The Saccharomyces cerevisiae Telomerase Subunit Est3 Binds Telomeres in a Cell Cycle– and Est1–Dependent Manner and Interacts Directly with Est1 In Vitro

Mature mouse oocytes are arrested at metaphase of the second meiotic division. Completion of meiosis and a block to polyspermy is caused by a series of repetitive Ca2+ transients triggered by the sperm at fertilization. These Ca2+ transients have been widely reported to last for a number of hours but when, or why, they cease is not known. Here we show that Ca2+ transients cease during entry into interphase, at the time when pronuclei are forming. In fertilized oocytes arrested at metaphase using colcemid, Ca2+ transients continued for as long as measurements were made, up to 18 hours after fertilization. Therefore sperm is able to induce Ca2+ transients during metaphase but not during interphase. In addition metaphase II oocytes, but not pronuclear stage 1-cell embryos showed highly repetitive Ca2+ oscillations in response to microinjection of inositol trisphosphate. This was explored further by treating in vitro maturing oocytes at metaphase I for 4–5 hours with cycloheximide, which induced nuclear progression to interphase (nucleus formation) and subsequent re-entry to metaphase (nuclear envelope breakdown). Fertilization of cycloheximide-treated oocytes revealed that continuous Ca2+ oscillations in response to sperm were observed after nuclear envelope breakdown but not during interphase. However interphase oocytes were able to generate Ca2+ transients in response to thimerosal. This data suggests that the ability of the sperm to trigger repetitive Ca2+ transients in oocytes is modulated in a cell cycle-dependent manner.

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Induction of a Mitosis Delay and Cell Lysis by High-Level Secretion of Mouse α-Amylase from Saccharomyces cerevisiae

Applied and Environmental Microbiology ◽

10.1128/aem.67.8.3693-3701.2001 ◽

2001 ◽

Vol 67 (8) ◽

pp. 3693-3701 ◽

Cited By ~ 3

Author(s):

Bi-Dar Wang ◽

Tsong-Teh Kuo

Keyword(s):

Saccharomyces Cerevisiae ◽

Cell Cycle ◽

Phosphorylation Site ◽

Cell Lysis ◽

Dependent Manner ◽

Foreign Proteins ◽

Phosphatase 2A ◽

A Cell ◽

Cycle Dependent ◽

High Level

ABSTRACT Some foreign proteins are produced in yeast in a cell cycle-dependent manner, but the cause of the cell cycle dependency is unknown. In this study, we found that Saccharomyces cerevisiae cells secreting high levels of mouse α-amylase have elongated buds and are delayed in cell cycle completion in mitosis. The delayed cell mitosis suggests that critical events during exit from mitosis might be disturbed. We found that the activities of PP2A (protein phosphatase 2A) and MPF (maturation-promoting factor) were reduced in α-amylase-oversecreting cells and that these cells showed a reduced level of assembly checkpoint protein Cdc55, compared to the accumulation in wild-type cells. MPF inactivation is due to inhibitory phosphorylation on Cdc28, as a cdc28mutant which lacks an inhibitory phosphorylation site on Cdc28 prevents MPF inactivation and prevents the defective bud morphology induced by overproduction of α-amylase. Our data also suggest that high levels of α-amylase may downregulate PPH22,leading to cell lysis. In conclusion, overproduction of heterologous α-amylase in S. cerevisiaeresults in a negative regulation of PP2A, which causes mitotic delay and leads to cell lysis.

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NSun2 Promotes Cell Growth via Elevating Cyclin-Dependent Kinase 1 Translation

Molecular and Cellular Biology ◽

10.1128/mcb.00742-15 ◽

2015 ◽

Vol 35 (23) ◽

pp. 4043-4052 ◽

Cited By ~ 38

Author(s):

Junyue Xing ◽

Jie Yi ◽

Xiaoyu Cai ◽

Hao Tang ◽

Zhenyun Liu ◽

...

