scholarly journals C. elegans Nuclear Envelope Proteins Emerin, MAN1, Lamin, and Nucleoporins Reveal Unique Timing of Nuclear Envelope Breakdown during Mitosis

2000 ◽  
Vol 11 (9) ◽  
pp. 3089-3099 ◽  
Author(s):  
Kenneth K. Lee ◽  
Yosef Gruenbaum ◽  
Perah Spann ◽  
Jun Liu ◽  
Katherine L. Wilson
Keyword(s):  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Integral Membrane Proteins ◽  
C Elegans ◽  
Nuclear Envelope Breakdown ◽  
Spindle Poles ◽  
Sds Page ◽  
Early Anaphase ◽  
Extraction Properties ◽  
Pore Complexes

Emerin, MAN1, and LAP2 are integral membrane proteins of the vertebrate nuclear envelope. They share a 43-residue N-terminal motif termed the LEM domain. We found three putative LEM domain genes inCaenorhabditis elegans, designated emr-1,lem-2, and lem-3. We analyzedemr-l, which encodes Ce-emerin, andlem-2, which encodes Ce-MAN1. Ce-emerin and Ce-MAN1 migrate on SDS-PAGE as 17- and 52-kDa proteins, respectively. Based on their biochemical extraction properties and immunolocalization, both Ce-emerin and Ce-MAN1 are integral membrane proteins localized at the nuclear envelope. We used antibodies against Ce-MAN1, Ce-emerin, nucleoporins, and Ce-lamin to determine the timing of nuclear envelope breakdown during mitosis in C. elegans. The C. elegans nuclear envelope disassembles very late compared with vertebrates and Drosophila. The nuclear membranes remained intact everywhere except near spindle poles during metaphase and early anaphase, fully disassembling only during mid-late anaphase. Disassembly of pore complexes, and to a lesser extent the lamina, depended on embryo age: pore complexes were absent during metaphase in >30-cell embryos but existed until anaphase in 2- to 24-cell embryos. Intranuclear mRNA splicing factors disassembled after prophase. The timing of nuclear disassembly in C. elegans is novel and may reflect its evolutionary position between unicellular and more complex eukaryotes.

scholarly journals Channel Nucleoporins Recruit PLK-1 to Nuclear Pore Complexes to Direct Nuclear Envelope Breakdown in C. elegans

2017 ◽  
Vol 43 (2) ◽  
pp. 157-171.e7 ◽  
Author(s):  
Lisa Martino ◽  
Stéphanie Morchoisne-Bolhy ◽  
Dhanya K. Cheerambathur ◽  
Lucie Van Hove ◽  
Julien Dumont ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
C Elegans ◽  
Nuclear Envelope Breakdown ◽  
Pore Complexes

scholarly journals Integral membrane proteins specific to the inner nuclear membrane and associated with the nuclear lamina.

1988 ◽  
Vol 107 (6) ◽  
pp. 2029-2036 ◽  
Author(s):  
A Senior ◽  
L Gerace
Keyword(s):  
Membrane Proteins ◽  
Nuclear Membrane ◽  
Immunofluorescence Microscopy ◽  
Nuclear Lamina ◽  
Integral Membrane Proteins ◽  
Inner Nuclear Membrane ◽  
Attachment Sites ◽  
Nonionic Detergent ◽  
Pore Complexes ◽  
Integral Proteins

We obtained a monoclonal antibody (RL13) that identifies three integral membrane proteins specific to the nuclear envelope of rat liver, a major 75-kD polypeptide and two more minor components of 68 and 55 kD. Immunogold labeling of isolated nuclear envelopes demonstrates that these antigens are localized specifically to the inner nuclear membrane, and that the RL13 epitope occurs on the inner membrane's nucleoplasmic surface where the nuclear lamina is found. When nuclear envelopes are extracted with solutions containing nonionic detergent and high salt to solubilize nuclear membranes and pore complexes, most of these integral proteins remain associated with the insoluble lamina. Since the polypeptides recognized by RL13 are relatively abundant, they may function as lamina attachment sites in the inner nuclear membrane. Major cross-reacting antigens are found by immunoblotting and immunofluorescence microscopy in all rat cells examined. Therefore, these integral proteins are biochemical markers for the inner nuclear membrane and will be useful models for studying nuclear membrane biogenesis.

