scholarly journals Pom33, a novel transmembrane nucleoporin required for proper nuclear pore complex distribution

2010 ◽  
Vol 189 (5) ◽  
pp. 795-811 ◽  
Author(s):  
Anne Chadrin ◽  
Barbara Hess ◽  
Mabel San Roman ◽  
Xavier Gatti ◽  
Bérangère Lombard ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Transmembrane Protein ◽  
Functional Characterization ◽  
Interaction Network ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Loss Of Function ◽  
Yeast Viability ◽  
Pore Complexes

The biogenesis of nuclear pore complexes (NPCs) represents a paradigm for the assembly of high-complexity macromolecular structures. So far, only three integral pore membrane proteins are known to function redundantly in NPC anchoring within the nuclear envelope. Here, we describe the identification and functional characterization of Pom33, a novel transmembrane protein dynamically associated with budding yeast NPCs. Pom33 becomes critical for yeast viability in the absence of a functional Nup84 complex or Ndc1 interaction network, which are two core NPC subcomplexes, and associates with the reticulon Rtn1. Moreover, POM33 loss of function impairs NPC distribution, a readout for a subset of genes required for pore biogenesis, including members of the Nup84 complex and RTN1. Consistently, we show that Pom33 is required for normal NPC density in the daughter nucleus and for proper NPC biogenesis and/or stability in the absence of Nup170. We hypothesize that, by modifying or stabilizing the nuclear envelope–NPC interface, Pom33 may contribute to proper distribution and/or efficient assembly of nuclear pores.

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.

scholarly journals The Three Fungal Transmembrane Nuclear Pore Complex Proteins of Aspergillus nidulans Are Dispensable in the Presence of an Intact An-Nup84-120 Complex

2009 ◽  
Vol 20 (2) ◽  
pp. 616-630 ◽  
Author(s):  
Hui-Lin Liu ◽  
Colin P.C. De Souza ◽  
Aysha H. Osmani ◽  
Stephen A. Osmani
Keyword(s):  
High Temperature ◽  
Nuclear Envelope ◽  
Aspergillus Nidulans ◽  
Nuclear Pore Complex ◽  
Mitotic Spindle ◽  
Spindle Pole ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Spindle Pole Bodies ◽  
Pore Complexes

In Aspergillus nidulans nuclear pore complexes (NPCs) undergo partial mitotic disassembly such that 12 NPC proteins (Nups) form a core structure anchored across the nuclear envelope (NE). To investigate how the NPC core is maintained, we affinity purified the major core An-Nup84-120 complex and identified two new fungal Nups, An-Nup37 and An-ELYS, previously thought to be vertebrate specific. During mitosis the An-Nup84-120 complex locates to the NE and spindle pole bodies but, unlike vertebrate cells, does not concentrate at kinetochores. We find that mutants lacking individual An-Nup84-120 components are sensitive to the membrane destabilizer benzyl alcohol (BA) and high temperature. Although such mutants display no defects in mitotic spindle formation, they undergo mitotic specific disassembly of the NPC core and transient aggregation of the mitotic NE, suggesting the An-Nup84-120 complex might function with membrane. Supporting this, we show cells devoid of all known fungal transmembrane Nups (An-Ndc1, An-Pom152, and An-Pom34) are viable but that An-ndc1 deletion combined with deletion of individual An-Nup84-120 components is either lethal or causes sensitivity to treatments expected to destabilize membrane. Therefore, the An-Nup84-120 complex performs roles, perhaps at the NPC membrane as proposed previously, that become essential without the An-Ndc1 transmembrane Nup.

scholarly journals In Vivo Dynamics of Nuclear Pore Complexes in Yeast

1997 ◽  
Vol 136 (6) ◽  
pp. 1185-1199 ◽  
Author(s):  
Mirella Bucci ◽  
Susan R. Wente
Keyword(s):  
Nuclear Envelope ◽  
Recipient Cell ◽  
Nucleocytoplasmic Transport ◽  
Yeast Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Central Location ◽  
Nuclear Membranes ◽  
Mutant Strains ◽  
Pore Complexes

