Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA322456 | ENA |
REPOSITORIES: ENA
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Project description:Variable chromatin secondary structures in live cells revealed by radiation-induced spatially correlated DNA cleavage mapping [RICC-Seq]
| PRJNA322621 | ENA
Project description:Variable chromatin structure revealed by in situ spatially correlated DNA cleavage mapping
| PRJNA322612 | ENA
Project description:Chromatin structure at the length scale encompassing nucleosome-nucleosome interactions is thought to play a crucial role in regulating transcription and access to DNA. However, this chromatin secondary structure remains poorly understood compared to the primary structure of single nucleosomes or the tertiary structure of long-range looping interactions. Here we report the first genome-wide map of chromatin conformation in human cells at the 1-3 nucleosome (50-500 bp) scale, obtained using ionizing radiation-induced spatially correlated cleavage of DNA with sequencing (RICC-seq). Unbiased analysis of RICC-seq DNA fragments in 1 Mb windows reveals a similar fragment length profile across the genome, with regional enrichment of characteristic fragments spanning tri-nucleosome units in heterochromatin. We observe differences in nucleosome-nucleosome contacts among euchromatin, H3K27me3-marked heterochromatin, and H3k9me3-marked heterochromatin. After calibrating RICC-seq signal to 3D distances, we show that compact 2-start helical fiber structures with stacked alternating nucleosomes are consistent with RICC-seq fragmentation patterns from H3K9me3-marked heterochromatin, while non-compact zig-zags and other extended structures are preferred in open chromatin. Our data support a model of heterochromatin condensation in native, intact nuclei consistent with longitudinal compaction of two-start helical fibers.
2016-12-26 | GSE81806 | GEO
Project description:Chromatin structure at the length scale encompassing nucleosome-nucleosome interactions is thought to play a crucial role in regulating transcription and access to DNA. However, this chromatin secondary structure remains poorly understood compared to the primary structure of single nucleosomes or the tertiary structure of long-range looping interactions. Here we report the first genome-wide map of chromatin conformation in human cells at the 1-3 nucleosome (50-500 bp) scale, obtained using ionizing radiation-induced spatially correlated cleavage of DNA with sequencing (RICC-seq). Unbiased analysis of RICC-seq DNA fragments in 1 Mb windows reveals a similar fragment length profile across the genome, with regional enrichment of characteristic fragments spanning tri-nucleosome units in heterochromatin. We observe differences in nucleosome-nucleosome contacts among euchromatin, H3K27me3-marked heterochromatin, and H3k9me3-marked heterochromatin. After calibrating RICC-seq signal to 3D distances, we show that compact 2-start helical fiber structures with stacked alternating nucleosomes are consistent with RICC-seq fragmentation patterns from H3K9me3-marked heterochromatin, while non-compact zig-zags and other extended structures are preferred in open chromatin. Our data support a model of heterochromatin condensation in native, intact nuclei consistent with longitudinal compaction of two-start helical fibers.
2016-12-26 | GSE81736 | GEO
Project description:The high-throughput DICER cleavage assays were conducted shRNA variants containing different sequences. We showcase a comprehensive cleavage activity of DICER on different shRNAs containing different secondary structures.
2022-02-21 | GSE182701 | GEO
Project description:Human Microprocessor cleaves pri-miRNAs to initiate miRNA biogenesis. The accuracy and efficiency of Microprocessor cleavage ensure appropriate miRNA sequence and expression and thus its proper gene regulation. However, Microprocessor cleaves many pri-miRNAs incorrectly, so it requires assistance from its many cofactors. For example, SRSF3 enhances Microprocessor cleavage by interacting with the CNNC motif in pri-miRNAs. However, whether SRSF3 can function with other motifs and/or requires the motifs in a certain secondary structure is unknown. In addition, the function of SRSF7 (a paralog of SRSF3) in miRNA biogenesis still needs to be discovered. Here, we demonstrated that SRSF7 could stimulate Microprocessor cleavage. In addition, by conducting high-throughput pri-miRNA cleavage assays for Microprocessor and SRSF7 or SRSF3, we demonstrated that SRSF7 and SRSF3 function with the CRC and CNNC motifs, adopting certain secondary structures. In addition, SRSF7 and SRSF3 affect the Microprocessor cleavage sites in human cells. Our findings demonstrate the roles of SRSF7 in miRNA biogenesis and provide a comprehensive view of the molecular mechanism of SRSF7 and SRSF3 in enhancing Microprocessor cleavage.
