scholarly journals Nuclear localization of barrier-to-autointegration factor is correlated with progression of S phase in human cells

2007 ◽  
Vol 120 (12) ◽  
pp. 1967-1977 ◽  
Author(s):  
T. Haraguchi ◽  
T. Koujin ◽  
H. Osakada ◽  
T. Kojidani ◽  
C. Mori ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
S Phase ◽  
Human Cells

scholarly journals High-throughput analysis of DNA replication in single human cells reveals constrained variability in the location and timing of replication initiation

2021 ◽  
Author(s):  
Dashiell J Massey ◽  
Amnon Koren
Keyword(s):  
Dna Replication ◽  
Replication Origin ◽  
Replication Timing ◽  
S Phase ◽  
Human Cells ◽  
Replication Initiation ◽  
High Throughput Analysis ◽  
Timing Variability ◽  
Fixed Set ◽  
Fixed Order

DNA replication occurs throughout the S phase of the cell cycle, initiating from replication origin loci that fire at different times. Debate remains about whether origins are a fixed set of loci used across all cells or a loose agglomeration of potential origins used stochastically in individual cells, and about how consistent their firing time during S phase is across cells. Here, we develop an approach for profiling DNA replication in single human cells and apply it to 2,305 replicating cells spanning the entire S phase. The resolution and scale of the data enabled us to specifically analyze initiation sites and show that these sites have confined locations that are consistently used among individual cells. Further, we find that initiation sites are activated in a similar, albeit not fixed, order across cells. Taken together, our results suggest that replication timing variability is constrained both spatially and temporally, and that the degree of variation is consistent across human cell lines.

Nuclear localization of vertebrate cyclin A correlates with its ability to form complexes with cdk catalytic subunits

1993 ◽  
Vol 106 (2) ◽  
pp. 535-544 ◽  
Author(s):  
G. Maridor ◽  
P. Gallant ◽  
R. Golsteyn ◽  
E.A. Nigg
Keyword(s):  
Nuclear Localization ◽  
Immunofluorescence Microscopy ◽  
Cyclin A ◽  
S Phase ◽  
Catalytic Subunits ◽  
Kinase Activation ◽  
Indirect Immunofluorescence Microscopy ◽  
C Terminus ◽  
Dependent Protein ◽  
Cycle Regulation

Cyclins control the activities of cyclin-dependent protein kinases (cdks) and hence play a key role in cell cycle regulation. While B-type cyclins associate with p34cdc2 to trigger entry into mitosis, progression through S phase requires cyclin A, presumably in association with p33cdk2. Vertebrate A- and B-type cyclins display strikingly distinct subcellular localizations, but the mechanisms underlying these differential distributions are unknown. Here, we have begun to study the requirements for nuclear localization of cyclin A. We have isolated a cDNA coding for chicken cyclin A and constructed a series of deletion mutants. These were then transfected into HeLa cells, and the subcellular distribution of the mutant cyclin A proteins was determined by indirect immunofluorescence microscopy. In parallel, the cyclin A mutants were assayed for their ability to form complexes with cdk subunits. We found that deletion of more than 100 residues from the N terminus of cyclin A did not impair nuclear localization or cdk subunit binding and kinase activation. In contrast, removal of as few as 15 residues from the C terminus, or deletion of part of the internal cyclin box domain, abolished nuclear localization of cyclin A as well as its ability to bind to and activate cdk subunits. These results suggest that nuclear transport of cyclin A may depend on the formation of multiprotein complexes comprising cdk catalytic subunits.

scholarly journals With Age Comes Maturity: Biochemical and Structural Transformation of a Human Centriole in the Making

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1429 ◽  
Author(s):  
Catherine Sullenberger ◽  
Alejandra Vasquez-Limeta ◽  
Dong Kong ◽  
Jadranka Loncarek
Keyword(s):  
S Phase ◽  
Human Cells ◽  
Cellular Structures ◽  
Age Difference ◽  
Proliferating Cells ◽  
Cell Cycles ◽  
Controlled Processes ◽  
The Third ◽  
Centriole Assembly ◽  
Lengthy Process

