scholarly journals Lamin B receptor plays a role in stimulating nuclear envelope production and targeting membrane vesicles to chromatin during nuclear envelope assembly through direct interaction with importin beta

2007 ◽  
Vol 120 (3) ◽  
pp. 520-530 ◽  
Author(s):  
Y. Ma ◽  
S. Cai ◽  
Q. Lv ◽  
Q. Jiang ◽  
Q. Zhang ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Direct Interaction ◽  
Membrane Vesicles ◽  
Lamin B ◽  
Importin Beta ◽  
Lamin B Receptor ◽  
Nuclear Envelope Assembly

scholarly journals Temporal control of nuclear envelope assembly by phosphorylation of lamin B receptor

2011 ◽  
Vol 22 (18) ◽  
pp. 3306-3317 ◽  
Author(s):  
Li-Chuan Tseng ◽  
Rey-Huei Chen
Keyword(s):  
Membrane Protein ◽  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Chromatin Binding ◽  
Temporal Control ◽  
Lamin B ◽  
Lamin B Receptor ◽  
Nuclear Envelope Assembly ◽  
Nuclear Membrane Protein

The nuclear envelope of metazoans disassembles during mitosis and reforms in late anaphase after sister chromatids have well separated. The coordination of these mitotic events is important for genome stability, yet the temporal control of nuclear envelope reassembly is unknown. Although the steps of nuclear formation have been extensively studied in vitro using the reconstitution system from egg extracts, the temporal control can only be studied in vivo. Here, we use time-lapse microscopy to investigate this process in living HeLa cells. We demonstrate that Cdk1 activity prevents premature nuclear envelope assembly and that phosphorylation of the inner nuclear membrane protein lamin B receptor (LBR) by Cdk1 contributes to the temporal control. We further identify a region in the nucleoplasmic domain of LBR that inhibits premature chromatin binding of the protein. We propose that this inhibitory effect is partly mediated by Cdk1 phosphorylation. Furthermore, we show that the reduced chromatin-binding ability of LBR together with Aurora B activity contributes to nuclear envelope breakdown. Our studies reveal for the first time a mechanism that controls the timing of nuclear envelope reassembly through modification of an integral nuclear membrane protein.

scholarly journals Requirement for Lamin B Receptor and Its Regulation by Importin β and Phosphorylation in Nuclear Envelope Assembly during Mitotic Exit

2010 ◽  
Vol 285 (43) ◽  
pp. 33281-33293 ◽  
Author(s):  
Xuelong Lu ◽  
Yang Shi ◽  
Quanlong Lu ◽  
Yan Ma ◽  
Jia Luo ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Mitotic Exit ◽  
Lamin B ◽  
Lamin B Receptor ◽  
Nuclear Envelope Assembly

Nuclear Envelope Dynamics During Mitosis

1988 ◽  
Vol 46 ◽  
pp. 224-225
Author(s):  
Brian Burke
Keyword(s):  
Nuclear Envelope ◽  
Membrane Vesicles ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Animal Cells ◽  
Interphase Chromosome ◽  
Lamin B ◽  
Chromosome Architecture ◽  
Complex Membrane ◽  
Pore Complexes

The nuclear envelope is a complex membrane structure that forms the boundary of the nuclear compartment in eukaryotes. It regulates the passage of macromolecules between the two compartments and may be important for organizing interphase chromosome architecture. In interphase animal cells it forms a remarkably stable structure consisting of a double membrane ouerlying a protein meshwork or lamina and penetrated by nuclear pore complexes. The latter form the channels for nucleocytoplasmic exchange of macromolecules, At the onset of mitosis, however, it rapidly disassembles, the membranes fragment to yield small vesicles and the lamina, which is composed of predominantly three polypeptides, lamins R, B and C (MW approx. 74, 68 and 65 kDa respectiuely), breaks down. Lamins B and C are dispersed as monomers throughout the mitotic cytoplasm, while lamin B remains associated with the nuclear membrane vesicles.

