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 Replicon Clusters Are Stable Units of Chromosome Structure: Evidence That Nuclear Organization Contributes to the Efficient Activation and Propagation of S Phase in Human Cells

1998 ◽  
Vol 140 (6) ◽  
pp. 1285-1295 ◽  
Author(s):  
Dean A. Jackson ◽  
Ana Pombo
Keyword(s):  
Mammalian Cells ◽  
Chromosome Structure ◽  
Nuclear Organization ◽  
Short Interval ◽  
S Phase ◽  
Replication Forks ◽  
Proliferating Cells ◽  
Cell Cycles ◽  
Replication Sites ◽  
Replication Foci

In proliferating cells, DNA synthesis must be performed with extreme precision. We show that groups of replicons, labeled together as replicon clusters, form stable units of chromosome structure. HeLa cells were labeled with 5-bromodeoxyuridine (BrdU) at different times of S phase. At the onset of S phase, clusters of replicons were activated in each of ∼750 replication sites. The majority of these replication “foci” were shown to be individual replicon clusters that remained together, as stable cohorts, throughout the following 15 cell cycles. In individual cells, the same replication foci were labeled with BrdU and 5-iododeoxyuridine at the beginning of different cell cycles. In DNA fibers, 95% of replicons in replicon clusters that were labeled at the beginning of one S phase were also labeled at the beginning of the next. This shows that a subset of origins are activated both reliably and efficiently in different cycles. The majority of replication forks activated at the onset of S phase terminated 45–60 min later. During this interval, secondary replicon clusters became active. However, while the activation of early replicons is synchronized at the onset of S phase, different secondary clusters were activated at different times. Nevertheless, replication foci pulse labeled during any short interval of S phase were stable for many cell cycles. We propose that the coordinated replication of related groups of replicons, that form stable replicon clusters, contributes to the efficient activation and propagation of S phase in mammalian cells.

scholarly journals A New Immunocytochemical Technique for Ultrastructural Analysis of DNA Replication in Proliferating Cells After Application of Two Halogenated Deoxyuridines

1998 ◽  
Vol 46 (10) ◽  
pp. 1203-1209 ◽  
Author(s):  
Françoise Jaunin ◽  
Astrid E. Visser ◽  
Dusan Cmarko ◽  
Jacob A. Aten ◽  
Stanislav Fakan
Keyword(s):  
Electron Microscopy ◽  
Dna Replication ◽  
Salt Concentration ◽  
Chinese Hamster ◽  
S Phase ◽  
Tween 20 ◽  
Proliferating Cells ◽  
Specific Staining ◽  
Double Labeling ◽  
Chinese Hamster Cells

We describe a colloidal gold immunolabeling technique for electron microscopy which allows one to differentially visualize portions of DNA replicated during different periods of S-phase. This was performed by incorporating two halogenated deoxyuridines (IdUrd and CldUrd) into Chinese hamster cells and, after cell processing, by detecting them with selected antibodies. This technique, using in particular appropriate blocking solutions and also Tris buffer with a high salt concentration and 1% Tween-20, prevents nonspecific background and crossreaction of both antibodies. Controls such as digestion with DNase and specific staining of DNA with osmium ammine show that labeling corresponds well to replicated DNA. Different patterns of labeling distribution, reflecting different periods of DNA replication during S-phase, were characterized. Cells in early S-phase display a diffuse pattern of labeling with many spots, whereas cells in late S-phase show labeling confined to larger domains, often at the periphery of the nucleus or associated with the nucleolus. The good correlation between our observations and previous double labeling results in immunofluorescence also proved the technique to be reliable.

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.

scholarly journals Fate of the M-phase-assembled centrioles during the cell cycle in the TP53;PCNT;CEP215-deleted cells

2020 ◽  
Author(s):  
Gee In Jung ◽  
Kunsoo Rhee
Keyword(s):  
Cell Cycle ◽  
Cancer Cells ◽  
Cell Lines ◽  
S Phase ◽  
M Phase ◽  
Dividing Cells ◽  
Centriole Assembly

ABSTRACTCancer cells frequently include supernumerary centrioles. Here, we generated TP53;PCNT;CEP215 triple knockout cell lines and observed precocious separation and amplification of the centrioles at M phase. Many of the triple KO cells maintained supernumerary centrioles throughout the cell cycle. The M-phase-assembled centrioles lack an ability to function as templates for centriole assembly during S phase. They also lack an ability to organize microtubules in interphase. However, we found that a fraction of them acquired an ability to organize microtubules during M phase. Our works provide an example how supernumerary centrioles behave in dividing cells.

