Project description:To determine direct targets of PTBP2-dependent alternative splicing, we performed CLIP-seq analysis of PTBP2 binding in both human cortical tissue and human neurons derived from induced-pluripotent stem cells (iPSC-neurons), and we combine this with splicing analysis following PTBP2 depletion in iPSC-neurons.
Project description:Two polypyrimidine tract RNA-binding proteins (PTBs), one near-ubiquitously expressed (Ptbp1) and another highly tissue-restricted (Ptbp2), regulate RNA in interrelated but incompletely understood ways. Ptbp1, a splicing regulator, is replaced in the brain and differentiated neuronal cell lines by Ptbp2. To define the roles of Ptbp2 in the nervous system, we generated two independent Ptbp2-null strains, unexpectedly revealing that Ptbp2 is expressed in neuronal progenitors and is essential for postnatal survival. A HITS-CLIP (high-throughput sequencing crosslinking immunoprecipitation)-generated map of reproducible Ptbp2–RNA interactions in the developing mouse neocortex, combined with results from splicing-sensitive microarrays, demonstrated that the major action of Ptbp2 is to inhibit adult-specific alternative exons by binding pyrimidine-rich sequences upstream of and/or within them. These regulated exons are present in mRNAs encoding proteins associated with control of cell fate, proliferation, and the actin cytoskeleton, suggesting a role for Ptbp2 in neurogenesis. Indeed, neuronal progenitors in the Ptbp2-null brain exhibited an aberrant polarity and were associated with regions of premature neurogenesis and reduced progenitor pools. Thus, Ptbp2 inhibition of a discrete set of adult neuronal exons underlies early brain development prior to neuronal differentiation and is essential for postnatal survival. Eight Ptbp2 HITS-CLIP libraries generated from mouse embryonic brain (four libraries from each of two biologic replicates).
Project description:Two polypyrimidine tract RNA-binding proteins (PTBs), one near-ubiquitously expressed (Ptbp1) and another highly tissue-restricted (Ptbp2), regulate RNA in interrelated but incompletely understood ways. Ptbp1, a splicing regulator, is replaced in the brain and differentiated neuronal cell lines by Ptbp2. To define the roles of Ptbp2 in the nervous system, we generated two independent Ptbp2-null strains, unexpectedly revealing that Ptbp2 is expressed in neuronal progenitors and is essential for postnatal survival. A HITS-CLIP (high-throughput sequencing crosslinking immunoprecipitation)-generated map of reproducible Ptbp2–RNA interactions in the developing mouse neocortex, combined with results from splicing-sensitive microarrays, demonstrated that the major action of Ptbp2 is to inhibit adult-specific alternative exons by binding pyrimidine-rich sequences upstream of and/or within them. These regulated exons are present in mRNAs encoding proteins associated with control of cell fate, proliferation, and the actin cytoskeleton, suggesting a role for Ptbp2 in neurogenesis. Indeed, neuronal progenitors in the Ptbp2-null brain exhibited an aberrant polarity and were associated with regions of premature neurogenesis and reduced progenitor pools. Thus, Ptbp2 inhibition of a discrete set of adult neuronal exons underlies early brain development prior to neuronal differentiation and is essential for postnatal survival.
Project description:RNA binding proteins (RBPs) play essential roles in cellular physiology by interacting with target RNAs. As defects in protein-RNA recognition lead to human disease, UV-crosslinking and immunoprecipitation (CLIP) of ribonuclear complexes followed by deep sequencing (-seq) is critical in constructing protein-RNA maps to expand our understanding of RBP function. However, current CLIP protocols are technically demanding and involve low complexity libraries that yield squandered sequencing of PCR duplicates and high experimental failure rates. To enable truly large-scale implementation of CLIP-seq, we have developed an enhanced CLIP methodology (eCLIP) that features a decrease of ~10 cycles of requisite amplification with a concomitant >60% decrease in discarded PCR duplicate reads, while maintaining the ability to identify RNA binding with single-nucleotide resolution. By simplifying the generation of paired IgG and size-matched input controls, eCLIP also dramatically improves specificity in discovery of authentic binding sites. To demonstrate that eCLIP enables large-scale and robust profiling of RBPs, 102 eCLIP experiments in biological duplicate for a diverse collection of 74 RBPs in HepG2 and K562 cells were completed (available at https://www.encodeproject.org). We establish that eCLIP is comparable in amplification and sample requirements to ChIP-seq, and enables integrative analysis of diverse RBPs to reveal factor-specific profiles, common artifacts for CLIP experiments and RNA-centric perspectives of RBP activity.
Project description:RNA binding proteins (RBPs) play essential roles in cellular physiology by interacting with target RNAs. As defects in protein-RNA recognition lead to human disease, UV-crosslinking and immunoprecipitation (CLIP) of ribonuclear complexes followed by deep sequencing (-seq) is critical in constructing protein-RNA maps to expand our understanding of RBP function. However, current CLIP protocols are technically demanding and involve low complexity libraries that yield squandered sequencing of PCR duplicates and high experimental failure rates. To enable truly large-scale implementation of CLIP-seq, we have developed an enhanced CLIP methodology (eCLIP) that features a decrease of ~10 cycles of requisite amplification with a concomitant >60% decrease in discarded PCR duplicate reads, while maintaining the ability to identify RNA binding with single-nucleotide resolution. By simplifying the generation of paired IgG and size-matched input controls, eCLIP also dramatically improves specificity in discovery of authentic binding sites. To demonstrate that eCLIP enables large-scale and robust profiling of RBPs, 102 eCLIP experiments in biological duplicate for a diverse collection of 74 RBPs in HepG2 and K562 cells were completed (available at https://www.encodeproject.org). We establish that eCLIP is comparable in amplification and sample requirements to ChIP-seq, and enables integrative analysis of diverse RBPs to reveal factor-specific profiles, common artifacts for CLIP experiments and RNA-centric perspectives of RBP activity.
