scholarly journals Nup153 Affects Entry of Messenger and Ribosomal Ribonucleoproteins into the Nuclear Basket during Export

2005 ◽  
Vol 16 (12) ◽  
pp. 5610-5620 ◽  
Author(s):  
Teresa Soop ◽  
Birgitta Ivarsson ◽  
Birgitta Björkroth ◽  
Nathalie Fomproix ◽  
Sergej Masich ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Pore ◽  
Chironomus Tentans ◽  
Balbiani Ring ◽  
Ribosomal Subunits ◽  
Step Process ◽  
Antibody Binding Site ◽  
Messenger Ribonucleoprotein ◽  
In Transit ◽  
Nuclear Injection

A specific messenger ribonucleoprotein (RNP) particle, Balbiani ring (BR) granules in the dipteran Chironomus tentans, can be visualized during passage through the nuclear pore complex (NPC). We have now examined the transport through the nuclear basket preceding the actual translocation through the NPC. The basket consists of eight fibrils anchored to the NPC core by nucleoprotein Nup153. On nuclear injection of anti-Nup153, the transport of BR granules is blocked. Many granules are retained on top of the nuclear basket, whereas no granules are seen in transit through NPC. Interestingly, the effect of Nup153 seems distant from the antibody-binding site at the base of the basket. We conclude that the entry into the basket is a two-step process: an mRMP first binds to the tip of the basket fibrils and only then is it transferred into the basket by a Nup153-dependent process. It is indicated that ribosomal subunits follow a similar pathway.

scholarly journals Structural interaction between the nuclear pore complex and a specific translocating RNP particle.

1995 ◽  
Vol 129 (5) ◽  
pp. 1205-1216 ◽  
Author(s):  
H Mehlin ◽  
B Daneholt ◽  
U Skoglund
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Pore ◽  
Initial Contact ◽  
Chironomus Tentans ◽  
Central Channel ◽  
Balbiani Ring ◽  
Salivary Gland Cells ◽  
Larval Salivary Gland ◽  
Nuclear Ring ◽  
Precise Area

The transport of Balbiani ring (BR) premessenger RNP particles in the larval salivary gland cells of the dipteran Chironomus tentans can be followed using electron microscopy. A BR RNP particle consists of an RNP ribbon bent into a ringlike structure. Upon translocation through the nuclear pore complex (NPC), the ribbon is straightened and enters the central channel of the NPC with the 5' end of the transcript in the lead. The translocating ribbon is likely to interact with the central channel but, in addition, the remaining portion of the ribbon ring makes contact with the periphery of the NPC. To determine the nature of this latter interaction, we have now studied the connections between the RNP particle and the border of the NPC during different stages of translocation using electron microscope tomography. It was observed that the 3' terminal domain of the ribbon always touches the nuclear ring of the NPC, but the precise area of contact is variable. Sometimes also a region on the opposite side of the ribbon ring reaches the nuclear ring. The pattern of contacts could be correlated to the stage of translocation, and it was concluded that the particle-nuclear ring interactions reflect a rotation of the ribbon ring in front of the central channel, the rotation being secondary to the successive translocation of the ribbon through the channel. The particle's mode of interaction with the NPC suggests that the initial contact between the 5' end domain of the ribbon and the entrance to the central channel is probably crucial to accomplish the ordered translocation of the premessenger RNP particle through the NPC.

scholarly journals The hrp23 Protein in the Balbiani Ring Pre-mRNP Particles Is Released Just before or at the Binding of the Particles to the Nuclear Pore Complex

1998 ◽  
Vol 142 (5) ◽  
pp. 1181-1193 ◽  
Author(s):  
Xin Sun ◽  
Alla T. Alzhanova-Ericsson ◽  
Neus Visa ◽  
Youssef Aissouni ◽  
Jian Zhao ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Rna Binding ◽  
Rna Binding Protein ◽  
Salivary Proteins ◽  
Nuclear Pore ◽  
Chironomus Tentans ◽  
Balbiani Ring ◽  
Specific Flow ◽  
New Protein

