scholarly journals Stepwise reassembly of the nuclear envelope at the end of mitosis

1993 ◽  
Vol 122 (2) ◽  
pp. 295-306 ◽  
Author(s):  
N Chaudhary ◽  
JC Courvalin
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Pore ◽  
Membrane Domains ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Domain Specific ◽  
Lamin B Receptor ◽  
Different Populations ◽  
Pore Complexes

The nuclear envelope consists of three distinct membrane domains: the outer membrane with the bound ribosomes, the inner membrane with the bound lamina, and the pore membrane with the bound pore complexes. Using biochemical and morphological methods, we observed that the nuclear membranes of HeLa cells undergoing mitosis are disassembled in a domain-specific manner, i.e., integral membrane proteins representing the inner nuclear membrane (the lamin B receptor) and the nuclear pore membrane (gp210) are segregated into different populations of mitotic vesicles. At the completion of mitosis, the inner nuclear membrane-derived vesicles associate with chromatin first, beginning in anaphase, whereas the pore membranes and the lamina assemble later, during telophase and cytokinesis. Our data suggest that the ordered reassembly of the nuclear envelope is triggered by the early attachment of inner nuclear membrane-derived vesicles to the chromatin.

scholarly journals Induction of a Massive Endoplasmic Reticulum and Perinuclear Space Expansion by Expression of Lamin B Receptor Mutants and the Related Sterol Reductases TM7SF2 and DHCR7

2010 ◽  
Vol 21 (2) ◽  
pp. 354-368 ◽  
Author(s):  
Monika Zwerger ◽  
Thorsten Kolb ◽  
Karsten Richter ◽  
Iakowos Karakesisoglou ◽  
Harald Herrmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Cell Lines ◽  
Nuclear Membrane ◽  
Cultured Cells ◽  
Membrane Separation ◽  
Reductase Activity ◽  
Nuclear Pore ◽  
Lamin B ◽  
Lamin B Receptor

Lamin B receptor (LBR) is an inner nuclear membrane protein involved in tethering the nuclear lamina and the underlying chromatin to the nuclear envelope. In addition, LBR exhibits sterol reductase activity. Mutations in the LBR gene cause two different human diseases: Pelger-Huët anomaly and Greenberg skeletal dysplasia, a severe chrondrodystrophy causing embryonic death. Our study aimed at investigating the effect of five LBR disease mutants on human cultured cells. Three of the tested LBR mutants caused a massive compaction of chromatin coincidental with the formation of a large nucleus-associated vacuole (NAV) in several human cultured cell lines. Live cell imaging and electron microscopy revealed that this structure was generated by the separation of the inner and outer nuclear membrane. During NAV formation, nuclear pore complexes and components of the linker of nucleoskeleton and cytoskeleton complex were lost in areas of membrane separation. Concomitantly, a large number of smaller vacuoles formed throughout the cytoplasm. Notably, forced expression of the two structurally related sterol reductases transmembrane 7 superfamily member 2 and 7-dehydrocholesterol reductase caused, even in their wild-type form, a comparable phenotype in susceptible cell lines. Hence, LBR mutant variants and sterol reductases can severely interfere with the regular organization of the nuclear envelope and the endoplasmic reticulum.

Reticulon-like REEP4 at the inner nuclear membrane promotes nuclear pore complex formation

2021 ◽  
Vol 221 (2) ◽  
Author(s):  
Banafsheh Golchoubian ◽  
Andreas Brunner ◽  
Helena Bragulat-Teixidor ◽  
Annett Neuner ◽  
Busra A. Akarlar ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Inner Nuclear Membrane ◽  
Pore Complexes ◽  
Late Stages ◽  
Protein Complex Assembly

