scholarly journals Gland cells in Hydra: cell cycle kinetics and development

1986 ◽  
Vol 85 (1) ◽  
pp. 197-215
Author(s):  
T. Schmidt ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
The Body ◽  
Proliferating Cells ◽  
Gland Cells ◽  
A Cell ◽  
Different Populations ◽  
Mucus Cells ◽  
Dna Measurements ◽  
Body Column

The proliferative capacity of gland cells in Hydra attenuata was investigated. The results indicate that both gland cell proliferation and interstitial cell differentiation to gland cells contribute to the maintenance of the whole population. On the basis of [3H]thymidine incorporation and nuclear DNA measurements, gland cells consist of at least three different populations. One population consists of rapidly proliferating cells with a cell cycle of about 72 h. These cells are distributed throughout the body column. In the lower gastric region there is a population of non-cycling cells in G2 while in the upper gastric region there is a population of non-cycling cells in G1. About half the G1 population becomes a new antigen, SEC 1, which is typical of mucus cells.

S-phase-specific expression of the Mad3 gene in proliferating and differentiating cells

2001 ◽  
Vol 359 (2) ◽  
pp. 361-367 ◽  
Author(s):  
Elizabeth J. FOX ◽  
Stephanie C. WRIGHT
Keyword(s):  
Cell Cycle ◽  
Cellular Proliferation ◽  
Cultured Cells ◽  
S Phase ◽  
Proliferating Cells ◽  
Specific Expression ◽  
Related Function ◽  
Erythroleukemia Cells ◽  
A Cell ◽  
Pass Through

The Myc/Max/Mad transcription factor network plays a central role in the control of cellular proliferation, differentiation and apoptosis. In order to elucidate the biological function of Mad3, we have analysed the precise temporal patterns of Mad3 mRNA expression during the cell cycle and differentiation in cultured cells. We show that Mad3 is induced at the G1/S transition in proliferating cells; expression persists throughout S-phase, and then declines as cells pass through G2 and mitosis. The expression pattern of Mad3 is coincident with that of Cdc2 throughout the cell cycle. In contrast, the expression of Mad3 during differentiation of cultured mouse erythroleukemia cells shows two transient peaks of induction. The first of these occurs at the onset of differentiation, and does not correlate with the S-phase of the cell cycle, whereas the second is coincident with the S-phase burst that precedes the terminal stages of differentiation. Our results therefore suggest that Mad3 serves a cell-cycle-related function in both proliferating and differentiating cells, and that it may also have a distinct role at various stages of differentiation.

scholarly journals Pocket Protein Complexes Are Recruited to Distinct Targets in Quiescent and Proliferating Cells

2005 ◽  
Vol 25 (18) ◽  
pp. 8166-8178 ◽  
Author(s):  
Egle Balciunaite ◽  
Alexander Spektor ◽  
Nathan H. Lents ◽  
Hugh Cam ◽  
Hein te Riele ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Regulatory Networks ◽  
Protein Complexes ◽  
Proliferating Cells ◽  
Quiescent Cells ◽  
Pocket Protein ◽  
Genome Wide ◽  
E2f Transcription Factor ◽  
A Cell ◽  
Cycle Dependent

ABSTRACT Biochemical and genetic studies have determined that retinoblastoma protein (pRB) tumor suppressor family members have overlapping functions. However, these studies have largely failed to distinguish functional differences between the highly related p107 and p130 proteins. Moreover, most studies pertaining to the pRB family and its principal target, the E2F transcription factor, have focused on cells that have reinitiated a cell cycle from quiescence, although recent studies suggest that cycling cells exhibit layers of regulation distinct from mitogenically stimulated cells. Using genome-wide chromatin immunoprecipitation, we show that there are distinct classes of genes directly regulated by unique combinations of E2F4, p107, and p130, including a group of genes specifically regulated in cycling cells. These groups exhibit both distinct histone acetylation signatures and patterns of mammalian Sin3B corepressor recruitment. Our findings suggest that cell cycle-dependent repression results from recruitment of an unexpected array of diverse complexes and reveals specific differences between transcriptional regulation in cycling and quiescent cells. In addition, factor location analyses have, for the first time, allowed the identification of novel and specific targets of the highly related transcriptional regulators p107 and p130, suggesting new and distinct regulatory networks engaged by each protein in continuously cycling cells.

