Project description:DNA-replication is a key process in life and can lead to disease when disturbed. Cell-type specific early and late replication domains have been discovered throughout genomes by analysis of DNA from populations of cells. However, cell to cell differences and the association of these differences with other cellular processes remain largely elusive. Here we demonstrate for the first time that consecutive domains of early and late DNA-replication can be detected in single S-phase cells using array comparative genomic hybridization, providing proof-of-concept for a novel tool to investigate DNA-replication genome wide at the single-cell level. Furthermore, methods to profile the genome of a single cell for DNA-copy number aberrations are revolutionizing both basic genome research and clinical genetic diagnosis. It is thus important to apprehend not only technical but also biological reasons for false positive copy number detection. None of the current single-cell copy number calling methods distinguishes between a cell in G1-, S- or G2/M-phase of the cell cycle and mostly use cells isolated randomly from populations. We demonstrate that the oscillating pattern between early and late replicating loci instigates significantly more false-positive DNA copy-number calls in a diploid cell in S-phase cells than in G1- or G2/M-phase, depending on the specific aCGH-signal normalization method used. We propose a work-flow to detect single cells in S-phase and to correct for DNA-replication bias before copy number profiling. The genome of 1 S-phase, 2 M-phase and 1 G-phase single cells was amplified using the Sureplex amplification system. These test samples were hybridized comparatively to commercial male reference DNA,
Project description:DNA-replication is a key process in life and can lead to disease when disturbed. Cell-type specific early and late replication domains have been discovered throughout genomes by analysis of DNA from populations of cells. However, cell to cell differences and the association of these differences with other cellular processes remain largely elusive. Here we demonstrate for the first time that consecutive domains of early and late DNA-replication can be detected in single S-phase cells using array comparative genomic hybridization, providing proof-of-concept for a novel tool to investigate DNA-replication genome wide at the single-cell level. Furthermore, methods to profile the genome of a single cell for DNA-copy number aberrations are revolutionizing both basic genome research and clinical genetic diagnosis. It is thus important to apprehend not only technical but also biological reasons for false positive copy number detection. None of the current single-cell copy number calling methods distinguishes between a cell in G1-, S- or G2/M-phase of the cell cycle and mostly use cells isolated randomly from populations. We demonstrate that the oscillating pattern between early and late replicating loci instigates significantly more false-positive DNA copy-number calls in a diploid cell in S-phase cells than in G1- or G2/M-phase, depending on the specific aCGH-signal normalization method used. We propose a work-flow to detect single cells in S-phase and to correct for DNA-replication bias before copy number profiling. DNA was extracted from many cells from 1 S-phase, 1 G1-phase and 1 G2/Mphase enriched cell population from an EBV-transformed lymphoblastoid cell line from a male carrying a 750kb amplification on the short arm of chromosome 4. These test samples were hybridized comparatively to commercial male reference DNA.
Project description:DNA-replication is a key process in life and can lead to disease when disturbed. Cell-type specific early and late replication domains have been discovered throughout genomes by analysis of DNA from populations of cells. However, cell to cell differences and the association of these differences with other cellular processes remain largely elusive. Here we demonstrate for the first time that consecutive domains of early and late DNA-replication can be detected in single S-phase cells using array comparative genomic hybridization, providing proof-of-concept for a novel tool to investigate DNA-replication genome wide at the single-cell level. Furthermore, methods to profile the genome of a single cell for DNA-copy number aberrations are revolutionizing both basic genome research and clinical genetic diagnosis. It is thus important to apprehend not only technical but also biological reasons for false positive copy number detection. None of the current single-cell copy number calling methods distinguishes between a cell in G1-, S- or G2/M-phase of the cell cycle and mostly use cells isolated randomly from populations. We demonstrate that the oscillating pattern between early and late replicating loci instigates significantly more false-positive DNA copy-number calls in a diploid cell in S-phase cells than in G1- or G2/M-phase, depending on the specific aCGH-signal normalization method used. We propose a work-flow to detect single cells in S-phase and to correct for DNA-replication bias before copy number profiling. The genome of 4 S-phase, 3 M-phase and 4 G-phase single cells was amplified using the Sureplex amplification system. These test samples were hybridized comparatively to commercial male reference DNA,
Project description:DNA-replication is a key process in life and can lead to disease when disturbed. Cell-type specific early and late replication domains have been discovered throughout genomes by analysis of DNA from populations of cells. However, cell to cell differences and the association of these differences with other cellular processes remain largely elusive. Here we demonstrate for the first time that consecutive domains of early and late DNA-replication can be detected in single S-phase cells using array comparative genomic hybridization, providing proof-of-concept for a novel tool to investigate DNA-replication genome wide at the single-cell level. Furthermore, methods to profile the genome of a single cell for DNA-copy number aberrations are revolutionizing both basic genome research and clinical genetic diagnosis. It is thus important to apprehend not only technical but also biological reasons for false positive copy number detection. None of the current single-cell copy number calling methods distinguishes between a cell in G1-, S- or G2/M-phase of the cell cycle and mostly use cells isolated randomly from populations. We demonstrate that the oscillating pattern between early and late replicating loci instigates significantly more false-positive DNA copy-number calls in a diploid cell in S-phase cells than in G1- or G2/M-phase, depending on the specific aCGH-signal normalization method used. We propose a work-flow to detect single cells in S-phase and to correct for DNA-replication bias before copy number profiling. The genome of 2 S-phase, 1 M-phase and 1 G-phase single cells were amplified using the Sureplex amplification system. These test samples were hybridized comparatively to commercial male reference DNA,