scholarly journals Histone mRNAs Do Not Accumulate during S Phase of either Mitotic or Endoreduplicative Cycles in the Chordate Oikopleura dioica

2004 ◽  
Vol 24 (12) ◽  
pp. 5391-5403 ◽  
Author(s):  
Mariacristina Chioda ◽  
Fabio Spada ◽  
Ragnhild Eskeland ◽  
Eric M. Thompson
Keyword(s):  
Cell Cycle ◽  
S Phase ◽  
Model Organisms ◽  
Promoter Elements ◽  
Oikopleura Dioica ◽  
Stem Loop ◽  
Transcript Levels ◽  
Cell Cycles ◽  
Histone Mrnas ◽  
Complete Cell

ABSTRACT Metazoan histones are generally classified as replication-dependent or replacement variants. Replication-dependent histone genes contain cell cycle-responsive promoter elements, their transcripts terminate in an unpolyadenylated conserved stem-loop, and their mRNAs accumulate sharply during S phase. Replacement variant genes lack cell cycle-responsive promoter elements, their polyadenylated transcripts lack the stem-loop, and they are expressed at low levels throughout the cell cycle. During early development of some organisms with rapid cleavage cycles, replication-dependent mRNAs are not fully S phase restricted until complete cell cycle regulation is achieved. The accumulation of polyadenylated transcripts during this period has been considered incompatible with metazoan development. We show here that histone metabolism in the urochordate Oikopleura dioica does not accord with some key tenets of the replication-dependent/replacement variant paradigm. During the premetamorphic mitotic phase of development, expressed variants shared characteristics of replication-dependent histones, including the 3′ stem-loop, but, in contrast, were extensively polyadenylated. After metamorphosis, when cells in many tissues enter endocycles, there was a global downregulation of histone transcript levels, with most variant transcripts processed at the stem-loop. Contrary to the 30-fold S-phase upregulation of histone transcripts described in common metazoan model organisms, we observed essentially constant histone transcript levels throughout both mitotic and endoreduplicative cell cycles.

scholarly journals The spindle checkpoint, APC/CCdc20, and APC/CCdh1 play distinct roles in connecting mitosis to S phase

2013 ◽  
Vol 201 (7) ◽  
pp. 1013-1026 ◽  
Author(s):  
Linda Clijsters ◽  
Janneke Ogink ◽  
Rob Wolthuis
Keyword(s):  
Spindle Checkpoint ◽  
Cyclin B1 ◽  
S Phase ◽  
Animal Cells ◽  
Proliferating Cells ◽  
Cell Cycle Entry ◽  
Sister Chromatids ◽  
Mitotic Cyclin ◽  
Bona Fide ◽  
Subsequent Activation

DNA replication depends on a preceding licensing event by Cdt1 and Cdc6. In animal cells, relicensing after S phase but before mitosis is prevented by the Cdt1 inhibitor geminin and mitotic cyclin activity. Here, we show that geminin, like cyclin B1 and securin, is a bona fide target of the spindle checkpoint and APC/CCdc20. Cyclin B1 and geminin are degraded simultaneously during metaphase, which directs Cdt1 accumulation on segregating sister chromatids. Subsequent activation of APC/CCdh1 leads to degradation of Cdc6 well before Cdt1 becomes unstable in a replication-coupled manner. In mitosis, the spindle checkpoint supports Cdt1 accumulation, which promotes S phase onset. We conclude that the spindle checkpoint, APC/CCdc20, and APC/CCdh1 act successively to ensure that the disappearance of licensing inhibitors coincides exactly with a peak of Cdt1 and Cdc6. Whereas cell cycle entry from quiescence requires Cdc6 resynthesis, our results indicate that proliferating cells use a window of time in mitosis, before Cdc6 is degraded, as an earlier opportunity to direct S phase.

scholarly journals PPP1R35 ensures centriole homeostasis by promoting centriole-to-centrosome conversion

2018 ◽  
Vol 29 (23) ◽  
pp. 2801-2808 ◽  
Author(s):  
Chii Shyang Fong ◽  
Kanako Ozaki ◽  
Meng-Fu Bryan Tsou
Keyword(s):  
Protein Phosphatase ◽  
S Phase ◽  
Essential Factor ◽  
Centriole Duplication ◽  
G2 Phase ◽  
Centriole Assembly