While much is known about the role of nuclear pore complexes (NPCs) in nucleocytoplasmic transport, the mechanism of NPC assembly into pores formed through the double lipid bilayer of the nuclear envelope is not well defined. To investigate the dynamics of NPCs, we developed a live-cell assay in the yeast Saccharomyces cerevisiae. The nucleoporin Nup49p was fused to the green fluorescent protein (GFP) of Aequorea victoria and expressed in nup49 null haploid yeast cells. When the GFP–Nup49p donor cell was mated with a recipient cell harboring only unlabeled Nup49p, the nuclei fused as a consequence of the normal mating process. By monitoring the distribution of the GFP–Nup49p, we could assess whether NPCs were able to move from the donor section of the nuclear envelope to that of the recipient nucleus. We observed that fluorescent NPCs moved and encircled the entire nucleus within 25 min after fusion. When assays were done in mutant kar1-1 strains, where nuclear fusion does not occur, GFP–Nup49p appearance in the recipient nucleus occurred at a very slow rate, presumably due to new NPC biogenesis or to exchange of GFP– Nup49p into existing recipient NPCs. Interestingly, in a number of existing mutant strains, NPCs are clustered together at permissive growth temperatures. This has been explained with two different hypotheses: by movement of NPCs through the double nuclear membranes with subsequent clustering at a central location; or, alternatively, by assembly of all NPCs at a central location (such as the spindle pole body) with NPCs in mutant cells unable to move away from this point. Using the GFP–Nup49p system with a mutant in the NPCassociated factor Gle2p that exhibits formation of NPC clusters only at 37°C, it was possible to distinguish between these two models for NPC dynamics. GFP– Nup49p-labeled NPCs, assembled at 23°C, moved into clusters when the cells were shifted to growth at 37°C. These results indicate that NPCs can move through the double nuclear membranes and, moreover, can do so to form NPC clusters in mutant strains. Such clusters may result by releasing NPCs from a nuclear tether, or by disappearance of a protein that normally prevents pore aggregation. This system represents a novel approach for identifying regulators of NPC assembly and movement in the future.

scholarly journals Phosphorylation-dependent mitotic SUMOylation drives nuclear envelope–chromatin interactions

2021 ◽  
Vol 220 (12) ◽  
Author(s):  
Christopher Ptak ◽  
Natasha O. Saik ◽  
Ashwini Premashankar ◽  
Diego L. Lapetina ◽  
John D. Aitchison ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nuclear Envelope ◽  
Spatial Organization ◽  
G1 Phase ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Chromatin Binding ◽  
Chromatin Interactions ◽  
Sumo Ligase ◽  
Pore Complexes

In eukaryotes, chromatin binding to the inner nuclear membrane (INM) and nuclear pore complexes (NPCs) contributes to spatial organization of the genome and epigenetic programs important for gene expression. In mitosis, chromatin–nuclear envelope (NE) interactions are lost and then formed again as sister chromosomes segregate to postmitotic nuclei. Investigating these processes in S. cerevisiae, we identified temporally and spatially controlled phosphorylation-dependent SUMOylation events that positively regulate postmetaphase chromatin association with the NE. Our work establishes a phosphorylation-mediated targeting mechanism of the SUMO ligase Siz2 to the INM during mitosis, where Siz2 binds to and SUMOylates the VAP protein Scs2. The recruitment of Siz2 through Scs2 is further responsible for a wave of SUMOylation along the INM that supports the assembly and anchorage of subtelomeric chromatin at the INM and localization of an active gene (INO1) to NPCs during the later stages of mitosis and into G1-phase.

The preparation and ultrastructure of avian erythrocyte nuclear envelope enclosed by the plasma membrane

1978 ◽  
Vol 34 (1) ◽  
pp. 81-90
Author(s):  
J.R. Harris
Keyword(s):  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Ammonium Molybdate ◽  
Negative Staining ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Thin Sectioning ◽  
Avian Erythrocyte ◽  
Pore Complexes ◽  
Low Ionic Strength