Nuclear pore complexes (NPCs) are channels within the nuclear envelope that mediate nucleocytoplasmic transport. NPCs form within the closed nuclear envelope during interphase or assemble concomitantly with nuclear envelope reformation in late stages of mitosis. Both interphase and mitotic NPC biogenesis require coordination of protein complex assembly and membrane deformation. During early stages of mitotic NPC assembly, a seed for new NPCs is established on chromatin, yet the factors connecting the NPC seed to the membrane of the forming nuclear envelope are unknown. Here, we report that the reticulon homology domain protein REEP4 not only localizes to high-curvature membrane of the cytoplasmic endoplasmic reticulum but is also recruited to the inner nuclear membrane by the NPC biogenesis factor ELYS. This ELYS-recruited pool of REEP4 promotes NPC assembly and appears to be particularly important for NPC formation during mitosis. These findings suggest a role for REEP4 in coordinating nuclear envelope reformation with mitotic NPC biogenesis.

scholarly journals Cell Cycle Dynamics of the Nuclear Envelope

2003 ◽  
Vol 3 ◽  
pp. 1-20 ◽  
Author(s):  
Roland Foisner
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Lamin B ◽  
Binding Domains ◽  
Lamin B Receptor ◽  
Core Components ◽  
Pore Complexes ◽  
Cell Cycle Dynamics

The nuclear envelope (NE) consists of an inner and an outer membrane, nuclear pore complexes, and the underlying nuclear lamina, a filamentous scaffold structure formed by lamins. The inner membrane is linked to the lamina and chromatin by its integral membrane proteins, such as lamin B receptor (LBR), emerin, and various isoforms of lamina-associated polypeptides (LAP) 1 and 2, which bind lamins and/or chromatin. During mitosis, the NE is disassembled upon phosphorylation of its core components, and the NE is torn apart by a dynein-driven microtubule-dependent mechanism. Nuclear reassembly after sister chromatid separation requires a timely coordinated and dephosphorylation-dependent association of lamin-binding proteins and lamins with chromosomal proteins and targeting of membranes to specific sites on chromosomes. Various chromatin-binding domains in lamina proteins, such as the LEM domain, present in all LAP2 isoforms and in emerin, as well as unique regions in lamina proteins and in specific LAP2 isoforms have been implicated in defined steps of NE reformation. Furthermore, novel mechanisms of membrane fusion involving Ran GTPase are just beginning to emerge.

scholarly journals REEP4 is recruited to the inner nuclear membrane by ELYS and promotes nuclear pore complex formation

2020 ◽  
Author(s):  
Banafsheh Golchoubian ◽  
Andreas Brunner ◽  
Helena Bragulat-Teixidor ◽  
Busra A. Akarlar ◽  
Nurhan Ozlu ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Nucleocytoplasmic Transport ◽  
Local Deformation ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Membrane Remodeling ◽  
Inner Nuclear Membrane ◽  
Pore Complexes

AbstractNuclear pore complexes (NPCs) are channels within the nuclear envelope that mediate nucleocytoplasmic transport. NPCs assemble either into the closed nuclear envelope during interphase or concomitantly with nuclear envelope reformation during anaphase. Both, interphase and post-mitotic NPC biogenesis require local deformation of membrane. Yet, the factors that control proper membrane remodeling for post-mitotic NPC assembly are unknown. Here, we report that the reticulon homology domain-protein REEP4 localizes not only to high-curvature membrane of the cytoplasmic endoplasmic reticulum (ER) but also to the inner nuclear membrane (INM). We show that REEP4 is recruited to the INM by the NPC biogenesis factor ELYS and promotes NPC assembly. REEP4 contributes mainly to anaphase NPC assembly, suggesting that REEP4 has an unexpected role in coordinating nuclear envelope reformation with post-mitotic NPC biogenesis.

scholarly journals Synthesis, transport and incorporation into the nuclear envelope of A-type lamins and inner nuclear membrane proteins

2011 ◽  
Vol 39 (6) ◽  
pp. 1758-1763 ◽  
Author(s):  
Jose M. González ◽  
Vicente Andrés
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Complex Structure ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Inner Nuclear Membrane ◽  
Perinuclear Space ◽  
Interphase Cells ◽  
Pore Complexes

