Cyclin B gene and its cell cycle-dependent differential expression in the toxic dinoflagellate Alexandrium fundyense Atama Group I/Clade I

Cholera and Shiga toxin bind to the cell surface via glycolipid receptors GM1 and Gb3, respectively. Surprisingly, the majority of Vero cells from a non-synchronized population bind either Cholera or Shiga toxin but not both toxins. The hypothesis that the differential expression of toxin receptors is regulated by the cell cycle was tested. We find that Cholera toxin binds preferentially in G0/G1, with little binding through S-phase to telophase,whereas Shiga toxin binds maximally through G2 to telophase but does not bind during G0/G1 and S-phase. The changes result from the corresponding changes in Gb3 and GM1 synthesis, not from variations of receptor transport to the cell surface. The changes do not reflect competition of Gb3 and GM1 synthesis for lactosylceramide. Cells as diverse as Vero cells, PC12 cells and astrocytes show the same cell-cycle-dependent regulation of glycosphingolipid receptors,suggesting that this novel phenomenon is based on a conserved regulatory mechanism.

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The RNA Binding Activity of a Ribosome Biogenesis Factor, Nucleophosmin/B23, Is Modulated by Phosphorylation with a Cell Cycle-dependent Kinase and by Association with Its Subtype

Molecular Biology of the Cell ◽

10.1091/mbc.02-03-0036 ◽

2002 ◽

Vol 13 (6) ◽

pp. 2016-2030 ◽

Cited By ~ 120

Author(s):

Mitsuru Okuwaki ◽

Masafumi Tsujimoto ◽

Kyosuke Nagata

Keyword(s):

Cell Cycle ◽

Ribosome Biogenesis ◽

Cellular Localization ◽

Rna Binding ◽

Intracellular Localization ◽

Binding Activity ◽

Cyclin B ◽

Cycle Dependent

Nucleophosmin/B23 is a nucleolar phosphoprotein. It has been shown that B23 binds to nucleic acids, digests RNA, and is localized in nucleolar granular components from which preribosomal particles are transported to cytoplasm. The intracellular localization of B23 is significantly changed during the cell cycle. Here, we have examined the cellular localization of B23 proteins and the effect of mitotic phosphorylation of B23.1 on its RNA binding activity. Two splicing variants of B23 proteins, termed B23.1 and B23.2, were complexed both in vivo and in vitro. The RNA binding activity of B23.1 was impaired by hetero-oligomer formation with B23.2. Both subtypes of B23 proteins were phosphorylated during mitosis by cyclin B/cdc2. The RNA binding activity of B23.1 was repressed through cyclin B/cdc2-mediated phosphorylation at specific sites in B23. Thus, the RNA binding activity of B23.1 is stringently modulated by its phosphorylation and subtype association. Interphase B23.1 was mainly localized in nucleoli, whereas B23.2 and mitotic B23.1, those of which were incapable of binding to RNA, were dispersed throughout the nucleoplasm and cytoplasm, respectively. These results suggest that nucleolar localization of B23.1 is mediated by its ability to associate with RNA.

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Cell Cycle-dependent Regulation of Structure of Endoplasmic Reticulum and Inositol 1,4,5-Trisphosphate-induced Ca2+ Release in Mouse Oocytes and Embryos

Molecular Biology of the Cell ◽

10.1091/mbc.e02-07-0431 ◽

2003 ◽

Vol 14 (1) ◽

pp. 288-301 ◽

Cited By ~ 50

Author(s):

Greg FitzHarris ◽

Petros Marangos ◽

John Carroll

Keyword(s):

Cell Cycle ◽

Endoplasmic Reticulum ◽

Mitotic Spindle ◽

Mitotic Division ◽

Cyclin B ◽

Dependent Manner ◽

Inositol 1,4,5 Trisphosphate ◽

A Cell ◽

Cycle Dependent ◽

Mouse Eggs

The organization of endoplasmic reticulum (ER) was examined in mouse eggs undergoing fertilization and in embryos during the first cell cycle. The ER in meiosis II (MII)-arrested mouse eggs is characterized by accumulations (clusters) that are restricted to the cortex of the vegetal hemisphere of the egg. Monitoring ER structure with DiI18 after egg activation has demonstrated that ER clusters disappear at the completion of meiosis II. The ER clusters can be maintained by inhibiting the decrease in cdk1-cyclin B activity by using the proteasome inhibitor MG132, or by microinjecting excess cyclin B. A role for cdk1-cyclin B in ER organization is further suggested by the finding that the cdk inhibitor roscovitine causes the loss of ER clusters in MII eggs. Cortical clusters are specific to meiosis as they do not return in the first mitotic division; rather, the ER aggregates around the mitotic spindle. Inositol 1,4,5-trisphosphate-induced Ca2+ release is also regulated in a cell cycle-dependent manner where it is increased in MII and in the first mitosis. The cell cycle dependent effects on ER structure and inositol 1,4,5-trisphosphate-induced Ca2+ release have implications for understanding meiotic and mitotic control of ER structure and inheritance, and of the mechanisms regulating mitotic Ca2+signaling.

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Deacetylation of catalytic lysine in CDK1 is essential for Cyclin-B binding and cell cycle

10.1101/420000 ◽

2018 ◽

Author(s):

Shaunak Deota ◽

Sivasudhan Rathnachalam ◽

Kanojia Namrata ◽

Mayank Boob ◽

Amit Fulzele ◽

...

