Nuclear envelope proteins and their role in nuclear positioning and replication

2010 ◽  
Vol 38 (3) ◽  
pp. 741-746 ◽  
Author(s):  
Katja Graumann ◽  
John Runions ◽  
David E. Evans
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Root Hair ◽  
Nuclear Proteins ◽  
Present Review ◽  
Light Touch ◽  
Nuclear Positioning ◽  
Novel Proteins ◽  
Cellular Events ◽  
Chromosome Attachment

Controlled movement of the nucleus is important in a wide variety of plant cellular events. Positioning involving intact nuclei occurs in cell division, development, tip growing systems such as the root hair and in response to stimuli, including light, touch and infection. Positioning is also essential in the division and replication of nuclear components, ranging from chromosome attachment to the breakdown and reformation of the nuclear envelope. Although description and understanding of the processes involved have advanced rapidly in recent years, significant gaps remain in our knowledge, especially concerning nuclear proteins involved in anchoring and interacting with cytoskeletal and nucleoskeletal elements involved in movement. In the present review, processes involving the movement and positioning of nuclei and nuclear components are described together with novel proteins implicated in nucleoskeletal and cytoskeletal interactions.

scholarly journals Bridging centrioles and PCM in proper space and time

2018 ◽  
Vol 62 (6) ◽  
pp. 793-801 ◽  
Author(s):  
Ramya Varadarajan ◽  
Nasser M. Rusan
Keyword(s):  
Nuclear Envelope ◽  
Regulatory Mechanisms ◽  
Proper Function ◽  
Spindle Formation ◽  
Multipolar Spindle ◽  
Microtubule Organizing Centers ◽  
Nuclear Envelope Breakdown ◽  
Cellular Events ◽  
Chromosome Attachment ◽  
Correct Location

Throughout biology, specifying cellular events at the correct location and time is necessary for ensuring proper function. The formation of robust microtubule organizing centers (MTOCs) in mitosis is one such event that must be restricted in space to centrosomes to prevent ectopic MTOC formation elsewhere in the cell, a situation that can result in multipolar spindle formation and aneuploidy. The process of reaching maximum centrosome MTOC activity in late G2, known as centrosome maturation, ensures accurate timing of nuclear envelope breakdown and proper chromosome attachment. Although centrosome maturation has been recognized for over a century, the spatial and temporal regulatory mechanisms that direct MTOC activation are poorly understood. Here, we review Sas-4/CPAP, Asterless/Cep152, Spd-2/Cep192, and PLP/Pericentrin, a group of proteins we refer to as ‘bridge’ proteins that reside at the surface of centrioles, perfectly positioned to serve as the gatekeepers of proper centrosome maturation at the perfect place and time.

The Ultrastructure of the Nuclear Events of Binary Fission in Paramecium bursaria and the Effects of Colchicine on Cell Division

1974 ◽  
Vol 32 ◽  
pp. 276-277
Author(s):  
L. M. Lewis
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Condensed Chromatin ◽  
Binary Fission ◽  
Paramecium Bursaria ◽  
Nuclear Events ◽  
Division Axis

The effects of colchicine on extranuclear microtubules associated with the macronucleus of Paramecium bursaria were studied to determine the possible role that these microtubules play in controlling the shape of the macronucleus. In the course of this study, the ultrastructure of the nuclear events of binary fission in control cells was also studied.During interphase in control cells, the micronucleus contains randomly distributed clumps of condensed chromatin and microtubular fragments. Throughout mitosis the nuclear envelope remains intact. During micronuclear prophase, cup-shaped microfilamentous structures appear that are filled with condensing chromatin. Microtubules are also present and are parallel to the division axis.

scholarly journals The nucleoporin Nup205/NPP-3 is lost near centrosomes at mitotic onset and can modulate the timing of this process in Caenorhabditis elegans embryos

2012 ◽  
Vol 23 (16) ◽  
pp. 3111-3121 ◽  
Author(s):  
Virginie Hachet ◽  
Coralie Busso ◽  
Mika Toya ◽  
Asako Sugimoto ◽  
Peter Askjaer ◽  
...  
Keyword(s):  
Cell Division ◽  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Aurora A Kinase ◽  
Aurora A ◽  
Time And Space ◽  
Local Loss ◽  
Necessary And Sufficient

