Effect of transfection manipulations on mouse cell cycle progression

1991 ◽  
Vol 69 (9) ◽  
pp. 665-669 ◽  
Author(s):  
Carol A. K. McBroom ◽  
Rose Sheinin

BalB/C-3T3 mouse fibroblasts and a temperature-sensitive derivative, ts 2e, were transfected by the calcium phosphate-dimethyl sulphoxide procedure to examine the effect of this manipulation on cell cycle progression. Cells were synchronized by growth to confluence in the presence of [2-14C]thymidine to generally label cellular DNA, and then subcultured from the G0 state. Plasmid pSV3-neo or pSV2-neo DNA was added to cells at 24 h post-plating, at peak Sphase. At designated intervals prior to, during, and after the transfection procedure, cells were labelled with [methyl-H]thymidine for 1 h to monitor nascent DNA synthesis and thereby assess cell cycle position. In all experiments performed, irrespective of the time of DNA addition, the transfection manipulations resulted in a reproducible, transient interruption of cell cycle progression, of about 5 h, and manifested as a delay in movement across the subsequent G1–S interface. Thereafter, the cycle resumed normally. The results indicated that the temporal sequence of the cell duplication cycle is altered when cells are exposed to exogenous DNA:Ca3 (PO4)2.Key words: transfection, cell cycle progression.

2006 ◽  
Vol 80 (8) ◽  
pp. 3872-3883 ◽  
Author(s):  
Dustin T. Petrik ◽  
Kimberly P. Schmitt ◽  
Mark F. Stinski

ABSTRACT Human cytomegalovirus (HCMV) expresses several proteins that manipulate normal cellular functions, including cellular transcription, apoptosis, immune response, and cell cycle control. The IE2 gene, which is expressed from the HCMV major immediate-early (MIE) promoter, encodes the IE86 protein. IE86 is a multifunctional protein that is essential for viral replication. The functions of IE86 include transactivation of cellular and viral early genes, negative autoregulation of the MIE promoter, induction of cell cycle progression from G0/G1 to G1/S, and arresting cell cycle progression at the G1/S transition in p53-positive human foreskin fibroblast (HFF) cells. Mutations were introduced into the IE2 gene in the context of the viral genome using bacterial artificial chromosomes (BACs). From these HCMV BACs, a recombinant virus (RV) with a single amino acid substitution in the IE86 protein was isolated that replicates slower and to lower titers than wild-type HCMV. HFF cells infected with the Q548R RV undergo cellular DNA synthesis and do not arrest at any point in the cell cycle. The Q548R RV is able to negatively autoregulate the MIE promoter, transactivate viral early genes, activate cellular E2F-responsive genes, and produce infectious virus. This is the first report of a viable recombinant HCMV that is unable to inhibit cellular DNA synthesis in infected HFF cells.


2010 ◽  
Vol 9 (10) ◽  
pp. 1418-1431 ◽  
Author(s):  
Emma L. Turner ◽  
Mackenzie E. Malo ◽  
Marnie G. Pisclevich ◽  
Megan D. Dash ◽  
Gerald F. Davies ◽  
...  

ABSTRACT The anaphase-promoting complex (APC), a large evolutionarily conserved ubiquitin ligase complex, regulates cell cycle progression through mitosis and G1. Here, we present data suggesting that APC-dependent cell cycle progression relies on a specific set of posttranslational histone-modifying enzymes. Multiple APC subunit mutants were impaired in total and modified histone H3 protein content. Acetylated H3K56 (H3K56Ac) levels were as reduced as those of total H3, indicating that loading histones with H3K56Ac is unaffected in APC mutants. However, under restrictive conditions, H3K9Ac and dimethylated H3K79 (H3K79me2) levels were more greatly reduced than those of total H3. In a screen for histone acetyltransferase (HAT) and histone deacetylase (HDAC) mutants that genetically interact with the apc5 CA (chromatin assembly) mutant, we found that deletion of GCN5 or ELP3 severely hampered apc5 CA temperature-sensitive (ts) growth. Further analyses showed that (i) the elp3Δ gcn5Δ double mutant ts defect was epistatic to that observed in apc5 CA cells; (ii) gcn5Δ and elp3Δ mutants accumulate in mitosis; and (iii) turnover of the APC substrate Clb2 is not impaired in elp3Δ gcn5Δ cells. Increased expression of ELP3 and GCN5, as well as genes encoding the HAT Rtt109 and the chromatin assembly factors Msi1 and Asf1, suppressed apc5 CA defects, while increased APC5 expression partially suppressed elp3Δ gcn5Δ growth defects. Finally, we demonstrate that Gcn5 is unstable during G1 and following G1 arrest and is stabilized in APC mutants. We present our working model in which Elp3/Gcn5 and the APC work together to facilitate passage through mitosis and G1. To progress into S, we propose that at least Gcn5 must then be targeted for degradation in an APC-dependent fashion.