Keyword(s):

Cell Cycle ◽

Cell Division ◽

Cell Division Cycle ◽

Mrna Levels ◽

Dependent Manner ◽

Cyclin Dependent Kinase ◽

A Cell ◽

Cycle Dependent ◽

Insight Into

The tRNA methytransferase NSun2 promotes cell proliferation, but the molecular mechanism has not been elucidated. Here, we report that NSun2 regulates cyclin-dependent kinase 1 (CDK1) expression in a cell cycle-dependent manner. Knockdown of NSun2 decreased the CDK1 protein level, while overexpression of NSun2 elevated it without alteringCDK1mRNA levels. Further studies revealed that NSun2 methylatedCDK1mRNAin vitroand in cells and that methylation by NSun2 enhanced CDK1 translation. Importantly, NSun2-mediated regulation of CDK1 expression had an impact on the cell division cycle. These results provide new insight into the regulation of CDK1 during the cell division cycle.

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A cell cycle kinase-phosphatase module restrains PI3K-Akt activity in an mTORC1-dependent manner

10.1101/2020.11.26.399915 ◽

2020 ◽

Author(s):

Belén Sanz-Castillo ◽

Begoña Hurtado ◽

Aicha El Bakkali ◽

Dario Hermida ◽

Beatriz Salvador-Barbero ◽

...

Keyword(s):

Cell Cycle ◽

Cell Growth ◽

Glucose Tolerance ◽

Feedback Loop ◽

Dependent Manner ◽

Adult Mice ◽

A Cell ◽

Mtor Activity ◽

Cell Cycle Kinase

AbstractThe AKT-mTOR pathway is a central regulator of cell growth and metabolism. Upon sustained mTOR activity, AKT activity is attenuated by a feedback loop that restrains upstream signaling. However, how cells control the signals that limit AKT activity is not fully understood. Here we show that MASTL/Greatwall, a cell-cycle kinase that supports mitosis by phosphorylating the PP2A/B55 inhibitors ENSA/ARPP19, inhibits PI3K-AKT activity by sustaining mTORC1- and S6K1-dependent phosphorylation of IRS1 and GRB10. Genetic depletion of MASTL results in an inefficient feedback loop and AKT hyperactivity. These defects are rescued by expression of phospho-mimetic ENSA/ARPP19 or inhibition of PP2A/B55 phosphatases. MASTL is directly phosphorylated by mTORC1, thereby limiting the PP2A/B55-dependent dephosphorylation of IRS1 and GRB10 downstream of mTORC1. Downregulation of MASTL results in increased glucose uptake in vitro and increased glucose tolerance in adult mice, suggesting the relevance of the MASTL-PP2A/B55 kinase-phosphatase module in controlling AKT and maintaining metabolic homeostasis.

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Cell Cycle-Dependent Regulation of Human DNA Polymerase α-Primase Activity by Phosphorylation

Molecular and Cellular Biology ◽

10.1128/mcb.19.1.646 ◽

1999 ◽

Vol 19 (1) ◽

pp. 646-656 ◽

Cited By ~ 53

Author(s):

Christian Voitenleitner ◽

Christoph Rehfuess ◽

Melissa Hilmes ◽

Lynda O’Rear ◽

Pao-Chi Liao ◽

...

Keyword(s):

Cell Cycle ◽

Dna Polymerase ◽

Cyclin E ◽

Cyclin A ◽

Human Cells ◽

Dependent Manner ◽

Dna Polymerase Α ◽

A Cell ◽

Cycle Dependent

ABSTRACT DNA polymerase α-primase is known to be phosphorylated in human and yeast cells in a cell cycle-dependent manner on the p180 and p68 subunits. Here we show that phosphorylation of purified human DNA polymerase α-primase by purified cyclin A/cdk2 in vitro reduced its ability to initiate simian virus 40 (SV40) DNA replication in vitro, while phosphorylation by cyclin E/cdk2 stimulated its initiation activity. Tryptic phosphopeptide mapping revealed a family of p68 peptides that was modified well by cyclin A/cdk2 and poorly by cyclin E/cdk2. The p180 phosphopeptides were identical with both kinases. By mass spectrometry, the p68 peptide family was identified as residues 141 to 160. Cyclin A/cdk2- and cyclin A/cdc2-modified p68 also displayed a phosphorylation-dependent shift to slower electrophoretic mobility. Mutation of the four putative phosphorylation sites within p68 peptide residues 141 to 160 prevented its phosphorylation by cyclin A/cdk2 and the inhibition of replication activity. Phosphopeptide maps of the p68 subunit of DNA polymerase α-primase from human cells, synchronized and labeled in G1/S and in G2, revealed a cyclin E/cdk2-like pattern in G1/S and a cyclin A/cdk2-like pattern in G2. The slower-electrophoretic-mobility form of p68 was absent in human cells in G1/S and appeared as the cells entered G2/M. Consistent with this, the ability of DNA polymerase α-primase isolated from synchronized human cells to initiate SV40 replication was maximal in G1/S, decreased as the cells completed S phase, and reached a minimum in G2/M. These results suggest that the replication activity of DNA polymerase α-primase in human cells is regulated by phosphorylation in a cell cycle-dependent manner.