Balbiani ring (BR) pre-mRNP particles reside in the nuclei of salivary glands of the dipteran Chironomus tentans and carry the message for giant-sized salivary proteins. In the present study, we identify and characterize a new protein component in the BR ribonucleoprotein (RNP) particles, designated hrp23. The protein with a molecular mass of 20 kD has a single RNA-binding domain and a glycine-arginine-serine–rich auxiliary domain. As shown by immunoelectron microscopy, the hrp23 protein is added to the BR transcript concomitant with transcription, is still present in the BR particles in the nucleoplasm, but is absent from the BR particles that are bound to the nuclear pore complex or are translocating through the central channel of the complex. Thus, hrp23 is released just before or at the binding of the particles to the nuclear pore complex. It is noted that hrp23 behaves differently from two other BR RNP proteins earlier studied: hrp36 and hrp45. These proteins both reach the nuclear pore complex, and hrp36 even accompanies the RNA into the cytoplasm. It is concluded that each BR RNA-binding protein seems to have a specific flow pattern, probably related to the particular role of the protein in gene expression.

scholarly journals Endogenously expressed Ranbp2 (Nup358) is not at the axon initial segment

2021 ◽  
pp. jcs.256180
Author(s):  
Yuki Ogawa ◽  
Matthew N. Rasband
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Initial Segment ◽  
Axon Initial Segment ◽  
Nuclear Pore ◽  
Cultured Neurons ◽  
Epitope Tag ◽  
Antibody Binding Site ◽  
Axon Initial Segments ◽  
Primary Cultured Neurons

Ranbp2 (also known as Nup358) is a member of the nucleoporin family that comprises the nuclear pore complex. Ranbp2 localizes at the nuclear membrane and was recently reported at the axon initial segment (AIS). However, we show the anti-Ranbp2 antibody used in previous studies is not specific for Ranbp2. We mapped the antibody binding site to the amino acid sequence KPLQG that is present in both Ranbp2 and Neurofascin, a well-known AIS protein. After silencing Neurofascin expression in neurons, the AIS was not stained by the antibody. Surprisingly, an exogenously expressed N-terminal fragment of Ranbp2 localizes at the AIS. We show this fragment interacts with stable microtubules. Finally, using CRISPR-Cas9 in primary cultured neurons, we inserted an HA-epitope tag at N-terminal, C-terminal, or internal sites of the endogenously expressed Ranbp2. No matter the location of the HA-epitope, endogenous Ranbp2 was found at the nuclear membrane but not the AIS. These results show that endogenously expressed Ranbp2 is not found at axon initial segments.

scholarly journals The L1 stalk is required for efficient export of nascent large ribosomal subunits in yeast

2019 ◽  
Author(s):  
Sharmishtha Musalgaonkar ◽  
Joshua J. Black ◽  
Arlen W. Johnson
Keyword(s):  
Ribosomal Protein ◽  
Nuclear Pore Complex ◽  
Nuclear Export ◽  
Nuclear Pore ◽  
Structural Studies ◽  
Ribosomal Subunits

AbstractThe ribosomal protein Rpl1 (uL1 in universal nomenclature) is essential in yeast and constitutes part of the L1 stalk which interacts with E site ligands on the ribosome. Structural studies of nascent pre-60S complexes in yeast have shown that a domain of the Crm1-dependent nuclear export adapter Nmd3, binds in the E site and interacts with Rpl1, inducing closure of the L1 stalk. Based on this observation, we decided to reinvestigate the role of the L1 stalk in nuclear export of pre-60S subunits despite previous work showing that Rpl1-deficient ribosomes are exported from the nucleus and engage in translation. Large cargoes, such as ribosomal subunits, require multiple export factors to facilitate their transport through the nuclear pore complex. Here, we show that pre-60S subunits lacking Rpl1 or truncated for the RNA of the L1 stalk are exported inefficiently. Surprisingly, this is not due to a measurable defect in recruitment of Nmd3 but appears to result from inefficient recruitment of the Mex67-Mtr2 heterodimer.

