scholarly journals S-Phase Synchronization Facilitates the Early Progression of Induced-Cardiomyocyte Reprogramming through Enhanced Cell-Cycle Exit

2018 ◽  
Author(s):  
Emre Bektik ◽  
Adrienne Dennis ◽  
Gary Pawlowski ◽  
Danielle Maleski ◽  
Satoru Takahashi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Phase Synchronization ◽  
Time Lapse ◽  
S Phase ◽  
Great Promise ◽  
Cell Cycle Exit ◽  
Early Progression ◽  
Fundamental Biological Process ◽  
Time Lapse Imaging ◽  
Cycle Regulation

Direct reprogramming of fibroblasts into induced cardiomyocytes (iCMs) holds a great promise for regenerative medicine and has been studied in several major directions. However, cell-cycle regulation, a fundamental biological process, has not been investigated during iCM-reprogramming. Here, our time-lapse imaging on iCMs, reprogrammed by Gata4, Mef2c, and Tbx5 (GMT) monocistronic retroviruses, revealed that iCM-reprogramming was majorly initiated at late-G1- or S-phase and nearly half of GMT-reprogrammed iCMs divided soon after reprogramming. iCMs exited cell cycle along the process of reprogramming with decreased percentage of EdU+/αMHC-GFP+ cells. S-phase synchronization post-GMT-infection could enhance cell-cycle exit of reprogrammed iCMs and yield more GFPhigh iCMs, which achieved an advanced reprogramming with more expression of cardiac genes than GFPlow cells; however, S-phase synchronization didn’t enhance the polycistronic-MGT reprogramming, in which cell-cycle exit had been accelerated. In conclusion, post-infection synchronization of S-phase facilitated the early progression of GMT-reprogramming through a mechanism of enhanced cell-cycle exit.

scholarly journals S-phase Synchronization Facilitates the Early Progression of Induced-Cardiomyocyte Reprogramming through Enhanced Cell-Cycle Exit

2018 ◽  
Vol 19 (5) ◽  
pp. 1364 ◽  
Author(s):  
Emre Bektik ◽  
Adrienne Dennis ◽  
Gary Pawlowski ◽  
Chen Zhou ◽  
Danielle Maleski ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Phase Synchronization ◽  
S Phase ◽  
Cell Cycle Exit ◽  
Early Progression

scholarly journals Fluctuation in radioresponse of HeLa cells during the cell cycle evaluated based on micronucleus frequency

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hiroaki Shimono ◽  
Atsushi Kaida ◽  
Hisao Homma ◽  
Hitomi Nojima ◽  
Yusuke Onozato ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Hela Cells ◽  
Time Lapse ◽  
S Phase ◽  
G1 Phase ◽  
M Phase ◽  
G2 Phase ◽  
The Difference ◽  
Time Lapse Imaging ◽  
First Time

AbstractIn this study, we examined the fluctuation in radioresponse of HeLa cells during the cell cycle. For this purpose, we used HeLa cells expressing two types of fluorescent ubiquitination-based cell cycle indicators (Fucci), HeLa-Fucci (CA)2 and HeLa-Fucci (SA), and combined this approach with the micronucleus (MN) assay to assess radioresponse. The Fucci system distinguishes cell cycle phases based on the colour of fluorescence and cell morphology under live conditions. Time-lapse imaging allowed us to further identify sub-positions within the G1 and S phases at the time of irradiation by two independent means, and to quantitate the number of MNs by following each cell through M phase until the next G1 phase. Notably, we found that radioresponse was low in late G1 phase, but rapidly increased in early S phase. It then decreased until late S phase and increased in G2 phase. For the first time, we demonstrated the unique fluctuation of radioresponse by the MN assay during the cell cycle in HeLa cells. We discuss the difference between previous clonogenic experiments using M phase-synchronised cell populations and ours, as well as the clinical implications of the present findings.

scholarly journals Cell cycle inertia underlies a bifurcation in cell fates after DNA damage

2021 ◽  
Vol 7 (3) ◽  
pp. eabe3882
Author(s):  
Jenny F. Nathans ◽  
James A. Cornwell ◽  
Marwa M. Afifi ◽  
Debasish Paul ◽  
Steven D. Cappell
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Cell Tracking ◽  
Time Lapse ◽  
S Phase ◽  
Cdk Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Cell Fates ◽  
Damage Response ◽  
Time Lapse Imaging

The G1-S checkpoint is thought to prevent cells with damaged DNA from entering S phase and replicating their DNA and efficiently arrests cells at the G1-S transition. Here, using time-lapse imaging and single-cell tracking, we instead find that DNA damage leads to highly variable and divergent fate outcomes. Contrary to the textbook model that cells arrest at the G1-S transition, cells triggering the DNA damage checkpoint in G1 phase route back to quiescence, and this cellular rerouting can be initiated at any point in G1 phase. Furthermore, we find that most of the cells receiving damage in G1 phase actually fail to arrest and proceed through the G1-S transition due to persistent cyclin-dependent kinase (CDK) activity in the interval between DNA damage and induction of the CDK inhibitor p21. These observations necessitate a revised model of DNA damage response in G1 phase and indicate that cells have a G1 checkpoint.

scholarly journals Posttranslational Phosphorylation and Ubiquitination of the Saccharomyces cerevisiae Poly(A) Polymerase at the S/G2 Stage of the Cell Cycle

2000 ◽  
Vol 20 (8) ◽  
pp. 2794-2802 ◽  
Author(s):  
Neptune Mizrahi ◽  
Claire Moore
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Sorting ◽  
S Phase ◽  
Phase Arrest ◽  
Phosphatase Treatment ◽  
M Phase ◽  
64 Kda Protein ◽  
Mitotic Phosphorylation ◽  
Cycle Regulation

