The structure and interactions of components of nuclear envelopes from Xenopus oocyte germinal vesicles observed by heavy metal shadowing

1988 ◽  
Vol 90 (3) ◽  
pp. 409-423 ◽  
Author(s):  
MURRAY STEWART ◽  
SUE WHYTOCK
Keyword(s):  
Xenopus Oocyte ◽  
Freeze Drying ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Air Drying ◽  
Freeze Dried ◽  
Germinal Vesicles ◽  
Pore Complexes ◽  
Different Levels

We have examined the structure of the nuclear envelope of oocytes of Xenopus laevis by electronmicroscopy of metal-shadowed specimens. Material was prepared by either freeze-drying ora rapid protocol using air-drying after dehydration in ethanol followed by amyl acetate. These methods emphasized different aspects of the structure and enabled an integrated view of the arrangement of nuclear pore complexes, nuclear lamina and pore-connecting fibrils to be assembled. In specimens prepared by either air drying or freeze-drying, the lamina meshwork beneath the nuclear face of the envelope was well preserved, but the fine structure of the nuclearpores was superior in freeze-dried preparations. Both methods also showed pore-connecting fibrils that were clearly not components of the lamina. By using stereo pairs, we established criteria for recognizing the cytoplasmic and nucleoplasmic faces of shadowed nuclear envelopes. These views also enabled us to identify the levels atwhich different fibrous components were attached to the pores. In particular, we were able to visualize the nuclear lamina fibres and poreconnecting fibrils simultaneously and show that they attach to the pore complexes at different levels. We supplemented this work by using arange of treatments to disrupt the nuclear envelopes lightly and gained several insights into this structure as a result. Sometimes pore complexes and their connecting fibrils were stripped from the envelope. This enabled a clearer view of these connections to be obtained without the lamina present. Moreover, in some conditions, the nuclearpore complexes and fibrous lamina began to disintegrate, there by showing some of the morphological components from which they were assembled.

Selective digestion of nuclear envelopes from Xenopus oocyte germinal vesicles: possible structural role for the nuclear lamina

1990 ◽  
Vol 97 (3) ◽  
pp. 571-580
Author(s):  
S. Whytock ◽  
R.D. Moir ◽  
M. Stewart
Keyword(s):  
Nuclear Envelope ◽  
Xenopus Oocyte ◽  
Structural Integrity ◽  
Marked Change ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Structural Role ◽  
Germinal Vesicles ◽  
Pore Complexes

We have used enzymic digestion as a structural probe to investigate components of the nuclear envelope of germinal vesicles from Xenopus oocytes. Previous studies have shown that these envelopes are composed of a double membrane in which nuclear pore complexes are embedded. The nuclear pore complexes are linked to a fibrous lamina that underlies the nucleoplasmic face of the envelope. The pores are also linked by pore-connecting fibrils that attach near their cytoplasmic face. Xenopus oocyte nuclear envelopes were remarkably resistant to extraction with salt solutions and, even after treatment with 1 M NaCl or 3 M MgCl2, pores, lamina and pore-connecting fibrils remained intact. However, mild proteolysis with trypsin selectively removed the lamina fibres from Triton-extracted nuclear envelopes to leave only the pore complexes and connecting fibrils. This observation confirmed that the pore-connecting fibrils were different from the lamina fibres and were probably constructed from different proteins. Trypsin digestion followed by Triton treatment resulted in the complete disintegration of the nuclear envelope, providing direct evidence for a structural role for the lamina in maintaining envelope integrity. Digestion with ribonuclease did not produce any marked change in the structure of Triton-extracted nuclear envelopes, indicating that probably neither the pore-connecting fibrils nor the cytoplasmic granules on the pore complexes contained a substantial proportion of RNA that was vital for their structural integrity.

scholarly journals Concentration-dependent lamin assembly and its roles in the localization of other nuclear proteins

2014 ◽  
Vol 25 (8) ◽  
pp. 1287-1297 ◽  
Author(s):  
Yuxuan Guo ◽  
Youngjo Kim ◽  
Takeshi Shimi ◽  
Robert D. Goldman ◽  
Yixian Zheng
Keyword(s):  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Lamin A ◽  
Nuclear Pore Complexes ◽  
Developmental Defects ◽  
Protein Levels ◽  
Lamin B1 ◽  
Mouse Cells ◽  
Pore Complexes ◽  
And Function

