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Nuclear pore complex

Kai Wen Teng, Yuji Ishitsuka, Pin Ren, Yeoan Youn, Xiang Deng, Pinghua Ge, Andrew S Belmont, Paul R Selvin
Site-specific fluorescent labeling of proteins inside live mammalian cells has been achieved by employing Streptolysin O, a bacterial enzyme which forms temporary pores in the membrane and allows delivery of virtually any fluorescent probes, ranging from labeled IgG's to small ligands, with high efficiency (>85% of cells). The whole process, including recovery, takes 30 min, and the cell is ready to be imaged immediately. A variety of cell viability tests were performed after treatment with SLO to ensure that the cells have intact membranes, are able to divide, respond normally to signaling molecules, and maintains healthy organelle morphology...
December 9, 2016: ELife
Christopher L Lord, Ophir Ospovat, Susan R Wente
Nuclear pore complexes (NPCs), which are composed of nucleoporins (Nups) and regulate transport between the nucleus and cytoplasm, significantly impact the replicative life span (RLS) of Saccharomyces cerevisiae We previously reported that deletion of the non-essential gene NUP100 increases RLS, although the molecular basis for this effect was unknown. In this study, we find that nuclear tRNA accumulation contributes to increased longevity in nup100Δ cells. Fluorescence in situ hybridization (FISH) experiments demonstrate several specific tRNAs accumulate in the nuclei of nup100Δ mutants...
December 8, 2016: RNA
Shintaro Aibara, James M B Gordon, Anja S Riesterer, Stephen H McLaughlin, Murray Stewart
In Saccharomyces cerevisiae generation of export-competent mRNPs terminates the nuclear phase of the gene expression pathway and facilitates transport to the cytoplasm for translation. Nab2 functions in this process to control both mRNP compaction that facilitates movement through nuclear pore complexes and the length of transcript poly(A) tails. Nab2 has a modular structure that includes seven CCCH Zn fingers that bind to A-rich RNAs and fingers 5-7 are critical for these functions. Here, we demonstrate, using both biophysical and structural methods, that binding A11G RNA induces dimerization of Zn fingers 5-7 mediated by the novel spatial arrangement of the fingers promoting each RNA chain binding two protein chains...
December 8, 2016: Nucleic Acids Research
Kazunari Iwamoto, Yuki Shindo, Koichi Takahashi
Cellular heterogeneity, which plays an essential role in biological phenomena, such as drug resistance and migration, is considered to arise from intrinsic (i.e., reaction kinetics) and extrinsic (i.e., protein variability) noise in the cell. However, the mechanistic effects of these types of noise to determine the heterogeneity of signal responses have not been elucidated. Here, we report that the output of epidermal growth factor (EGF) signaling activity is modulated by cellular noise, particularly by extrinsic noise of particular signaling components in the pathway...
November 2016: PLoS Computational Biology
Yi Ning
Chromosome translocations leading to gene fusions have emerged as important oncogenic drivers of various types of malignancies. Detection and characterization of these fusion genes not only help diagnosis and management of specific malignancies, but also contribute to our understanding of the genetic basis and pathogenesis of these diseases. NUP98 gene encodes a 98 kDa nucleoporin, which is a component of the nuclear pore complex that mediates transport of mRNA and proteins between the nucleus and the cytoplasm...
December 2016: Best Practice & Research. Clinical Haematology
Alejandro Gozalo, Maya Capelson
Knowing the configuration of the nuclear pore is essential for appreciating the underlying mechanisms of nucleo-cytoplasmic communication. Now, Fernandez-Martinez et al. present a high-resolution structure of the cytoplasmic nuclear pore-mRNA export holo-complex, challenging our textbook depiction of this massive membrane-embedded complex.
November 17, 2016: Cell
Marion Weberruss, Wolfram Antonin
The nucleus is enclosed by the nuclear envelope, a double membrane which creates a selective barrier between the cytoplasm and the nuclear interior. Its barrier and transport characteristics are determined by nuclear pore complexes (NPCs) that are embedded within the nuclear envelope, and control molecular exchange between the cytoplasm and nucleoplasm. In this Commentary, we discuss the biogenesis of these huge protein assemblies from approximately one thousand individual proteins. We will summarize current knowledge about distinct assembly modes in animal cells that are characteristic for different cell cycle phases and their regulation...