A procedure is described for the preparation of avian erythrocyte nuclear envelope ghosts which remain enclosed by the ellipsoid plasma membrane. Haemoglobin-free nucleated chicken erythrocyte ghosts are treated in a low ionic strength buffer plus heparin which brings about decondensation of the chromatin. This is followed by solubilization of the chromatin by digestion with pancreatic deoxyribonuclease-1. When studied by light microscopy using either phase-contrast or Nomarski interference optics, the ellipsoid plasma membrane is clearly seen to remain with the collapsed nuclear envelope trapped inside. This interpretation is supported by negative-staining electron microscopy using ammonium molybdate, which in addition reveals the presence of the nuclear pore complexes. The suggestion is advanced that structural protection is provided for the fragile nuclear envelope system by the surrounding plasma membrane, which might account for the final nuclear envelope being in the form of relatively intact ghosts with well defined nuclear pore complexes. The nuclear envelope is highly fragmented when the plasma membrane is absent, the nuclear pore complexes showing appreciable breakdown. Thin sectioning supports the results of negative staining and in addition shows the nuclear envelope retained within the plasma membrane to be composed of both inner and outer nuclear membranes, but the nuclear pore complexes are not clearly defined.

scholarly journals Nuclear envelope organization in Dictyostelium discoideum

2019 ◽  
Vol 63 (8-9-10) ◽  
pp. 509-519 ◽  
Author(s):  
Petros Batsios ◽  
Ralph Gräf ◽  
Michael P. Koonce ◽  
Denis A. Larochelle ◽  
Irene Meyer
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Major Constituent ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Linc Complex ◽  
Family Protein ◽  
Import And Export ◽  
Pore Complexes

The nuclear envelope consists of the outer and the inner nuclear membrane, the nuclear lamina and the nuclear pore complexes, which regulate nuclear import and export. The major constituent of the nuclear lamina of Dictyostelium is the lamin NE81. It can form filaments like B-type lamins and it interacts with Sun1, as well as with the LEM/HeH-family protein Src1. Sun1 and Src1 are nuclear envelope transmembrane proteins involved in the centrosome-nucleus connection and nuclear envelope stability at the nucleolar regions, respectively. In conjunction with a KASH-domain protein, Sun1 usually forms a so-called LINC complex. Two proteins with functions reminiscent of KASH-domain proteins at the outer nuclear membrane of Dictyostelium are known; interaptin which serves as an actin connector and the kinesin Kif9 which plays a role in the microtubule-centrosome connector. However, both of these lack the conserved KASH-domain. The link of the centrosome to the nuclear envelope is essential for the insertion of the centrosome into the nuclear envelope and the appropriate spindle formation. Moreover, centrosome insertion is involved in permeabilization of the mitotic nucleus, which ensures access of tubulin dimers and spindle assembly factors. Our recent progress in identifying key molecular players at the nuclear envelope of Dictyostelium promises further insights into the mechanisms of nuclear envelope dynamics.

scholarly journals Nuclear Envelope and Nuclear Pore Complexes in Neurodegenerative Diseases—New Perspectives for Therapeutic Interventions

2020 ◽  
Author(s):  
Naomi Hachiya ◽  
Marta Sochocka ◽  
Anna Brzecka ◽  
Takuto Shimizu ◽  
Kazimierz Gąsiorowski ◽  
...  
Keyword(s):  
Gene Expression ◽  
Neurodegenerative Diseases ◽  
Nuclear Envelope ◽  
Neurodegenerative Disorders ◽  
Nuclear Transport ◽  
Therapeutic Interventions ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Pore Complexes ◽  
Bidirectional Exchange

Abstract Transport of proteins, transcription factors, and other signaling molecules between the nucleus and cytoplasm is necessary for signal transduction. The study of these transport phenomena is particularly challenging in neurons because of their highly polarized structure. The bidirectional exchange of molecular cargoes across the nuclear envelope (NE) occurs through nuclear pore complexes (NPCs), which are aqueous channels embedded in the nuclear envelope. The NE and NPCs regulate nuclear transport but are also emerging as relevant regulators of chromatin organization and gene expression. The alterations in nuclear transport are regularly identified in affected neurons associated with human neurodegenerative diseases. This review presents insights into the roles played by nuclear transport defects in neurodegenerative disease, focusing primarily on NE proteins and NPCs. The subcellular mislocalization of proteins might be a very desirable means of therapeutic intervention in neurodegenerative disorders.

scholarly journals Lamin B1 protein is required for dendrite development in primary mouse cortical neurons

2016 ◽  
Vol 27 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Caterina Giacomini ◽  
Sameehan Mahajani ◽  
Roberta Ruffilli ◽  
Roberto Marotta ◽  
Laura Gasparini
Keyword(s):  
Cortical Neurons ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Loss Of Function ◽  
Lamin B1 ◽  
Dendrite Development ◽  
Primary Mouse ◽  
Nuclear Shuttling ◽  
Pore Complexes