The nuclear lamina (NL) consists of lamin polymers and proteins that bind to the polymers. Disruption of NL proteins such as lamin and emerin leads to developmental defects and human diseases. However, the expression of multiple lamins, including lamin-A/C, lamin-B1, and lamin-B2, in mammals has made it difficult to study the assembly and function of the NL. Consequently, it has been unclear whether different lamins depend on one another for proper NL assembly and which NL functions are shared by all lamins or are specific to one lamin. Using mouse cells deleted of all or different combinations of lamins, we demonstrate that the assembly of each lamin into the NL depends primarily on the lamin concentration present in the nucleus. When expressed at sufficiently high levels, each lamin alone can assemble into an evenly organized NL, which is in turn sufficient to ensure the even distribution of the nuclear pore complexes. By contrast, only lamin-A can ensure the localization of emerin within the NL. Thus, when investigating the role of the NL in development and disease, it is critical to determine the protein levels of relevant lamins and the intricate shared or specific lamin functions in the tissue of interest.

Recombinant Nup153 Incorporates in Vivo into Xenopus Oocyte Nuclear Pore Complexes

2000 ◽  
Vol 129 (2-3) ◽  
pp. 306-312 ◽  
Author(s):  
Nelly Panté ◽  
Franziska Thomas ◽  
Ueli Aebi ◽  
Brian Burke ◽  
Ricardo Bastos
Keyword(s):  
Xenopus Oocyte ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Pore Complexes

scholarly journals Nuclear envelope organization in Dictyostelium discoideum

2019 ◽  
Vol 63 (8-9-10) ◽  
pp. 509-519 ◽  
Author(s):  
Petros Batsios ◽  
Ralph Gräf ◽  
Michael P. Koonce ◽  
Denis A. Larochelle ◽  
Irene Meyer
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Major Constituent ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Linc Complex ◽  
Family Protein ◽  
Import And Export ◽  
Pore Complexes

The nuclear envelope consists of the outer and the inner nuclear membrane, the nuclear lamina and the nuclear pore complexes, which regulate nuclear import and export. The major constituent of the nuclear lamina of Dictyostelium is the lamin NE81. It can form filaments like B-type lamins and it interacts with Sun1, as well as with the LEM/HeH-family protein Src1. Sun1 and Src1 are nuclear envelope transmembrane proteins involved in the centrosome-nucleus connection and nuclear envelope stability at the nucleolar regions, respectively. In conjunction with a KASH-domain protein, Sun1 usually forms a so-called LINC complex. Two proteins with functions reminiscent of KASH-domain proteins at the outer nuclear membrane of Dictyostelium are known; interaptin which serves as an actin connector and the kinesin Kif9 which plays a role in the microtubule-centrosome connector. However, both of these lack the conserved KASH-domain. The link of the centrosome to the nuclear envelope is essential for the insertion of the centrosome into the nuclear envelope and the appropriate spindle formation. Moreover, centrosome insertion is involved in permeabilization of the mitotic nucleus, which ensures access of tubulin dimers and spindle assembly factors. Our recent progress in identifying key molecular players at the nuclear envelope of Dictyostelium promises further insights into the mechanisms of nuclear envelope dynamics.

scholarly journals Nuclear pore complexes form immobile networks and have a very low turnover in live mammalian cells

2001 ◽  
Vol 154 (1) ◽  
pp. 71-84 ◽  
Author(s):  
Nathalie Daigle ◽  
Joël Beaudouin ◽  
Lisa Hartnell ◽  
Gabriela Imreh ◽  
Einar Hallberg ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Global Changes ◽  
Nuclear Pore Complexes ◽  
Annulate Lamellae ◽  
Lamin B1 ◽  
Green Fluorescent ◽  
Pore Complexes