scholarly journals Integral Membrane Proteins of the Nuclear Envelope Are Dispersed throughout the Endoplasmic Reticulum during Mitosis

1997 ◽  
Vol 137 (6) ◽  
pp. 1199-1210 ◽  
Author(s):  
Li Yang ◽  
Tinglu Guan ◽  
Larry Gerace
Keyword(s):  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Mammalian Cells ◽  
Polyclonal Antibodies ◽  
Integral Membrane Proteins ◽  
Immunogold Electron Microscopy ◽  
Nuclear Pore ◽  
Nuclear Lamins ◽  
Nuclear Membranes

We have analyzed the fate of several integral membrane proteins of the nuclear envelope during mitosis in cultured mammalian cells to determine whether nuclear membrane proteins are present in a vesicle population distinct from bulk ER membranes after mitotic nuclear envelope disassembly or are dispersed throughout the ER. Using immunofluorescence staining and confocal microscopy, we compared the localization of two inner nuclear membrane proteins (laminaassociated polypeptides 1 and 2 [LAP1 and LAP2]) and a nuclear pore membrane protein (gp210) to the distribution of bulk ER membranes, which was determined with lipid dyes (DiOC6 and R6) and polyclonal antibodies. We found that at the resolution of this technique, the three nuclear envelope markers become completely dispersed throughout ER membranes during mitosis. In agreement with these results, we detected LAP1 in most membranes containing ER markers by immunogold electron microscopy of metaphase cells. Together, these findings indicate that nuclear membranes lose their identity as a subcompartment of the ER during mitosis. We found that nuclear lamins begin to reassemble around chromosomes at the end of mitosis at the same time as LAP1 and LAP2 and propose that reassembly of the nuclear envelope at the end of mitosis involves sorting of integral membrane proteins to chromosome surfaces by binding interactions with lamins and chromatin.

scholarly journals High-Throughput Identification of Nuclear Envelope Protein Interactions in Schizosaccharomyces pombe Using an Arrayed Membrane Yeast-Two Hybrid Library

2020 ◽  
Vol 10 (12) ◽  
pp. 4649-4663 ◽  
Author(s):  
Joseph M. Varberg ◽  
Jennifer M. Gardner ◽  
Scott McCroskey ◽  
Snehabala Saravanan ◽  
William D. Bradford ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Schizosaccharomyces Pombe ◽  
High Throughput ◽  
Protein Interactions ◽  
Transmembrane Protein ◽  
Integral Membrane Proteins ◽  
Model Organisms ◽  
Yeast Two Hybrid ◽  
Two Hybrid

The nuclear envelope (NE) contains a specialized set of integral membrane proteins that maintain nuclear shape and integrity and influence chromatin organization and gene expression. Advances in proteomics techniques and studies in model organisms have identified hundreds of proteins that localize to the NE. However, the function of many of these proteins at the NE remains unclear, in part due to a lack of understanding of the interactions that these proteins participate in at the NE membrane. To assist in the characterization of NE transmembrane protein interactions we developed an arrayed library of integral and peripheral membrane proteins from the fission yeast Schizosaccharomyces pombe for high-throughput screening using the split-ubiquitin based membrane yeast two -hybrid system. We used this approach to characterize protein interactions for three conserved proteins that localize to the inner nuclear membrane: Cut11/Ndc1, Lem2 and Ima1/Samp1/Net5. Additionally, we determined how the interaction network for Cut11 is altered in canonical temperature-sensitive cut11-ts mutants. This library and screening approach is readily applicable to characterizing the interactomes of integral membrane proteins localizing to various subcellular compartments.

scholarly journals Dynamic Rearrangement of Nucleoporins during Fungal “Open” Mitosis

2008 ◽  
Vol 19 (3) ◽  
pp. 1230-1240 ◽  
Author(s):  
Ulrike Theisen ◽  
Anne Straube ◽  
Gero Steinberg
Keyword(s):  
Nuclear Envelope ◽  
Protein Import ◽  
Complex Dynamics ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Pores ◽  
Basic Principles ◽  
Early Anaphase ◽  
Pore Complexes ◽  
Corn Smut