Internal organisation of the nuclear pore complex by surface imaging with field emission in lens SEM (FEISEM)

1996 ◽  
Vol 54 ◽  
pp. 822-823
Author(s):  
T.D. Allen ◽  
E.V. Kiseleva ◽  
M.W. Goldberg
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Pore ◽  
Surface Imaging ◽  
Balbiani Ring ◽  
Structural Alterations ◽  
3 Dimensional ◽  
Large Numbers ◽  
New Information ◽  
Evolutionarily Conserved

We have been working towards a 3 dimensional structural understanding of the Nuclear Pore Complex (NPC) with a view to investigating structural alterations associated with the molecular mechanism of transport across the nuclear envelope. FEISEM allows direct visualisation of changes in individual NPCs which will complement information from TEM 3D reconstructions. FEISEM has produced significant new information on the more peripheral elements of the NPC, most notably the nuclear pore basket or ‘fishtrap’ and the nuclear envelope lattice. NPC baskets have been recognised in both avian and insect species as well as amphibia and are likely to be evolutionarily conserved. In the salivary gland nuclei of Chironomus different configurations of basket structure have been recognised undergoing interaction with Balbiani Ring particles during mRNA export. (Fig 1).The ability to observe and directly compare large numbers of NPCs on isolated NEs from either the cytoplasmic or nucleoplasmicface, at equivalent biological resolution to TEM has enabled us to access internal NPC organisation by surface imaging.

scholarly journals RanBP2/Nup358 enhances miRNA activity by sumoylating Argonautes

PLoS Genetics ◽  
2021 ◽  
Vol 17 (2) ◽  
pp. e1009378
Author(s):  
Qingtang Shen ◽  
Yifan E. Wang ◽  
Mathew Truong ◽  
Kohila Mahadevan ◽  
Jingze J. Wu ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Interleukin 6 ◽  
Nuclear Pore ◽  
Acute Necrotizing Encephalopathy ◽  
Messenger Ribonucleoprotein ◽  
Cytoplasmic Filaments ◽  
Acute Necrotizing ◽  
Main Components

Mutations in RanBP2 (also known as Nup358), one of the main components of the cytoplasmic filaments of the nuclear pore complex, contribute to the overproduction of acute necrotizing encephalopathy (ANE1)-associated cytokines. Here we report that RanBP2 represses the translation of the interleukin 6 (IL6) mRNA, which encodes a cytokine that is aberrantly up-regulated in ANE1. Our data indicates that soon after its production, the IL6 messenger ribonucleoprotein (mRNP) recruits Argonautes bound to let-7 microRNA. After this mRNP is exported to the cytosol, RanBP2 sumoylates mRNP-associated Argonautes, thereby stabilizing them and enforcing mRNA silencing. Collectively, these results support a model whereby RanBP2 promotes an mRNP remodelling event that is critical for the miRNA-mediated suppression of clinically relevant mRNAs, such as IL6.

scholarly journals Cytoplasmic transport of ribosomal subunits microinjected into the Xenopus laevis oocyte nucleus: a generalized, facilitated process.

1990 ◽  
Vol 111 (4) ◽  
pp. 1571-1582 ◽  
Author(s):  
N Bataillé ◽  
T Helser ◽  
H M Fried
Keyword(s):  
Nuclear Pore Complex ◽  
Wheat Germ Agglutinin ◽  
Xenopus Oocyte ◽  
Wheat Germ ◽  
Ribosomal Subunit ◽  
Oocyte Nucleus ◽  
Nuclear Pore ◽  
Xenopus Laevis Oocyte ◽  
Ribosomal Subunits ◽  
Cytoplasmic Transport

To study the biochemistry of ribonucleoprotein export from the nucleus, we characterized an in vivo assay in which the cytoplasmic appearance of radiolabeled ribosomal subunits was monitored after their microinjection into Xenopus oocyte nuclei. Denaturing gel electrophoresis and sucrose density gradient sedimentation demonstrated that injected subunits were transported intact. Consistent with the usual subcellular distribution of ribosomes, transport was unidirectional, as subunits injected into the cytoplasm did not enter the nucleus. Transport displayed properties characteristic of a facilitated, energy-dependent process; the rate of export was saturable and transport was completely inhibited either by lowering the temperature or by depleting nuclei of ATP; the effect of lowered temperature was completely reversible. Transport of injected subunits was likely a process associated with the nuclear pore complex, since export was also inhibited by prior or simultaneous injection of wheat germ agglutinin, a lectin known to inhibit active nuclear transport by binding to N-acetyl glucosamine-containing glycoproteins present in the NPC (Hart, G. W., R. S. Haltiwanger, G. D. Holt, and W. G. Kelly. 1989. Annu. Rev. Biochem. 58:841-874). Although GlcNAc modified proteins exist on both the nuclear and cytoplasmic sides of the nuclear pore complex, ribosomal subunit export was inhibited only when wheat germ agglutinin was injected into the nucleus. Finally, we found that ribosomal subunits from yeast and Escherichia coli were efficiently exported from Xenopus oocyte nuclei, suggesting that export of some RNP complexes may be directed by a collective biochemical property rather than by specific macromolecular primary sequences or structures.

