Project description:Purpose: To identify gene expression changes in entorhinal cortex layer II (ECII) neurons upon Ptbp1 modulation (silencing and overexpression) Method: bacterial artificial chromosome - Translating Ribosome Affinity Purification (bacTRAP) to isolate actively translated mRNA in ECII neurons, 2 weeks after stereotaxic injection of an AAV1 vector in the EC of ECII-bacTRAP mice; followed by RNAseq. Note: Ptbp1 was significantly overexpressed in the overexpression experiment, but no silencing was achieved with the silencing vector, probably because of tight control of Ptbp1 expression
Project description:All brain functionality arises from the activity in neural circuits in different anatomical regions. These regions contain different circuits comprising unique cell types. An integral part to understanding neural circuits is a full census of the constituent parts, i.e., the neural cell types. This census can be based on different characteristics. Previously combinations of morphology and physiology, gene expression, and chromatin accessibility have been used in various cortical and subcortical regions. This has given an extensive yet incomplete overview of neural cell types. However, these techniques have not been applied to all brain regions. Here we apply single cell analysis of accessible chromatin on two similar but different cortical regions, the medial and the lateral entorhinal cortices. Even though these two regions are anatomically similar, their intrinsic and extrinsic connectivity are different. In 4136 cells we identify 20 different clusters representing different cell types. As expected, excitatory cells show regionally specific clusters, whereas inhibitory neurons are shared between regions. We find that several deep layer excitatory neuronal cell types as defined by chromatin profile are also shared between the two different regions. Integration with a larger scRNA-seq dataset maintains this shared characteristic for cells in Layer Vb. Interestingly, this Layer contains three clusters, two specific to either subregion and one shared between the two. These clusters can be putatively associated with particular functional and anatomical cell types found in this layer. This information is a step forwards into elucidating the cell types within the entorhinal circuit and by extension its functional underpinnings.
Project description:We report the first full transcriptome analysis of layer II and deep layers of the medial and lateral entorhinal cortex during postnatal development. Our analysis showed that postnatal timepoint was the most important element in entorhinal cortex transcriptional dynamics, followed by laminar differences. There were fewer differentially expressed genes between the medial and lateral parts of the entorhinal cortex, and most of these were found in layer II.
Project description:We describe an improved individual nucleotide resolution CLIP protocol (iiCLIP), which can be completed within 4 days from UV crosslinking to libraries for sequencing. For benchmarking, we directly compared PTBP1 iiCLIP libraries with the iCLIP2 protocol produced under standardised conditions with 1 million HEK293 cells, and with public eCLIP and iCLIP PTBP1 data. There are 3 PTBP1 iiCLIP libraries, 1 input iiCLIP library and 1 PTBP1 iCLIP2 library produced in this study.
Project description:Ribosomopathies constitute a range of disabling conditions associated with defective protein synthesis mainly affecting hematopoietic stem cells (HSCs) and erythroid development. Here we demonstrate that deletion of Polypyrimidine Tract Binding Protein 1 (PTBP1) in the hematopoietic compartment led to the development of a ribosomopathy-like condition. Specifically, loss of PTBP1 was associated with a decrease in HSC self-renewal, erythroid differentiation and protein synthesis. Consistent with its function as a splicing regulator, PTBP1 deficiency led to splicing defects in hundreds of genes and we demonstrate that the up-regulation of a specific isoform of CDC42 could partly mimic the protein synthesis defect associated with loss of PTBP1. Furthermore, PTBP1 deficiency was associated with a marked defect in ribosome biogenesis and a selective reduction in the translation of mRNAs encoding ribosomal proteins. Collectively, this work identifies PTBP1 as a key integrator of ribosomal functions and highlights the broad functional repertoire of RNA binding proteins.
Project description:We examined the role of PTBP1 in regulation of co-transcriptional splicing process by depleting this RNA-binding protein from embryonic stem cells using the auxin-inducible degron technology and analysing the total and chromatin-associated RNA fractions by RNA-seq. We also performed mNET-seq and ChIP-seq analyses using RNA polymerase II- and PTBP1-specific antibodies, respectively. Our data suggest that PTBP1 activates co-transcriptional splicing of hundreds of introns, a surprising effect given that PTBP1 is better known as a splicing repressor. Importantly, some co-transcriptionally activated introns fail to be spliced post-transcriptionally without PTBP1. In a striking example of this regulation, lasting retention of a PTBP1-dependent intron triggers nonsense-mediated decay of mRNAs encoding DNA methyltransferase DNMT3B, explaining their natural expression dynamics in development. Our further analyses suggest that this mechanism may protect differentiation-specific genes from aberrant methylation. We conclude that PTBP1-activated co-transcriptional splicing underlies biologically important decisions.
Project description:IMR90 ER:RAS cells were stably transduced with either an empty vector or 2 deconvoluted shRNAs targeting PTBP1. Following selection with puromycin, the cells were treated with 4OHT to induce senescence. 6 days later the cells were collected for total mRNA analysis. PTBP1 is a regulator of alternative splicing. Our previous experiments had shown that PTBP1 depletion inhibits the expression of pro-inflammatory genes without affecting other senescence-associated phenotypes. By performing RNA-seq we confirmed those observations at a global level and analysed how PTBP1 knockdown alters alternative splicing as a potential mechanism of action.
Project description:To investigate the effect of IGFRIL/PTBP1 in HCC, we established HepG2 cell lines in which IGFRIL/PTBP1 mRNA has been degraded using siRNA.
Project description:We demonstrated that knocking down Ptbp1 can reprogram GBM cells into neuron-like cells. In order to further explore the mechanism of Ptbp1 causing this phenomenon, we performed mRNA sequencing on U251 cells infected with sh-Luci-3d, sh-Ptbp1-3d and sh-Ptbp1-7d.