Centriole-to-centrosome conversion (CCC) safeguards centriole homeostasis by coupling centriole duplication with segregation, and is essential for stabilization of mature vertebrate centrioles naturally devoid of the geometric scaffold or the cartwheel. Here we identified PPP1R35, a putative regulator of the protein phosphatase PP1, as a novel centriolar protein required for CCC. We found that PPP1R35 is enriched at newborn daughter centrioles in S or G2 phase. In the absence of PPP1R35, centriole assembly initiates normally in S phase, but none of the nascent centrioles can form active centrosomes or recruit CEP295, an essential factor for CCC. Instead, all PPP1R35-null centrioles, although stable during their birth in interphase, become disintegrated after mitosis upon cartwheel removal. Surprisingly, we found that neither the centriolar localization nor the function of PPP1R35 in CCC requires the putative PP1-interacting motif. PPP1R35 is thus acting upstream of CEP295 to induce CCC for proper centriole maintenance.

Maturation promoting factor and cell cycle regulation

Development ◽  
1985 ◽  
Vol 89 (Supplement) ◽  
pp. 271-284
Author(s):  
C. C. Ford
Keyword(s):  
Dna Synthesis ◽  
Cell Cycle Regulation ◽  
Nuclear Division ◽  
S Phase ◽  
Early Cleavage ◽  
Cell Cycles ◽  
Nuclear Envelope Breakdown ◽  
Cytostatic Factor ◽  
Cycle Regulation ◽  
Maturation Promoting Factor

Cell cycles in early amphibian embryos are characterized by the absence of G1 and G2 phases. The simple cycle of S phase and mitosis does show similarities with other systems, particularly in the presence of cytoplasmic components advancing nuclei into DNA synthesis and mitosis. Maturation-promoting factor induces nuclear envelope breakdown and subsequent chromosome condensation. Cytoplasmic factors appear during maturation which are capable of inducing DNA synthesis, and arrest of the nuclear division cycle in metaphase (cytostatic factor). The timing of appearance of these activities is considered and their relationship in integrating DNA synthesis during early cleavage is discussed.

PTHrP and Indian hedgehog control differentiation of growth plate chondrocytes at multiple steps

Development ◽  
2002 ◽  
Vol 129 (12) ◽  
pp. 2977-2986 ◽  
Author(s):  
Tatsuya Kobayashi ◽  
Ung-il Chung ◽  
Ernestina Schipani ◽  
Michael Starbuck ◽  
Gerard Karsenty ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Mouse Models ◽  
Articular Surface ◽  
Indian Hedgehog ◽  
Chondrocyte Differentiation ◽  
Proliferating Cells ◽  
Growth Plate Chondrocytes ◽  
The Third ◽  
Mutual Regulation ◽  
Pthrp Receptor

In developing murine growth plates, chondrocytes near the articular surface (periarticular chondrocytes) proliferate, differentiate into flat column-forming proliferating cells (columnar chondrocytes), stop dividing and finally differentiate into hypertrophic cells. Indian hedgehog (Ihh), which is predominantly expressed in prehypertrophic cells, stimulates expression of parathyroid hormone (PTH)-related peptide (PTHrP) which negatively regulates terminal chondrocyte differentiation through the PTH/PTHrP receptor (PPR). However, the roles of PTHrP and Ihh in regulating earlier steps in chondrocyte differentiation are unclear. We present novel mouse models with PPR abnormalities that help clarify these roles. In mice with chondrocyte-specific PPR ablation and mice with reduced PPR expression, chondrocyte differentiation was accelerated not only at the terminal step but also at an earlier step: periarticular to columnar differentiation. In these models, upregulation of Ihh action in the periarticular region was also observed. In the third model in which the PPR was disrupted in about 30% of columnar chondrocytes, Ihh action in the periarticular chondrocytes was upregulated because of ectopically differentiated hypertrophic chondrocytes that had lost PPR. Acceleration of periarticular to columnar differentiation was also noted in this mouse, while most of periarticular chondrocytes retained PPR signaling. These data suggest that Ihh positively controls differentiation of periarticular chondrocytes independently of PTHrP. Thus, chondrocyte differentiation is controlled at multiple steps by PTHrP and Ihh through the mutual regulation of their activities.

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