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Regulation of Melanosome Movement in the Cell Cycle by Reversible Association with Myosin V

The Journal of Cell Biology ◽

10.1083/jcb.146.6.1265 ◽

1999 ◽

Vol 146 (6) ◽

pp. 1265-1276 ◽

Cited By ~ 105

Author(s):

Stephen L. Rogers ◽

Ryan L. Karcher ◽

Joseph T. Roland ◽

Alexander A. Minin ◽

Walter Steffen ◽

...

Keyword(s):

Cell Cycle ◽

Actin Filaments ◽

Organelle Transport ◽

Dependent Manner ◽

Myosin V ◽

In Vitro Motility ◽

Egg Extracts ◽

A Cell ◽

Cycle Dependent

Previously, we have shown that melanosomes of Xenopus laevis melanophores are transported along both microtubules and actin filaments in a coordinated manner, and that myosin V is bound to purified melanosomes (Rogers, S., and V.I. Gelfand. 1998. Curr. Biol. 8:161–164). In the present study, we have demonstrated that myosin V is the actin-based motor responsible for melanosome transport. To examine whether myosin V was regulated in a cell cycle-dependent manner, purified melanosomes were treated with interphase- or metaphase-arrested Xenopus egg extracts and assayed for in vitro motility along Nitella actin filaments. Motility of organelles treated with mitotic extract was found to decrease dramatically, as compared with untreated or interphase extract-treated melanosomes. This mitotic inhibition of motility correlated with the dissociation of myosin V from melanosomes, but the activity of soluble motor remained unaffected. Furthermore, we find that myosin V heavy chain is highly phosphorylated in metaphase extracts versus interphase extracts. We conclude that organelle transport by myosin V is controlled by a cell cycle-regulated association of this motor to organelles, and that this binding is likely regulated by phosphorylation of myosin V during mitosis.

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PapRIV, a BV-2 microglial cell activating quorum sensing peptide

Scientific Reports ◽

10.1038/s41598-021-90030-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yorick Janssens ◽

Nathan Debunne ◽

Anton De Spiegeleer ◽

Evelien Wynendaele ◽

Marta Planas ◽

...

Keyword(s):

Quorum Sensing ◽

Cell Model ◽

Dependent Manner ◽

Communication Signals ◽

Gram Positive Bacteria ◽

A Cell ◽

Gastro Intestinal Tract

AbstractQuorum sensing peptides (QSPs) are bacterial peptides produced by Gram-positive bacteria to communicate with their peers in a cell-density dependent manner. These peptides do not only act as interbacterial communication signals, but can also have effects on the host. Compelling evidence demonstrates the presence of a gut-brain axis and more specifically, the role of the gut microbiota in microglial functioning. The aim of this study is to investigate microglial activating properties of a selected QSP (PapRIV) which is produced by Bacillus cereus species. PapRIV showed in vitro activating properties of BV-2 microglia cells and was able to cross the in vitro Caco-2 cell model and reach the brain. In vivo peptide presence was also demonstrated in mouse plasma. The peptide caused induction of IL-6, TNFα and ROS expression and increased the fraction of ameboid BV-2 microglia cells in an NF-κB dependent manner. Different metabolites were identified in serum, of which the main metabolite still remained active. PapRIV is thus able to cross the gastro-intestinal tract and the blood–brain barrier and shows in vitro activating properties in BV-2 microglia cells, hereby indicating a potential role of this quorum sensing peptide in gut-brain interaction.

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The Olive Leaves Extract Has Anti-Tumor Effects against Neuroblastoma through Inhibition of Cell Proliferation and Induction of Apoptosis

Nutrients ◽

10.3390/nu13072178 ◽

2021 ◽

Vol 13 (7) ◽

pp. 2178

Author(s):

Fabio Morandi ◽

Veronica Bensa ◽

Enzo Calarco ◽

Fabio Pastorino ◽

Patrizia Perri ◽

...

