Epithelial tip progenitor cells are an important epithelial progenitor population in the developing lung. At early stages of development they produce SOX2+ bronchiolar progenitor cells. At later stages of embryonic lung development they produce SOX2- alveolar progenitor cells.
Lung epithelial tip progenitors integrate glucocorticoid- and STAT3-mediated signals to control progeny fate.
Specimen part
View SamplesDuring translation elongation, the ribosome ratchets along its mRNA template, incorporating each new amino acid and translocating from one codon to the next. The elongation cycle requires dramatic structural rearrangements of the ribosome. We show here that deep sequencing of ribosome-protected mRNA fragments reveals not only the position of each ribosome but also, unexpectedly, its particular stage of the elongation cycle. Sequencing reveals two distinct populations of ribosome footprints, 28-30 nucleotides and 20-22 nucleotides long, representing translating ribosomes in distinct states, differentially stabilized by specific elongation inhibitors. We find that the balance of small and large footprints varies by codon and is correlated with translation speed. The ability to visualize conformational changes in the ribosome during elongation, at single-codon resolution, provides a new way to study the detailed kinetics of translation and a new probe with which to identify the factors that affect each step in the elongation cycle. Overall design: Ribosome profiling, or sequencing of ribosome-protected mRNA fragments, in yeast. We assay ribosome footprint sizes and positions in three conditions: untreated yeast (3 replicates) and yeast treated with translation inhibitors cycloheximide (2 replicates) and anisomycin (2 biological replicates, one technical replicate). We also treat yeast with 3-aminotriazole to measure the effect of limited histidine tRNAs on ribosome footprint size and distribution (two treatment durations).
Distinct stages of the translation elongation cycle revealed by sequencing ribosome-protected mRNA fragments.
Cell line, Treatment, Subject
View SamplesEpigenetic events, including covalent post-translational modification of histones, have frequently been demonstrated to play critical roles in tumor development and progression. The transcriptional coactivator, p300/CBP, possesses both histone acetyltransferase (HAT) activity as well as scaffolding properties that directly influence transcriptional activation of targeted genes. We have used a recently reported small molecule inhibitor of p300 HAT activity, C646, to explore the specific contribution of p300/CBP HAT activity to tumor development and progression. We find that C646 inhibits the growth of lineage-specific tumor cell lines including human melanomas through direct transcriptional regulation of cell cycle regulatory proteins. Further evaluation of the p300 HAT transcriptome in human melanoma cells using comprehensive gene expression profiling reveals that p300 HAT activity globally promotes cell cycle progression, nucleosome assembly, and the DNA damage checkpoint through direct transcriptional regulatory mechanisms. Additionally, C646 promotes sensitivity to DNA damaging agents leading to enhanced apoptosis of melanoma cells following combination treatment with cisplatin. Together our data suggest that p300 HAT activity regulates critical growth regulatory pathways in tumors and may serve as a novel therapeutic target for melanoma and other malignancies by promoting cellular responses to DNA damaging agents.
Selective inhibition of p300 HAT blocks cell cycle progression, induces cellular senescence, and inhibits the DNA damage response in melanoma cells.
Cell line, Treatment, Time
View SamplesBase Editing has been touted the most intelligent and precise application of the CRISPR platform so far, merging the simplicity of RNA-guided nucleases with deaminases that allow for the programmable generation of single base substitutions - without introduction of double-strand breaks. Even though the two-component system has been expected to cause off-target substitutions, studies involving cytosine base editors (CBEs) showed that in most cases, relatively few single base off-targets could be detected on DNA. We introduce the concept of multi-dimensional off-targeting, presenting an extensive amount of RNA cytidines being edited by DNA base editors. Epitranscriptomic off-target effects affected different cell lines and were independent of the guide RNAs used, suggesting Cas9-independent activity of the cytidine deaminase rAPOBEC1 on single-stranded RNA. With the help of protein engineering, we developed CBE variants with massively reduced inadvertent mutation of RNA that preserve and enhance DNA base editing capabilities. Overall design: HEK293T and HepG2 cells were transfected with regular and modified pCAG-BE3-P2A-EGFP or control pCAG-nCas9(D10A)-UGI-NLS-P2A-EGFP or control pCAG-P2A-EGFP constructs with various gRNAs as described below. Cells were sorted for top 5% GFP or all GFP + cells based on FITC signal. RNA-seq was performed to measure transcriptional changes associated with different constructs and guides.
Transcriptome-wide off-target RNA editing induced by CRISPR-guided DNA base editors.
Cell line, Treatment, Subject
View SamplesBase Editing has been touted the most intelligent and precise application of the CRISPR platform so far, merging the simplicity of RNA-guided nucleases with deaminases that allow for the programmable generation of single base substitutions - without introduction of double-strand breaks. Even though the two-component system has been expected to cause off-target substitutions, studies involving cytosine base editors (CBEs) showed that in most cases, relatively few single base off-targets could be detected on DNA. We introduce the concept of multi-dimensional off-targeting, presenting an extensive amount of RNA cytidines being edited by DNA base editors. Epitranscriptomic off-target effects affected different cell lines and were independent of the guide RNAs used, suggesting Cas9-independent activity of the cytidine deaminase rAPOBEC1 on single-stranded RNA. With the help of protein engineering, we developed CBE variants with massively reduced inadvertent mutation of RNA that preserve and enhance DNA base editing capabilities. Overall design: HEK293T and HepG2 cells were transfected with pCAG-BE3-P2A-EGFP or control pCAG-nCas9(D10A)-UGI-NLS-P2A-EGFP or control pCAG-P2A-EGFP constructs with various gRNAs as described below. Cells were sorted for top 5% GFP or all GFP + cells based on FITC signal. RNA-seq was performed to measure transcriptional changes associated with different constructs and guides.