Alterations of nuclear envelope and chromatin organization in mandibuloacral dysplasia, a rare form of laminopathy

2005 ◽  
Vol 23 (2) ◽  
pp. 150-158 ◽  
Author(s):  
Ilaria Filesi ◽  
Francesca Gullotta ◽  
Giovanna Lattanzi ◽  
Maria Rosaria D'Apice ◽  
Cristina Capanni ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Protein A ◽  
Nuclear Architecture ◽  
Mendelian Inheritance ◽  
Premature Aging ◽  
Lamin A ◽  
Lamin B ◽  
Lamin B Receptor ◽  
Epigenetic Events ◽  
Mandibuloacral Dysplasia

Autosomal recessive mandibuloacral dysplasia [mandibuloacral dysplasia type A (MADA); Online Mendelian Inheritance in Man (OMIM) no. 248370 ] is caused by a mutation in LMNA encoding lamin A/C. Here we show that this mutation causes accumulation of the lamin A precursor protein, a marked alteration of the nuclear architecture and, hence, chromatin disorganization. Heterochromatin domains are altered or completely lost in MADA nuclei, consistent with the finding that heterochromatin-associated protein HP1β and histone H3 methylated at lysine 9 and their nuclear envelope partner protein lamin B receptor (LBR) are delocalized and solubilized. Both accumulation of lamin A precursor and chromatin defects become more severe in older patients. These results strongly suggest that altered chromatin remodeling is a key event in the cascade of epigenetic events causing MADA and could be related to the premature-aging phenotype.

BAF is required for emerin assembly into the reforming nuclear envelope

2001 ◽  
Vol 114 (24) ◽  
pp. 4575-4585 ◽  
Author(s):  
Tokuko Haraguchi ◽  
Takako Koujin ◽  
Miriam Segura-Totten ◽  
Kenneth K. Lee ◽  
Yosuke Matsuoka ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Hela Cells ◽  
Core Region ◽  
Lamin B ◽  
The Core ◽  
Double Stranded Dna ◽  
Recessive Form ◽  
Nuclear Envelope Assembly

Mutations in emerin cause the X-linked recessive form of Emery-Dreifuss muscular dystrophy (EDMD). Emerin localizes at the inner membrane of the nuclear envelope (NE) during interphase, and diffuses into the ER when the NE disassembles during mitosis. We analyzed the recruitment of wildtype and mutant GFP-tagged emerin proteins during nuclear envelope assembly in living HeLa cells. During telophase, emerin accumulates briefly at the ‘core’ region of telophase chromosomes, and later distributes over the entire nuclear rim. Barrier-to-autointegration factor (BAF), a protein that binds nonspecifically to double-stranded DNA in vitro, co-localized with emerin at the ‘core’ region of chromosomes during telophase. An emerin mutant defective for binding to BAF in vitro failed to localize at the ‘core’ in vivo, and subsequently failed to localize at the reformed NE. In HeLa cells that expressed BAF mutant G25E, which did not show ‘core’ localization, the endogenous emerin proteins failed to localize at the ‘core’ region during telophase, and did not assemble into the NE during the subsequent interphase. BAF mutant G25E also dominantly dislocalized LAP2β and lamin A from the NE, but had no effect on the localization of lamin B. We conclude that BAF is required for the assembly of emerin and A-type lamins at the reforming NE during telophase, and may mediate their stability in the subsequent interphase.

scholarly journals Induction of a Massive Endoplasmic Reticulum and Perinuclear Space Expansion by Expression of Lamin B Receptor Mutants and the Related Sterol Reductases TM7SF2 and DHCR7

2010 ◽  
Vol 21 (2) ◽  
pp. 354-368 ◽  
Author(s):  
Monika Zwerger ◽  
Thorsten Kolb ◽  
Karsten Richter ◽  
Iakowos Karakesisoglou ◽  
Harald Herrmann
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Cell Lines ◽  
Nuclear Membrane ◽  
Cultured Cells ◽  
Membrane Separation ◽  
Reductase Activity ◽  
Nuclear Pore ◽  
Lamin B ◽  
Lamin B Receptor

Lamin B receptor (LBR) is an inner nuclear membrane protein involved in tethering the nuclear lamina and the underlying chromatin to the nuclear envelope. In addition, LBR exhibits sterol reductase activity. Mutations in the LBR gene cause two different human diseases: Pelger-Huët anomaly and Greenberg skeletal dysplasia, a severe chrondrodystrophy causing embryonic death. Our study aimed at investigating the effect of five LBR disease mutants on human cultured cells. Three of the tested LBR mutants caused a massive compaction of chromatin coincidental with the formation of a large nucleus-associated vacuole (NAV) in several human cultured cell lines. Live cell imaging and electron microscopy revealed that this structure was generated by the separation of the inner and outer nuclear membrane. During NAV formation, nuclear pore complexes and components of the linker of nucleoskeleton and cytoskeleton complex were lost in areas of membrane separation. Concomitantly, a large number of smaller vacuoles formed throughout the cytoplasm. Notably, forced expression of the two structurally related sterol reductases transmembrane 7 superfamily member 2 and 7-dehydrocholesterol reductase caused, even in their wild-type form, a comparable phenotype in susceptible cell lines. Hence, LBR mutant variants and sterol reductases can severely interfere with the regular organization of the nuclear envelope and the endoplasmic reticulum.

scholarly journals A trypsin-sensitive receptor on membrane vesicles is required for nuclear envelope formation in vitro.