Project description:DNA-replication is a key process in life and can lead to disease when disturbed. Cell-type specific early and late replication domains have been discovered throughout genomes by analysis of DNA from populations of cells. However, cell to cell differences and the association of these differences with other cellular processes remain largely elusive. Here we demonstrate for the first time that consecutive domains of early and late DNA-replication can be detected in single S-phase cells using array comparative genomic hybridization, providing proof-of-concept for a novel tool to investigate DNA-replication genome wide at the single-cell level. Furthermore, methods to profile the genome of a single cell for DNA-copy number aberrations are revolutionizing both basic genome research and clinical genetic diagnosis. It is thus important to apprehend not only technical but also biological reasons for false positive copy number detection. None of the current single-cell copy number calling methods distinguishes between a cell in G1-, S- or G2/M-phase of the cell cycle and mostly use cells isolated randomly from populations. We demonstrate that the oscillating pattern between early and late replicating loci instigates significantly more false-positive DNA copy-number calls in a diploid cell in S-phase cells than in G1- or G2/M-phase, depending on the specific aCGH-signal normalization method used. We propose a work-flow to detect single cells in S-phase and to correct for DNA-replication bias before copy number profiling. The genome of 7 S-phase, 2 M-phase and 2 G-phase single cells was amplified using the Sureplex amplification system. These test samples were hybridized comparatively to commercial male reference DNA.
Project description:DNA-replication is a key process in life and can lead to disease when disturbed. Cell-type specific early and late replication domains have been discovered throughout genomes by analysis of DNA from populations of cells. However, cell to cell differences and the association of these differences with other cellular processes remain largely elusive. Here we demonstrate for the first time that consecutive domains of early and late DNA-replication can be detected in single S-phase cells using array comparative genomic hybridization, providing proof-of-concept for a novel tool to investigate DNA-replication genome wide at the single-cell level. Furthermore, methods to profile the genome of a single cell for DNA-copy number aberrations are revolutionizing both basic genome research and clinical genetic diagnosis. It is thus important to apprehend not only technical but also biological reasons for false positive copy number detection. None of the current single-cell copy number calling methods distinguishes between a cell in G1-, S- or G2/M-phase of the cell cycle and mostly use cells isolated randomly from populations. We demonstrate that the oscillating pattern between early and late replicating loci instigates significantly more false-positive DNA copy-number calls in a diploid cell in S-phase cells than in G1- or G2/M-phase, depending on the specific aCGH-signal normalization method used. We propose a work-flow to detect single cells in S-phase and to correct for DNA-replication bias before copy number profiling. DNA was extracted from many cells from 1 S-phase, 1 G1-phase and 1 G2/Mphase enriched cell population for two female normal control EBV-transformed lymphoblastoid cell lines. These test samples were hybridized comparatively to commercial male reference DNA.
Project description:DNA-replication is a key process in life and can lead to disease when disturbed. Cell-type specific early and late replication domains have been discovered throughout genomes by analysis of DNA from populations of cells. However, cell to cell differences and the association of these differences with other cellular processes remain largely elusive. Here we demonstrate for the first time that consecutive domains of early and late DNA-replication can be detected in single S-phase cells using array comparative genomic hybridization, providing proof-of-concept for a novel tool to investigate DNA-replication genome wide at the single-cell level. Furthermore, methods to profile the genome of a single cell for DNA-copy number aberrations are revolutionizing both basic genome research and clinical genetic diagnosis. It is thus important to apprehend not only technical but also biological reasons for false positive copy number detection. None of the current single-cell copy number calling methods distinguishes between a cell in G1-, S- or G2/M-phase of the cell cycle and mostly use cells isolated randomly from populations. We demonstrate that the oscillating pattern between early and late replicating loci instigates significantly more false-positive DNA copy-number calls in a diploid cell in S-phase cells than in G1- or G2/M-phase, depending on the specific aCGH-signal normalization method used. We propose a work-flow to detect single cells in S-phase and to correct for DNA-replication bias before copy number profiling. DNA was extracted from many cells from 1 S-phase, 1 G1-phase and 1 G2/Mphase enriched cell population from an EBV-transformed lymphoblastoid cell line from a male carrying a 750kb amplification on the short arm of chromosome 4. These test samples were hybridized comparatively to commercial male reference DNA.
