Partial Nuclear Pore Complex Disassembly during Closed Mitosis in Aspergillus nidulans

Souza, Colin P. C. De; Osmani, Aysha H.; Hashmi, Shahr B.; Osmani, Stephen A.

doi:10.1016/j.cub.2004.10.050

Cited by 202 publications

(238 citation statements)

References 66 publications

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“…Our unexpected result was however corroborated by a study that came out while this manuscript was under revision, revealing that human Nup58 remains longer than Nup133 (another constituent of the Nup107 complex) in fragments of the NE during disassembly (Dultz et al, 2008). During the closed mitosis of the fungus Aspergillus nidulans, however, FG-nups, including those making up the central channel, disperse throughout the cell, whereas constituents of the Nup107 subcomplex persist at NPCs (De Souza et al, 2004;Osmani et al, 2006). Accordingly, the fate of NPC components in Drosophila and human cells, in which all NPC constituents disassemble, seems to be distinct from that occurring during the closed mitosis of A. nidulans.…”

Section: Npc Disassembly and Reassembly In Drosophila Mitosissupporting

confidence: 53%

In Vivo Dynamics ofDrosophilaNuclear Envelope Components

Katsani

Karess

Dostatni

et al. 2008

MBoC

120

128

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Nuclear pore complexes (NPCs) are multisubunit protein entities embedded into the nuclear envelope (NE). Here, we examine the in vivo dynamics of the essential Drosophila nucleoporin Nup107 and several other NE-associated proteins during NE and NPCs disassembly and reassembly that take place within each mitosis. During both the rapid mitosis of syncytial embryos and the more conventional mitosis of larval neuroblasts, Nup107 is gradually released from the NE, but it remains partially confined to the nuclear (spindle) region up to late prometaphase, in contrast to nucleoporins detected by wheat germ agglutinin and lamins. We provide evidence that in all Drosophila cells, a structure derived from the NE persists throughout metaphase and early anaphase. Finally, we examined the dynamics of the spindle checkpoint proteins Mad2 and Mad1. During mitotic exit, Mad2 and Mad1 are actively imported back from the cytoplasm into the nucleus after the NE and NPCs have reformed, but they reassociate with the NE only later in G1, concomitantly with the recruitment of the basket nucleoporin Mtor (the Drosophila orthologue of vertebrate Tpr). Surprisingly, Drosophila Nup107 shows no evidence of localization to kinetochores, despite the demonstrated importance of this association in mammalian cells. INTRODUCTIONIn eukaryotes, the nuclear envelope (NE) defines the limits between the nucleus and the cytoplasm. The outer NE membrane is considered to be structurally and functionally part of the endoplasmic reticulum network, whereas the inner membrane, with its distinct protein composition, provides anchoring points for the chromatin and nuclear lamina. Nuclear pore complexes (NPCs) are embedded at the points of fusion between the inner and outer NE membrane and represent the sole channels of transport across the NE. NPCs are composed of multiple copies of ϳ30 different proteins termed nucleoporins (Nups), most of which are organized into subcomplexes that associate with each other to build up the mature NPCs (for reviews, see Hetzer et al., 2005;Schwartz, 2005;Lim and Fahrenkrog, 2006;Tran and Wente, 2006). During cell division, the NE and NPCs are subjected to major rearrangements. However, the extent to which the NE and NPCs disassemble at mitotic entry varies among organisms (for reviews, see Margalit et al., 2005;Prunuske and Ullman, 2006). Unlike in most yeast and fungi, characterized by a "closed mitosis," NE disassembly is required in animal cells to allow spindle microtubule access to chromosomes. In vertebrates, cell division leads to complete NE breakdown at the prophase-prometaphase transition. During this "open mitosis," integral membrane proteins of the NE and the soluble subcomplexes of the NPCs redistribute throughout the endoplasmic reticulum and the mitotic cytoplasm (for reviews, see Hetzer et al., 2005;Margalit et al., 2005;Prunuske and Ullman, 2006). In Drosophila and Caenorhabditis elegans embryos, however, the NE only partially disassembles near spindle poles in early mitosis. NPCs disassemble during prometapha...

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Section: Npc Disassembly and Reassembly In Drosophila Mitosissupporting

confidence: 53%

In Vivo Dynamics ofDrosophilaNuclear Envelope Components

Katsani

Karess

Dostatni

et al. 2008

MBoC

120

128

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“…Binding to Nup53p inhibits the translocation of Kap121p and its cargo into the nucleus, thus specifically regulating this pathway during mitosis (Makhnevych et al, 2003). Other examples of regulated changes in nup interactions have also been observed in Aspergillus nidulans (De Souza et al, 2004). Here, alterations in the NPC are correlated with phosphorylation of the nups Gle2/Rae1 and Nup98 by the mitotic kinase NIMA.…”

Section: Introductionmentioning

confidence: 88%

Vertebrate Nup53 Interacts with the Nuclear Lamina and Is Required for the Assembly of a Nup93-containing Complex