Project description:To determine targets of PTBP2-dependent alternative splicing, we depleted PTBP2 in human neurons derived from induced-pluripotent stem cells (iPSC-neurons) using an LNA gapmer and performed RNA-seq on untreated, negative control-treated, and knock-down samples.
Project description:To identify PTBP2 targets important for neural fate acqusition, miR-9/9*-124-mediated direct conversion of human fibroblasts into neurons was employed. We showed that PTBP2 is important for the successful acquisition of neuronal fate and profiled fibroblasts and reprogrammed neurons with and without PTBP2 knockdown to identify neuronal-associated PTBP2 targets during reprogramming.
Project description:RNA binding proteins (RBPs) play essential roles in cellular physiology by interacting with target RNAs. As defects in protein-RNA recognition lead to human disease, UV-crosslinking and immunoprecipitation (CLIP) of ribonuclear complexes followed by deep sequencing (-seq) is critical in constructing protein-RNA maps to expand our understanding of RBP function. However, current CLIP protocols are technically demanding and involve low complexity libraries that yield squandered sequencing of PCR duplicates and high experimental failure rates. To enable truly large-scale implementation of CLIP-seq, we have developed an enhanced CLIP methodology (eCLIP) that features a decrease of ~10 cycles of requisite amplification with a concomitant >60% decrease in discarded PCR duplicate reads, while maintaining the ability to identify RNA binding with single-nucleotide resolution. By simplifying the generation of paired IgG and size-matched input controls, eCLIP also dramatically improves specificity in discovery of authentic binding sites. To demonstrate that eCLIP enables large-scale and robust profiling of RBPs, 102 eCLIP experiments in biological duplicate for a diverse collection of 74 RBPs in HepG2 and K562 cells were completed (available at https://www.encodeproject.org). We establish that eCLIP is comparable in amplification and sample requirements to ChIP-seq, and enables integrative analysis of diverse RBPs to reveal factor-specific profiles, common artifacts for CLIP experiments and RNA-centric perspectives of RBP activity.
Project description:RNA binding proteins (RBPs) play essential roles in cellular physiology by interacting with target RNAs. As defects in protein-RNA recognition lead to human disease, UV-crosslinking and immunoprecipitation (CLIP) of ribonuclear complexes followed by deep sequencing (-seq) is critical in constructing protein-RNA maps to expand our understanding of RBP function. However, current CLIP protocols are technically demanding and involve low complexity libraries that yield squandered sequencing of PCR duplicates and high experimental failure rates. To enable truly large-scale implementation of CLIP-seq, we have developed an enhanced CLIP methodology (eCLIP) that features a decrease of ~10 cycles of requisite amplification with a concomitant >60% decrease in discarded PCR duplicate reads, while maintaining the ability to identify RNA binding with single-nucleotide resolution. By simplifying the generation of paired IgG and size-matched input controls, eCLIP also dramatically improves specificity in discovery of authentic binding sites. To demonstrate that eCLIP enables large-scale and robust profiling of RBPs, 102 eCLIP experiments in biological duplicate for a diverse collection of 74 RBPs in HepG2 and K562 cells were completed (available at https://www.encodeproject.org). We establish that eCLIP is comparable in amplification and sample requirements to ChIP-seq, and enables integrative analysis of diverse RBPs to reveal factor-specific profiles, common artifacts for CLIP experiments and RNA-centric perspectives of RBP activity.
Project description:Human pluripotent stem cells (hPSCs) require precise control of post-transcriptional RNA networks to maintain proliferation and survival. Using a recently developed enhanced UV crosslinking and immunoprecipitation (eCLIP) approach, we identify RNA targets of the IMP/IGF2BP family of RNA-binding proteins in hPSCs. At the broad region- and binding site-level IMP1 and IMP2 show reproducible binding to a large and overlapping set of 3'UTR-enriched targets. RNA Bind-N-Seq applied to recombinant full-length IMP1 and IMP2 reveals CA-rich motifs that are enriched in eCLIP-defined binding sites. We observe that IMP1 loss in hPSCs recapitulates IMP1 phenotypes, including a reduction in cell adhesion and an increase in cell death. For cell adhesion, in hPSCs we find IMP1 maintains levels of integrin mRNA, specifically regulating RNA stability of ITGB5. Additionally, we show IMP1 can be linked to hPSC survival via direct target BCL2. Thus, transcriptome-wide binding profiles identify hPSC targets modulating well-characterized IMP1 roles. eCLIP-seq was performed in biological replicate for IGF2BP1/IMP1 and IGF2BP2/IMP2, as well as one replicate each for IGF2BP3/IMP3, RBFOX2, and an IgG control. Each sample has a size-matched input control for analysis