1999 ◽  
Vol 9 (12) ◽  
pp. 1663-1666 ◽  
Author(s):  
Robert T Crow ◽  
Betty Rosenbaum ◽  
Roger Smith ◽  
Yu Guo ◽  
Kenneth S Ramos ◽  
...  

1999 ◽  
Vol 19 (7) ◽  
pp. 4623-4632 ◽  
Author(s):  
Masahiro Hitomi ◽  
Dennis W. Stacey

ABSTRACT Novel techniques were used to determine when in the cell cycle of proliferating NIH 3T3 cells cellular Ras and cyclin D1 are required. For comparison, in quiescent cells, all four of the inhibitors of cell cycle progression tested (anti-Ras, anti-cyclin D1, serum removal, and cycloheximide) became ineffective at essentially the same point in G1 phase, approximately 4 h prior to the beginning of DNA synthesis. To extend these studies to cycling cells, a time-lapse approach was used to determine the approximate cell cycle position of individual cells in an asynchronous culture at the time of inhibitor treatment and then to determine the effects of the inhibitor upon recipient cells. With this approach, anti-Ras antibody efficiently inhibited entry into S phase only when introduced into cells prior to the preceding mitosis, several hours before the beginning of S phase. Anti-cyclin D1, on the other hand, was an efficient inhibitor when introduced up until just before the initiation of DNA synthesis. Cycloheximide treatment, like anti-cyclin D1 microinjection, was inhibitory throughout G1 phase (which lasts a total of 4 to 5 h in these cells). Finally, serum removal blocked entry into S phase only during the first hour following mitosis. Kinetic analysis and a novel dual-labeling technique were used to confirm the differences in cell cycle requirements for Ras, cyclin D1, and cycloheximide. These studies demonstrate a fundamental difference in mitogenic signal transduction between quiescent and cycling NIH 3T3 cells and reveal a sequence of signaling events required for cell cycle progression in proliferating NIH 3T3 cells.


2003 ◽  
Vol 8 (4) ◽  
pp. 311-324 ◽  
Author(s):  
Koichi Kitamura ◽  
Keiko Mizuno ◽  
Akiko Etoh ◽  
Yoshiko Akita ◽  
Akitomo Miyamoto ◽  
...  

2000 ◽  
Vol 20 (4) ◽  
pp. 1134-1139 ◽  
Author(s):  
Elizabeth L. Dunphy ◽  
Theron Johnson ◽  
Scott S. Auerbach ◽  
Edith H. Wang

ABSTRACT The TATA-binding protein (TBP)-associated factor TAFII250 is the largest component of the basal transcription factor IID (TFIID). A missense mutation that maps to the acetyltransferase domain of TAFII250 induces the temperature-sensitive (ts) mutant hamster cell lines ts13 and tsBN462 to arrest in late G1. At the nonpermissive temperature (39.5°C), transcription from only a subset of protein encoding genes, including the G1 cyclins, is dramatically reduced in the mutant cells. Here we demonstrate that the ability of the ts13 allele of TAFII250 to acetylate histones in vitro is temperature sensitive suggesting that this enzymatic activity is compromised at 39.5°C in the mutant cells. Mutagenesis of a putative acetyl coenzyme A binding site produced a TAFII250 protein that displayed significantly reduced histone acetyltransferase activity but retained TBP and TAFII150 binding. Expression of this mutant in ts13 cells was unable to complement the cell cycle arrest or transcriptional defect observed at 39.5°C. These data suggest that TAFII250 acetyltransferase activity is required for cell cycle progression and regulates the expression of essential proliferative control genes.


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