Persistence of a micrococcal nuclease sensitive region spanning the promoter–coding region junction of a cell cycle regulated human H4 histone gene throughout the cell cycle

1988 ◽  
Vol 66 (2) ◽  
pp. 132-137 ◽  
Author(s):  
M. L. Moreno ◽  
U. Pauli ◽  
S. Chrysogelos ◽  
J. L. Stein ◽  
G. S. Stein
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
Histone Gene ◽  
Micrococcal Nuclease ◽  
Start Codon ◽  
Coding Region ◽  
Cycle Times ◽  
Sensitive Region ◽  
Coding Regions ◽  
Nucleosomal Structure

We have examined the chromatin structure of the cell cycle regulated human H4 histone gene FO108 A at various times during the cell cycle, by treating nuclei isolated from synchronized HeLa S3 cells with micrococcal nuclease. Purified DNA was fractionated electrophoretically, transferred to nitrocellulose, and hybridized to small (150–250 nucleotides) radiolabeled probes from various portions of the promoter and coding regions of the gene. Our results indicate the existence of a micrococcal nuclease sensitive region located between positions −60 and +90 base pairs (bp) from the start codon of the gene, which includes the TATA box. This nuclease-sensitive region persists at all the cell cycle times analyzed. Hybridization with a 250-bp probe containing only coding region sequences reveals a disrupted nucleosomal ladder during early S phase, when this H4 histone gene replicates and exhibits an enhanced level of transcription. By mid-S phase, the regular nucleosomal structure of the coding region is restored and persists during subsequent phases of the cell cycle. The disruption of a normal nucleosomal organization in the promoter and mRNA coding regions of this H4 histone gene is also supported by the sensitivity of these sequences to S1 nuclease.

scholarly journals Maximal binding levels of an H1 histone gene-specific factor in S-phase correlate with maximal H1 gene transcription.

1988 ◽  
Vol 8 (10) ◽  
pp. 4576-4578 ◽  
Author(s):  
S Dalton ◽  
J R Wells
Keyword(s):  
Cell Cycle ◽  
Nucleic Acids ◽  
Gene Transcription ◽  
S Phase ◽  
Histone Gene ◽  
Specific Factor ◽  
Synchronized Cells ◽  
Phase Regulation ◽  
G2 Phase ◽  
Binding Component

Levels of trans-acting factor (H1-SF) binding to the histone H1 gene-specific motif (5'-AAACACA-3' [L. S. Coles and J. R. E. Wells, Nucleic Acids Res. 13:585-594, 1985]) increase 12-fold from G1 to S-phase in synchronized cells and decrease again in G2 phase of the cell cycle. Since the H1 element is required for S-phase expression of H1 genes (S. Dalton and J. R. E. Wells, EMBO J. 7:49-56, 1988), it is likely that the increased levels of H1-SF binding component play an important role in S-phase regulation of H1 gene transcription.

Identification of a new set of cell cycle-regulatory genes that regulate S-phase transcription of histone genes in Saccharomyces cerevisiae

1992 ◽  
Vol 12 (11) ◽  
pp. 5249-5259 ◽  
Author(s):  
H Xu ◽  
U J Kim ◽  
T Schuster ◽  
M Grunstein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Replication ◽  
Gene Transcription ◽  
S Phase ◽  
Histone Gene ◽  
Mrna Synthesis ◽  
Histone Mrna ◽  
Complementation Groups ◽  
Histone Gene Transcription

Histone mRNA synthesis is tightly regulated to S phase of the yeast Saccharomyces cerevisiae cell cycle as a result of transcriptional and posttranscriptional controls. Moreover, histone gene transcription decreases rapidly if DNA replication is inhibited by hydroxyurea or if cells are arrested in G1 by the mating pheromone alpha-factor. To identify the transcriptional controls responsible for cycle-specific histone mRNA synthesis, we have developed a selection for mutations which disrupt this process. Using this approach, we have isolated five mutants (hpc1, hpc2, hpc3, hpc4, and hpc5) in which cell cycle regulation of histone gene transcription is altered. All of these mutations are recessive and belong to separate complementation groups. Of these, only one (hpc1) falls in one of the three complementation groups identified previously by other means (M. A. Osley and D. Lycan, Mol. Cell. Biol. 7:4204-4210, 1987), indicating that at least seven different genes are involved in the cell cycle-specific regulation of histone gene transcription. hpc4 is unique in that derepression occurs only in the presence of hydroxyurea but not alpha-factor, suggesting that at least one of the regulatory factors is specific to histone gene transcription after DNA replication is blocked. One of the hpc mutations (hpc2) suppresses delta insertion mutations in the HIS4 and LYS2 loci. This effect allowed the cloning and sequence analysis of HPC2, which encodes a 67.5-kDa, highly charged basic protein.

scholarly journals In vivo determination of cell cycle kinetics of non-Hodgkin's lymphomas using iododeoxyuridine and bromodeoxyuridine.