The mammalian NE (nuclear envelope), which separates the nucleus from the cytoplasm, is a complex structure composed of nuclear pore complexes, the outer and inner nuclear membranes, the perinuclear space and the nuclear lamina (A- and B-type lamins). The NE is completely disassembled and reassembled at each cell division. In the present paper, we review recent advances in the understanding of the mechanisms implicated in the transport of inner nuclear membrane and nuclear lamina proteins from the endoplasmic reticulum to the nucleus in interphase cells and mitosis, with special attention to A-type lamins.

scholarly journals An ESCRT-LEM domain inner nuclear membrane protein surveillance system is poised to directly monitor the integrity of the nuclear envelope barrier and nuclear transport system

2019 ◽  
Author(s):  
David J. Thaller ◽  
Matteo Allegretti ◽  
Sapan Borah ◽  
Paolo Ronchi ◽  
Martin Beck ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Transport System ◽  
Nuclear Membrane ◽  
Surveillance System ◽  
Electron Tomography ◽  
Nuclear Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Inner Nuclear Membrane ◽  
Pore Complexes

AbstractThe integrity of the nuclear envelope membranes coupled to the diffusion barrier and selective transport properties of nuclear pore complexes (NPCs) are a prerequisite for the robust segregation of nucleoplasm and cytoplasm. Recent work supports that mechanical membrane disruption or perturbation to NPC assembly can trigger an ESCRT-dependent surveillance system that seals nuclear envelope pores: how these pores are sensed and sealed remains to be fully defined. Here, we show that the principal components of the nuclear envelope surveillance system in yeast, which includes the ESCRT Chm7 and the integral inner nuclear membrane (INM) protein Heh1, are spatially segregated by the nuclear transport system. Specifically, at steady state Chm7 is actively restricted from the nucleus by Crm1/Xpo1. Consistent with the idea that it is the exposure of the INM that triggers surveillance, the expression of a transmembrane anchor and the winged helix domain of Heh1 is sufficient to recruit and activate Chm7 at a membrane interface. Correlative light electron tomography under conditions of Chm7 hyper-activation further show the formation of an elaborate network of fenestrated sheets at the INM and suggest ER-membrane delivery at sites of nuclear envelope herniation. Our data point to a model in which exposure of Chm7 to Heh1, driven by any perturbation in the nuclear envelope barrier would lead to local nuclear envelope remodeling to promote membrane sealing. Our findings have implications for disease mechanisms associated with defects in NPC assembly and nuclear envelope integrity.

Nuclear Envelope Dynamics During Mitosis

1988 ◽  
Vol 46 ◽  
pp. 224-225
Author(s):  
Brian Burke
Keyword(s):  
Nuclear Envelope ◽  
Membrane Vesicles ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Animal Cells ◽  
Interphase Chromosome ◽  
Lamin B ◽  
Chromosome Architecture ◽  
Complex Membrane ◽  
Pore Complexes

The nuclear envelope is a complex membrane structure that forms the boundary of the nuclear compartment in eukaryotes. It regulates the passage of macromolecules between the two compartments and may be important for organizing interphase chromosome architecture. In interphase animal cells it forms a remarkably stable structure consisting of a double membrane ouerlying a protein meshwork or lamina and penetrated by nuclear pore complexes. The latter form the channels for nucleocytoplasmic exchange of macromolecules, At the onset of mitosis, however, it rapidly disassembles, the membranes fragment to yield small vesicles and the lamina, which is composed of predominantly three polypeptides, lamins R, B and C (MW approx. 74, 68 and 65 kDa respectiuely), breaks down. Lamins B and C are dispersed as monomers throughout the mitotic cytoplasm, while lamin B remains associated with the nuclear membrane vesicles.