Regulation of mitosis in time and space is critical for proper cell division. We conducted an RNA interference–based modifier screen to identify novel regulators of mitosis in Caenorhabditis elegans embryos. Of particular interest, this screen revealed that the Nup205 nucleoporin NPP-3 can negatively modulate the timing of mitotic onset. Furthermore, we discovered that NPP-3 and nucleoporins that are associated with it are lost from the nuclear envelope (NE) in the vicinity of centrosomes at the onset of mitosis. We demonstrate that centrosomes are both necessary and sufficient for NPP-3 local loss, which also requires the activity of the Aurora-A kinase AIR-1. Our findings taken together support a model in which centrosomes and AIR-1 promote timely onset of mitosis by locally removing NPP-3 and associated nucleoporins from the NE.

Structural diversity of band 4.1 superfamily members

1994 ◽  
Vol 107 (7) ◽  
pp. 1921-1928 ◽  
Author(s):  
K. Takeuchi ◽  
A. Kawashima ◽  
A. Nagafuchi ◽  
S. Tsukita
Keyword(s):  
Plasma Membrane ◽  
Tyrosine Kinases ◽  
Plasma Membranes ◽  
Structural Diversity ◽  
Gene Families ◽  
Cdna Clones ◽  
New Members ◽  
F9 Cells ◽  
Novel Proteins ◽  
Cellular Events

Several proteins contain the domain homologous to the N-terminal half of band 4.1 protein, indicating the existence of a superfamily. The members of this ‘band 4.1’ superfamily are thought to play crucial roles in the regulation of cytoskeleton-plasma membrane interaction just beneath plasma membranes. We examined the structural diversity of this superfamily by means of the polymerase chain reaction using synthesized mixed primers. We thus identified many members of the band 4.1 superfamily that were expressed in mouse teratocarcinoma F9 cells and mouse brain tissue. In total, 15 cDNA clones were obtained; 8 were identical to the corresponding parts of cDNAs for the known members, while 7 appeared to encode novel proteins (NBL1-7: novel band 4.1-like proteins). Sequence analyses of these clones revealed that the band 4.1 superfamily can be subdivided into 5 gene families; band 4.1 protein, ERM (ezrin/radixin/moesin/merlin/NBL6/NBL7+ ++), talin, PTPH1 (PTPH1/PTPMEG/NBL1-3), and NBL4 (NBL4/NBL5) families. The NBL4 family was first identified here, and the full-length cDNA encoding NBL4 was cloned. The deduced amino acid sequence revealed a myristoylation site, as well as phosphorylation sites for A-kinase and tyrosine kinases in its N-terminal half, suggesting its involvement in the phosphorylation-dependent regulation of cellular events just beneath the plasma membrane. In this study, we describe the initial characterization of these new members and discuss the evolution of the band 4.1 superfamily.

scholarly journals The Torsin/ NEP1R1-CTDNEP1/ Lipin axis regulates nuclear envelope lipid metabolism for nuclear pore complex insertion

2020 ◽  
Author(s):  
Julie Jacquemyn ◽  
Joyce Foroozandeh ◽  
Katlijn Vints ◽  
Jef Swerts ◽  
Patrik Verstreken ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Lipid Droplets ◽  
Nuclear Pore ◽  
List Type ◽  
Unknown Mechanism ◽  
Structure Lipid ◽  
Cellular Events ◽  
Upstream Regulator

AbstractTorsin ATPases of the endoplasmic reticulum (ER) and nuclear envelope (NE) lumen inhibit Lipin-mediated phosphatidate (PA) to diacylglycerol (DAG) conversion by an unknown mechanism. This excess PA metabolism is implicated in TOR1A/TorsinA diseases, but it is unclear whether it explains why Torsin concomitantly affects nuclear structure, lipid droplets (LD), organelle and cell growth. Here a fly miniscreen identified that Torsins affect these events via the NEP1R1-CTDNEP1 phosphatase complex. Further, Torsin homo-oligomerization rather than ATPase activity was key to function. NEP1R1-CTDNEP1 activates Lipin by dephosphorylation. We show that Torsin prevents CTDNEP1 from accumulating in the NE and excludes Lipin from the nucleus. Moreover, this repression of nuclear PA metabolism is required for interphase nuclear pore biogenesis. We conclude that Torsin is an upstream regulator of the NEP1R1-CTDNEP1/ Lipin pathway. This connects the ER/NE lumen with PA metabolism, and affects numerous cellular events including it has a previously unrecognized role in nuclear pore biogenesis.HighlightsNuclear envelope PA-DAG-TAG synthesis is independently regulated by Torsin and Torip/LAP1Torsin removes CTDNEP1 from the nuclear envelope and excludes Lipin from the nucleusExcess nuclear envelope NEP1R1-CTDNEP1/ Lipin activity impairs multiple aspects of NPC biogenesisNEP1R1-CTDNEP1/ Lipin inhibition prevents cellular defects associated with TOR1A and TOR1AIP1 / LAP1 disease