scholarly journals Commitment during nematocyte differentiation in Hydra

1981 ◽  
Vol 48 (1) ◽  
pp. 207-222 ◽  
Author(s):  
T. Fujisawa ◽  
C.N. David
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Distal Region ◽  
The Body ◽  
Distal Half ◽  
Proximal Half ◽  
Dissociated Cells ◽  
Time Required ◽  
Kinetics Of ◽  
Body Column

Nematocytes in Hydra differentiate from interstitial stem cells. Desmonemes differentiate mainly in the distal half of the body column while stenoteles differentiate predominantly in the proximal half. This difference was used to determine the timing of nematocyte-type commitment in the differentiation pathway. Cells were transferred from distal or proximal regions to all positions in the body column to test when the proportion of stenotele and desmoneme differentiation changed to reflect the new environment. In the first experiment, the distal region of the body column was isolated and permitted to regenerate a whole Hydra. In the second experiment, dissociated cells from distal or proximal regions were transplanted into regenerating aggregates of Hydra tissue. Both experiments effectively transferred cells from distal or proximal positions to positions throughout the body column. By comparing the kinetics of stenotele and differentiation with the time required for distal or proximal cells to differentiate stenoteles and desmonemes in accord with their new environment, it was possible to conclude that stenotele and desmoneme commitment occurs during the terminal cell cycle prior to nematocyte differentiation and not at the stem cell. Additional experiments indicated that the number of rounds of cell division preceding differentiation is fixed at the time stem cells enter the nematocyte pathway.

scholarly journals Nuclear pore heterogeneity influences HIV-1 infection and the antiviral activity of MX2

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Melissa Kane ◽  
Stephanie V Rebensburg ◽  
Matthew A Takata ◽  
Trinity M Zang ◽  
Masahiro Yamashita ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nuclear Dna ◽  
Cyclophilin A ◽  
Nuclear Pore ◽  
Dependent Manner ◽  
Cell Type ◽  
Antiviral Protein ◽  
Interphase Cells ◽  
A Cell ◽  
Hiv 1

HIV-1 accesses the nuclear DNA of interphase cells via a poorly defined process involving functional interactions between the capsid protein (CA) and nucleoporins (Nups). Here, we show that HIV-1 CA can bind multiple Nups, and that both natural and manipulated variation in Nup levels impacts HIV-1 infection in a manner that is strikingly dependent on cell-type, cell-cycle, and cyclophilin A (CypA). We also show that Nups mediate the function of the antiviral protein MX2, and that MX2 can variably inhibit non-viral NLS function. Remarkably, both enhancing and inhibiting effects of cyclophilin A and MX2 on various HIV-1 CA mutants could be induced or abolished by manipulating levels of the Nup93 subcomplex, the Nup62 subcomplex, NUP88, NUP214, RANBP2, or NUP153. Our findings suggest that several Nup-dependent ‘pathways’ are variably exploited by HIV-1 to target host DNA in a cell-type, cell-cycle, CypA and CA-sequence dependent manner, and are differentially inhibited by MX2.

scholarly journals Cell cycle inhibitor Whi5 records environmental information to coordinate growth and division in yeast

2019 ◽  
Author(s):  
Yimiao Qu ◽  
Jun Jiang ◽  
Xiang Liu ◽  
Ping Wei ◽  
Xiaojing Yang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Doubling Time ◽  
Optimal Timing ◽  
Proliferating Cells ◽  
Cell Cycle Entry ◽  
Cellular Decision Making ◽  
Need To Evaluate ◽  
A Cell ◽  
Made In

