scholarly journals Nuclear size, nuclear pore number and cell cycle

Nucleus ◽  
2011 ◽  
Vol 2 (2) ◽  
pp. 113-118 ◽  
Author(s):  
Kazuhiro Maeshima ◽  
Haruki Iino ◽  
Saera Hihara ◽  
Naoko Imamoto
Keyword(s):  
Cell Cycle ◽  
Nuclear Size ◽  
Nuclear Pore ◽  
Pore Number

scholarly journals EFFECT OF METABOLIC INHIBITORS ON NUCLEAR PORE FORMATION DURING THE HELA S3 CELL CYCLE

1973 ◽  
Vol 59 (3) ◽  
pp. 669-676 ◽  
Author(s):  
Helmut M. Maul ◽  
Betty Yee Li Hsu ◽  
Thaddeus M. Borun ◽  
Gerd G. Maul
Keyword(s):  
Cell Cycle ◽  
Pore Formation ◽  
Atp Synthesis ◽  
Nuclear Size ◽  
Size Increase ◽  
Metabolic Inhibitors ◽  
Nuclear Pore ◽  
Nuclear Surface ◽  
Etching Technique ◽  
Hela S3

The effect of various antimetabolites on nuclear pore formation was studied in synchronized HeLa S3 cells. The nuclear size was determined by light microscopy and the pore number per unit area of nuclear surface by the freeze-etching technique and electron microscopy. It was found that the inhibition of DNA replication or ribosomal RNA synthesis has no effect on nuclear size increase or pore formation. However, the inhibition of ATP synthesis effectively stops nuclear pore formation. Cycloheximide blocks nuclear pore formation at the same time during G1 phase of the cell cycle when nuclear size increase is blocked by high concentrations of actinomycin D. This suggests that certain proteins or other factors leading to pore formation and nuclear size increase are transcribed and synthesized at about 3–4 h after mitosis, i.e., about 1–2 h before S phase begins.

scholarly journals A Novel Class of RanGTP Binding Proteins

1997 ◽  
Vol 138 (1) ◽  
pp. 65-80 ◽  
Author(s):  
Dirk Görlich ◽  
Marylena Dabrowski ◽  
F. Ralf Bischoff ◽  
Ulrike Kutay ◽  
Peer Bork ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nuclear Import ◽  
Cell Cycle Progression ◽  
Binding Proteins ◽  
Nuclear Pore ◽  
Sequence Motif ◽  
Nucleotide Exchange ◽  
Direct Function ◽  
Entire Class ◽  
Dependent Transport

The importin-α/β complex and the GTPase Ran mediate nuclear import of proteins with a classical nuclear localization signal. Although Ran has been implicated also in a variety of other processes, such as cell cycle progression, a direct function of Ran has so far only been demonstrated for importin-mediated nuclear import. We have now identified an entire class of ∼20 potential Ran targets that share a sequence motif related to the Ran-binding site of importin-β. We have confirmed specific RanGTP binding for some of them, namely for two novel factors, RanBP7 and RanBP8, for CAS, Pse1p, and Msn5p, and for the cell cycle regulator Cse1p from Saccharomyces cerevisiae. We have studied RanBP7 in more detail. Similar to importin-β, it prevents the activation of Ran's GTPase by RanGAP1 and inhibits nucleotide exchange on RanGTP. RanBP7 binds directly to nuclear pore complexes where it competes for binding sites with importin-β, transportin, and apparently also with the mediators of mRNA and U snRNA export. Furthermore, we provide evidence for a Ran-dependent transport cycle of RanBP7 and demonstrate that RanBP7 can cross the nuclear envelope rapidly and in both directions. On the basis of these results, we propose that RanBP7 might represent a nuclear transport factor that carries an as yet unknown cargo, which could apply as well for this entire class of related RanGTP-binding proteins.

Cell Cycle-Dependent Phosphorylation of Nucleoporins and Nuclear Pore Membrane Protein Gp210†

Biochemistry ◽  
1996 ◽  
Vol 35 (24) ◽  
pp. 8035-8044 ◽  
Author(s):  
Catherine Favreau ◽  
Howard J. Worman ◽  
Richard W. Wozniak ◽  
Thierry Frappier ◽  
Jean-Claude Courvalin
Keyword(s):  
Cell Cycle ◽  
Membrane Protein ◽  
Nuclear Pore ◽  
Cycle Dependent

scholarly journals TIME SEQUENCE OF NUCLEAR PORE FORMATION IN PHYTOHEMAGGLUTININ-STIMULATED LYMPHOCYTES AND IN HELA CELLS DURING THE CELL CYCLE

