Project description:We describe a method, MADS (Microarray Analysis of Differential Splicing), for discovery of differential alternative splicing from exon tiling microarrays. MADS incorporates a series of low-level analysis algorithms motivated by the “probe-rich” design of exon arrays, including background correction, iterative probe selection, and removal of sequence-specific cross-hybridization to off-target transcripts. We used MADS to analyze Affymetrix Exon 1.0 array data on a mouse neuroblastoma cell line after shRNA-mediated knockdown of the splicing factor PTB. From a list of exons with pre-determined inclusion/exclusion profiles in response to PTB depletion, MADS recognized all exons known to have large changes in transcript inclusion levels, and offered improvement over Affymetrix’s analysis procedure. We also identified numerous novel PTB-dependent splicing events. 30 novel events were tested by RT-PCR, and 27 were confirmed. This work demonstrates that the exon tiling microarray design is an efficient and powerful approach for global, unbiased analysis of pre-mRNA splicing. Keywords: control / knockdown comparison
Project description:We describe a method, MADS (Microarray Analysis of Differential Splicing), for discovery of differential alternative splicing from exon tiling microarrays. MADS incorporates a series of low-level analysis algorithms motivated by the “probe-rich” design of exon arrays, including background correction, iterative probe selection, and removal of sequence-specific cross-hybridization to off-target transcripts. We used MADS to analyze Affymetrix Exon 1.0 array data on a mouse neuroblastoma cell line after shRNA-mediated knockdown of the splicing factor PTB. From a list of exons with pre-determined inclusion/exclusion profiles in response to PTB depletion, MADS recognized all exons known to have large changes in transcript inclusion levels, and offered improvement over Affymetrix’s analysis procedure. We also identified numerous novel PTB-dependent splicing events. 30 novel events were tested by RT-PCR, and 27 were confirmed. This work demonstrates that the exon tiling microarray design is an efficient and powerful approach for global, unbiased analysis of pre-mRNA splicing. Keywords: control / knockdown comparison Short hairpin knockdown of PTB in mouse N2A neuroblastoma cells was performed as described before (Boutz et al., 2007, Genes Dev 21:1636-1652). The efficiency of the PTB knockdown was monitored by western blot using PTB-NT primary antibody and Cy5 labeled secondary antibody (GE Life Sciences). The blots were imaged using Typhoon 9410 (GE Life Sciences). The band intensities were measured using ImageQuant and normalized to GAPDH. In all cases the efficiency of the knockdown was close to 80% (data not shown). We conducted Exon array profiling on RNAs from three shRNA-PTB treated samples and three mock-treated controls (using empty vectors).
Project description:In Alternative Expression Analysis (ALEXA)-Seq we developed a method to analyze massively parallel RNA sequence data to catalogue transcripts and assess differential and alternative expression of known and predicted messenger RNA (mRNA) isoforms in cells and tissues. As proof-of-principle, we applied the approach to a comparison of fluorouracil responsive and non-responsive human colorectal cancer cell lines. The sensitivity and specificity of the approach were assessed by comparison to exon tiling and splicing microarrays. Validations were conducted by reverse transcription polymerase chain reaction (PCR), quantitative PCR and Sanger sequencing. We observed global disruption of splicing in resistant cells characterized by expression of novel mRNA isoforms resulting from exon skipping, alternative splice site usage and intron retention. Alternative expression annotation databases, source code, a data viewer and other resources to facilitate analysis are available at our website: www.AlexaPlatform.org. See Griffith et al. 2010 in Nature Methods for further details.
Project description:Alternative splicing generates functional diversity in higher organisms through alternative first and last exons, skipped and included exons, intron retentions and alternative donor and acceptor sites. In large-scale microarray studies in human and mouse, emphasis so far has been placed on exon-skip events, leaving the prevalence and importance of other splice types largely unexplored. Using a new human splice variant database and a genome-wide microarray to probes thousands of splice events of each type, we measured differential expression of splice types across 6 pairs of diverse cell lines and validated the database annotation process. Results suggest that splicing in human is more complex than simple exon skip events, which account for a minority of splicing differences. The relative frequency of differential expression of the splice types correlates with what is found by our annotation efforts. In conclusion, alternative splicing in human cells is considerably more complex than the canonical example of the exon-skip. The complementary approaches of genome-wide annotation of alternative splicing in human and design of genome-wide splicing microarrays to measure differential splicing in biological samples provide a powerful high-throughput tool to study the role of alternative splicing in human biology. Keywords: alternative splicing
Project description:Exon level expression analysis for the HGPS pathological aging study data set to analyze the effect of progerin expression on alternative splicing in keratinocytes of HGPS mice. Analysis of the effect of pathological aging (transgenic progerin expression) on alternative splicing (AS) using exon microarrays to interrogate the differential exon usage of the entire genome of HGPS mice (postnatal day 24 and 35) and their wild-type litter mates. Our results suggests that early expression of progerin impairs developmental splicing but that as progerin accumulates, the number of genes with AS increases, similar to what is observed in aging wild-type mice. This dataset is one of the 2 datasets in the overall study. An additional data set series is available with exon expression analysis of aging wild-type mice to analyze the effect of age on alternative splicing during physiological aging. The two datasets are linked together in the SuperSeries GSE67289. A link to the SuperSeries is available at the bottom of this page.
