Project description:Hnrnpu is the largest member of the heterogenous nuclear ribonucleoprotein family of RNA binding proteins. Hnrnpu is involved in pre-mRNA alternative splicing regulation. We used high throughput sequencing to determine how Hnrnpu regulates skeletal muscle physiology.
Project description:Crosslinking and immunoprecipitation (CLIP) is increasingly used to map transcriptome-wide binding sites of RNA-binding proteins (RBPs). We developed a method for CLIP data analysis and applied it to compare 254 nm CLIP with PAR-CLIP, which involves crosslinking of photoreactive nucleotides with 365 nm UV light. We found small differences in the accuracy of these methods in identifying binding sites of HuR, a protein that binds low-complexity sequences and Argonaute 2, which has a complex binding specificity. We show that crosslink-induced mutations lead to single-nucleotide resolution for both PAR-CLIP and CLIP. Our results confirm the expectation from original CLIP publications that RNA-binding proteins do not protect sufficiently their sites under the denaturing conditions used during the CLIP procedure, and we show that extensive digestion with sequence-specific ribonucleases strongly biases the set of recovered binding sites. We finally show that this bias can be substantially reduced by milder nuclease digestion conditions. We performed duplicate experiments for each variant of the CLIP protocol (CLIP, PAR-CLIP), each protein (HuR, Ago2), and enzymatic digestion (complete T1 digestion, mild MNase digestion). In addition, we performed a single PAR-CLIP experiment with mild T1 digestion.
Project description:This SuperSeries is composed of the following subset Series: GSE21574: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: QKI data GSE21575: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: IGF2BP data GSE21577: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: miRNA inhibition data GSE21918: Transcriptome-wide identification of RNA-binding protein and microRNA target sites by PAR-CLIP: sequencing data Refer to individual Series
Project description:Here we show that HNRNPU, the major nuclear matrix attachment factor, is necessary to maintain proper nuclear architecture in mouse hepatocytes. Upon HNRNPU depletion, the interactions between chromatin and nuclear lamina have been changed dramatically;chromatin organization is globally changed; boundaries of topologically associating domains (TADs) become weaker; inter-TAD interactions are increased; thousands of genes are significantly altered coincident with 3D chromatin changes. Mechanically, HNRNPU interacts with CTCF and RAD21, which affects the binding of RAD21 to the chromatin significantly, whereas CTCF bindings are almost unchanged, what’ more, the decrease of binding strengths are highly correlated with the weakness of loop bounded by Rad21. Taken together, we identify HNRNPU as a key regulator of chromatin architecture, and our data suggest the importance of nuclear matrix associating factors in 3D genome organization.