scholarly journals Regulated docking of nuclear membrane vesicles to vimentin filaments during mitosis.

1993 ◽  
Vol 123 (6) ◽  
pp. 1491-1505 ◽  
Author(s):  
C Maison ◽  
H Horstmann ◽  
S D Georgatos
Keyword(s):  
Nuclear Membrane ◽  
Magnetic Beads ◽  
Membrane Vesicles ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Endosomal Membrane ◽  
Nuclear Lamins ◽  
Nuclear Lamin ◽  
Vimentin Filaments

During mitosis, several types of intermediate-sized filaments (IFs) undergo an extensive remodelling in response to phosphorylation by cdc 2 and other protein kinases. However, unlike the nuclear lamins, the cytoplasmic IFs do not seem to follow a fixed disassembly stereotype and often retain their physical continuity without depolymerizing into soluble subunits. To investigate potential interactions between mitotically modified IFs and other cellular structures, we have examined prometaphase-arrested cells expressing the IF protein vimentin. We demonstrate here that vimentin filaments associate in situ and co-fractionate with a distinct population of mitotic vesicles. These vesicles carry on their surfaces nuclear lamin B, the inner nuclear membrane protein p58, and wheat germ agglutinin (WGA)-binding proteins. Consistent with a tight interaction between the IFs and the mitotic membranes, vimentin, nuclear lamin B, and a 180-kD WGA-binding protein are co-isolated when whole mitotic homogenates are incubated with anti-vimentin or anti-lamin B antibodies immobilized on magnetic beads. The vimentin-associated vesicles are essentially depleted of ER, Golgi and endosomal membrane proteins. The interaction of vimentin with lamin B-carrying membranes depends on phosphorylation and is weakened by dephosphorylation during nuclear reassembly in vitro. These observations reveal a novel interaction between IFs and cellular membranes and further suggest that the vimentin filaments may serve as a transient docking site for inner nuclear membrane vesicles during mitosis.

scholarly journals The fates of chicken nuclear lamin proteins during mitosis: evidence for a reversible redistribution of lamin B2 between inner nuclear membrane and elements of the endoplasmic reticulum.

1988 ◽  
Vol 107 (2) ◽  
pp. 397-406 ◽  
Author(s):  
R Stick ◽  
B Angres ◽  
C F Lehner ◽  
E A Nigg
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Membrane Vesicles ◽  
Soluble Form ◽  
Lamin A ◽  
Cell Fractionation ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Nuclear Lamin ◽  
Mitotic Cells

In chicken, three structurally distinct nuclear lamin proteins have been described. According to their migration on two-dimensional gels, these proteins have been designated as lamins A, B1, and B2. To investigate the functional relationship between chicken lamins and their mammalian counterparts, we have examined here the state of individual chicken lamin proteins during mitosis. Current models proposing functional specializations of mammalian lamin subtypes are in fact largely based on the observation that during mitosis mammalian lamin B remains associated with membrane vesicles, whereas lamins A and C become freely soluble. Cell fractionation experiments combined with immunoblotting show that during mitosis both chicken lamins B1 and B2 remain associated with membranes, whereas lamin A exists in a soluble form. In situ immunoelectron microscopy carried out on mitotic cells also reveals membrane association of lamin B2, whereas the distribution of lamin A is random. From these results we conclude that both chicken lamins B1 and B2 may functionally resemble mammalian lamin B. Interestingly, immunolabeling of mitotic cells revealed an association of lamin B2 with extended membrane cisternae that resembled elements of the endoplasmic reticulum. Quantitatively, we found that all large endoplasmic reticulum-like membranes present in metaphase cells were decorated with lamin B2-specific antibodies. Given that labeling of these mitotic membranes was lower than labeling of interphase nuclear envelopes, it appears likely that during mitotic disassembly and reassembly of the nuclear envelope lamin B2 may reversibly distribute between the inner nuclear membrane and the endoplasmic reticulum.