ABSTRACT The poly(A) polymerase of the budding yeast Saccharomyces cerevisiae (Pap1) is a 64-kDa protein essential for the maturation of mRNA. We have found that a modified Pap1 of 90 kDa transiently appears in cells after release from α-factor-induced G1 arrest or from a hydroxyurea-induced S-phase arrest. While a small amount of modification occurs in hydroxyurea-arrested cells, fluorescence-activated cell sorting analysis and microscopic examination of bud formation indicate that the majority of modified enzyme is found at late S/G2 and disappears by the time cells have reached M phase. The reduction of the 90-kDa product upon phosphatase treatment indicates that the altered mobility is due to phosphorylation. A preparation containing primarily the phosphorylated Pap1 has no poly(A) addition activity, but this activity is restored by phosphatase treatment. A portion of Pap1 is also polyubiquitinated concurrent with phosphorylation. However, the bulk of the 64-kDa Pap1 is a stable protein with a half-life of 14 h. The timing, nature, and extent of Pap1 modification in comparison to the mitotic phosphorylation of mammalian poly(A) polymerase suggest an intriguing difference in the cell cycle regulation of this enzyme in yeast and mammalian systems.

scholarly journals Live-cell time-lapse imaging and single-cell tracking of in vitro cultured neural stem cells – Tools for analyzing dynamics of cell cycle, migration, and lineage selection

Methods ◽  
2018 ◽  
Vol 133 ◽  
pp. 81-90 ◽  
Author(s):  
Katja M. Piltti ◽  
Brian J. Cummings ◽  
Krystal Carta ◽  
Ayla Manughian-Peter ◽  
Colleen L. Worne ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Neural Stem Cells ◽  
Single Cell ◽  
Cell Tracking ◽  
Time Lapse ◽  
Live Cell ◽  
Time Lapse Imaging

scholarly journals Cellular Ras and Cyclin D1 Are Required during Different Cell Cycle Periods in Cycling NIH 3T3 Cells

1999 ◽  
Vol 19 (7) ◽  
pp. 4623-4632 ◽  
Author(s):  
Masahiro Hitomi ◽  
Dennis W. Stacey
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Cyclin D1 ◽  
Cell Cycle Progression ◽  
Time Lapse ◽  
S Phase ◽  
3T3 Cells ◽  
Cycle Progression ◽  
Nih 3T3 ◽  
Nih 3T3 Cells

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.

scholarly journals WEE1 kinase inhibitor AZD1775 induces CDK1 kinase-dependent origin firing in unperturbed G1- and S-phase cells

2019 ◽  
Vol 116 (48) ◽  
pp. 23891-23893 ◽  
Author(s):  
Tatiana N. Moiseeva ◽  
Chenao Qian ◽  
Norie Sugitani ◽  
Hatice U. Osmanbeyoglu ◽  
Christopher J. Bakkenist
Keyword(s):  
Cell Cycle ◽  
Clinical Trials ◽  
Cell Cycle Regulation ◽  
Kinase Inhibitor ◽  
S Phase ◽  
Origin Firing ◽  
Replicative Helicase ◽  
Origin Licensing ◽  
Wee1 Kinase ◽  
Cycle Regulation

WEE1 kinase is a key regulator of the G2/M transition. The WEE1 kinase inhibitor AZD1775 (WEE1i) induces origin firing in replicating cells. We show that WEE1i induces CDK1-dependent RIF1 phosphorylation and CDK2- and CDC7-dependent activation of the replicative helicase. WEE1 suppresses CDK1 and CDK2 kinase activities to regulate the G1/S transition after the origin licensing is complete. We identify a role for WEE1 in cell cycle regulation and important effects of AZD1775, which is in clinical trials.

scholarly journals Cell Cycle Regulation by Light inProchlorococcus Strains

2001 ◽  
Vol 67 (2) ◽  
pp. 782-790 ◽  
Author(s):  
Stéphan Jacquet ◽  
Frédéric Partensky ◽  
Dominique Marie ◽  
Raffaella Casotti ◽  
Daniel Vaulot
Keyword(s):  
Cell Cycle ◽  
High Irradiance ◽  
S Phase ◽  
Low Light ◽  
Close Coupling ◽  
Cell Cycles ◽  
Flow Cytometric ◽  
Initiation Of Dna Replication ◽  
Cell Cycling ◽  
Cycle Regulation

ABSTRACT The effect of light on the synchronization of cell cycling was investigated in several strains of the oceanic photosynthetic prokaryote Prochlorococcus using flow cytometry. When exposed to a light-dark (L-D) cycle with an irradiance of 25 μmol of quanta · m−2 s−1, the low-light-adapted strain SS 120 appeared to be better synchronized than the high-light-adapted strain PCC 9511. Submitting L-D-entrained populations to shifts (advances or delays) in the timing of the “light on” signal translated to corresponding shifts in the initiation of the S phase, suggesting that this signal is a key parameter for the synchronization of population cell cycles. Cultures that were shifted from an L-D cycle to continuous irradiance showed persistent diel oscillations of flow-cytometric signals (light scatter and chlorophyll fluorescence) but with significantly reduced amplitudes and a phase shift. Complete darkness arrested most of the cells in the G1 phase of the cell cycle, indicating that light is required to trigger the initiation of DNA replication and cell division. However, some cells also arrested in the S phase, suggesting that cell cycle controls in Prochlorococcus spp. are not as strict as in marine Synechococcus spp. ShiftingProchlorococcus cells from low to high irradiance translated quasi-instantaneously into an increase of cells in both the S and G2 phases of the cell cycle and then into faster growth, whereas the inverse shift induced rapid slowing of the population growth rate. These data suggest a close coupling between irradiance levels and cell cycling in Prochlorococcus spp.

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