Gene expression changes upon Lamin A and Lamin B2 depletion in a diploid colorectal cancer cell line - DLD1
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ABSTRACT: Small interfering RNA (siRNA) mediated depletion of Lamin A/C and Lamin B2 was performed in a diploid colorectal cancer cell line - DLD1 with an aim to identify transcription deregulation across the genome.
Project description:Tetraploidisation has been implicated in tumorigenesis and in aneuploidy which is frequently observed in most human cancers. In this study we aim to reveal differences in gene expression profile of p53 defective isogenic diploid and tetraploid cell populations. Isogenic DLD1 populations were obtained by transient Dihydro-Cytochalasin B treatment and cell sorting of pure diploid and tetraploid populations by cell cycle profile several days after release from DCB. RNA isolation: Two technical replicas were collected for each population from two different passages (biological replicas) of 60-80% confluent cells.
Project description:Gene expression is regulated by chromatin DNA methylation and other features, including histone post-translational modifications (PTMs), chromatin remodelers, and transcription factor occupancy. A complete understanding of gene regulation will require the mapping of these chromatin features in small cell number samples. Here we describe a novel genome-wide chromatin profiling technology, named as Nicking Enzyme Epitope targeted DNA sequencing (NEED-seq). NEED-seq offers antibody-targeted controlled nicking by Nt.CviPII-pGL fusion to study specific protein-DNA complexes in formaldehyde fixed cells, allowing for both visual and genomic resolution of epitope bound chromatin. When applied to nuclei, NEED-seq yielded genome-wide profile of chromatin associated proteins and histone PTMs. Additionally, NEED-seq of lamin B1 and B2 demonstrated their association with heterochromatin. Lamin B1 and B2 associated domains (LAD) segregated to three different states, and states with stronger LAD correlated with heterochromatic marks. Hi-C analysis displayed A and B compartment with equal lamin B1 and B2 distribution, although methylated DNA remained high in B compartment. LAD clustering with Hi-C resulted in subcompartments, with lamin B1 and B2 partitioning to facultative and constitutive heterochromatin respectively and were associated with neuronal development. Thus, lamin B1 and B2 show structural and functional partitioning in mammalian nucleus.
Project description:DLD1 is an APC mut, KRAS mut, P53 mut CRC cell line. PROX1 transcription factor, target of Wnt pathway in CRC, is our protein of interest.DLD1 cells are PROX1 negative. We overexpressed through lentiviral expression PROX1 protein or the empty vector psd44, through selection of the cells in puromycin resistance. Afterwards we compared the transcriptional program of the DLD1-PROX1 and DLD1-Control cells growing in monolayer in vitro.
Project description:Heart muscle cells, cardiomyocytes, are highly differentiated cells that usually do not proliferate . During the non-proliferative state, extracellular signals control cardiomyocyte contractile function. However, during development and regeneration, cardiomyocytes enter the cell cycle and divide. It is unknown how cardiomyocytes modify their intracellular signaling to direct the cell cycle program. Here, we show that the nuclear lamina protein Lamin B2 (Lmnb2) regulates cardiomyocyte cell cycle activity using a gatekeeper mechanism. We identified Lmnb2 as a candidate for regulating intracellular signaling with deep transcriptional profiling of single cardiomyocytes. Lmnb2 was sufficient and necessary for cardiomyocyte cycling in the presence of serum. Lmnb2 increased the nucleoporin NUP98 and permeability of the nuclear membrane for phosphorylated ERK1/2. In vivo, the Lmnb2 gene was required for cardiomyocyte cell cycle activity during development. Increasing the expression of Lmnb2 in neonatal mice promoted cardiomyocyte M-phase and cytokinesis. LmnB2 gene transfer in neonatal mice that received a myocardial injury increased cardiomyocyte division and myocardial function in the injury border zone, indicating that the regenerated cardiomyocytes were functionally integrated. We propose a gatekeeper function of Lmnb2 that can be targeted to increase cardiomyocyte regeneration without the administration of exogenous growth factors.
Project description:To investigate the function of ZNF692 in colorectal cancer, we established DLD1 cell lines in which target gene has been knocked out by CRISPR-cas. We then performed gene expression profiling analysis using data obtained from DLD1 colorectal human cells wt (sgC for guide control) or crispr knockout for ZNF692 (sgZ1 for guide 1, and sgZ3 for guide 3). We have each condition in triplicates.
Project description:The nuclear lamins are extremely long-lived proteins in most cell types. As a consequence, lamin function cannot be effectively dissected with temporal precision using standard knock-down approaches. Here, we apply the auxin inducible degron (AID) system to rapidly deplete each lamin isoform within one cell cycle and reveal the immediate impacts of lamin loss on the nucleus . Surprisingly, neither acute lamin A/C (LA/C), lamin B1 (LB1), nor lamin B2 (LB2) depletion altered nuclear shape or induced nuclear blebbing, indicating that acute lamin loss is not sufficient to alter nuclear morphology. LB1 depletion is immediately followed by LA/C meshwork disorganization due to actin cytoskeletal forces on the lamina, yet neither LA/C nor LB1 depletion induced nuclear rupturing. We found that the abundant inner nuclear membrane protein LAP2β protects nuclear integrity in the absence of LB1, as depletion of both LB1 and LAP2β induced severe LA/C disorganization and frequent nuclear rupturing. Depolymerization of the actin cytoskeleton halts nuclear rupture in LAP2β- and LB1-depleted nuclei. We conclude that both LB1 and LAP2β resist cytoskeletal force to maintain regular lamin A/C meshwork organization and preserve nuclear integrity.
Project description:The nuclear lamina (NL) is a filamentous layer lining the inner-nuclear-membrane (INM) that aids in the organization of the genome in large domains of low transcriptional activity. Recently, it was shown that the single-cell genome-NL interactions are much more dynamic than previously anticipated, which challenges the concept of the NL as a safe guard for transcriptional repressed genes. Here we discuss the role of the NL in light of these new findings and introduce Lamin A and BAF as potential modulators of LAD positioning BAF-chromatin and Lamin B2-chromatin interactions were assayed in human HT1080 by DamID on Nimblegen microarrays, with two biological replicates each, that were hybridized in a dye-swap design.
Project description:We performed ChIP coupled with high-throughput sequencing (ChIP-seq) for H3K27me3 in DLD1 parental cells and DLD1 p85β K477A/R478A mutant cells