2023-01-23 | GSE215790 | GEO
Project description:The extreme radiation resistance of Deinococcus bacteria requires the radiation-stimulated cleavage of protein DdrO by a specific metalloprotease called IrrE. DdrO is the repressor of a predicted radiation/desiccation response (RDR) regulon, composed of radiation-induced genes having a conserved DNA motif (RDRM) in their promoter regions. Here, we showed that addition of zinc ions to purified apo-IrrE, and short exposure of Deinococcus cells to zinc ions, resulted in cleavage of DdrO in vitro and in vivo, respectively. Binding of IrrE to RDRM-containing DNA or interaction of IrrE with DNA-bound DdrO was not observed. The data are in line with IrrE being a zinc peptidase, and indicate that increased zinc availability, caused by oxidative stress, triggers the in vivo cleavage of DdrO unbound to DNA. Transcriptomics and proteomics of Deinococcus deserti confirmed the IrrE-dependent regulation of predicted RDR regulon genes and also revealed additional members of this regulon. Comparative analysis showed that the RDR regulon is largely well conserved in Deinococcus species, but also showed diversity in the regulon composition. Notably, several RDR genes with an important role in radiation resistance in Deinococcus radiodurans, for example pprA, are not conserved in some other radiation-resistant Deinococcus species.
2017-04-03 | GSE95658 | GEO
Project description:Arthrospira is an edible cyanobacterium used in the food supplement “Spirulina”. The aim of this work was to characterise its response to ionising radiation. Live cells of Arthrospira sp. PCC 8005 were irradiated with 60Co gamma rays. Arthrospira sp. PCC 8005 recovered and resumed photosynthetic proliferation after exposure to a dose of even 6400 Gy, which is a dose about 1000x higher than the lethal dose for most plant, animal and human cells. Biochemical, proteomic and transcriptomic analysis after irradiation with 3200 or 5000 Gy showed a strong reduction in photosynthesis activity and reduced pigment content. Irradiated cells showed reduced transcription for carbon fixation, and for pigment, lipid and secondary metabolite synthesis; while induced transcription of thiol-based antioxidant systems, photosensing and signalling pathways. Cells irradiated with 3200 or 5000 Gy did not show clear dsDNA damage, but transcriptomics did show significant activation of ssDNA repair systems and mobile genetic elements at RNA-level. Irradiated cells also expressed a group of conserved proteins of which the function in radiation resistance remains to be elucidated. This study revealed for the first time the high radiation resistance of Arthrospira, and the molecular systems involved, paving the way for its further exploitation for radiation protection.
2014-12-01 | GSE57456 | GEO
Project description:MicroRNAs (miRNAs) are short non-coding RNAs that play essential roles in RNA silencing and gene regulation. The human Microprocessor (MP) is the key factor to initiate miRNA biogenesis by cleaving primary microRNAs (pri-miRNAs). However, the Microprocessor alone cannot precisely and efficiently cleave all pri-miRNAs; thus, it requires cofactors to assist its cleavage. SRSF3 interacts with CNNC in pri-miRNAs, enhancing the MP cleavage. However, it is unknown if SRSF3 can function with other non-CNNC motifs and if secondary structure might influce CNNC function. In addition, function of SRSF7, a paralog of SRSF3, in the SR proteins family, in miRNA biogenesis is largely unknown. In this study, by conducting the high-throughput pri-miRNA cleavage assays for the MP with SRSF3 or SRSF7 and randomized pri-miRNAs, we discovered that SRSF7 also stimulate MP clevage. Futhermore, we found that both SRSF3 and SRSF7 can function with some non-CNNC motifs and with CNNC motifs with certain secondary structures. Furthermore, we also demonstrated that SRSF7 and SRSF3 governed the cleavage sites of the Microprocessor in human cells. Our findings disclose the roles SRSF7 in miRNA biogenesis, demonstrate a compresenhive moleucalr mechanism of SFSF3 and SRSF7 in enhancing cleavage of MP and described in more detail the RNA-binding features of SRSF7 and SRSF3.
2023-01-23 | GSE221996 | GEO
Project description:we combined Assay for Transposase-Accessible Chromatin and lattice light-sheet PALM microscopy (3D ATAC-PALM) to selectively image key features of the 3D accessible genome in single cells. We found that accessible chromatin domains (ACDs) form spatially segregated clusters in the nucleus. Rapid depletion of CTCF or Cohesin (RAD21 subunit) induced extensive 3D spatial mixing of ACD clusters and reduced physical separation between ACDs within chromosomes. Experimental perturbations and modeling suggest that both weak, multivalent, dynamic protein-protein interactions together with loop extrusion influence ACD organization. Live-cell studies suggest that ACD clustering regulates transcription factor binding site distribution, target search kinetics and binding dynamics. Here we report the ATAC-seq results from Tn5 PA549 and nextera Tn5 upon various chemical and genetic perturbations.
2022-02-01 | GSE144505 | GEO