Mitosis in animals starts with the disassembly of the nuclear pore complexes and the breakdown of the nuclear envelope. In contrast to many fungi, the corn smut fungus Ustilago maydis also removes the nuclear envelope. Here, we report on the dynamic behavior of the nucleoporins Nup214, Pom152, Nup133, and Nup107 in this “open” fungal mitosis. In prophase, the nuclear pore complexes disassembled and Nup214 and Pom152 dispersed in the cytoplasm and in the endoplasmic reticulum, respectively. Nup107 and Nup133 initially spread throughout the cytoplasm, but in metaphase and early anaphase occurred on the chromosomes. In anaphase, the Nup107-subcomplex redistributed to the edge of the chromosome masses, where the new envelope was reconstituted. Subsequently, Nup214 and Pom152 are recruited to the nuclear pores and protein import starts. Recruitment of nucleoporins and protein import reached a steady state in G2 phase. Formation of the nuclear envelope and assembly of nuclear pores occurred in the absence of microtubules or F-actin, but not if both were disrupted. Thus, the basic principles of nuclear pore complex dynamics seem to be conserved in organisms displaying open mitosis.

scholarly journals Caenorhabditis elegans Nucleoporins Nup93 and Nup205 Determine the Limit of Nuclear Pore Complex Size Exclusion In Vivo

2003 ◽  
Vol 14 (12) ◽  
pp. 5104-5115 ◽  
Author(s):  
Vincent Galy ◽  
Iain W. Mattaj ◽  
Peter Askjaer
Keyword(s):  
Caenorhabditis Elegans ◽  
Nuclear Envelope ◽  
Protein Import ◽  
Chromatin Condensation ◽  
Size Exclusion ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
C Elegans ◽  
Pore Complexes

Nuclear pore complexes (NPCs) span the nuclear envelope and mediate communication between the nucleus and the cytoplasm. To obtain insight into the structure and function of NPCs of multicellular organisms, we have initiated an extensive analysis of Caenorhabditis elegans nucleoporins. Of 20 assigned C. elegans nucleoporin genes, 17 were found to be essential for embryonic development either alone or in combination. In several cases, depletion of nucleoporins by RNAi caused severe defects in nuclear appearance. More specifically, the C. elegans homologs of vertebrate Nup93 and Nup205 were each found to be required for normal NPC distribution in the nuclear envelope in vivo. Depletion of Nup93 or Nup205 caused a failure in nuclear exclusion of nonnuclear macromolecules of ∼70 kDa without preventing active nuclear protein import or the assembly of the nuclear envelope. The defects in NPC exclusion were accompanied by abnormal chromatin condensation and early embryonic arrest. Thus, the contribution to NPC structure of Nup93 and Nup205 is essential for establishment of normal NPC function and for cell viability.

scholarly journals Nup358 integrates nuclear envelope breakdown with kinetochore assembly

2003 ◽  
Vol 162 (6) ◽  
pp. 991-1001 ◽  
Author(s):  
Davide Salina ◽  
Paul Enarson ◽  
J.B. Rattner ◽  
Brian Burke
Keyword(s):  
Nuclear Envelope ◽  
Mitotic Checkpoint ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Envelope Breakdown ◽  
Chromosome Congression ◽  
Chromatid Segregation ◽  
Pore Complexes ◽  
Membrane Components ◽  
And Function

Nuclear envelope breakdown (NEBD) and release of condensed chromosomes into the cytoplasm are key events in the early stages of mitosis in metazoans. NEBD involves the disassembly of all major structural elements of the nuclear envelope, including nuclear pore complexes (NPCs), and the dispersal of nuclear membrane components. The breakdown process is facilitated by microtubules of the mitotic spindle. After NEBD, engagement of spindle microtubules with chromosome-associated kinetochores leads to chromatid segregation. Several NPC subunits relocate to kinetochores after NEBD. siRNA-mediated depletion of one of these proteins, Nup358, reveals that it is essential for kinetochore function. In the absence of Nup358, chromosome congression and segregation are severely perturbed. At the same time, the assembly of other kinetochore components is strongly inhibited, leading to aberrant kinetochore structure. The implication is that Nup358 plays an essential role in integrating NEBD with kinetochore maturation and function. Mitotic arrest associated with Nup358 depletion further suggests that mitotic checkpoint complexes may remain active at nonkinetochore sites.

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