SUMMARYProliferating cells need to evaluate the environment to determine the optimal timing for cell cycle entry, which is essential for coordinating cell division and growth. In the budding yeast Saccharomyces cerevisiae, the commitment to the next round of division is made in G1 at the Start, triggered by the inactivation of the inhibitor Whi5 through multiple mechanisms. However, how a cell reads environmental condition and uses this information to regulate Start is poorly understood. Here, we show that Whi5 is a key environmental indicator and plays a crucial role in coordinating cell growth and division. We found that under a variety of nutrient and stress conditions, the concentration of Whi5 in G1 is proportional to the doubling time in the environment. Thus, under a poorer condition a longer doubling time results in a higher Whi5 concentration, which in turn delays the next cell cycle entry to ensure sufficient cell growth. In addition, the coordination between division and the environment is further fine-tuned in G1 by environmentally dependent G1 cyclin-Cdk1 contribution and Whi5 threshold at Start. Our results show that Whi5 serves as an environmental ‘memory’ and that the cell adopts a simple and elegant mechanism to achieve an adaptive cellular decision making.

Tubulin polyglutamylase: isozymic variants and regulation during the cell cycle in HeLa cells

1999 ◽  
Vol 112 (23) ◽  
pp. 4281-4289 ◽  
Author(s):  
C. Regnard ◽  
E. Desbruyeres ◽  
P. Denoulet ◽  
B. Edde
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Molecular Motors ◽  
Dependent Manner ◽  
Proliferating Cells ◽  
Beta Tubulin ◽  
Microtubule Associated Proteins ◽  
Associated Proteins ◽  
A Cell ◽  
Cycle Dependent

Polyglutamylation is a posttranslational modification of tubulin that is very common in neurons and ciliated or flagellated cells. It was proposed to regulate the binding of microtubule associated proteins (MAPs) and molecular motors as a function of the length of the polyglutamyl side-chain. Though much less common, this modification of tubulin also occurs in proliferating cells like HeLa cells where it is associated with centrioles and with the mitotic spindle. Recently, we partially purified tubulin polyglutamylase from mouse brain and described its enzymatic properties. In this work, we focused on tubulin polyglutamylase activity from HeLa cells. Our results support the existence of a tubulin polyglutamylase family composed of several isozymic variants specific for alpha- or beta-tubulin subunits. In the latter case, the specificity probably also concerns the different beta-tubulin isotypes. Interestingly, we found that tubulin polyglutamylase activity is regulated in a cell cycle dependent manner and peaks in G(2)-phase while the level of glutamylated tubulin peaks in mitosis. Consistent results were obtained by treating the cells with hydroxyurea, nocodazole or taxotere. In particular, in mitotic cells, tubulin polyglutamylase activity was always low while glutamylation level was high. Finally, tubulin polyglutamylase activity and the level of glutamylated tubulin appeared to be inversely related. This paradox suggests a complex regulation of both tubulin polyglutamylase and the reverse deglutamylase activity.

scholarly journals Tetrapyrrole signal as a cell-cycle coordinator from organelle to nuclear DNA replication in plant cells

2009 ◽  
Vol 106 (3) ◽  
pp. 803-807 ◽  
Author(s):  
Yuki Kobayashi ◽  
Yu Kanesaki ◽  
Ayumi Tanaka ◽  
Haruko Kuroiwa ◽  
Tsuneyoshi Kuroiwa ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Nuclear Dna ◽  
Plant Cells ◽  
A Cell

scholarly journals CycleFlow quantifies cell-cycle heterogeneity in vivo

2020 ◽  
Author(s):  
Adrien Jolly ◽  
Ann-Kathrin Fanti ◽  
Ines Gräßer ◽  
Nils B. Becker ◽  
Thomas Höfer
Keyword(s):  
Cell Cycle ◽  
Cycle Length ◽  
Proliferating Cells ◽  
Average Cell ◽  
Quiescent Cells ◽  
A Cell ◽  
Cell Cycle Length ◽  
Combined Measurements

AbstractWhile the average cell-cycle length in a cell population can be derived from pulse-chase experiments, proliferative heterogeneity has been difficult to quantify. Here we describe CycleFlow, a broadly applicable method that applies Bayesian inference to combined measurements of EdU incorporation and DNA content. CycleFlow accurately quantifies the fraction of proliferating versus quiescent cells and the durations of cell-cycle phases of the proliferating cells in vitro and in vivo.

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