Sequential PKC- and Cdc2-mediated phosphorylation events elicit zebrafish nuclear envelope disassembly

1999 ◽  
Vol 112 (6) ◽  
pp. 977-987 ◽  
Author(s):  
P. Collas
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Cdc2 Kinase ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Nuclear Envelope Breakdown ◽  
Simultaneous Inhibition ◽  
Integral Proteins

Molecular markers of the zebrafish inner nuclear membrane (NEP55) and nuclear lamina (L68) were identified, partially characterized and used to demonstrate that disassembly of the zebrafish nuclear envelope requires sequential phosphorylation events by first PKC, then Cdc2 kinase. NEP55 and L68 are immunologically and functionally related to human LAP2beta and lamin B, respectively. Exposure of zebrafish nuclei to meiotic cytosol elicits rapid phosphorylation of NEP55 and L68, and disassembly of both proteins. L68 phosphorylation is completely inhibited by simultaneous inhibition of Cdc2 and PKC and only partially blocked by inhibition of either kinase. NEP55 phosphorylation is completely prevented by inhibition or immunodepletion of cytosolic Cdc2. Inhibition of cAMP-dependent kinase, MEK or CaM kinase II does not affect NEP55 or L68 phosphorylation. In vitro, nuclear envelope disassembly requires phosphorylation of NEP55 and L68 by both mammalian PKC and Cdc2. Inhibition of either kinase is sufficient to abolish NE disassembly. Furthermore, novel two-step phosphorylation assays in cytosol and in vitro indicate that PKC-mediated phosphorylation of L68 prior to Cdc2-mediated phosphorylation of L68 and NEP55 is essential to elicit nuclear envelope breakdown. Phosphorylation elicited by Cdc2 prior to PKC prevents nuclear envelope disassembly even though NEP55 is phosphorylated. The results indicate that sequential phosphorylation events elicited by PKC, followed by Cdc2, are required for zebrafish nuclear disassembly. They also argue that phosphorylation of inner nuclear membrane integral proteins is not sufficient to promote nuclear envelope breakdown, and suggest a multiple-level regulation of disassembly of nuclear envelope components during meiosis and at mitosis.

scholarly journals Fibroblasts lacking nuclear lamins do not have nuclear blebs or protrusions but nevertheless have frequent nuclear membrane ruptures

2018 ◽  
Vol 115 (40) ◽  
pp. 10100-10105 ◽  
Author(s):  
Natalie Y. Chen ◽  
Paul Kim ◽  
Thomas A. Weston ◽  
Lovelyn Edillo ◽  
Yiping Tu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Membrane Integrity ◽  
Nuclear Lamina ◽  
Virtual Absence ◽  
Inner Nuclear Membrane ◽  
Nuclear Lamins ◽  
Transmission Electron ◽  
Nuclear Lamin

The nuclear lamina, an intermediate filament meshwork lining the inner nuclear membrane, is formed by the nuclear lamins (lamins A, C, B1, and B2). Defects or deficiencies in individual nuclear lamin proteins have been reported to elicit nuclear blebs (protrusions or outpouchings of the nuclear envelope) and increase susceptibility for nuclear membrane ruptures. It is unclear, however, how a complete absence of nuclear lamins would affect nuclear envelope morphology and nuclear membrane integrity (i.e., whether nuclear membrane blebs or protrusions would occur and, if not, whether cells would be susceptible to nuclear membrane ruptures). To address these issues, we generated mouse embryonic fibroblasts (MEFs) lacking all nuclear lamins. The nuclear lamin-deficient MEFs had irregular nuclear shapes but no nuclear blebs or protrusions. Despite a virtual absence of nuclear blebs, MEFs lacking nuclear lamins had frequent, prolonged, and occasionally nonhealing nuclear membrane ruptures. By transmission electron microscopy, the inner nuclear membrane in nuclear lamin-deficient MEFs have a “wavy” appearance, and there were discrete discontinuities in the inner and outer nuclear membranes. Nuclear membrane ruptures were accompanied by a large increase in DNA damage, as judged by γ-H2AX foci. Mechanical stress increased both nuclear membrane ruptures and DNA damage, whereas minimizing transmission of cytoskeletal forces to the nucleus had the opposite effects.

The Nuclear Envelope and Human Disease

Physiology ◽  
2004 ◽  
Vol 19 (5) ◽  
pp. 309-314 ◽  
Author(s):  
Antoine Muchir ◽  
Howard J. Worman
Keyword(s):  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Intermediate Filament ◽  
Human Disease ◽  
Aging Process ◽  
Intermediate Filament Proteins ◽  
Inner Nuclear Membrane ◽  
Nuclear Lamins ◽  
Nuclear Lamin

Mutations in nuclear lamins A and C, intermediate filament proteins of the nuclear envelope, cause diseases affecting various tissues and the aging process. We review what is known about nuclear lamin function and the different diseases caused by mutations in lamins A and C and associated inner nuclear membrane proteins.