scholarly journals The ultrastructure of cell division in Euglena gracilis

1978 ◽  
Vol 31 (1) ◽  
pp. 25-35
Author(s):  
M.A. Gillott ◽  
R.E. Triemer
Keyword(s):  
Cell Division ◽  
Nuclear Envelope ◽  
Basal Body ◽  
Euglena Gracilis ◽  
Equatorial Region ◽  
Basal Bodies ◽  
Cleavage Furrow ◽  
Free Zone ◽  
Prophase Nucleus

The ultrastructure of mitosis in Euglena gracilis was investigated. At preprophase the nucleus migrates anteriorly and associates with the basal bodies. Flagella and basal bodies replicate at preprophase. Cells retain motility throughout division. The reservoir and the prophase nucleus elongate perpendicular to the incipient cleavage furrow. One basal body pair surrounded by a ribosome-free zone is found at each of the nuclear poles. The spindle forms within the intact nuclear envelope- Polar fenestrae are absent. At metaphase, the endosome is elongated from pole to pole, and chromosomes are loosely arranged in the equatorial region. Distinct, trilayered kinetochores are present. Spindle elongates as chromosomes migrate to the poles forming a dumb-bell shaped nucleus by telophase. Daughter nuclei are formed by constriction of the nuclear envelope. Cytokinesis is accomplished by furrowing. Cell division in Euglena is compared with that of certain other algae.

scholarly journals The Role of Phosphatases in Nuclear Envelope Disassembly and Reassembly and Their Relevance to Pathologies

Cells ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 687 ◽  
Author(s):  
Florentin Huguet ◽  
Shane Flynn ◽  
Paola Vagnarelli
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Nuclear Envelope ◽  
Current Understanding ◽  
The Past ◽  
Pathological Conditions ◽  
Regulation Of Cell Cycle

The role of kinases in the regulation of cell cycle transitions is very well established, however, over the past decade, studies have identified the ever-growing importance of phosphatases in these processes. It is well-known that an intact or otherwise non-deformed nuclear envelope (NE) is essential for maintaining healthy cells and any deviation from this can result in pathological conditions. This review aims at assessing the current understanding of how phosphatases contribute to the remodelling of the nuclear envelope during its disassembling and reformation after cell division and how errors in this process may lead to the development of diseases.

scholarly journals NETosis proceeds by cytoskeleton and endomembrane disassembly and PAD4-mediated chromatin decondensation and nuclear envelope rupture

2020 ◽  
Vol 117 (13) ◽  
pp. 7326-7337 ◽  
Author(s):  
Hawa Racine Thiam ◽  
Siu Ling Wong ◽  
Rong Qiu ◽  
Mark Kittisopikul ◽  
Amir Vahabikashi ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Time Lapse ◽  
Extracellular Dna ◽  
Sterile Inflammation ◽  
Human Neutrophils ◽  
Chromatin Decondensation ◽  
Membrane Rupture ◽  
Cellular Events