Centrioles are microtubule-based cellular structures present in most human cells that build centrosomes and cilia. Proliferating cells have only two centrosomes and this number is stringently maintained through the temporally and spatially controlled processes of centriole assembly and segregation. The assembly of new centrioles begins in early S phase and ends in the third G1 phase from their initiation. This lengthy process of centriole assembly from their initiation to their maturation is characterized by numerous structural and still poorly understood biochemical changes, which occur in synchrony with the progression of cells through three consecutive cell cycles. As a result, proliferating cells contain three structurally, biochemically, and functionally distinct types of centrioles: procentrioles, daughter centrioles, and mother centrioles. This age difference is critical for proper centrosome and cilia function. Here we discuss the centriole assembly process as it occurs in somatic cycling human cells with a focus on the structural, biochemical, and functional characteristics of centrioles of different ages.

scholarly journals ABCE1 is essential for S phase progression in human cells

Cell Cycle ◽  
2016 ◽  
Vol 15 (9) ◽  
pp. 1234-1247 ◽  
Author(s):  
Marina Toompuu ◽  
Kairi Kärblane ◽  
Pille Pata ◽  
Erkki Truve ◽  
Cecilia Sarmiento
Keyword(s):  
S Phase ◽  
Human Cells ◽  
Phase Progression

scholarly journals Role of inhibitory CDC2 phosphorylation in radiation-induced G2 arrest in human cells.

1996 ◽  
Vol 134 (4) ◽  
pp. 963-970 ◽  
Author(s):  
P Jin ◽  
Y Gu ◽  
D O Morgan
Keyword(s):  
Dna Damage ◽  
Chromatin Condensation ◽  
S Phase ◽  
Human Cells ◽  
G2 Arrest ◽  
Hela Cell Lines ◽  
Radiation Induced ◽  
G2 Delay ◽  
In Cells

The activity of the mitosis-promoting kinase CDC2-cyclin B is normally suppressed in S phase and G2 by inhibitory phosphorylation at Thr14 and Tyr15. This work explores the possibility that these phosphorylations are responsible for the G2 arrest that occurs in human cells after DNA damage. HeLa cell lines were established in which CDC2AF, a mutant that cannot be phosphorylated at Thr14 and Tyr15, was expressed from a tetracycline-repressible promoter. Expression of CDC2AF did not induce mitotic events in cells arrested at the beginning of S phase with DNA synthesis inhibitors, but induced low levels of premature chromatin condensation in cells progressing through S phase and G2. Expression of CDC2AF greatly reduced the G2 delay that resulted when cells were X-irradiated in S phase. However, a significant G2 delay was still observed and was accompanied by high CDC2-associated kinase activity. Expression of wild-type CDC2, or the related kinase CDK2AF, had no effect on the radiation-induced delay. Thus, inhibitory phosphorylation of CDC2, as well as additional undefined mechanisms, delay mitosis after DNA damage.

scholarly journals FANCD2 Alleviates Physiologic Replication Stress in Fetal Liver HSC

2020 ◽  
Author(s):  
Makiko Mochizuki-Kashio ◽  
Young me Yoon ◽  
Theresa Menna ◽  
Markus Grompe ◽  
Peter Kurre
Keyword(s):  
Nuclear Localization ◽  
Fetal Liver ◽  
Bone Marrow Failure ◽  
Physiological Role ◽  
Replication Stress ◽  
S Phase ◽  
Core Component ◽  
Hematopoietic Stem ◽  
Pool Formation

ABSTRACTBone marrow failure (BMF) in Fanconi Anemia (FA) results from exhaustion of hematopoietic stem cells (HSC), but the physiological role of FA proteins in HSC pool integrity remains unknown. Herein we demonstrate that FANCD2, a core component of the FA pathway, counters replication stress during developmental HSC expansion in the fetal liver (FL). Rapid rates of proliferation and FANCD2 deficient result in excess RPA-coated ssDNA, and provoke pChk1 activation and Cdkn1a(p21) nuclear localization in fetal Fancd2−/− HSC. Checkpoint mediated S-phase delays induced by Cdkn1a(p21) are rescued by Tgf-β inhibition, but pChk1 activation is further aggravated. Our observations reveal the mechanism and physiological context by which FANCD2 safeguards HSC pool formation during development.

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