Keyword(s):

Cell Cycle ◽

Cell Proliferation ◽

Cell Viability ◽

Cell Cycle Progression ◽

Treatment Strategies ◽

Annexin V ◽

Dependent Manner ◽

Induction Of Apoptosis ◽

Dose Dependent

Neuroblastoma (NB) is the most common extra-cranial solid tumor of pediatric age. The prognosis for high-risk NB patients remains poor, and new treatment strategies are desirable. The olive leaf extract (OLE) is constituted by phenolic compounds, whose health beneficial effects were reported. Here, the anti-tumor effects of OLE were investigated in vitro on a panel of NB cell lines in terms of (i) reduction of cell viability; (ii) inhibition of cell proliferation through cell cycle arrest; (iii) induction of apoptosis; and (iv) inhibition of cell migration. Furthermore, cytotoxicity experiments, by combining OLE with the chemotherapeutic topotecan, were also performed. OLE reduced the cell viability of NB cells in a time- and dose-dependent manner in 2D and 3D models. NB cells exposed to OLE underwent inhibition of cell proliferation, which was characterized by an arrest of the cell cycle progression in G0/G1 phase and by the accumulation of cells in the sub-G0 phase, which is peculiar of apoptotic death. This was confirmed by a dose-dependent increase of Annexin V+ cells (peculiar of apoptosis) and upregulation of caspases 3 and 7 protein levels. Moreover, OLE inhibited the migration of NB cells. Finally, the anti-tumor efficacy of the chemotherapeutic topotecan, in terms of cell viability reduction, was greatly enhanced by its combination with OLE. In conclusion, OLE has anti-tumor activity against NB by inhibiting cell proliferation and migration and by inducing apoptosis.

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Truncated APC regulates the transcriptional activity of β-catenin in a cell cycle dependent manner

Human Molecular Genetics ◽

10.1093/hmg/ddl464 ◽

2006 ◽

Vol 16 (2) ◽

pp. 199-209 ◽

Cited By ~ 38

Author(s):

Jean Schneikert ◽

Annette Grohmann ◽

Jürgen Behrens

Keyword(s):

Cell Cycle ◽

Transcriptional Activity ◽

Dependent Manner ◽

A Cell ◽

Cycle Dependent

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The Xenopus protein kinase pEg2 associates with the centrosome in a cell cycle-dependent manner, binds to the spindle microtubules and is involved in bipolar mitotic spindle assembly

Journal of Cell Science ◽

10.1242/jcs.111.5.557 ◽

1998 ◽

Vol 111 (5) ◽

pp. 557-572 ◽

Cited By ~ 19

Author(s):

C. Roghi ◽

R. Giet ◽

R. Uzbekov ◽

N. Morin ◽

I. Chartrain ◽

...

Keyword(s):

Cell Cycle ◽

Protein Kinase ◽

Mitotic Spindle ◽

Cultured Cells ◽

Dependent Manner ◽

Egg Extracts ◽

Pericentriolar Material ◽

Spindle Microtubules ◽

Cycle Dependent

By differential screening of a Xenopus laevis egg cDNA library, we have isolated a 2,111 bp cDNA which corresponds to a maternal mRNA specifically deadenylated after fertilisation. This cDNA, called Eg2, encodes a 407 amino acid protein kinase. The pEg2 sequence shows significant identity with members of a new protein kinase sub-family which includes Aurora from Drosophila and Ipl1 (increase in ploidy-1) from budding yeast, enzymes involved in centrosome migration and chromosome segregation, respectively. A single 46 kDa polypeptide, which corresponds to the deduced molecular mass of pEg2, is immunodetected in Xenopus oocyte and egg extracts, as well as in lysates of Xenopus XL2 cultured cells. In XL2 cells, pEg2 is immunodetected only in S, G2 and M phases of the cell cycle, where it always localises to the centrosomal region of the cell. In addition, pEg2 ‘invades’ the microtubules at the poles of the mitotic spindle in metaphase and anaphase. Immunoelectron microscopy experiments show that pEg2 is located precisely around the pericentriolar material in prophase and on the spindle microtubules in anaphase. We also demonstrate that pEg2 binds directly to taxol stabilised microtubules in vitro. In addition, we show that the presence of microtubules during mitosis is not necessary for an association between pEg2 and the centrosome. Finally we show that a catalytically inactive pEg2 kinase stops the assembly of bipolar mitotic spindles in Xenopus egg extracts.

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