scholarly journals ZC3HC1 Is a Novel Inherent Component of the Nuclear Basket, Resident in a State of Reciprocal Dependence with TPR

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1937
Author(s):  
Philip Gunkel ◽  
Haruki Iino ◽  
Sandra Krull ◽  
Volker C. Cordes
Keyword(s):  
Somatic Cell ◽  
Nuclear Pore Complex ◽  
Structural Integrity ◽  
Coiled Coil ◽  
Cell Types ◽  
Fibrillar Structure ◽  
Nuclear Pore ◽  
Differentiated Cells ◽  
Vertebrate Protein ◽  
Inherent Component

The nuclear basket (NB) scaffold, a fibrillar structure anchored to the nuclear pore complex (NPC), is regarded as constructed of polypeptides of the coiled-coil dominated protein TPR to which other proteins can bind without contributing to the NB’s structural integrity. Here we report vertebrate protein ZC3HC1 as a novel inherent constituent of the NB, common at the nuclear envelopes (NE) of proliferating and non-dividing, terminally differentiated cells of different morphogenetic origin. Formerly described as a protein of other functions, we instead present the NB component ZC3HC1 as a protein required for enabling distinct amounts of TPR to occur NB-appended, with such ZC3HC1-dependency applying to about half the total amount of TPR at the NEs of different somatic cell types. Furthermore, pointing to an NB structure more complex than previously anticipated, we discuss how ZC3HC1 and the ZC3HC1-dependent TPR polypeptides could enlarge the NB’s functional repertoire.

scholarly journals Role of the Ndc1 interaction network in yeast nuclear pore complex assembly and maintenance

2009 ◽  
Vol 185 (3) ◽  
pp. 475-491 ◽  
Author(s):  
Evgeny Onischenko ◽  
Leslie H. Stanton ◽  
Alexis S. Madrid ◽  
Thomas Kieselbach ◽  
Karsten Weis
Keyword(s):  
Nuclear Pore Complex ◽  
Structural Integrity ◽  
Fluorescent Protein ◽  
Interaction Network ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Binding Partners ◽  
Interaction Partners ◽  
Redundant Functions

The nuclear pore complex (NPC) mediates all nucleocytoplasmic transport, yet its structure and biogenesis remain poorly understood. In this study, we have functionally characterized interaction partners of the yeast transmembrane nucleoporin Ndc1. Ndc1 forms a distinct complex with the transmembrane proteins Pom152 and Pom34 and two alternative complexes with the soluble nucleoporins Nup53 and Nup59, which in turn bind to Nup170 and Nup157. The transmembrane and soluble Ndc1-binding partners have redundant functions at the NPC, and disruption of both groups of interactions causes defects in Ndc1 targeting and in NPC structure accompanied by significant pore dilation. Using photoconvertible fluorescent protein fusions, we further show that the depletion of Pom34 in cells that lack NUP53 and NUP59 blocks new NPC assembly and leads to the reversible accumulation of newly made nucleoporins in cytoplasmic foci. Therefore, Ndc1 together with its interaction partners are collectively essential for the biosynthesis and structural integrity of yeast NPCs.

scholarly journals Functional Analysis of Tpr: Identification of Nuclear Pore Complex Association and Nuclear Localization Domains and a Role in mRNA Export

1998 ◽  
Vol 143 (7) ◽  
pp. 1801-1812 ◽  
Author(s):  
Peter Bangs ◽  
Brian Burke ◽  
Christine Powers ◽  
Roger Craig ◽  
Aruna Purohit ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Pore Complex ◽  
Ectopic Expression ◽  
Coiled Coil ◽  
Full Length ◽  
Nuclear Localization Sequence ◽  
Nuclear Pore ◽  
Nuclear Interior ◽  
Mammalian Cell Lines ◽  
Localization Sequence

Tpr is a 270-kD coiled-coil protein localized to intranuclear filaments of the nuclear pore complex (NPC). The mechanism by which Tpr contributes to the structure and function of the nuclear pore is currently unknown. To gain insight into Tpr function, we expressed the full-length protein and several subdomains in mammalian cell lines and examined their effects on nuclear pore function. Through this analysis, we identified an NH2-terminal domain that was sufficient for association with the nucleoplasmic aspect of the NPC. In addition, we unexpectedly found that the acidic COOH terminus was efficiently transported into the nuclear interior, an event that was apparently mediated by a putative nuclear localization sequence. Ectopic expression of the full-length Tpr caused a dramatic accumulation of poly(A)+ RNA within the nucleus. Similar results were observed with domains that localized to the NPC and the nuclear interior. In contrast, expression of these proteins did not appear to affect nuclear import. These data are consistent with a model in which Tpr is tethered to intranuclear filaments of the NPC by its coiled coil domain leaving the acidic COOH terminus free to interact with soluble transport factors and mediate export of macromolecules from the nucleus.

scholarly journals nup1 mutants exhibit pleiotropic defects in nuclear pore complex function.