Project description:A large-scale characterization of the methylation states of candidate CpG islands (CGIs) throughout the gastric cancer methylome has not previously been conducted. Genome-wide DNA methylation profiles were compared between 4 metastatic and 4 non-metastatic gastric carcinomas (GCs) and their surgical margins (SMs). The GC genome showed significantly higher proportions of hypomethylation in the promoter and exon-1 regions, as well as increased hypermethylation of intragenic fragments when compared to SMs. Differential methylation was observed in CGIs near transcription start sites of 546 genes between GCs and SMs, and 601 genes between metastatic and non-metastatic GCs. From the list of differentially methylated CGIs, 68 candidate genes and 10 known tumor-related genes were selected for further characterization based on their known molecular function using DHPLC. Significant differential methylation was validated in the CGIs of 15 genes between GCs and SMs (Ps<0.05) and confirmed using bisulfite-sequencing. These genes include BMP3, BNIP3, CDKN2A, ECEL1, ELK1, GFRA1, HOXD10, KCNH1, PSMD10, PTPRT, SIGIRR, SRF, TBX5, TFPI2, and ZNF382. Hypomethylation of CGIs correlated with up-regulation of GFRA1 expression in GCs, while hypermethylation of other genes inactivated their transcription. Most importantly, prevalence of GFRA1, SRF, and ZNF382 methylation alterations were inversely and coordinately associated with GC metastasis and the patients’ overall survival throughout discovery and testing cohorts in China as well as independent validation cohorts in Japan and Korea. In conclusion, methylation changes in the CGIs of 15 genes correlated strongly with GC development. GFRA1 hypomethylation and SRF and ZNF382 hypermethylation are potential synergistic biomarkers for the prediction of GC metastasis. To identify differential methylation of CGIs related to GC development and metastasis, genome-wide DNA methylation changes in 8 pairs of GC and SM samples were analysed using the MCAM assay with a 99K custom-designed Agilent oligonucleotide microarray composed of 99,027 probes targeting 6,177 unique protein-coding genes containing at least two methylation-sensitive/insensitive SmaI/ XmaI restriction sites (CCC|GGG/ C|CmCGGG) as described in Shen et al, PLoS Genet 3, 2023-2036 (2007).
Project description:Comparative genomic hybridization was performed to compare levels of gDNA in third instar salivary glands of Drosophila mutants/nulls in the SuUR and orc proteins, compared with 0-2hr diploid embryo gDNA. This illustrates regions of differential replication in the genome. CGH of salivary gland DNA compared with diploid early embryonic samples for four different Drosophila strains
Project description:For many oncogenes, increased expression resulting from copy number gain confers a selective advantage to cells that consequently make up the tumour bulk. To identify oncogenes of potential biological significance in cervical squamous cell carcinoma (SCC), 36 primary samples and ten cell lines were screened by array comparative genomic hybridization (CGH). The most commonly occurring regions of copy number gain that also showed amplification were 5p15.2–14.3 (59%), 5p13.3 (65%), and 5p13.2–13.1 (63%). Gene copy numbers were significantly associated with expression levels for three candidate oncogenes at these loci: OSMR (oncostatin M receptor) (p = 0.03), PDZK3 (PDZ domain containing protein 3) (p = 0.04), and TRIO (triple functional domain) (p = 0.03). Further examination by fluorescence in situ hybridization on a tissue microarray of 110 primary cervical SCC samples revealed copy number gain frequencies of 60.9%, 57.3%, and 54.5% for OSMR, PDZK3, and TRIO, respectively, with OSMR adversely influencing overall patient survival independently of tumour stage (p = 0.046). By array CGH, copy number gain of OSMR was not seen in any of 40 microdissected precursor cervical squamous intraepithelial lesions (SILs). Moreover, global mRNA expression analysis, using Affymetrix U133A 2.0 Arrays, showed no overexpression of OSMR in SILs, suggesting that OSMR gain and overexpression are relatively late steps in cervical carcinogenesis. In the cervical SCC cell lines CaSki and SW756, exogenous OSM activated downstream-signalling elements of OSMR including STAT3, p44/42 MAPK, and S6 ribosomal protein, and induced transcription of the angiogenic factor VEGF, effects that were reduced by OSMR depletion using RNA interference. We conclude that copy number gain of OSMR is frequently found in cervical SCC and is associated with adverse clinical outcome. As well as being a potential prognostic marker, OSMR is a candidate cell surface therapeutic target 36 primary cervical SCC samples, and 10 cervical SCC cell lines were subject to 1 Mb aCGH using a dye swapped approach. Two samples were subject to repeat. (J Pathol. 2007 Jul;212(3):325-34.)