scholarly journals Nuclear envelope lipids request border surveillance

2021 ◽  
Vol 220 (3) ◽  
Author(s):  
Alwin Köhler
Keyword(s):  
Phosphatidic Acid ◽  
Nuclear Envelope ◽  
Nuclear Pore ◽  
Nuclear Pore Assembly ◽  
Border Surveillance

In this issue, Thaller et al. (2021. J. Cell Biol.https://doi.org/10.1083/jcb.202004222) explore how the ESCRT protein Chm7 is recruited to sites of defective nuclear pore assembly. They show that a lipid, phosphatidic acid, is enriched at pathological nuclear envelope herniations, where it promotes Chm7 recruitment for membrane surveillance and repair.

scholarly journals A short perinuclear amphipathic α-helix in Apq12 promotes nuclear pore complex biogenesis

2021 ◽  
Author(s):  
Elmar Schiebel ◽  
Wanlu Zhang ◽  
Azqa Khan ◽  
Jlenia Vitale ◽  
Annett Neuner ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Phosphatidic Acid ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Membrane ◽  
Integral Membrane Protein ◽  
Nuclear Pore ◽  
Binding Properties ◽  
Perinuclear Space ◽  
Α Helix

The integral membrane protein Apq12 is an important nuclear envelope (NE)/ER modulator that cooperates with the nuclear pore complex (NPC) biogenesis factors Brl1 and Brr6. How Apq12 executes these functions is unknown. Here we identified a short amphipathic α-helix (AαH) in Apq12 that links the two transmembrane domains in the perinuclear space and has liposome-binding properties. Cells expressing an APQ12 (apq12-ah) version in which AαH is disrupted show NPC biogenesis and NE integrity defects, without impacting upon Apq12-ah topology or NE/ER localization. Overexpression of APQ12 but not apq12-ah triggers striking over-proliferation of the outer nuclear membrane (ONM)/ER and promotes accumulation of phosphatidic acid (PA) at the NE. Apq12 and Apq12-ah both associate with NPC biogenesis intermediates and removal of AαH increases both Brl1 levels and the interaction between Brl1 and Brr6. We conclude that the short amphipathic α-helix of Apq12 regulates the function of Brl1 and Brr6 and promotes PA accumulation at the NE during NPC biogenesis.

scholarly journals Direct binding of ESCRT protein Chm7 to phosphatidic acid–rich membranes at nuclear envelope herniations

2021 ◽  
Vol 220 (3) ◽  
Author(s):  
David J. Thaller ◽  
Danqing Tong ◽  
Christopher J. Marklew ◽  
Nicholas R. Ader ◽  
Philip J. Mannino ◽  
...  
Keyword(s):  
Amino Acids ◽  
Phosphatidic Acid ◽  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Binding Capacity ◽  
Nuclear Pore ◽  
Membrane Remodeling ◽  
Functional Importance ◽  
Direct Binding ◽  
Domain Protein

Mechanisms that control nuclear membrane remodeling are essential to maintain the integrity of the nucleus but remain to be fully defined. Here, we identify a phosphatidic acid (PA)–binding capacity in the nuclear envelope (NE)–specific ESCRT, Chm7, in budding yeast. Chm7’s interaction with PA-rich membranes is mediated through a conserved hydrophobic stretch of amino acids, which confers recruitment to the NE in a manner that is independent of but required for Chm7’s interaction with the LAP2-emerin-MAN1 (LEM) domain protein Heh1 (LEM2). Consistent with the functional importance of PA binding, mutation of this region abrogates recruitment of Chm7 to membranes and abolishes Chm7 function in the context of NE herniations that form during defective nuclear pore complex (NPC) biogenesis. In fact, we show that a PA sensor specifically accumulates within these NE herniations. We suggest that local control of PA metabolism is important for ensuring productive NE remodeling and that its dysregulation may contribute to pathologies associated with defective NPC assembly.

scholarly journals Formation of the postmitotic nuclear envelope from extended ER cisternae precedes nuclear pore assembly

2011 ◽  
Vol 194 (3) ◽  
pp. 425-440 ◽  
Author(s):  
Lei Lu ◽  
Mark S. Ladinsky ◽  
Tomas Kirchhausen
Keyword(s):  
Nuclear Envelope ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Current Model ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Envelope Formation ◽  
Pore Complexes ◽  
Nuclear Pore Assembly ◽  
A Current

During mitosis, the nuclear envelope merges with the endoplasmic reticulum (ER), and nuclear pore complexes are disassembled. In a current model for reassembly after mitosis, the nuclear envelope forms by a reshaping of ER tubules. For the assembly of pores, two major models have been proposed. In the insertion model, nuclear pore complexes are embedded in the nuclear envelope after their formation. In the prepore model, nucleoporins assemble on the chromatin as an intermediate nuclear pore complex before nuclear envelope formation. Using live-cell imaging and electron microscope tomography, we find that the mitotic assembly of the nuclear envelope primarily originates from ER cisternae. Moreover, the nuclear pore complexes assemble only on the already formed nuclear envelope. Indeed, all the chromatin-associated Nup107–160 complexes are in single units instead of assembled prepores. We therefore propose that the postmitotic nuclear envelope assembles directly from ER cisternae followed by membrane-dependent insertion of nuclear pore complexes.

scholarly journals Cytosol dependent membrane fusion in ER, nuclear envelope and nuclear pore assembly

Nucleus ◽  
2010 ◽  
Vol 1 (6) ◽  
pp. 487-491 ◽  
Author(s):  
Elvira R. Rafikova ◽  
Kamran Melikov ◽  
Leonid V. Chernomordik
Keyword(s):  
Nuclear Envelope ◽  
Membrane Fusion ◽  
Nuclear Pore ◽  
Nuclear Pore Assembly

scholarly journals Author response: Nuclear pore assembly proceeds by an inside-out extrusion of the nuclear envelope

2016 ◽  
Author(s):  
Shotaro Otsuka ◽  
Khanh Huy Bui ◽  
Martin Schorb ◽  
M Julius Hossain ◽  
Antonio Z Politi ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Author Response ◽  
Nuclear Pore ◽  
Nuclear Pore Assembly ◽  
Inside Out

scholarly journals Nuclear pore assembly proceeds by an inside-out extrusion of the nuclear envelope

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Shotaro Otsuka ◽  
Khanh Huy Bui ◽  
Martin Schorb ◽  
M Julius Hossain ◽  
Antonio Z Politi ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Electron Tomography ◽  
Super Resolution ◽  
Nucleocytoplasmic Transport ◽  
Ring Structure ◽  
Nuclear Pore ◽  
Resolution Electron ◽  
Nuclear Pore Assembly ◽  
Inside Out

The nuclear pore complex (NPC) mediates nucleocytoplasmic transport through the nuclear envelope. How the NPC assembles into this double membrane boundary has remained enigmatic. Here, we captured temporally staged assembly intermediates by correlating live cell imaging with high-resolution electron tomography and super-resolution microscopy. Intermediates were dome-shaped evaginations of the inner nuclear membrane (INM), that grew in diameter and depth until they fused with the flat outer nuclear membrane. Live and super-resolved fluorescence microscopy revealed the molecular maturation of the intermediates, which initially contained the nuclear and cytoplasmic ring component Nup107, and only later the cytoplasmic filament component Nup358. EM particle averaging showed that the evagination base was surrounded by an 8-fold rotationally symmetric ring structure from the beginning and that a growing mushroom-shaped density was continuously associated with the deforming membrane. Quantitative structural analysis revealed that interphase NPC assembly proceeds by an asymmetric inside-out extrusion of the INM.

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.

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