The Formation, Structure, Distribution and Frequency of Nuclear Pores

1971 ◽  
Vol 29 ◽  
pp. 518-519
Author(s):  
G. G. Maul
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Dynamic Structure ◽  
Nuclear Pore ◽  
Nuclear Pores ◽  
Filter Function ◽  
Etching Technique ◽  
Selective Filter ◽  
Membranous Part

The chromatin of eukaryotic cells is separated from the cytoplasm by a double membrane. One obvious structural specialization of the nuclear membrane is the presence of pores which have been implicated to facilitate the selective nucleocytoplasmic exchange of a variety of large molecules. Thus, the function of nuclear pores has mainly been regarded to be a passive one. Non-membranous diaphragms, radiating fibers, central rings, and other pore-associated structures were thought to play a role in the selective filter function of the nuclear pore complex. Evidence will be presented that suggests that the nuclear pore is a dynamic structure which is non-randomly distributed and can be formed during interphase, and that a close relationship exists between chromatin and the membranous part of the nuclear pore complex.Octagonality of the nuclear pore complex has been confirmed by a variety of techniques. Using the freeze-etching technique, it was possible to show that the membranous part of the pore complex has an eight-sided outline in human melanoma cells in vitro. Fibers which traverse the pore proper at its corners are continuous and indistinguishable from chromatin at the nucleoplasmic side, as seen in conventionally fixed and sectioned material. Chromatin can be seen in octagonal outline if serial sections are analyzed which are parallel but do not include nuclear membranes (Fig. 1). It is concluded that the shape of the pore rim is due to fibrous material traversing the pore, and may not have any functional significance. In many pores one can recognize a central ring with eight fibers radiating to the corners of the pore rim. Such a structural arrangement is also found to connect eight ribosomes at the nuclear membrane.

Structure, assembly and interactions of the nuclear lamina and the nuclear pore complex

1992 ◽  
Vol 50 (1) ◽  
pp. 490-491
Author(s):  
N. Panté ◽  
M. Jarnik ◽  
E. Heitlinger ◽  
U. Aebi
Keyword(s):  
Nuclear Pore Complex ◽  
Divalent Cations ◽  
Nuclear Lamina ◽  
Dynamic Structure ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Cytoplasmic Filaments ◽  
Radial Spokes ◽  
Nuclear Ring ◽  
Central Plug

The nuclear pore complex (NPC) is a ∼120 MD supramolecular machine implicated in nucleocytoplasmic transport, that is embedded in the double-membraned nuclear envelope (NE). The basic framework of the ∼120 nm diameter NPC consists of a 32 MD cytoplasmic ring, a 66 MD ‘plug-spoke’ assembly, and a 21 MD nuclear ring. The ‘central plug’ seen in en face views of the NPC reveals a rather variable appearance indicating that it is a dynamic structure. Projecting from the cytoplasmic ring are 8 short, twisted filaments (Fig. 1a), whereas the nuclear ring is topped with a ‘fishtrap’ made of 8 thin filaments that join distally to form a fragile, 30-50 nm distal diameter ring centered above the NPC proper (Fig. 1b). While the cytoplasmic filaments are sensitive to proteases, they as well as the nuclear fishtraps are resistant to RNase treatment. Removal of divalent cations destabilizes the distal rings and thereby opens the fishtraps, addition causes them to reform. Protruding from the tips of the radial spokes into perinuclear space are ‘knobs’ that might represent the large lumenal domain of gp210, a membrane-spanning glycoprotein (Fig. 1c) which, in turn, may play a topogenic role in membrane folding and/or act as a membrane-anchoring site for the NPC. The lectin wheat germ agglutinin (WGA) which is known to recognize the ‘nucleoporins’, a family of glycoproteins having O-linked N-acetyl-glucosamine, is found in two locations on the NPC (Fig. 1. d-f): (i) whereas the cytoplasmic filaments appear unlabelled (Fig. 1d&e), WGA-gold labels sites between the central plug and the cytoplasmic ring (Fig. le; i.e., at a radius of 25-35 nm), and (ii) it decorates the distal ring of the nuclear fishtraps (Fig. 1, d&f; arrowheads).

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