Hawryluk-Gara

Shibuya

Wozniak

2005

MBoC

125

149

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The nuclear pore complex (NPC) is an evolutionarily conserved structure that mediates exchange of macromolecules across the nuclear envelope (NE). It is comprised of ϳ30 proteins termed nucleoporins that are each present in multiple copies. We have investigated the function of the human nucleoporin Nup53, the ortholog of Saccharomyces cerevisiae Nup53p. Both cell fractionation and in vitro binding data suggest that Nup53 is tightly associated with the NE membrane and the lamina where it interacts with lamin B. We have also shown that Nup53 is capable of physically interacting with a group of nucleoporins including Nup93, Nup155, and Nup205. Consistent with this observation, depletion of Nup53 using small interfering RNAs causes a decrease in the cellular levels of these nucleoporins as well as the spindle checkpoint protein Mad1, likely due to destabilization of Nup53-containing complexes. The cellular depletion of this group of nucleoporins, induced by depleting either Nup53 or Nup93, severely alters nuclear morphology producing phenotypes similar to that previously observed in cells depleted of lamin A and Mad1. On basis of these data, we propose a model in which Nup53 is positioned near the pore membrane and the lamina where it anchors an NPC subcomplex containing Nup93, Nup155, and Nup205. INTRODUCTIONThe nuclear envelope (NE) is a specialized membrane system that functions to separate the eukaryotic genome from the cytoplasm. The NE consists of an inner and an outer nuclear membrane. The former contains a distinct set of associated proteins, whereas the latter is structurally equivalent to the endoplasmic reticulum (reviewed in Mattaj, 2004). The nucleoplasmic face of the metazoan inner nuclear membrane is connected to a fibrous protein meshwork termed the nuclear lamina that forms a shell around the underlying chromatin mass. The lamina is composed of Aand B-type lamins, which are closely related to one another and to the intermediate filament-like family of proteins (reviewed in Burke, 2001). The nuclear lamina has been suggested to be involved in maintaining the structural integrity of the NE and influencing chromatin structure and function. The association of the lamina with transcriptionally inactive heterochromatin has led to the suggestion that it may play a role in regulating gene expression and some recent data support this idea (reviewed in Mattout-Drubezki and Gruenbaum, 2003).At numerous points along the NE the inner and outer nuclear membranes fuse to form pores ϳ100 nm in diameter. These pores are occupied by complex macromolecular structures termed nuclear pore complexes (NPCs). The NPCs are associated with euchromatin channels that extend into the interior of the nucleus, interrupting the continuity of the lamina and the heterochromatin. These complex structures have an estimated mass of ϳ60 million Daltons, but are composed of a relatively small number of proteins (ϳ30; Rout et al., 2000;Cronshaw et al., 2002) termed nucleoporins or nups. This is explained by the fact that all of these prot...

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“…We have previously isolated mutations in two nucleoporins, SONA Gle2 and SONBn Nup98 , which suppress a nimA1 G 2 arrest and allow entry into mitosis (Wu et al 1998;De Souza et al 2003). Both SONA Gle2 and SONBn Nup98 disperse from the NPC during the partial disassembly of the NPC in A. nidulans (De Souza et al 2004). It is likely that these NPC mutants suppress the nimA1 G 2 arrest by allowing sufficient Cdc2/cyclinB and tubulin into the nucleus to allow mitotic entry (Wu et al 1998;De Souza et al 2004).…”

Section: Mre11mentioning

confidence: 99%

A Point Mutation in theAspergillus nidulans sonBNup98 Nuclear Pore Complex Gene Causes Conditional DNA Damage Sensitivity

Souza

Hashmi

Horn³

et al. 2006

Genetics

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The nuclear pore complex (NPC) is embedded in the nuclear envelope where it mediates transport between the cytoplasm and nucleus and helps to organize nuclear architecture. We previously isolated sonB1, a mutation encoding a single amino acid substitution within the Aspergillus nidulans SONBn Nup98 NPC protein (nucleoporin). Here we demonstrate that this mutation causes marked DNA damage sensitivity at 42°. Although SONBn Nup98 has roles in the G 2 transition, we demonstrate that the G 2 DNA damage checkpoint is functional in the sonB1 mutant at 42°. The MRN complex is composed of MRE11, RAD50, and NBS1 and functions in checkpoint signaling, DNA repair, and telomere maintenance. At 42°w e find that the DNA damage response defect of sonB1 mutants causes synthetic lethality when combined with mutations in scaA NBS1 , the A. nidulans homolog of NBS1. We provide evidence that this synthetic lethality is independent of MRN cell cycle checkpoint functions or MREA MRE11-mediated DNA repair functions. We also demonstrate that the single A. nidulans histone H2A gene contains the C-terminal SQE motif of histone H2AX isoforms and that this motif is required for the DNA damage response. We propose that the sonB1 nucleoporin mutation causes a defect in a novel part of the DNA damage response.

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Partial Nuclear Pore Complex Disassembly during Closed Mitosis in Aspergillus nidulans

Cited by 202 publications

References 66 publications

In Vivo Dynamics ofDrosophilaNuclear Envelope Components

In Vivo Dynamics ofDrosophilaNuclear Envelope Components

Vertebrate Nup53 Interacts with the Nuclear Lamina and Is Required for the Assembly of a Nup93-containing Complex

A Point Mutation in theAspergillus nidulans sonBNup98 Nuclear Pore Complex Gene Causes Conditional DNA Damage Sensitivity

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