Project description:27 sample pairs were conducted exon microarrays and 25 sample pairs were retain for our further alternative splicing analysis. 260 genes showed differential expression in more than 50% of our samples and 21 genes among them were validated by real-time PCR. Six genes with splicing events, which were firstly found in gastric cancer, were confirmed by RT-PCR. Keywords: Transcriptome analysis
Project description:We describe the application of a new microarray platform, which combines information from exon body and splice-junction probes, to analyze the regulation of 3126 alternative splicing events in ten mouse tissues. The details of the methods and algorithms are described in this paper: Revealing global regulatory features of mammalian alternative splicing using a quantitative microarray platform (Molecular Cell, Dec., 2004) Keywords = A new quantitative alternative splicing microarray platform
Project description:Most human transcripts are alternatively spliced, and many disease-causing mutations affect RNA splicing. Towards better modeling the sequence determinants of alternative splicing, we measured the splicing patterns of nearly 2 million (M) synthetic mini-genes, which include degenerate subsequences totaling to nearly 100M bases of variation. The massive size of these training data allowed us to improve upon current models of splicing as well as to gain new mechanistic insights. Our results show that a vast majority of hexamer sequence motifs measurably influence splice site selection when positioned within alternative exons, with multiple motifs acting additively rather than cooperatively. Intriguingly, motifs that enhance (suppress) exon inclusion in alternative 5’ splicing also enhance (suppress) exon inclusion in alternative 3’ or cassette exon splicing, suggesting a universal mechanism for alternative exon recognition. Finally, our empirically trained models are highly predictive of the effects of naturally occurring variants on alternative splicing in vivo.
Project description:Transcription and co-transcriptional pre-mRNA splicing are kinetically coupled as shown by the widespread effects of transcription speed on alternative splicing. The molecular basis for kinetic coupling is incompletely understood, but one potential mechanism is through elongation rate dependent alternative folding pathways of the nascent pre-mRNA. To search for RNA structures in nascent pre-mRNA, we modified SPLASH (1) (Sequencing of Psoralen Crosslinked, Ligated And Selected Hybrids) for use with Chromatin Associated RNA. We applied this new method called CAR-SPLASH to cells expressing WT and slow mutant pol II and identified >3000 intragenic RNA structures of which >400 are proximal to splice sites. ASO disruption of several structures identified by CAR-SPLASH that sequester splice sites changed alternative splicing outcomes in vivo. We identified three examples of novel regulatory elements we designate “RNA kinetic switches”. ASO disruption of these structures modified alternative splicing of NISCH Exon 18 GAK Exon 7 and MEGF8 Exon 24 in a way that depended on the rate of transcription elongation. These results demonstrate that individual RNA structures can mediate kinetic coupling between transcription and pre-mRNA splicing and that nascent RNA structures can serve as targets for splice modifying ASO’s.
Project description:Transcription and co-transcriptional pre-mRNA splicing are kinetically coupled as shown by the widespread effects of transcription speed on alternative splicing. The molecular basis for kinetic coupling is incompletely understood, but one potential mechanism is through elongation rate dependent alternative folding pathways of the nascent pre-mRNA. To search for RNA structures in nascent pre-mRNA, we modified SPLASH (1) (Sequencing of Psoralen Crosslinked, Ligated And Selected Hybrids) for use with Chromatin Associated RNA. We applied this new method called CAR-SPLASH to cells expressing WT and slow mutant pol II and identified >3000 intragenic RNA structures of which >400 are proximal to splice sites. ASO disruption of several structures identified by CAR-SPLASH that sequester splice sites changed alternative splicing outcomes in vivo. We identified three examples of novel regulatory elements we designate “RNA kinetic switches”. ASO disruption of these structures modified alternative splicing of NISCH Exon 18 GAK Exon 7 and MEGF8 Exon 24 in a way that depended on the rate of transcription elongation. These results demonstrate that individual RNA structures can mediate kinetic coupling between transcription and pre-mRNA splicing and that nascent RNA structures can serve as targets for splice modifying ASO’s.