Keyword(s):

Cell Cycle ◽

High Resolution ◽

Cell Cycle Progression ◽

Molecular Mechanisms ◽

Current Model ◽

Cyclin B ◽

Cycle Progression ◽

Cyclin Dependent Kinases ◽

Evolutionarily Conserved ◽

Cycle Dependent

AbstractCyclin-dependent-kinases (CDKs) are essential for cell cycle progression. While dependence of CDK activity on Cyclin levels is established, molecular mechanisms that regulate their binding are less studied. Here, we show that CDKl:Cyclin-B interactions are regulated by acetylation, which was hitherto unknown. We demonstrate that cell cycle dependent acetylation of the evolutionarily conserved catalytic lysine in CDK1 or eliminating its charge state abrogates Cyclin-B binding. Opposing activities of SIRT1 and P300 regulate acetylation, which marks a reserved pool of CDK1. Our high resolution structural analyses into the formation of kinase competent CDK1: Cyclin-B complex have unveiled long-range effects of catalytic lysine in configuring the CDK1 interface for Cyclin-B binding. Cells expressing acetylation mimic mutant of Cdc2 in yeast are arrested in G2 and fail to divide. Thus, by illustrating cell cycle dependent deacetylation as a determinant of CDK1:Cyclin-B interaction, our results redefine the current model of CDK1 activation and cell cycle progression.

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Katanin Is Responsible for the M-Phase Microtubule-severing Activity in Xenopus Eggs

Molecular Biology of the Cell ◽

10.1091/mbc.9.7.1847 ◽

1998 ◽

Vol 9 (7) ◽

pp. 1847-1861 ◽

Cited By ~ 78

Author(s):

Francis J. McNally ◽

Susan Thomas

Keyword(s):

Cell Cycle ◽

Human Fibroblasts ◽

Cyclin B ◽

Microtubule Severing ◽

Spindle Poles ◽

M Phase ◽

Egg Extracts ◽

Dynamic Structures ◽

Cycle Dependent ◽

Xenopus Egg Extracts

Microtubules are dynamic structures whose proper rearrangement during the cell cycle is essential for the positioning of membranes during interphase and for chromosome segregation during mitosis. The previous discovery of a cyclin B/cdc2-activated microtubule-severing activity in M-phase Xenopus egg extracts suggested that a microtubule-severing protein might play an important role in cell cycle-dependent changes in microtubule dynamics and organization. However, the isolation of three different microtubule-severing proteins, p56, EF1α, and katanin, has only confused the issue because none of these proteins is directly activated by cyclin B/cdc2. Here we use immunodepletion with antibodies specific for a vertebrate katanin homologue to demonstrate that katanin is responsible for the majority of M-phase severing activity inXenopus eggs. This result suggests that katanin is responsible for changes in microtubules occurring at mitosis. Immunofluorescence analysis demonstrated that katanin is concentrated at a microtubule-dependent structure at mitotic spindle poles inXenopus A6 cells and in human fibroblasts, suggesting a specific role in microtubule disassembly at spindle poles. Surprisingly, katanin was also found in adult mouse brain, indicating that katanin may have other functions distinct from its mitotic role.

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Differential expression of human replacement and cell cycle dependent H3 histone genes

Gene ◽

10.1016/s0378-1119(03)00609-7 ◽

2003 ◽

Vol 312 ◽

pp. 135-143 ◽

Cited By ~ 43

Author(s):

Derk Frank ◽

Detlef Doenecke ◽

Werner Albig

Keyword(s):

Cell Cycle ◽

Differential Expression ◽

Histone Genes ◽

Cycle Dependent

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Identification and Characterization of Three Differentially Expressed Genes, Encoding S-Adenosylhomocysteine Hydrolase, Methionine Aminopeptidase, and a Histone-Like Protein, in the Toxic Dinoflagellate Alexandrium fundyense

Applied and Environmental Microbiology ◽

10.1128/aem.66.5.2105-2112.2000 ◽

2000 ◽

Vol 66 (5) ◽

pp. 2105-2112 ◽

Cited By ~ 64

Author(s):

Gaspar Taroncher-Oldenburg ◽

Donald M. Anderson

Keyword(s):

Cell Cycle ◽

Amino Acid ◽

Small Sample ◽

Amino Acid Sequences ◽

Methionine Aminopeptidase ◽

Toxic Dinoflagellate ◽

Alexandrium Fundyense ◽

Adenosylhomocysteine Hydrolase ◽

Experimental Constraint ◽

Genes Encoding

ABSTRACT Genes showing differential expression related to the early G1 phase of the cell cycle during synchronized circadian growth of the toxic dinoflagellate Alexandrium fundyensewere identified and characterized by differential display (DD). The determination in our previous work that toxin production inAlexandrium is relegated to a narrow time frame in early G1 led to the hypothesis that transcriptionally up- or downregulated genes during this subphase of the cell cycle might be related to toxin biosynthesis. Three genes, encodingS-adenosylhomocysteine hydrolase (Sahh), methionine aminopeptidase (Map), and a histone-like protein (HAf), were isolated. Sahh was downregulated, while Map and HAf were upregulated, during the early G1 phase of the cell cycle. Sahh andMap encoded amino acid sequences with about 90 and 70% similarity to those encoded by several eukaryotic and prokaryoticSahh and Map genes, respectively. The partialMap sequence also contained three cobalt binding motifs characteristic of all Map genes. HAf encoded an amino acid sequence with 60% similarity to those of two histone-like proteins from the dinoflagellate Crypthecodinium cohniiBiecheler. This study documents the potential of applying DD to the identification of genes that are related to physiological processes or cell cycle events in phytoplankton under conditions where small sample volumes represent an experimental constraint. The identification of an additional 21 genes with various cell cycle-related DD patterns also provides evidence for the importance of pretranslational or transcriptional regulation in dinoflagellates, contrary to previous reports suggesting the possibility that translational mechanisms are the primary means of circadian regulation in this group of organisms.

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