1992 ◽  
Vol 40 (5) ◽  
pp. 723-728 ◽  
Author(s):  
G Yanik ◽  
N Yousuf ◽  
M A Miller ◽  
S H Swerdlow ◽  
B Lampkin ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Lymphoma ◽  
Large Cell ◽  
S Phase ◽  
Total Cell ◽  
Growth Fraction ◽  
Cycle Times ◽  
Large Cell Lymphoma ◽  
Hodgkin's Lymphomas

Using sequential infusions of two S-phase-specific drugs, iododeoxyuridine and bromodeoxyuridine, we have developed an in vivo method for determining the labeling index (LI), the S-phase duration (Ts), and total cell cycle times (Tc) of non-Hodgkin's lymphomas. In nine non-Hodgkin's lymphomas studied, the LI ranged from 1.5% in a follicular small cleaved-cell lymphoma to 29.6% in a diffuse large-cell lymphoma. The Ts ranged from 16 hr in a large-cell lymphoma (immunoblastic type) to 117 hr in a follicular small cleaved-cell lymphoma. The Tc varied from 69 hr in a large-cell lymphoma (immunoblastic type) to over 1000 hr in all low-grade lymphomas studied. Immunohistochemical methods using anti-BrdU antibodies were used to detect cell incorporation of the two S-phase-specific drugs. In this manner, cell cycle times could be calculated while the architecture of the tumor specimen was preserved. Difficulties in using this methodology, specifically in the calculation of the growth fraction and total cell cycle times, are pointed out. This in vivo method does, however, allow for Ts calculations independent of growth fraction considerations. Correlations of cell cycle data with various biological and clinical factors await further patient follow-up.

Maximal binding levels of an H1 histone gene-specific factor in S-phase correlate with maximal H1 gene transcription

1988 ◽  
Vol 8 (10) ◽  
pp. 4576-4578
Author(s):  
S Dalton ◽  
J R Wells
Keyword(s):  
Cell Cycle ◽  
Nucleic Acids ◽  
Gene Transcription ◽  
S Phase ◽  
Histone Gene ◽  
Specific Factor ◽  
Synchronized Cells ◽  
Phase Regulation ◽  
G2 Phase ◽  
Binding Component

Levels of trans-acting factor (H1-SF) binding to the histone H1 gene-specific motif (5'-AAACACA-3' [L. S. Coles and J. R. E. Wells, Nucleic Acids Res. 13:585-594, 1985]) increase 12-fold from G1 to S-phase in synchronized cells and decrease again in G2 phase of the cell cycle. Since the H1 element is required for S-phase expression of H1 genes (S. Dalton and J. R. E. Wells, EMBO J. 7:49-56, 1988), it is likely that the increased levels of H1-SF binding component play an important role in S-phase regulation of H1 gene transcription.

Chromosome segregation from cell hybrids.II. Do differences in parental cell growth rates and phase times determine direction of loss?

1986 ◽  
Vol 28 (5) ◽  
pp. 735-743 ◽  
Author(s):  
Jennifer A. Marshall Graves ◽  
Jaclyn M. Wrigley
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Chinese Hamster ◽  
Parental Cell ◽  
S Phase ◽  
Chromosome Loss ◽  
Parent Cell ◽  
Cycle Times ◽  
Cell Hybrids ◽  
The One

The hypothesis that the direction of chromosome segregation in cell hybrids is determined by the interaction of parent cell cycles, or S-phase times, predicts that the segregant parent will always be the one with the longer cycle, or the longer S phase, and that late replicating chromosomes will be more frequently lost. We have tested this hypothesis by studying cell cycle parameters of mouse, Chinese hamster, and platypus parent cells and by observing chromosome loss and replication patterns in hybrids between them. Two types of hybrids have been studied: mouse–hamster hybrids showed gradual segregation, in one or other direction, of 10–60% chromosomes, while rodent–platypus hybrids (which could be selected under conditions optimal for either parent cell) showed rapid and extreme segregation of platypus chromosomes. We found no correlation between the direction of segregation and the relative lengths of parental cycle times, or phase times, nor between sequence of replication and frequency with which segregant chromosomes are lost. We therefore conclude that the direction and extent of segregation is not directly determined by the interaction of parental cycle or phase times.Key words: cell hybrids, chromosome loss, cell cycle, S phase.

scholarly journals The E2F transcription factor activates a replication-dependent human H2A gene in early S phase of the cell cycle.

