expression of SNHG1 was validated by RT-qPCR in NB cell lines. Survival analysis revealed that higher expression of SNHG1 significantly associates with poor patient survival. Moreover, knockdown of MYCN in MYCN-amplified NB cell lines inhibited SNHG1 expression. Furthermore, to unravel the role of SNHG1 in NB, we extracted SNHG1-interacting proteins by RNA-protein pull down assay coupled with doi:10.6342/NTU201701980 ! ! VI liquid chromatography-tandem mass spectrometry (LC-MS/MS). We identified 27 SNHG1-interacting proteins in common from three NB cell lines. However, only three SNHG1-interacting proteins, MATR3, YBX1 and HHRNPL have binding site detected by DeepBind motif analysis. Western blot confirms interaction of MATR3 with SNHG1. Additionally, we further validated the direct interaction between MATR3 and SNHG1 by RNA-immunoprecipation (IP). MATR3 is known to be involved in RNA transport and stabilization. Therefore, we proposed that MATR3 after interacting with SNHG1 might help in SNHG1 transcription and stabilization. In conclusion, our study unveils that SNHG1 could be a prognostic marker for high-risk NB and possibly stabilized by MATR3. Our results might provide future directions for the development of therapeutic strategies against high-risk NB.
Project description:Chromatin-associated long non-coding RNAs (ca-lncRNAs) play important roles in transcriptional regulation. To comprehensively investigate the chromatin interactome of an enhancer-derived ca-lncRNA, LEENE, we performed the Chromatin isolation by RNA purification (ChIRP) to pull down LEENE-associated DNAs, which were subjected to DNA-seq. Specifically, we used 10 previously validated tiling nucleotides targeting different domains based on the predicted secondary structure. LEENE was overexpressed by adenovirus to enhance the ChIRP-seq signals.
Project description:The investigation of the association of long non-coding RNAs (lncRNAs) with DNMT1 by RIP-seq reveals that DNMT1 interacts with DACOR1. We identified the genomic occupancy sites of DACOR1 through ChIRP-seq, which we found to significantly overlap with known differentially methylated regions (DMRs) in colon tumors. Induction of DACOR1 in colon cancer cell lines significantly reduced their ability to form colonies in vitro, suggesting a growth suppressor function. Consistent with the observed phenotype, induction of DACOR1 led to the activation of tumor-suppressor pathways and attenuation of cancer-associated metabolic pathways. Notably, DACOR1 induction resulted in down-regulation of Cystathionine ?-synthase (CBS), which is known to lead to increased levels of S-adenosyl methionine (SAM) – the key methyl donor for DNA methylation. The DNA methyltransferase DNMT1 was immunoprecipitated and all associated RNAs were identified by RNA-seq and subsequent bioinformatic analyses. Samples were prepared for DNA sequencing through the ChIRP-seq protocol which uses antisense DNA oligos to bind to DACOR1 and pull down associated DNA in complex. We sequenced one sample with DACOR1 specific probes and non-specific DNA probes as control. Three samples were collected for each control lentivirus transduced V852 colon cancer line and DACOR1 lentivirus transduced V852. Samples were processed for RNA-sequencing and analyzed through differential expression analysis.
Project description:Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a long non-coding RNA (lncRNA) that was first discovered as a prognostic marker for lung cancer metastasis. MALAT1 has been implicated in the tumorigenesis of numerous tumor types. To further delineate the underlying molecular mechanism, we established a high-throughput strategy to characterize the interacting proteins of MALAT1 by combining RNA pull down, quantitative proteomics, bioinformatics analysis, and experimental validation.