1994 ◽  
Vol 127 (2) ◽  
pp. 319-332 ◽  
Author(s):  
A M Bogerd ◽  
J A Hoffman ◽  
D C Amberg ◽  
G R Fink ◽  
L I Davis
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Structural Integrity ◽  
Mutational Analysis ◽  
Complex Function ◽  
Spindle Pole ◽  
Nuclear Pore ◽  
Temperature Sensitive ◽  
Amino Terminal ◽  
Carboxy Terminal

The NUP1 gene of Saccharomyces cerevisiae encodes one member of a family of nuclear pore complex proteins (nucleoporins) conserved from yeast to vertebrates. We have used mutational analysis to investigate the function of Nup1p. Deletion of either the amino- or carboxy-terminal domain confers a lethal phenotype, but partial truncations at either end affect growth to varying extents. Amino-terminal truncation causes mislocalization and degradation of the mutant protein, suggesting that this domain is required for targeting Nup1p to the nuclear pore complex. Carboxy-terminal mutants are stable but do not have wild-type function, and confer a temperature sensitive phenotype. Both import of nuclear proteins and export of poly(A) RNA are defective at the nonpermissive temperature. In addition, nup1 mutant cells become multinucleate at all temperatures, a phenotype suggestive of a defect in nuclear migration. Tubulin staining revealed that the mitotic spindle appears to be oriented randomly with respect to the bud, in spite of the presence of apparently normal cytoplasmic microtubules connecting one spindle pole body to the bud tip. EM analysis showed that the nuclear envelope forms long projections extending into the cytoplasm, which appear to have detached from the bulk of the nucleus. Our results suggest that Nup1p may be required to retain the structural integrity between the nuclear envelope and an underlying nuclear scaffold, and that this connection is required to allow reorientation of the nucleus in response to cytoskeletal forces.

scholarly journals Nup84, A Novel Nucleoporin That Is Associated With CAN/Nup214 on the Cytoplasmic Face of the Nuclear Pore Complex

1997 ◽  
Vol 137 (5) ◽  
pp. 989-1000 ◽  
Author(s):  
Ricardo Bastos ◽  
Lluis Ribas de Pouplana ◽  
Mark Enarson ◽  
Khaldon Bodoor ◽  
Brian Burke
Keyword(s):  
Nuclear Pore Complex ◽  
Sequence Similarity ◽  
Coiled Coil ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Significant Sequence Similarity ◽  
Expression Studies ◽  
Cytoplasmic Face ◽  
Secondary Structure Predictions ◽  
Pore Complexes

The short filaments extending from the cytoplasmic face of nuclear pore complexes are thought to contain docking sites for nuclear import substrates. One component of these filaments is the large O-linked glycoprotein CAN/Nup214. Immunoprecipitation studies carried out under nondenaturing conditions, and using a variety of antibodies, reveal a novel nonglycosylated nucleoporin, Nup84, that is tightly associated with CAN/Nup214. Consistent with such an association, Nup84 is found to be exposed on the cytoplasmic face of the nuclear pore complex. cDNA sequence analyses indicate that Nup84 contains neither the GLFG nor the XFXFG repeats that are a characteristic of a number of other nuclear pore complex proteins. Secondary structure predictions, however, suggest that Nup84 contains a coiled–coil COOH-terminal domain, a conclusion supported by the observation of significant sequence similarity between this region of the molecule and various members of the tropomyosin family. Mutagenesis and expression studies indicate that the putative coiled–coil domain is required for association with the cytoplasmic face of the nuclear pore complex, whereas it is the NH2-terminal region of Nup84 that contains the site of interaction with CAN/Nup214. These findings suggest a model in which Nup84 may function in the attachment of CAN/Nup214 to the central framework of the nuclear pore complex. In this way, Nup84 could play a central role in the organization of the interface between the pore complex and the cytoplasm.