Lamin B1, a key component of the nuclear lamina, plays an important role in brain development and function. A duplication of the human lamin B1 ( LMNB1) gene has been linked to adult-onset autosomal dominant leukodystrophy, and mouse and human loss-of-function mutations in lamin B1 are susceptibility factors for neural tube defects. In the mouse, experimental ablation of endogenous lamin B1 (Lmnb1) severely impairs embryonic corticogenesis. Here we report that in primary mouse cortical neurons, LMNB1 overexpression reduces axonal outgrowth, whereas deficiency of endogenous Lmnb1 results in aberrant dendritic development. In the absence of Lmnb1, both the length and complexity of dendrites are reduced, and their growth is unresponsive to KCl stimulation. This defective dendritic outgrowth stems from impaired ERK signaling. In Lmnb1-null neurons, ERK is correctly phosphorylated, but phospho-ERK fails to translocate to the nucleus, possibly due to delocalization of nuclear pore complexes (NPCs) at the nuclear envelope. Taken together, these data highlight a previously unrecognized role of lamin B1 in dendrite development of mouse cortical neurons through regulation of nuclear shuttling of specific signaling molecules and NPC distribution.

scholarly journals LEM2 recruits CHMP7 for ESCRT-mediated nuclear envelope closure in fission yeast and human cells

2017 ◽  
Vol 114 (11) ◽  
pp. E2166-E2175 ◽  
Author(s):  
Mingyu Gu ◽  
Dollie LaJoie ◽  
Opal S. Chen ◽  
Alexander von Appen ◽  
Mark S. Ladinsky ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Fission Yeast ◽  
Nuclear Membrane ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Human Cells ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Loss Of Function

Endosomal sorting complexes required for transport III (ESCRT-III) proteins have been implicated in sealing the nuclear envelope in mammals, spindle pole body dynamics in fission yeast, and surveillance of defective nuclear pore complexes in budding yeast. Here, we report that Lem2p (LEM2), a member of the LEM (Lap2-Emerin-Man1) family of inner nuclear membrane proteins, and the ESCRT-II/ESCRT-III hybrid protein Cmp7p (CHMP7), work together to recruit additional ESCRT-III proteins to holes in the nuclear membrane. InSchizosaccharomyces pombe, deletion of the ATPasevps4leads to severe defects in nuclear morphology and integrity. These phenotypes are suppressed by loss-of-function mutations that arise spontaneously inlem2orcmp7, implying that these proteins may function upstream in the same pathway. Building on these genetic interactions, we explored the role of LEM2 during nuclear envelope reformation in human cells. We found that CHMP7 and LEM2 enrich at the same region of the chromatin disk periphery during this window of cell division and that CHMP7 can bind directly to the C-terminal domain of LEM2 in vitro. We further found that, during nuclear envelope formation, recruitment of the ESCRT factors CHMP7, CHMP2A, and IST1/CHMP8 all depend on LEM2 in human cells. We conclude that Lem2p/LEM2 is a conserved nuclear site-specific adaptor that recruits Cmp7p/CHMP7 and downstream ESCRT factors to the nuclear envelope.

scholarly journals Piecing together nuclear pore complex assembly during interphase

2009 ◽  
Vol 185 (3) ◽  
pp. 377-379 ◽  
Author(s):  
Michael Rexach
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Supramolecular Structures ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Assembly Process ◽  
Nuclear Pores ◽  
Complex Assembly ◽  
Cell Biol ◽  
Pore Complexes

All nucleocytoplasmic traffic of macromolecules occurs through nuclear pore complexes (NPCs), which function as stents in the nuclear envelope to keep nuclear pores open but gated. Three studies in this issue (Flemming, D., P. Sarges, P. Stelter, A. Hellwig, B. Böttcher, and E. Hurt. 2009. J. Cell Biol. 185:387–395; Makio, T., L.H. Stanton, C.-C. Lin, D.S. Goldfarb, K. Weis, and R.W. Wozniak. 2009. J. Cell Biol. 185:459–491; Onishchenko, E., L.H. Stanton, A.S. Madrid, T. Kieselbach, and K. Weis. 2009. J. Cell Biol. 185:475–491) further our understanding of the NPC assembly process by reporting what happens when the supply lines of key proteins that provide a foundation for building these marvelous supramolecular structures are disrupted.

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