Cell-cycle-dependent dynamics of nuclear pores: pore-free islands and lamins

Maeshima, Kazuhiro; Yahata, Kazuhide; Sasaki, Yoko; Nakatomi, Reiko; Tachibana, Taro; Hashikawa, Tsutomu; Imamoto, Fumio; Imamoto, Naoko

doi:10.1242/jcs.03207

Cited by 131 publications

(156 citation statements)

References 61 publications

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“…Doublelabeled nuclei of fixed and permeabilized HeLa cells revealed that the immunofluorescence staining of NE protein markers distributed in characteristic patterns showing variable degrees of overlap ( Fig. 1), indicative of the existence of partially overlapping networks of NE proteins, consistent with previous studies (Liu et al, 2007;Lu et al, 2008;Maeshima et al, 2006;Shimi et al, 2008). We determined the degree of colocalization statistically by Pearson analysis using dual-channel image data from an optical plane corresponding to the lower nuclear surface.…”

Section: Samp1 Distributes In Distinct Micro-domains Of the Inner Nucsupporting

confidence: 82%

“…Investigations in different labs have shown that proteins of the nuclear lamina and the inner nuclear membrane are not evenly localized in the periphery of mammalian nuclei, but instead distribute in distinct but overlapping networks in the NE (Liu et al, 2007;Lu et al, 2008;Maeshima et al, 2006;Shimi et al, 2008). These networks might serve as scaffolds or fundaments for the assembly of a large variety of functional micro domains.…”

Section: Introductionmentioning

confidence: 99%

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Samp1 is functionally associated with the LINC complex and A-type lamina networks

Gudise

Figueroa

Lindberg

et al. 2011

Journal of Cell Science

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The transmembrane inner nuclear membrane (INM) protein Samp1 is required for anchoring centrosomes near the nuclei. Using high-resolution fluorescence microscopy we show that Samp1 is distributed in a distinct and characteristic pattern in the nuclear envelope (NE), where it partially colocalizes with the LINC complex protein Sun1. By studying the localization of Samp1 deletion mutants and fusion proteins, we conclude that the cysteine-rich N-terminal half of Samp1 is nucleoplasmically exposed and is responsible for targeting to the INM. It contains four conserved CxxC motifs with the potential to form zinc fingers. The distribution of cysteine-to-alanine substitution mutants, designed to prevent zinc finger formation, showed that NE localization of Samp1 depends on intact CxxC motifs. Overexpression of Samp1 zinc finger mutants produced an abnormal dominant phenotype characterized by disrupted organization of a selective subset NE proteins, including emerin, Sun1, endogenous Samp1 and, in some cases, lamin A/C, but not lamin B, Sun2 or nucleoporins. Silencing of Samp1 expression showed that emerin depends on Samp1 for its correct localization in the NE. Our results demonstrate that Samp1 is functionally associated with the LINC complex protein Sun1 and proteins of the A-type lamina network.

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Section: Samp1 Distributes In Distinct Micro-domains Of the Inner Nucsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Samp1 is functionally associated with the LINC complex and A-type lamina networks

Gudise

Figueroa

Lindberg

et al. 2011

Journal of Cell Science

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“…There is now strong evidence of an intimate link between the distribution of nuclear pores and the organisation of nuclear structures and processes. [34][35][36] According to our data, the nuclear pores in Leishmania exhibit a striking punctuated distribution, defining a reduced and relatively constant number of 'domains' at the nuclear periphery. This contrasts, however, with previous serial sectioning EM data that allowed Rout and Field 37 to identify 200 -300 nuclear pores per nucleus in T. brucei.…”

Section: Discussionsupporting

confidence: 53%

Inhibition of active nuclear transport is an intrinsic trigger of programmed cell death in trypanosomatids

et al. 2008

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The link between nucleocytoplasmic transport and apoptosis remains controversial. Nucleocytoplasmic exchange of molecules seems indeed essential for the initiation and execution of the apoptotic programme; but inhibition of nuclear transport factors may also represent a powerful apoptotic trigger. The GTPase Ran (together with its partners), first discovered to be essential in nucleocytoplasmic transport, has multiple key functions in cell biology, and particularly in spindle assembly, kinetochore function and nuclear envelope assembly. Among the Ran partners studied, NTF2 appears to be solely involved in nucleocytoplasmic transport. Here, we localised Ran and several of its partners, RanBP1, CAS and NTF2, at the nuclear membrane in the trypanosomatid Leishmania major. Remarkably, these proteins fused to GFP decorated a perinuclear 'collar' of about 15 dots, colocalising at nuclear pore complexes with the homologue of nucleoporin Sec13. In the other trypanosomatid Trypanosoma brucei, RNAi knockdown of the expression of the corresponding genes resulted in an apoptosis-like phenomenon. These phenotypes show that Ran and its partners have a key function in trypanosomatids like they have in mammals. Our data, notably those about TbNTF2 RNAi, support the idea that active nucleocytoplasmic transport is not essential for the initiation and execution of apoptosis, and, rather, the impairment of this transport constitutes an intrinsic signal for triggering PCD.

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“…28 However, the NPC density in replicative senescent cells was much higher, even though both the quiescent and senescent cells were in a nondividing state. 28 This is not so surprising because the proliferation signaling (Ras/ Erk) activates Cdks.…”

Section: Npc Formation Nuclear Growth and Tumor Cellsmentioning

confidence: 96%

Nuclear size, nuclear pore number and cell cycle

Maeshima

Iino

Hihara

et al. 2011

Nucleus

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In eukaryotic cells, the nucleus is a complex and sophisticated organelle containing genomic DNA and supports essential cellular activities. Its surface contains many nuclear pore complexes (NPCs), channels for macromolecular transport between the cytoplasm and nucleus. It has been observed that the nuclear volume and the number of NPCs almost doubles during interphase in dividing cells, but the coordination of these events with the cell cycle was poorly understood, particularly in mammalian cells. Recently, we demonstrated that cyclin-dependent protein kinases (Cdks) control interphase NPC formation in dividing human cells. Cdks drive the very early step of NPC formation because Cdk inhibition suppressed the generation of "nascent pores," which are considered to be immature NPCs, and disturbed expression and localization of some nucleoporins. Cdk inhibition did not affect nuclear volume, suggesting that these two processes have distinct regulatory mechanisms in the cell cycle. The details of our experimental systems and finding are discussed in more depth. With new findings recently reported, we also discuss possible molecular mechanisms of interphase NPC formation.

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Cell-cycle-dependent dynamics of nuclear pores: pore-free islands and lamins

Cited by 131 publications

References 61 publications

Samp1 is functionally associated with the LINC complex and A-type lamina networks

Samp1 is functionally associated with the LINC complex and A-type lamina networks

Inhibition of active nuclear transport is an intrinsic trigger of programmed cell death in trypanosomatids

Nuclear size, nuclear pore number and cell cycle

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