The nuclear pore complex (NPC) and its relationship to the nuclear envelope (NE) was characterized in living cells using POM121–green fluorescent protein (GFP) and GFP-Nup153, and GFP–lamin B1. No independent movement of single pore complexes was found within the plane of the NE in interphase. Only large arrays of NPCs moved slowly and synchronously during global changes in nuclear shape, strongly suggesting mechanical connections which form an NPC network. The nuclear lamina exhibited identical movements. NPC turnover measured by fluorescence recovery after photobleaching of POM121 was less than once per cell cycle. Nup153 association with NPCs was dynamic and turnover of this nucleoporin was three orders of magnitude faster. Overexpression of both nucleoporins induced the formation of annulate lamellae (AL) in the endoplasmic reticulum (ER). Turnover of AL pore complexes was much higher than in the NE (once every 2.5 min). During mitosis, POM121 and Nup153 were completely dispersed and mobile in the ER (POM121) or cytosol (Nup153) in metaphase, and rapidly redistributed to an immobilized pool around chromatin in late anaphase. Assembly and immobilization of both nucleoporins occurred before detectable recruitment of lamin B1, which is thus unlikely to mediate initiation of NPC assembly at the end of mitosis.

scholarly journals Lamin B1 protein is required for dendrite development in primary mouse cortical neurons

2016 ◽  
Vol 27 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Caterina Giacomini ◽  
Sameehan Mahajani ◽  
Roberta Ruffilli ◽  
Roberto Marotta ◽  
Laura Gasparini
Keyword(s):  
Cortical Neurons ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Loss Of Function ◽  
Lamin B1 ◽  
Dendrite Development ◽  
Primary Mouse ◽  
Nuclear Shuttling ◽  
Pore Complexes

Lamin B1, a key component of the nuclear lamina, plays an important role in brain development and function. A duplication of the human lamin B1 ( LMNB1) gene has been linked to adult-onset autosomal dominant leukodystrophy, and mouse and human loss-of-function mutations in lamin B1 are susceptibility factors for neural tube defects. In the mouse, experimental ablation of endogenous lamin B1 (Lmnb1) severely impairs embryonic corticogenesis. Here we report that in primary mouse cortical neurons, LMNB1 overexpression reduces axonal outgrowth, whereas deficiency of endogenous Lmnb1 results in aberrant dendritic development. In the absence of Lmnb1, both the length and complexity of dendrites are reduced, and their growth is unresponsive to KCl stimulation. This defective dendritic outgrowth stems from impaired ERK signaling. In Lmnb1-null neurons, ERK is correctly phosphorylated, but phospho-ERK fails to translocate to the nucleus, possibly due to delocalization of nuclear pore complexes (NPCs) at the nuclear envelope. Taken together, these data highlight a previously unrecognized role of lamin B1 in dendrite development of mouse cortical neurons through regulation of nuclear shuttling of specific signaling molecules and NPC distribution.

scholarly journals Internuclear exchange of an inner nuclear membrane protein (p55) in heterokaryons: in vivo evidence for the interaction of p55 with the nuclear lamina.

1990 ◽  
Vol 111 (6) ◽  
pp. 2225-2234 ◽  
Author(s):  
L Powell ◽  
B Burke
Keyword(s):  
Nuclear Membrane ◽  
Lateral Diffusion ◽  
Nuclear Lamina ◽  
Membrane System ◽  
Mouse Cell ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Inner Nuclear Membrane ◽  
Pore Complexes

The movement between nuclei of an integral protein of the inner nuclear membrane has been studied in rat/mouse and rat/hamster heterokaryons. This protein, p55, was found to equilibrate between nuclei over a period of approximately 6 h in the absence of new protein synthesis. When rat/mouse heterokaryons were constructed using an undifferentiated murine embryonal carcinoma (P19), which lacks lamins A and C, no accumulation of p55 in the mouse cell nucleus was observed. However, P19 nuclei could be rendered competent to accumulate p55 by transfecting the parent cells with human lamin A before cell fusion, supporting the notion that p55 may interact with the nuclear lamina. Since p55 does not appear to be able to dissociate from the nuclear membrane, it is concluded that this exchange between nuclei does not occur in the aqueous phase and instead is probably membrane mediated. It is proposed that this protein may be free to move between the inner and outer nuclear membranes via the continuities at the nuclear pore complexes and that transfer between nuclei occurs via lateral diffusion through the peripheral ER, which appears to form a single continuous membrane system in these heterokaryons. One implication of these observations is that accumulation of at least some integral proteins in the inner nuclear membrane may be mediated by interactions with other nuclear components and may not require a single defined targeting sequence.

