Project description:Gene expression must be reconfigured rapidly during the subsequent phases of the cell cycle to execute the cellular functions specific of each phase. Post-transcriptional regulation has a predominant role in modulating gene expression during the mitotic cell cycle, including among other mechanisms, protein phosphorylation and ubiquitination, differential protein stability and mRNA localization and translatability. Regulation at the transcriptional level is also important, as studies conducted in synchronized plant cell suspension cultures have identified hundreds of genes with periodic patterns of genes expression across the phases of the cell cycle. We describe here an alternative strategy to cell suspension cultures to profile the transcriptome of Arabidopsis root cells in the G2/M phase of the cell cycle. Through fluorescence activated cell sorting we first isolated cells in G2/M using CYCB1;1-GFP, a reporter of a mitotic cyclin. The analysis of the transcriptome of these cells allowed us to identify hundreds of genes whose expression is depleted or enriched in G2/M cells.
Project description:To identify the component(s) involved in cell cycle control in the protozoan Giardia lamblia, cells arrested at the G1- or G2-phase by treatment with nocodazole and aphidicolin were prepared from the synchronized cell cultures. RNA-sequencing analysis of the two stages of Giardia cell cycle identified several cell cycle genes that were up-regulated at the G2-phase. This result indicates that the cell cycle machinery operates in this protozoan, one of the earliest diverging eukaryotic lineages.
Project description:We compared the poly(A) tail length status of mRNAs of HeLa cells between two phases of the mitotic cell cycle: S and G2/M phases. Hundreds of mRNAs were found to be regulated by changes in their poly(A) tail length during mitotic cell cycle in a phase specific manner. Many of these differentially polyadenylated mRNAs encode proteins related to cell death, cell cycle and cellular growth and proliferation. HeLa cells were synchronized with double thymidine blockade (12 hours with 2 mM thymidine, 12 hours release, and 12 hours with 2 mM thymidine), and samples were taken after 2 hours release (S phase) and 8 hours release (G2/M phase). For each condition total RNA was purified by two different procedures: poly(U) chromatography and oligo(dT)-chromatography. Poly(U)-chromatography (Jacobson, 1987): 100 μg of total RNA were bound to poly(U)-sepharose (Sigma) and eluted at 35ºC to isolate mRNAs with short poly(A) tail (<30As, SHORT fraction). Oligo(dT) chromatography: mRNAs were purified independently of their poly(A) tail length with Ambion Poly(A)Purist kit from 20 μg total RNA (ALL fraction). Jacobson, A. Purification and fractionation of poly(A)+ RNA. Methods in Enzymology (1987) 152: 254-261. Keywords: time course Comparison of ALL fraction mRNAs and SHORT fraction mRNAs measured after 2 hours (S phase) and 8 hours release (G2/M) from double thymidine blockade; 3 biological replicates at each of the two time points; two technical replicates with dye swapping per comparison.
Project description:Dramatic change in DNA methylation patterns and levels both globally and/or locus-specifically is associated with the process of cell lineage specification and somatic reprogramming. We found the expression of DNA methyltransferase 1 (Dnmt1), the enzyme that maintains 5-methylcytosine (5mC) after DNA replication, is tightly regulated by the progression of cell cycle. Upregulation of Dnmt1 was observed in cells with shortened G1 and G2 phase. We hypothesize that 5mC level is not completely recovered by Dnmt1 immediately after DNA replication. In the attempt to clarify DNA methylation status before and after DNA replication, we performed Whole Genome Bisulfite Sequencing (WGBS) to map genome-wide DNA methylation separately in G1 and G2 phase of mouse embryonic fibroblasts (MEFs). Cells of different cell cycle phases were sorted by flow cytometry after Propidium iodide (PI) staining. We find an average of 2% decrease of global DNA methylation in G2 phase compared with G1, with the trend more magnificent in high CpG density regions. Generally, the results indicate that the G1 phase of cell cycle is an important time window for the stability of DNA methylation inheritance.