1972 ◽  
Vol 55 (2) ◽  
pp. 433-447 ◽  
Author(s):  
Gerd G. Maul ◽  
Helmut M. Maul ◽  
Joseph E. Scogna ◽  
Michael W. Lieberman ◽  
Gary S. Stein ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Hela Cells ◽  
Pore Formation ◽  
Human Lymphocytes ◽  
Time Sequence ◽  
S Phase ◽  
Nuclear Pore ◽  
Nuclear Surface ◽  
Nuclear Pores

The time sequence of nuclear pore frequency changes was determined for phytohemagglutinin (PHA)-stimulated human lymphocytes and for HeLa S-3 cells during the cell cycle. The number of nuclear pores/nucleus was calculated from the experimentally determined values of nuclear pores/µ2 and the nuclear surface. In the lymphocyte system the number of pores/nucleus approximately doubles during the 48 hr after PHA stimulation. The increase in pore frequency is biphasic and the first increase seems to be related to an increase in the rate of protein synthesis. The second increase in pores/nucleus appears to be correlated with the onset of DNA synthesis. In the HeLa cell system, we could also observe a biphasic change in pore formation. Nuclear pores are formed at the highest rate during the first hour after mitosis. A second increase in the rate of pore formation corresponds in time with an increase in the rate of nuclear acidic protein synthesis shortly before S phase. The total number of nuclear pores in HeLa cells doubles from ∼2000 in G1 to ∼4000 at the end of the cell cycle. The doubling of the nuclear volume and the number of nuclear pores might be correlated to the doubling of DNA content. Another correspondence with the nuclear pore number in S phase is found in the number of simultaneously replicating replication sites. This number may be fortuitous but leads to the rather speculative possibility that the nuclear pore might be the site of initiation and/or replication of DNA as well as the site of nucleocytoplasmic exchange. That is, the nuclear pore complex may have multiple functions.

scholarly journals Cdk Phosphorylation of a Nucleoporin Controls Localization of Active Genes through the Cell Cycle

2010 ◽  
Vol 21 (19) ◽  
pp. 3421-3432 ◽  
Author(s):  
Donna Garvey Brickner ◽  
Jason H. Brickner
Keyword(s):  
Cell Cycle ◽  
Nuclear Periphery ◽  
S Phase ◽  
Nuclear Pore ◽  
Cdk Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Initiation Of Dna Replication ◽  
Cdk Phosphorylation ◽  
Inducible Genes ◽  
Active Genes

Many inducible genes in yeast are targeted to the nuclear pore complex when active. We find that the peripheral localization of the INO1 and GAL1 genes is regulated through the cell cycle. Active INO1 and GAL1 localized at the nuclear periphery during G1, became nucleoplasmic during S-phase, and then returned to the nuclear periphery during G2/M. Loss of peripheral targeting followed the initiation of DNA replication and was lost in cells lacking a cyclin-dependent kinase (Cdk) inhibitor. Furthermore, the Cdk1 kinase and two Cdk phosphorylation sites in the nucleoporin Nup1 were required for peripheral targeting of INO1 and GAL1. Introduction of aspartic acid residues in place of either of these two sites in Nup1 bypassed the requirement for Cdk1 and resulted in targeting of INO1 and GAL1 to the nuclear periphery during S-phase. Thus, phosphorylation of a nuclear pore component by cyclin dependent kinase controls the localization of active genes to the nuclear periphery through the cell cycle.

Sex Chromatin, Nuclear Size and the Cell Cycle

1967 ◽  
Vol 6 (2) ◽  
pp. 120-144 ◽  
Author(s):  
D.E. Comings
Keyword(s):  
Cell Cycle ◽  
Nuclear Size ◽  
Sex Chromatin

scholarly journals Mitotic regulation of fungal cell-to-cell connectivity through septal pores involves the NIMA kinase

2014 ◽  
Vol 25 (6) ◽  
pp. 763-775 ◽  
Author(s):  
Kuo-Fang Shen ◽  
Aysha H. Osmani ◽  
Meera Govindaraghavan ◽  
Stephen A. Osmani
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Nuclear Pore ◽  
Fungal Cell ◽  
Intercellular Bridges ◽  
Dynamic Cell ◽  
Associated Proteins ◽  
Multicellular Organisms ◽  
Mitotic Regulation ◽  
Septal Pores

Intercellular bridges are a conserved feature of multicellular organisms. In multicellular fungi, cells are connected directly via intercellular bridges called septal pores. Using Aspergillus nidulans, we demonstrate for the first time that septal pores are regulated to be opened during interphase but closed during mitosis. Septal pore–associated proteins display dynamic cell cycle–regulated locations at mature septa. Of importance, the mitotic NIMA kinase locates to forming septa and surprisingly then remains at septa throughout interphase. However, during mitosis, when NIMA transiently locates to nuclei to promote mitosis, its levels at septa drop. A model is proposed in which NIMA helps keep septal pores open during interphase and then closed when it is removed from them during mitosis. In support of this hypothesis, NIMA inactivation is shown to promote interphase septal pore closing. Because NIMA triggers nuclear pore complex opening during mitosis, our findings suggest that common cell cycle regulatory mechanisms might control septal pores and nuclear pores such that they are opened and closed out of phase to each other during cell cycle progression. The study provides insights into how and why cytoplasmically connected Aspergillus cells maintain mitotic autonomy.