Neutrophil extracellular traps (NETs) are web-like DNA structures decorated with histones and cytotoxic proteins that are released by activated neutrophils to trap and neutralize pathogens during the innate immune response, but also form in and exacerbate sterile inflammation. Peptidylarginine deiminase 4 (PAD4) citrullinates histones and is required for NET formation (NETosis) in mouse neutrophils. While the in vivo impact of NETs is accumulating, the cellular events driving NETosis and the role of PAD4 in these events are unclear. We performed high-resolution time-lapse microscopy of mouse and human neutrophils and differentiated HL-60 neutrophil-like cells (dHL-60) labeled with fluorescent markers of organelles and stimulated with bacterial toxins or Candida albicans to induce NETosis. Upon stimulation, cells exhibited rapid disassembly of the actin cytoskeleton, followed by shedding of plasma membrane microvesicles, disassembly and remodeling of the microtubule and vimentin cytoskeletons, ER vesiculation, chromatin decondensation and nuclear rounding, progressive plasma membrane and nuclear envelope (NE) permeabilization, nuclear lamin meshwork and then NE rupture to release DNA into the cytoplasm, and finally plasma membrane rupture and discharge of extracellular DNA. Inhibition of actin disassembly blocked NET release. Mouse and dHL-60 cells bearing genetic alteration of PAD4 showed that chromatin decondensation, lamin meshwork and NE rupture and extracellular DNA release required the enzymatic and nuclear localization activities of PAD4. Thus, NETosis proceeds by a stepwise sequence of cellular events culminating in the PAD4-mediated expulsion of DNA.

scholarly journals The Vaccinia-related Kinases Phosphorylate the N′ Terminus of BAF, Regulating Its Interaction with DNA and Its Retention in the Nucleus

2006 ◽  
Vol 17 (5) ◽  
pp. 2451-2464 ◽  
Author(s):  
R. Jeremy Nichols ◽  
Matthew S. Wiebe ◽  
Paula Traktman
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Nuclear Envelope ◽  
Temperature Sensitivity ◽  
Nuclear Membrane ◽  
Essential Role ◽  
Nuclear Architecture ◽  
Nuclear Chromatin ◽  
N Terminus ◽  
Protein Barrier

The vaccinia-related kinases (VRKs) comprise a branch of the casein kinase family whose members are characterized by homology to the vaccinia virus B1 kinase. The VRK orthologues encoded by Caenorhabditis elegans and Drosophila melanogaster play an essential role in cell division; however, substrates that mediate this role have yet to be elucidated. VRK1 can complement the temperature sensitivity of a vaccinia B1 mutant, implying that VRK1 and B1 have overlapping substrate specificity. Herein, we demonstrate that B1, VRK1, and VRK2 efficiently phosphorylate the extreme N′ terminus of the BAF protein (Barrier to Autointegration Factor). BAF binds to both DNA and LEM domain-containing proteins of the inner nuclear membrane; in lower eukaryotes, BAF has been shown to play an important role during the reassembly of the nuclear envelope at the end of mitosis. We demonstrate that phosphorylation of ser4 and/or thr2/thr3 abrogates the interaction of BAF with DNA and reduces its interaction with the LEM domain. Coexpression of VRK1 and GFP-BAF greatly diminishes the association of BAF with the nuclear chromatin/matrix and leads to its dispersal throughout the cell. Cumulatively, our data suggest that the VRKs may modulate the association of BAF with nuclear components and hence play a role in maintaining appropriate nuclear architecture.

scholarly journals Regulation of the meiotic divisions of mammalian oocytes and eggs

2018 ◽  
Vol 46 (4) ◽  
pp. 797-806 ◽  
Author(s):  
Jessica R. Sanders ◽  
Keith T. Jones
Keyword(s):  
Cell Division ◽  
Luteinizing Hormone ◽  
Spindle Assembly Checkpoint ◽  
Asymmetric Cell Division ◽  
Homologous Chromosomes ◽  
Mammalian Oocyte ◽  
Cellular Events ◽  
The Hours ◽  
Meiosis I

Initiated by luteinizing hormone and finalized by the fertilizing sperm, the mammalian oocyte completes its two meiotic divisions. The first division occurs in the mature Graafian follicle during the hours preceding ovulation and culminates in an extreme asymmetric cell division and the segregation of the two pairs of homologous chromosomes. The newly created mature egg rearrests at metaphase of the second meiotic division prior to ovulation and only completes meiosis following a Ca2+ signal initiated by the sperm at gamete fusion. Here, we review the cellular events that govern the passage of the oocyte through meiosis I with a focus on the role of the spindle assembly checkpoint in regulating its timing. In meiosis II, we examine how the egg achieves its arrest and how the fertilization Ca2+ signal allows the initiation of embryo development.

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