Project description:We compared the poly(A) tail length status of mRNAs of HeLa cells between two phases of the mitotic cell cycle: S and G2/M phases. Hundreds of mRNAs were found to be regulated by changes in their poly(A) tail length during mitotic cell cycle in a phase specific manner. Many of these differentially polyadenylated mRNAs encode proteins related to cell death, cell cycle and cellular growth and proliferation. HeLa cells were synchronized with double thymidine blockade (12 hours with 2 mM thymidine, 12 hours release, and 12 hours with 2 mM thymidine), and samples were taken after 2 hours release (S phase) and 8 hours release (G2/M phase). For each condition total RNA was purified by two different procedures: poly(U) chromatography and oligo(dT)-chromatography. Poly(U)-chromatography (Jacobson, 1987): 100 μg of total RNA were bound to poly(U)-sepharose (Sigma) and eluted at 35ºC to isolate mRNAs with short poly(A) tail (<30As, SHORT fraction). Oligo(dT) chromatography: mRNAs were purified independently of their poly(A) tail length with Ambion Poly(A)Purist kit from 20 μg total RNA (ALL fraction). Jacobson, A. Purification and fractionation of poly(A)+ RNA. Methods in Enzymology (1987) 152: 254-261. Keywords: time course
Project description:To address the unusually long duration of imatinib therapy for chronic myelogenous leukemia, we sought to understand the expression of BCR-ABL gene expression with different phases of the cell cycle. A precedent for dynamic fusion oncoprotein expression already exists for the pediatric solid tumor, rhabdomyosarcoma. Quantitative immunocytochemistry was conducted to compare the expression of BCR-ABL with markers of each cell cycle phase: CDK6 for G1, CDK2 for S, phospho-CDC2 for G2, and phospho-HH3 for M phase. BCR-ABL expression was most strongly correlated with the G2 and S cell cycle phases. Low BCR-ABL expression only coincided with high cell cycle marker expression for the G1. BCR-ABL was rarely if at all expressed in M. Our results suggest a possible explanation for the prolonged nature of imatinib therapy, which may be only effective on S- and G2-phase actively replicating leukemia cells.
Project description:We compared the mRNAs expression profile of HeLa cells between two phases of the mitotic cell cycle: S and G2/M phases. Results provide insight into the regulation of transcript levels during mitotic cell cycle progression. HeLa cells were synchronized with double thymidine blockade (12 hours with 2 mM thymidine, 12 hours release, and 12 hours with 2 mM thymidine), and cells were taken after 2 hours release (S phase) and 8 hours release (G2/M phase). Keywords: time course Comparison of mRNAs measured at S phase (2 hours release after double thymidine blockade) and at G2/M phase (8 hours release after double thymidine blockade); 3 biological replicates at each of the two time points; two technical replicates with dye swapping per comparison; additional comparison between G2/M (8h) and S (2h).
Project description:Cell proliferation and division are fundamental processes of plant development and homeostasis. With the feature of high homogeneity, tobacco Bright Yellow-2 (BY-2) cells, a so-called “HeLa” cell line in plants, provide a useful system for study the cell cycle of plants, particularly when in combination with the latest high-throughput single-cell RNA sequencing (scRNA-seq) technology. Here, we generated both scRNA-seq and bulk RNA-seq data from the BY-2 cells and found that the enzymatic hydrolysis during protoplasting was the major factor contributing to cell clustering noise. We introduced the ppScoring concept to filter out confounding cells due to protoplasting and clustered the remaining cells into clusters corresponding to G0-G1, S, and G2-M phases as well as clusters with phase transition arrested or cell cycle exit cells. The clustering results were supported by cell cycle phase specific marker genes and reconstruction of the continuous full cell cycle phases, i.e., from G0-G1 to S to G2-M, based on pseudotime trajectory analysis. The clustering results also identified a set of 896 cell cycle marker genes. This work demonstrated cell cycle-dependent transcriptional heterogeneity of the BY-2 cell population, provided marker genes for study of the cell cycle of plants and new insights into the progression of cell division.
Project description:We compared the mRNAs expression profile of HeLa cells between two phases of the mitotic cell cycle: S and G2/M phases. Results provide insight into the regulation of transcript levels during mitotic cell cycle progression. HeLa cells were synchronized with double thymidine blockade (12 hours with 2 mM thymidine, 12 hours release, and 12 hours with 2 mM thymidine), and cells were taken after 2 hours release (S phase) and 8 hours release (G2/M phase). Keywords: time course
Project description:The actin-related proteins (ARPs) comprise a conserved protein family. Arp4p is found in large multisubunits of the INO80 and SWR1 chromatin remodeling complexes and in the NuA4 histone acetyltransferase complex. Here we show that arp4 (arp4S23AD159A) temperature-sensitive cells are defective in G2/M phase function. arp4 mutants are sensitive to the microtubule depolymering agent benomyl and arrest at G2/M phase at restrictive temperature. Arp4p is associated with centromeric and telomeric regions throughout cell cycle. Ino80p, Esa1p, and Swr1p, components of the INO80, NuA4, and SWR1 complexes, respectively, also associate with centromeres. The association of many kinetochore components including Cse4p, a component of the centromere nucleosome, Mtw1p, and Ctf3p is partially impaired in arp4 cells, suggesting that the G2/M arrest of arp4 mutant cells is due to a defect in formation of the chromosomal segregation apparatus. Keywords: ChIP-chip ⢠The goal of the experiment Genome-wide localization of Arp4 binding sites in Saccharomyces cerevisiae ⢠Experimental factors Distribution of Arp4 in WT in G2/M phase in the presence of nocodazole (Saccharomyces cerevisiae). ⢠Experimental design ChIP analysis: Hybridization data for ChIP fraction was compared with WCE (whole cell extract) fraction. Chromosome III, IV,V,VI S. cerevisiae: SC3456a520015F, P/N# 520015, affymetrix tiling array were used.