Transcriptome-wide off-target RNA editing induced by CRISPR-guided DNA base editors.
Cell line, Treatment, Subject
View SamplesBase Editing has been touted the most intelligent and precise application of the CRISPR platform so far, merging the simplicity of RNA-guided nucleases with deaminases that allow for the programmable generation of single base substitutions - without introduction of double-strand breaks. Even though the two-component system has been expected to cause off-target substitutions, studies involving cytosine base editors (CBEs) showed that in most cases, relatively few single base off-targets could be detected on DNA. We introduce the concept of multi-dimensional off-targeting, presenting an extensive amount of RNA cytidines being edited by DNA base editors. Epitranscriptomic off-target effects affected different cell lines and were independent of the guide RNAs used, suggesting Cas9-independent activity of the cytidine deaminase rAPOBEC1 on single-stranded RNA. With the help of protein engineering, we developed CBE variants with massively reduced inadvertent mutation of RNA that preserve and enhance DNA base editing capabilities. Overall design: HEK293T cells were transfected with pCAG-BE3-P2A-EGFP or variants thereof or control pCAG-nCas9(D10A)-UGI-NLS-P2A-EGFP or control pCAG-P2A-EGFP constructs with various gRNAs as described below. Cells were sorted for top 5% GFP or all GFP + cells based on FITC signal. RNA-seq was performed to measure transcriptional changes associated with different constructs and guides.
Transcriptome-wide off-target RNA editing induced by CRISPR-guided DNA base editors.
Cell line, Treatment, Subject
View SamplesBase Editing has been touted the most intelligent and precise application of the CRISPR platform so far, merging the simplicity of RNA-guided nucleases with deaminases that allow for the programmable generation of single base substitutions - without introduction of double-strand breaks. Even though the two-component system has been expected to cause off-target substitutions, studies involving cytosine base editors (CBEs) showed that in most cases, relatively few single base off-targets could be detected on DNA. We introduce the concept of multi-dimensional off-targeting, presenting an extensive amount of RNA cytidines being edited by DNA base editors. Epitranscriptomic off-target effects affected different cell lines and were independent of the guide RNAs used, suggesting Cas9-independent activity of the cytidine deaminase rAPOBEC1 on single-stranded RNA. With the help of protein engineering, we developed CBE variants with massively reduced inadvertent mutation of RNA that preserve and enhance DNA base editing capabilities. Overall design: HEK293T or HepG2 cells were transfected with P2A-EGFP. Cells were sorted for top 5% GFP based on FITC signal. RNA-seq was performed to measure transcriptional changes associated with different constructs.
Transcriptome-wide off-target RNA editing induced by CRISPR-guided DNA base editors.
Specimen part, Treatment, Subject
View SamplesIn vitro cultured CD34+ derived erythroblasts were sorted using surface markers and processed using RNA-seq Overall design: Biological replicates (3 or 4 per population) were processed across 2-3 biological donors for 8 sorted populations for RNA-seq
Transcriptional States and Chromatin Accessibility Underlying Human Erythropoiesis.
Subject
View SamplesHUDEP-2 cells were lentivirally infected with CRISPRi constructs using a nontargeting guide or guides targeting an enhancer in the TMCC2 locus Overall design: Whole transcriptome libraries were sequenced for three replicates of non-targeting gRNA and two replicates each for two different gRNA targeting a regulatory region upstream of the TMCC2 erythroid-specific isoform
Transcriptional States and Chromatin Accessibility Underlying Human Erythropoiesis.
Cell line, Subject
View SamplesHeterochromatin protein 1a (HP1a) is a chromatin associated protein that has been well studied in many model organisms, such as Drosophila, where it is a determining factor for classical heterochromatin. HP1a is associated with the two histone methyltransferases SETDB1 and Su(var)3-9, which mediate H3K9 methylation marks and participate in the establishment and spreading of HP1a enriched chromatin. While HP1a is generally regarded as a factor that represses gene transcription, several reports have linked HP1a binding to active genes, and in some cases, it has been shown to stimulate transcriptional activity. To clarify the function of HP1a in transcription regulation and its association with Su(var)3-9, SETDB1 and the chromosome 4 specific protein POF, we conducted genome-wide expression studies and combined the results with available binding data in Drosophila melanogaster. The results suggested that HP1a has a repressing function on chromosome 4, where it preferentially targets non-ubiquitously expressed genes (NUEGs), and a stimulating function in pericentromeric regions. Further, we showed that the effects of SETDB1 and Su(var)3-9 are similar to HP1a, and on chromosome 4, Su(var)3-9, SETDB1 and HP1a target the same genes. In contrast, transposons are repressed by HP1a and Su(var)3-9 but are un-affected by SETDB1 and POF. In addition, we found that the binding level and expression effects of HP1a are affected by gene length. Our results indicate that genes have adapted to be properly expressed in their local chromatin environment.
HP1a, Su(var)3-9, SETDB1 and POF stimulate or repress gene expression depending on genomic position, gene length and expression pattern in Drosophila melanogaster.
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