November 17, 2016: Journal of Cell Science
Tsung-Hsuan Lai, Ying-Yu Wu, Ya-Yun Wang, Mei-Feng Chen, Pei Wang, Tsung-Ming Chen, Yi-No Wu, Han-Sun Chiang, Pao-Lin Kuo, Ying-Hung Lin
Male factor infertility accounts for approximately 50 percent of infertile couples. The male factor-related causes of intracytoplasmic sperm injection failure include the absence of sperm, immotile sperm, immature sperm, abnormally structured sperm, and sperm with nuclear damage. Our knockout and knock-in mice models demonstrated that SEPTIN12 (SEPT12) is vital for the formation of sperm morphological characteristics during spermiogenesis. In the clinical aspect, mutated SEPT12 in men results in oligozoospermia or teratozoospermia or both...
November 16, 2016: International Journal of Molecular Sciences
Ryan T Behrens, Mounavya Aligeti, Ginger M Pocock, Christina A Higgins, Nathan M Sherer
: HIV-1's Rev protein forms a homooligomeric adaptor complex linking viral RNAs to the cellular CRM1/Ran-GTP nuclear export machinery through the activity of Rev's prototypical leucine-rich nuclear export signal (NES). In this study we used a functional fluorescently-tagged Rev fusion protein as a platform to study the effects of modulating Rev NES identity, number, position, or strength on Rev subcellular trafficking, viral RNA nuclear export, and infectious virion production. We found Rev activity to be remarkably tolerant of diverse NES sequences including supraphysiological NES (SNES) peptides that otherwise arrest CRM1 transport complexes at nuclear pores...
November 16, 2016: Journal of Virology
Alicia K Friedman, Lane A Baker
Synthetic hydrogels were utilized to explore influence of both charge and phenylalanine-glycine (FG) repeat concentration on translocation of select proteins. Hydrogels studied represent a biomimetic platform of the nuclear pore complex (NPC) found in eukaryotic cells. Polyacrylamide/phenylalanine-serine-phenylalanine-glycine (FSFG) peptide copolymers have previously demonstrated similar selectivity to native NPCs. Entry of a nuclear transport receptor (Impβ) into hydrogels was monitored with fluorescence microscopy and observed to be greater within gels that contained larger concentrations of FG peptide...
November 16, 2016: Soft Matter
Helene Andersen, Ladan Parhamifar, A Christy Hunter, Victor Shahin, S Moein Moghimi
It has been questioned as to whether polyplexes in the cytoplasm can reach the nuclear compartment and if so in what form. By applying atomic force microscopy (AFM) to the nuclear envelope and the nuclear pore complexes, we demonstrate that disposition of polyethylenimine (PEI)/DNA polyplexes that were microinjected into the oocytes of Xenopus laevis, as an example of a non-dividing cell, is exclusive to the nuclear pore complex (NPC). AFM images show NPCs clogged only with sub-50nm polyplexes. This mode of disposition neither altered the morphology/integrity of the nuclear membrane nor the NPC...
November 11, 2016: Journal of Controlled Release: Official Journal of the Controlled Release Society
Zbigniew Korwek, Karolina Tudelska, Paweł Nałęcz-Jawecki, Maciej Czerkies, Wiktor Prus, Joanna Markiewicz, Marek Kochańczyk, Tomasz Lipniacki
BACKGROUND: Importins and exportins influence gene expression by enabling nucleocytoplasmic shuttling of transcription factors. A key transcription factor of innate immunity, NF-κB, is sequestered in the cytoplasm by its inhibitor, IκBα, which masks nuclear localization sequence of NF-κB. In response to TNFα or LPS, IκBα is degraded, which allows importins to bind NF-κB and shepherd it across nuclear pores. NF-κB nuclear activity is terminated when newly synthesized IκBα enters the nucleus, binds NF-κB and exportin which directs the complex to the cytoplasm...
November 11, 2016: Biology Direct
Renjie Wang, Alain Kamgoue, Christophe Normand, Isabelle Léger-Silvestre, Thomas Mangeat, Olivier Gadal
How does the spatial organization of the genome depend on the nuclear shape is unknown, mostly because accurate nuclear size and shape measurement is technically challenging. In large cell populations of the yeast Saccharomyces cerevisiae, we assessed the geometry (size and shape) of nuclei in three dimensions (3D) with a resolution of 30 nm. We improved an automated fluorescent localization method by implementing a post-acquisition correction of the spherical microscopic aberration along the Z-axis, to detect the three dimensional (3D) positions of nuclear pore complexes (NPCs) in the nuclear envelope (NE)...
November 9, 2016: Journal of Cell Science
Doortje Borrenberghs, Lieve Dirix, Flore De Wit, Susana Rocha, Jolien Blokken, Stéphanie De Houwer, Rik Gijsbers, Frauke Christ, Johan Hofkens, Jelle Hendrix, Zeger Debyser
Nuclear entry is a selective, dynamic process granting the HIV-1 pre-integration complex (PIC) access to the chromatin. Classical analysis of nuclear entry of heterogeneous viral particles only yields averaged information. We now have employed single-virus fluorescence methods to follow the fate of single viral pre-integration complexes (PICs) during infection by visualizing HIV-1 integrase (IN). Nuclear entry is associated with a reduction in the number of IN molecules in the complexes while the interaction with LEDGF/p75 enhances IN oligomerization in the nucleus...