1996 ◽  
Vol 16 (5) ◽  
pp. 1889-1895 ◽  
Author(s):  
F Oswald ◽  
T Dobner ◽  
M Lipp
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Transcription Factor ◽  
Transcriptional Activation ◽  
Promoter Region ◽  
S Phase ◽  
Histone Gene ◽  
Luciferase Reporter ◽  
Transcriptional Level ◽  
Histone Gene Expression

Histone gene expression is restricted to the S phase of the cell cycle. Control is mediated by a complex network of sequence-specific DNA-binding factors and protein-protein interactions in response to cell cycle progression. To further investigate the regulatory functions that are associated at the transcriptional level, we analyzed the regulation of a replication-dependent human H2A.1-H2B.2 gene pair. We found that transcription factor E2F binds specifically to an E2F recognition motif in the H2A.1 promoter region. Activation of the H2A.1 promoter by E2F-1 was shown by use of luciferase reporter constructs of the intergenic promoter region. Overexpression of the human retinoblastoma suppressor gene product RB suppressed E2F-1 mediated transcriptional activation, indicating an E2F-dependent regulation of promoter activity during the G1-to-S-phase transition. Furthermore, the activity of the H2A.1 promoter was also downregulated by overexpression of the RB-related p107, a protein that has been detected in S-phase-specific protein complexes of cyclin A, E2F, and cdk2. In synchronized HeLa cells, expression of luciferase activity was induced at the beginning of DNA synthesis and was dependent on the presence of an E2F-binding site in the H2A.1 promoter. Together with the finding that E2F-binding motifs are highly conserved in H2A promoters of other species, our results suggest that E2F plays an important role in the coordinate regulation of S-phase-specific histone gene expression.

scholarly journals Restriction Point timing and cell cycle variability – a re-evaluation

2020 ◽  
Author(s):  
Robert F. Brooks
Keyword(s):  
Cell Cycle ◽  
Growth Factor ◽  
Mammalian Cell ◽  
Time Lapse ◽  
S Phase ◽  
Critical Transition ◽  
Restriction Point ◽  
Cycle Times ◽  
Mammalian Cell Cycle ◽  
Step Down

AbstractThe Restriction Point (R) in the mammalian cell cycle is regarded as a critical transition in G1 when cells become committed to enter S phase even in the absence of further growth factor stimulation. Classic time-lapse studies by Zetterberg and Larsson suggested that the acquisition of growth factor independence (i.e. passage of R) occurred very abruptly 3-4 hours after mitosis, with most cell cycle variability arising between R and entry into S phase. However, the cycle times of the post-R cells that continued on to mitosis after serum step-down without perturbation were far less variable than the control cells with which they were compared. A re-analysis of the data, presented here, shows that when the timing of R and entry in mitosis are compared for the same experiments, the curves are superimposable and statistically indistinguishable. This indicates that the data are compatible with the timing of R contributing to much of the overall variability in the cell cycle, contrary to the conclusions of Zetterberg and colleagues.

scholarly journals Cell cycle-dependent chromatin dynamics at replication origins

2021 ◽  
Author(s):  
Yulong Li ◽  
Alexander J. Hartemink ◽  
David MacAlpine
Keyword(s):  
Cell Cycle ◽  
Consensus Sequence ◽  
S Phase ◽  
Micrococcal Nuclease ◽  
Dependent Manner ◽  
Replication Origins ◽  
Chromatin Dynamics ◽  
Cell Cycles ◽  
Cycle Dependent ◽  
Replication Factors

Origins of DNA replication are specified by the ordered recruitment of replication factors in a cell cycle dependent manner. The assembly of the pre-replicative complex in G1 and the pre-initiation complex prior to activation in S-phase are well characterized; however, the interplay between the assembly of these complexes and the local chromatin environment is less well understood. To investigate the dynamic changes in chromatin organization at and surrounding replication origins, we used micrococcal nuclease (MNase) to generate genome-wide chromatin occupancy profiles of nucleosomes, transcription factors and replication proteins through consecutive cell cycles in Saccharomyces cerevisiae. During each G1 phase of two consecutive cell cycles, we observed the downstream repositioning of the origin-proximal +1 nucleosome and an increase in protected DNA fragments spanning the ARS consensus sequence (ACS) indicative of pre-RC assembly. We also found that the strongest correlation between the chromatin occupancy at the ACS and origin efficiency occurred in early S-phase consistent with the rate limiting formation of the Cdc45-Mcm2-7-GINS (CMG) complex being a determinant of origin activity. Finally, we observed nucleosome disruption and disorganization emanating from replication origins and traveling with the elongating replication forks across the genome in S-phase, likely reflecting the disassembly and assembly of chromatin ahead of and behind the replication fork, respectively. These results provide insights into cell cycle-regulated chromatin dynamics and how they relate to the regulation of origin activity.

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