scholarly journals A mosaic of old and young nucleoporins

2019 ◽  
Vol 218 (2) ◽  
pp. 385-386
Author(s):  
Takeshi Shimi ◽  
Hiroshi Kimura
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Pore ◽  
Quiescent Cells ◽  
Differentiated Cells ◽  
Cell Biol

Some nucleoporins, the nuclear pore complex (NPC) components, have exceptionally long lifetimes. In this issue, Toyama et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201809123) report that NPCs are maintained by a slow piecemeal replacement of NPC components in dividing and terminally differentiated cells and by whole-pore exchange in quiescent cells.

scholarly journals Nuclear pore complex evolution: a trypanosome Mlp analogue functions in chromosomal segregation but lacks transcriptional barrier activity

2014 ◽  
Vol 25 (9) ◽  
pp. 1421-1436 ◽  
Author(s):  
Jennifer M. Holden ◽  
Ludek Koreny ◽  
Samson Obado ◽  
Alexander V. Ratushny ◽  
Wei-Ming Chen ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Mitotic Spindle ◽  
Nuclear Periphery ◽  
Coiled Coil ◽  
Nuclear Lamina ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Dependent Manner ◽  
Major Barrier ◽  
African Trypanosomes

The nuclear pore complex (NPC) has dual roles in nucleocytoplasmic transport and chromatin organization. In many eukaryotes the coiled-coil Mlp/Tpr proteins of the NPC nuclear basket have specific functions in interactions with chromatin and defining specialized regions of active transcription, whereas Mlp2 associates with the mitotic spindle/NPC in a cell cycle–dependent manner. We previously identified two putative Mlp-related proteins in African trypanosomes, TbNup110 and TbNup92, the latter of which associates with the spindle. We now provide evidence for independent ancestry for TbNup92/TbNup110 and Mlp/Tpr proteins. However, TbNup92 is required for correct chromosome segregation, with knockout cells exhibiting microaneuploidy and lowered fidelity of telomere segregation. Further, TbNup92 is intimately associated with the mitotic spindle and spindle anchor site but apparently has minimal roles in control of gene transcription, indicating that TbNup92 lacks major barrier activity. TbNup92 therefore acts as a functional analogue of Mlp/Tpr proteins, and, together with the lamina analogue NUP-1, represents a cohort of novel proteins operating at the nuclear periphery of trypanosomes, uncovering complex evolutionary trajectories for the NPC and nuclear lamina.

scholarly journals Tpr, a large coiled coil protein whose amino terminus is involved in activation of oncogenic kinases, is localized to the cytoplasmic surface of the nuclear pore complex.

1994 ◽  
Vol 127 (6) ◽  
pp. 1515-1526 ◽  
Author(s):  
D A Byrd ◽  
D J Sweet ◽  
N Panté ◽  
K N Konstantinov ◽  
T Guan ◽  
...  
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Nuclear Pore Complex ◽  
Protein Import ◽  
Coiled Coil ◽  
In Vitro Translation ◽  
Immunogold Electron Microscopy ◽  
Nuclear Pore ◽  
Amino Terminal ◽  
Cytoplasmic Surface

From a panel of monoclonal antibodies raised against fractions of rat liver nuclear envelopes (NEs), we have identified an antibody, RL30, which reacts with novel nuclear pore complex (NPC) antigens that are not O-glycosylated. By immunofluorescence staining of cultured cells, RL30 reacts exclusively with the NE in a punctate pattern that largely coincides with that of identified NPC proteins. RL30 labels only the cytoplasmic surface of the NPC in immunogold electron microscopy, predominantly in peripheral regions nearby the cytoplasmic ring. In immunoblots of isolated rat liver NEs and cultured rat cells, RL30 recognizes a 265-kD band, as well as a series of 175-265-kD bands in rat liver NEs that are likely to be proteolytic products of p265. Sequencing of peptides from the 175- and 265-kD RL30 antigens of rat liver revealed that they are both closely related to human Tpr, a protein whose amino-terminal 150-250 amino acids appear in oncogenic fusions with the kinase domains of the met, trk, and raf protooncogenes. We found that in vitro translation of human Tpr mRNA yields a major 265-kD band. Considered together, these data indicate that the 265-kD RL30 antigen in the NPC is the rat homologue of Tpr. Interestingly, Tpr contains an exceptionally long predicted coiled coil domain (approximately 1600 amino acids). The localization and predicted structure of Tpr suggest that it is a component of the cytoplasmic fibrils of the NPC implicated in nuclear protein import. Immunofluorescence microscopy shows that during NPC reassembly at the end of mitosis, Tpr becomes concentrated at the NE significantly later than O-linked glycoproteins, including p62. This indicates that reassembly of the NPC after mitosis is a stepwise process, and that the Tpr-containing peripheral structures are assembled later than p62.