scholarly journals Spatial control of nucleoporin assembly by Fragile X-related proteins

2019 ◽  
Author(s):  
Arantxa Agote-Arán ◽  
Stephane Schmucker ◽  
Katerina Jerabkova ◽  
Inès Jmel Boyer ◽  
Alessandro Berto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
Fragile X Syndrome ◽  
Cell Cycle Progression ◽  
Fragile X ◽  
Nuclear Pore ◽  
Nuclear Morphology ◽  
Nuclear Pore Complexes ◽  
Cycle Progression ◽  
Pore Complexes

SummaryNucleoporins (Nups) build highly organized Nuclear Pore Complexes (NPCs) at the nuclear envelope (NE). Several Nups assemble into a sieve-like hydrogel within the central channel of the NPCs to regulate nucleocytoplasmic exchange. In the cytoplasm, a large excess of soluble Nups has been reported, but how their assembly is restricted to the NE is currently unknown. Here we show that Fragile X-related protein 1 (FXR1) can interact with several Nups and facilitate their localization to the NE during interphase through a microtubule and dynein-dependent mechanism. Downregulation of FXR1 or closely related orthologs FXR2 and Fragile X mental retardation protein (FMRP) leads to the accumulation of cytoplasmic Nup protein condensates. Likewise, several models of Fragile X syndrome (FXS), characterized by a loss of FMRP, also accumulate cytoplasmic Nup aggregates. These aggregate-containing cells display aberrant nuclear morphology and a delay in G1 cell cycle progression. Our results reveal an unexpected role for the FXR protein family and dynein in the spatial regulation of nucleoporin assembly.HighlightsCytoplasmic nucleoporins are assembled by Fragile X-related (FXR) proteins and dyneinFXR-Dynein pathway downregulation induces aberrant cytoplasmic aggregation of nucleoporinsCellular models of Fragile X syndrome accumulate aberrant cytoplasmic nucleoporin aggregates.FXR-Dynein pathway regulates nuclear morphology and G1 cell cycle progressioneTOC BlurbNucleoporins (Nups) form Nuclear Pore Complexes (NPCs) at the nuclear envelope. Agote-Arán at al. show how cells inhibit aberrant assembly of Nups in the cytoplasm and identify Fragile X-related (FXR) proteins and dynein that facilitate localization of Nups to the nuclear envelope and control G1 cell cycle progression.Graphical abstract

Dynamics of nuclear pore complex organization through the cell cycle

2004 ◽  
Vol 16 (3) ◽  
pp. 314-321 ◽  
Author(s):  
Gwénaël Rabut ◽  
Péter Lénárt ◽  
Jan Ellenberg
Keyword(s):  
Cell Cycle ◽  
Nuclear Pore Complex ◽  
Nuclear Pore ◽  
Complex Organization

scholarly journals Nuclear Pore Complex Number and Distribution throughout theSaccharomyces cerevisiaeCell Cycle by Three-Dimensional Reconstruction from Electron Micrographs of Nuclear Envelopes

1997 ◽  
Vol 8 (11) ◽  
pp. 2119-2132 ◽  
Author(s):  
Mark Winey ◽  
Defne Yarar ◽  
Thomas H. Giddings ◽  
David N. Mastronarde
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
Electron Micrographs ◽  
Three Dimensional ◽  
Spindle Pole ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Surface ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Cycle Stage

The number of nuclear pore complexes (NPCs) in individual nuclei of the yeast Saccharomyces cerevisiae was determined by computer-aided reconstruction of entire nuclei from electron micrographs of serially sectioned cells. Nuclei of 32 haploid cells at various points in the cell cycle were modeled and found to contain between 65 and 182 NPCs. Morphological markers, such as cell shape and nuclear shape, were used to determine the cell cycle stage of the cell being examined. NPC number was correlated with cell cycle stage to reveal that the number of NPCs increases steadily, beginning in G1-phase, suggesting that NPC assembly occurs continuously throughout the cell cycle. However, the accumulation of nuclear envelope observed during the cell cycle, indicated by nuclear surface area, is not continuous at the same rate, such that the density of NPCs per unit area of nuclear envelope peaks in apparent S-phase cells. Analysis of the nuclear envelope reconstructions also revealed no preferred NPC-to-NPC distance. However, NPCs were found in large clusters over regions of the nuclear envelope. Interestingly, clusters of NPCs were most pronounced in early mitotic nuclei and were found to be associated with the spindle pole bodies, but the functional significance of this association is unknown.

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