November 10, 2016: Scientific Reports
M M Kurshakova, S G Georgieva, D V Kopytova
The molecular mechanisms that coordinate transcription, processing, mRNP assembly, and mRNA export from the nucleus through nuclear pores into the cytoplasm have been the focus of intense research in recent years. Data demonstrating a tight association between the processes involved in gene expression are considered. The main protein complexes that play a role in mRNA export are described. The complexes are recruited to mRNA at steps preceding the mRNA export. The functions that the complexes perform at particular steps of gene expression are analyzed, and protein complexes responsible for quality control of mRNP discussed...
September 2016: Molekuliarnaia Biologiia
Arkaitz Ibarra, Chris Benner, Swati Tyagi, Jonah Cool, Martin W Hetzer
The organization of the genome in the three-dimensional space of the nucleus is coupled with cell type-specific gene expression. However, how nuclear architecture influences transcription that governs cell identity remains unknown. Here, we show that nuclear pore complex (NPC) components Nup93 and Nup153 bind superenhancers (SE), regulatory structures that drive the expression of key genes that specify cell identity. We found that nucleoporin-associated SEs localize preferentially to the nuclear periphery, and absence of Nup153 and Nup93 results in dramatic transcriptional changes of SE-associated genes...
October 15, 2016: Genes & Development
Yuya Hirai, Yasuhiro Hirano, Atsushi Matsuda, Yasushi Hiraoka, Tomoyuki Honda, Keizo Tomonaga
Animal-derived RNA viruses frequently generate viral factories in infected cells. However, the details of how RNA viruses build such intracellular structures are poorly understood. In this study, we examined the structure and formation of the viral factories, called viral speckle of transcripts (vSPOTs), that are produced in the nuclei of host cells by Borna disease virus (BDV). Super-resolution microscopic analysis showed that BDV assembled vSPOTs as intranuclear cage-like structures with 59-180-nm pores. The viral nucleoprotein formed the exoskeletons of vSPOTs, whereas the other viral proteins appeared to be mainly localized within these structures...
November 1, 2016: Journal of Biological Chemistry
Yasuhiro Mimura, Masatoshi Takagi, Michaela Clever, Naoko Imamoto
Lamin B receptor (LBR), an inner nuclear membrane (INM) protein, contributes to the functional integrity of the nucleus by tethering heterochromatin to the nuclear envelope. We have previously reported that the depletion of embryonic large molecule derived from yolk sac (ELYS; also known as AHCTF1), a component of the nuclear pore complex, from cells perturbs the localization of LBR to the INM, but little is known about the underlying molecular mechanism. In this study, we found that the depletion of ELYS promoted LBR phosphorylation at the residues known to be phosphorylated by cyclin-dependent kinase (CDK) and serine/arginine protein kinases 1 and 2 (SRPK1 and SRPK2, respectively)...
November 15, 2016: Journal of Cell Science
Catherine H Freudenreich, Xiaofeng A Su
Early screens in yeast for mutations exhibiting sensitivity to DNA damage identified nuclear pore components, but their role in DNA repair was not well understood. Over the last decade, studies have revealed that several types of persistent DNA lesions relocate to either the nuclear pore complex (NPC) or nuclear envelope. Of these two sites, the nuclear pore appears to be crucial for DNA repair of persistent double-strand breaks (DSBs), eroded telomeres, and sites of fork collapse at expanded CAG repeats. Using a combination of cell biological imaging techniques and yeast genetic assays for DNA repair, researchers have begun to understand both the how and why of lesion relocation to the NPC...
October 30, 2016: FEMS Yeast Research
Ethan Laudermilch, Pei-Ling Tsai, Morven Graham, Elizabeth Turner, Chenguang Zhao, Christian Schlieker
The human genome encodes four Torsin ATPases, the functions of which are poorly understood. In this study, we employ CRISPR/Cas9 engineering to delete all four Torsin ATPases individually and in combination. Using nuclear envelope (NE) blebbing as a phenotypic measure, we establish a direct correlation between the number of inactivated Torsin alleles and the occurrence of omega-shaped herniations within the lumen of the NE. A similar, though not identical, redundancy is observed for LAP1 and LULL1, which serve as regulatory cofactors for a subset of Torsin ATPases...
October 26, 2016: Molecular Biology of the Cell
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