scholarly journals Motor-driven motility of fungal nuclear pores organizes chromosomes and fosters nucleocytoplasmic transport

2012 ◽  
Vol 198 (3) ◽  
pp. 343-355 ◽  
Author(s):  
Gero Steinberg ◽  
Martin Schuster ◽  
Ulrike Theisen ◽  
Sreedhar Kilaru ◽  
Andrew Forge ◽  
...  
Keyword(s):  
Nuclear Lamina ◽  
Ustilago Maydis ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Pores ◽  
Gfp Reporter ◽  
Import And Export ◽  
Reporter Proteins ◽  
Pore Complexes

Exchange between the nucleus and the cytoplasm is controlled by nuclear pore complexes (NPCs). In animals, NPCs are anchored by the nuclear lamina, which ensures their even distribution and proper organization of chromosomes. Fungi do not possess a lamina and how they arrange their chromosomes and NPCs is unknown. Here, we show that motor-driven motility of NPCs organizes the fungal nucleus. In Ustilago maydis, Aspergillus nidulans, and Saccharomyces cerevisiae fluorescently labeled NPCs showed ATP-dependent movements at ∼1.0 µm/s. In S. cerevisiae and U. maydis, NPC motility prevented NPCs from clustering. In budding yeast, NPC motility required F-actin, whereas in U. maydis, microtubules, kinesin-1, and dynein drove pore movements. In the latter, pore clustering resulted in chromatin organization defects and led to a significant reduction in both import and export of GFP reporter proteins. This suggests that fungi constantly rearrange their NPCs and corresponding chromosomes to ensure efficient nuclear transport and thereby overcome the need for a structural lamina.

Relationships at the nuclear envelope: lamins and nuclear pore complexes in animals and plants

2010 ◽  
Vol 38 (3) ◽  
pp. 829-831 ◽  
Author(s):  
Jindriska Fiserova ◽  
Martin W. Goldberg
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nucleocytoplasmic Trafficking ◽  
Animal Cells ◽  
Cellular Processes ◽  
Associated Proteins ◽  
Pore Complexes

The nuclear envelope comprises a distinct compartment at the nuclear periphery that provides a platform for communication between the nucleus and cytoplasm. Signal transfer can proceed by multiple means. Primarily, this is by nucleocytoplasmic trafficking facilitated by NPCs (nuclear pore complexes). Recently, it has been indicated that signals can be transmitted from the cytoskeleton to the intranuclear structures via interlinking transmembrane proteins. In animal cells, the nuclear lamina tightly underlies the inner nuclear membrane and thus represents the protein structure located at the furthest boundary of the nucleus. It enables communication between the nucleus and the cytoplasm via its interactions with chromatin-binding proteins, transmembrane and membrane-associated proteins. Of particular interest is the interaction of the nuclear lamina with NPCs. As both structures fulfil essential roles in close proximity at the nuclear periphery, their interactions have a large impact on cellular processes resulting in affects on tissue differentiation and development. The present review concentrates on the structural and functional lamina–NPC relationship in animal cells and its potential implications to plants.

On the use of human autoantibodies in the determination of cytoskeletal-cell surface interactions

1991 ◽  
Vol 49 ◽  
pp. 16-17
Author(s):  
Robert D. Goldman ◽  
Jonathan C. R. Jones
Keyword(s):  
Cell Surface ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Surface ◽  
Nuclear Lamins ◽  
Adhesion Sites ◽  
Cell Surface Interactions ◽  
Pore Complexes ◽  
Type V

Intermediate filaments (IF) form a cytoskeletal system which appears to connect the nuclear surface with the cell surface. At the level of the nuclear surface, IF appear to be anchored to the outer nuclear envelope membrane and/or to nuclear pore complexes. In turn, these cytoplasmic IF are also thought to be linked in some unknown fashion to the nuclear lamina which is composed primarily of a polymer of the Type V IF proteins, the nuclear lamins. At the level of the cell surface, IF are connected to plasma membrane associated structures at sites of cell-cell and cellsubstrate adhesion. In epithelial cells, adhesion sites between cells include desmosomes and the major adhesion sites between basal cell surfaces and the basement membrane are termed hemidesmosomes.

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