Lamin B receptor: role on chromatin structure, cellular senescence and possibly aging

2020 ◽  
Vol 477 (14) ◽  
pp. 2715-2720
Author(s):  
Susana Castro-Obregón
Keyword(s):  
Cellular Senescence ◽  
Nuclear Membrane ◽  
Chromatin Structure ◽  
Cholesterol Synthesis ◽  
Reductase Activity ◽  
Chimeric Protein ◽  
Nuclear Lamina ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor

The nuclear envelope is composed by an outer nuclear membrane and an inner nuclear membrane, which is underlain by the nuclear lamina that provides the nucleus with mechanical strength for maintaining structure and regulates chromatin organization for modulating gene expression and silencing. A layer of heterochromatin is beneath the nuclear lamina, attached by inner nuclear membrane integral proteins such as Lamin B receptor (LBR). LBR is a chimeric protein, having also a sterol reductase activity with which it contributes to cholesterol synthesis. Lukasova et al. showed that when DNA is damaged by ɣ-radiation in cancer cells, LBR is lost causing chromatin structure changes and promoting cellular senescence. Cellular senescence is characterized by terminal cell cycle arrest and the expression and secretion of various growth factors, cytokines, metalloproteinases, etc., collectively known as senescence-associated secretory phenotype (SASP) that cause chronic inflammation and tumor progression when they persist in the tissue. Therefore, it is fundamental to understand the molecular basis for senescence establishment, maintenance and the regulation of SASP. The work of Lukasova et al. contributed to our understanding of cellular senescence establishment and provided the basis that lead to the further discovery that chromatin changes caused by LBR reduction induce an up-regulated expression of SASP factors. LBR dysfunction has relevance in several diseases and possibly in physiological aging. The potential bifunctional role of LBR on cellular senescence establishment, namely its role in chromatin structure together with its enzymatic activity contributing to cholesterol synthesis, provide a new target to develop potential anti-aging therapies.

Function and assembly of nuclear pore complex proteins

1999 ◽  
Vol 77 (4) ◽  
pp. 321-329 ◽  
Author(s):  
Khaldon Bodoor ◽  
Sarah Shaikh ◽  
Paul Enarson ◽  
Sharmin Chowdhury ◽  
Davide Salina ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Current View ◽  
Nuclear Pore ◽  
Dynamic Component ◽  
Inner Nuclear Membrane ◽  
Inner Nuclear Membrane Protein ◽  
Nuclear Membrane Protein

Nuclear pore complexes (NPCs) are extremely elaborate structures that mediate the bidirectional movement of macromolecules between the nucleus and cytoplasm. The current view of NPC organization features a massive symmetrical framework that is embedded in the double membranes of the nuclear envelope. It embraces a central channel of as yet ill-defined structure but which may accommodate particles with diameters up to 26 nm provided that they bear specific import/export signals. Attached to both faces of the central framework are peripheral structures, short cytoplasmic filaments, and a nuclear basket assembly, which interact with molecules transiting the NPC. The mechanisms of assembly and the nature of NPC structural intermediates are still poorly understood. However, mutagenesis and expression studies have revealed discrete sequences within certain NPC proteins that are necessary and sufficient for their appropriate targeting. In addition, some details are emerging from observations on cells undergoing mitosis where the nuclear envelope is disassembled and its components, including NPC subunits, are dispersed throughout the mitotic cytoplasm. At the end of mitosis, all of these components are reutilized to form nuclear envelopes in the two daughter cells. To date, it has been possible to define a time course of postmitotic assembly for a group of NPC components (CAN/Nup214, Nup153, POM121, p62 and Tpr) relative to the integral inner nuclear membrane protein LAP2 and the NPC membrane glycoprotein gp210. Nup153, a dynamic component of the nuclear basket, associates with chromatin towards the end of anaphase coincident with, although independent of, the inner nuclear membrane protein, LAP2. Assembly of the remaining proteins follows that of the nuclear membranes and occurs in the sequence POM121, p62, CAN/Nup214 and gp210/Tpr. Since p62 remains as a complex with three other NPC proteins (p58, p54, p45) during mitosis, and CAN/Nup214 maintains a similar interaction with its partner, Nup84, the relative timing of assembly of these additional four proteins may also be inferred. These observations suggest that there is a sequential association of NPC proteins with chromosomes during nuclear envelope reformation and the recruitment of at least eight of these precedes that of gp210. These findings support a model in which it is POM121 rather than gp210 that defines initial membrane-associated NPC assembly intermediates and which may therefore represent an essential component of the central framework of the NPC. Key words: nuclear pore complex, nucleoporin, mitosis, nuclear transport

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