Subcellular distribution of the Xenopus p58/lamin B receptor in oocytes and eggs

1999 ◽  
Vol 112 (15) ◽  
pp. 2583-2596 ◽  
Author(s):  
A. Gajewski ◽  
G. Krohne
Keyword(s):  
Nuclear Membrane ◽  
Xenopus Oocytes ◽  
Immunofluorescence Microscopy ◽  
Significant Proportion ◽  
Sperm Chromatin ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Amino Terminal ◽  
Lamin B Receptor

The p58/lamin B receptor of vertebrates is localized in the inner nuclear membrane. Antibodies raised against the bacterially expressed amino-terminal half of Xenopus p58 (Xp58) revealed that in Xenopus oocytes the vast majority of this membrane protein is localized in cytoplasmic membranes. Only very small amounts of p58 not detectable by immunofluorescence microscopy were contained in the oocyte nuclear envelope. In contrast, nuclear membranes of 2-cell stage embryos were successfully stained with p58 antibodies, nuclei reconstituted in vitro in Xenopus egg extracts contained p58, and the nucleoplasmic domain of Xp58 could be specifically bound to sperm chromatin in vitro. One major difference between oocytes and early embryonic cells is that no chromatin is associated with the oocyte inner nuclear membrane whereas the complement of lamins is identical in both cell types. To gain insight into the properties of oocyte p58 we microinjected isolated nuclei of cultured rat cells into the cytoplasm of Xenopus oocytes. The oocyte p58 was detectable by immunofluorescence microscopy within 16–20 hours in the nuclear membrane of rat nuclei. Our data indicate that the peripheral chromatin but not lamins are required for the retention of p58 in the inner nuclear membrane. Sucrose step gradient centrifugation of total oocyte membranes revealed that the oocyte p58 was predominantly recovered in membrane fractions that did not contain lamins whereas membrane associated lamins and p58 of unfertilized eggs were found in the same fractions. By electron microscopical immunolocalizations one major population of meiotic p58 vesicles was identified that contained exclusively p58 and a second minor population (ca. 11% of p58 vesicles) contained in addition to p58 membrane bound B-type lamins. Egg vesicles containing pore membrane proteins were predominantly recovered in gradient fractions that did not contain p58 and B-type lamins. Our data indicate that the targeting of p58 to chromatin at the end of mitosis in the early Xenopus embryo is a process independent from that of lamin targeting. Comparable to the situation in oocytes and eggs, a significant proportion of p58 of interphase cells could be recovered in fractions that did not contain lamins. This population of p58 molecules could be extracted from A6-cells with buffers containing 1% Triton X-100/0.15 M NaCl and could be pelleted by a 50,000 g centrifugation. A- and B-type lamins were not detectable in the p58 containing pellet.

Lamin B receptor: role on chromatin structure, cellular senescence and possibly aging

2020 ◽  
Vol 477 (14) ◽  
pp. 2715-2720
Author(s):  
Susana Castro-Obregón
Keyword(s):  
Cellular Senescence ◽  
Nuclear Membrane ◽  
Chromatin Structure ◽  
Cholesterol Synthesis ◽  
Reductase Activity ◽  
Chimeric Protein ◽  
Nuclear Lamina ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor

The nuclear envelope is composed by an outer nuclear membrane and an inner nuclear membrane, which is underlain by the nuclear lamina that provides the nucleus with mechanical strength for maintaining structure and regulates chromatin organization for modulating gene expression and silencing. A layer of heterochromatin is beneath the nuclear lamina, attached by inner nuclear membrane integral proteins such as Lamin B receptor (LBR). LBR is a chimeric protein, having also a sterol reductase activity with which it contributes to cholesterol synthesis. Lukasova et al. showed that when DNA is damaged by ɣ-radiation in cancer cells, LBR is lost causing chromatin structure changes and promoting cellular senescence. Cellular senescence is characterized by terminal cell cycle arrest and the expression and secretion of various growth factors, cytokines, metalloproteinases, etc., collectively known as senescence-associated secretory phenotype (SASP) that cause chronic inflammation and tumor progression when they persist in the tissue. Therefore, it is fundamental to understand the molecular basis for senescence establishment, maintenance and the regulation of SASP. The work of Lukasova et al. contributed to our understanding of cellular senescence establishment and provided the basis that lead to the further discovery that chromatin changes caused by LBR reduction induce an up-regulated expression of SASP factors. LBR dysfunction has relevance in several diseases and possibly in physiological aging. The potential bifunctional role of LBR on cellular senescence establishment, namely its role in chromatin structure together with its enzymatic activity contributing to cholesterol synthesis, provide a new target to develop potential anti-aging therapies.

scholarly journals The CaaX motif is required for isoprenylation, carboxyl methylation, and nuclear membrane association of lamin B2.