scholarly journals Nuclear Envelope Regulation of Oncogenic Processes: Roles in Pancreatic Cancer

Epigenomes ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 15 ◽  
Author(s):  
Claudia Preston ◽  
Randolph Faustino
Keyword(s):  
Pancreatic Cancer ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Structural Integrity ◽  
Radiation Treatment ◽  
Tumor Biology ◽  
Nuclear Lamina ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Linc Complex

Pancreatic cancer is an aggressive and intractable malignancy with high mortality. This is due in part to a high resistance to chemotherapeutics and radiation treatment conferred by diverse regulatory mechanisms. Among these, constituents of the nuclear envelope play a significant role in regulating oncogenesis and pancreatic tumor biology, and this review focuses on three specific components and their roles in cancer. The LINC complex is a nuclear envelope component formed by proteins with SUN and KASH domains that interact in the periplasmic space of the nuclear envelope. These interactions functionally and structurally couple the cytoskeleton to chromatin and facilitates gene regulation informed by cytoplasmic activity. Furthermore, cancer cell invasiveness is impacted by LINC complex biology. The nuclear lamina is adjacent to the inner nuclear membrane of the nuclear envelope and can actively regulate chromatin in addition to providing structural integrity to the nucleus. A disrupted lamina can impart biophysical compromise to nuclear structure and function, as well as form dysfunctional micronuclei that may lead to genomic instability and chromothripsis. In close relationship to the nuclear lamina is the nuclear pore complex, a large megadalton structure that spans both outer and inner membranes of the nuclear envelope. The nuclear pore complex mediates bidirectional nucleocytoplasmic transport and is comprised of specialized proteins called nucleoporins that are overexpressed in many cancers and are diagnostic markers for oncogenesis. Furthermore, recent demonstration of gene regulatory functions for discrete nucleoporins independent of their nuclear trafficking function suggests that these proteins may contribute more to malignant phenotypes beyond serving as biomarkers. The nuclear envelope is thus a complex, intricate regulator of cell signaling, with roles in pancreatic tumorigenesis and general oncogenic transformation.

scholarly journals Assembly and Preferential Localization of Nup116p on the Cytoplasmic Face of the Nuclear Pore Complex by Interaction with Nup82p

2000 ◽  
Vol 20 (15) ◽  
pp. 5736-5748 ◽  
Author(s):  
Albert K. Ho ◽  
Tian Xiang Shen ◽  
Kathryn J. Ryan ◽  
Elena Kiseleva ◽  
Marilyn Aach Levy ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Coiled Coil ◽  
Nuclear Pore ◽  
Binding Partners ◽  
Coiled Coil Region ◽  
Preferential Localization ◽  
Cytoplasmic Face ◽  
Microscopy Analysis ◽  
Import And Export ◽  
Two Hybrid

ABSTRACT The yeast Saccharomyces cerevisiae nucleoporin Nup116p serves as a docking site for both nuclear import and export factors. However, the mechanism for assembling Nup116p into the nuclear pore complex (NPC) has not been resolved. By conducting a two-hybrid screen with the carboxy (C)-terminal Nup116p region as bait, we identified Nup82p. The predicted coiled-coil region of Nup82p was not required for Nup116p interaction, making the binding requirements distinct from those for the Nsp1p-Nup82p-Nup159p subcomplex (N. Belgareh, C. Snay-Hodge, F. Pasteau, S. Dagher, C. N. Cole, and V. Doye, Mol. Biol. Cell 9:3475–3492, 1998). Immunoprecipitation experiments using yeast cell lysates resulted in the coisolation of a Nup116p-Nup82p subcomplex. Although the absence of Nup116p had no effect on the NPC localization of Nup82p, overexpression of C-terminal Nup116p in a nup116 null mutant resulted in Nup82p mislocalization. Moreover, NPC localization of Nup116p was specifically diminished in a nup82-Δ108 mutant after growth at 37°C. Immunoelectron microscopy analysis showed Nup116p was localized on both the cytoplasmic and nuclear NPC faces. Its distribution was asymmetric with the majority at the cytoplasmic face. Taken together, these results suggest that Nup82p and Nup116p interact at the cytoplasmic NPC face, with nucleoplasmic Nup116p localization utilizing novel binding partners.

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