1988 ◽  
Vol 107 (1) ◽  
pp. 57-68 ◽  
Author(s):  
K L Wilson ◽  
J Newport
Keyword(s):  
Nuclear Envelope ◽  
Protein Interactions ◽  
Membrane Vesicles ◽  
Integral Membrane Protein ◽  
Electron Microscopic ◽  
Vitro Assay ◽  
Nuclear Envelope Assembly ◽  
Microscopic Studies ◽  
Nuclear Envelope Formation

The reformation of functioning organelles at the end of mitosis presents a problem in vesicle targeting. Using extracts made from Xenopus laevis frog eggs, we have studied in vitro the vesicles that reform the nuclear envelope. In the in vitro assay, nuclear envelope growth is linear with time. Furthermore, the final surface area of the nuclear envelopes formed is directly dependent upon the amount of membrane vesicles added to the assay. Egg membrane vesicles could be fractionated into two populations, only one of which was competent for nuclear envelope assembly. We found that vesicles active in nuclear envelope assembly contained markers (BiP and alpha-glucosidase II) characteristic of the endoplasmic reticulum (ER), but that the majority of ER-derived vesicles do not contribute to nuclear envelope size. This functional distinction between nuclear vesicles and ER-derived vesicles implies that nuclear vesicles are unique and possess at least one factor required for envelope assembly that is lacking in other vesicles. Consistent with this, treatment of vesicles with trypsin destroyed their ability to form a nuclear envelope; electron microscopic studies indicate that the trypsin-sensitive proteins is required for vesicles to bind to chromatin. However, the protease-sensitive component(s) is resistant to treatments that disrupt protein-protein interactions, such as high salt, EDTA, or low ionic strength solutions. We propose that an integral membrane protein, or protein tightly associated with the membrane, is critical for nuclear vesicle targeting or function.

scholarly journals Cytomegaloviral proteins that associate with the nuclear lamina: components of a postulated nuclear egress complex

2009 ◽  
Vol 90 (3) ◽  
pp. 579-590 ◽  
Author(s):  
Jens Milbradt ◽  
Sabrina Auerochs ◽  
Heinrich Sticht ◽  
Manfred Marschall
Keyword(s):  
Nuclear Envelope ◽  
Transmembrane Protein ◽  
Nuclear Lamina ◽  
Cellular Proteins ◽  
Lamin B ◽  
Nuclear Egress ◽  
Lamin B Receptor ◽  
Individual Interaction ◽  
Sequence Elements ◽  
Protein Recruitment

The nuclear egress of cytomegaloviral capsids traversing the nuclear envelope is dependent on a locally restricted destabilization of the rigid nuclear lamina. It has been suggested that the multi-component nuclear egress complex (NEC) that is formed is comprised of both viral and cellular proteins which act to recruit lamin-phosphorylating protein kinases. Recently, we reported that the lamina-associated human cytomegalovirus-encoded proteins pUL50 and pUL53, conserved among herpesviruses, interact with each other and recruit protein kinase C (PKC) to the nuclear envelope in transfected cells. The multiple interactions of the transmembrane protein pUL50 with pUL53, PKC and cellular PKC-binding protein p32, appear crucial to the formation of the NEC. In this study, we mapped individual interaction sequence elements of pUL50 by coimmunoprecipitation analysis of deletion mutants and yeast two-hybrid studies. Amino acids 1–250 were shown to be responsible for interaction with pUL53, 100–280 for PKC and 100–358 for p32. Interestingly, p32 specifically interacted with multiple NEC components, including the kinases PKC and pUL97, thus possibly acting as an adaptor for protein recruitment to the lamin B receptor. Notably, p32 was the only protein that interacted with the lamin B receptor. Immunofluorescence studies visualized the colocalization of NEC components at the nuclear rim in coexpression studies. The data imply that a tight interaction between at least six viral and cellular proteins leads to the formation of a postulated multi-protein complex required for nuclear egress.

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