1991 ◽  
Vol 113 (1) ◽  
pp. 13-23 ◽  
Author(s):  
G T Kitten ◽  
E A Nigg
Keyword(s):  
Nuclear Membrane ◽  
Stop Codon ◽  
Mevalonic Acid ◽  
Cysteine Residue ◽  
Inner Nuclear Membrane ◽  
Nuclear Lamins ◽  
Carboxyl Methylation ◽  
Reticulocyte Lysates ◽  
Caax Motif

Recent evidence suggests that the conserved COOH-terminal CaaX motif of nuclear lamins may play a role in targeting newly synthesized proteins to the nuclear envelope. We have shown previously that in rabbit reticulocyte lysates the cysteine residue of the CaaX motif of chicken lamin B2 is necessary for incorporation of a derivative of mevalonic acid, the precursor of isoprenoids. Here we have analyzed the properties of normal and mutated forms of chicken lamin B2 stably expressed in mouse L cells. Mutation of the cysteine residue of the CaaX motif to alanine or introduction of a stop codon immediately after the cysteine residue was found to abolish both isoprenylation and carboxyl methylation of transfected lamin B2. Concomitantly, although nuclear import of the mutant lamin B2 proteins was preserved, their association with the inner nuclear membrane was severely impaired. From these results we conclude that the COOH-terminal CaaX motif is required for isoprenylation and carboxyl methylation of lamins in vivo, and that these modifications are important for association of B-type lamins with the nucleoplasmic surface of the inner nuclear membrane.

scholarly journals Temporal Association of Protamine 1 with the Inner Nuclear Membrane Protein Lamin B Receptor during Spermiogenesis

2003 ◽  
Vol 279 (12) ◽  
pp. 11626-11631 ◽  
Author(s):  
Ilias Mylonis ◽  
Victoria Drosou ◽  
Stefano Brancorsini ◽  
Eleni Nikolakaki ◽  
Paolo Sassone-Corsi ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Nuclear Membrane ◽  
Temporal Association ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor ◽  
Inner Nuclear Membrane Protein ◽  
Protamine 1 ◽  
Nuclear Membrane Protein

scholarly journals Lamin activity is essential for nuclear envelope assembly in a Drosophila embryo cell-free extract.

1992 ◽  
Vol 119 (1) ◽  
pp. 17-25 ◽  
Author(s):  
N Ulitzur ◽  
A Harel ◽  
N Feinstein ◽  
Y Gruenbaum
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Membrane Vesicles ◽  
Embryo Cell ◽  
Drosophila Embryo ◽  
Sperm Chromatin ◽  
Naked Dna ◽  
Nuclear Envelope Assembly

The role of the Drosophila lamin protein in nuclear envelope assembly was studied using a Drosophila in vitro assembly system that reconstitutes nuclei from added sperm chromatin or naked DNA. Upon incubation of the embryonic assembly extract with anti-Drosophila lamin antibodies, the attachment of nuclear membrane vesicles to chromatin surface and nuclear envelope formation did not occur. Lamina assembly and nuclear membrane vesicles attachment to the chromatin were inhibited only when the activity of the 75-kD lamin isoform was inhibited in both soluble and membrane-vesicles fractions. Incubation of decondensed sperm chromatin with an extract that was depleted of nuclear membranes revealed the presence of lamin molecules on the chromatin periphery. In addition, high concentrations of bacterially expressed lamin molecules added to the extract, were able to associate with the chromatin periphery, and did not inhibit nuclear envelope assembly. After nuclear reconstitution, a fraction of the lamin pool was converted into the typical 74- and 76-kD isoforms. Together, these data strongly support an essential role of the lamina in nuclear envelope assembly.

Sign in / Sign up

Export Citation Format

Share Document