98%
921
2 minutes
20
The P446L mutant Drosophila importin-beta (P446L-imp-beta) has been reported to prohibit--in dominant negative fashion--nuclear envelope (NE) assembly. Along elucidating the mode of action of P446L-imp-beta we studied in vitro NE assembly on Sepharose beads. While Drosophila embryo extracts support NE assembly over Sepharose beads coated with Ran, NE assembly does not take place in extracts supplied with exogenous P446L-imp-beta. A NE also forms over importin-beta-coated beads. Surprisingly, when immobilized to Sepharose beads P446L-imp-beta as efficiently recruits NE vesicles as normal importin-beta. The discrepancy in behavior of cytoplasmic and bead-bound P446L-imp-beta appears to be related to icreased--as compared to normal importin-beta--microtubule (MT) binding ability of P446L-imp-beta. While wild-type importin-beta is able to bind MTs and the binding decreases upon RanGTP interaction, P446L-imp-beta cannot be removed from the MTs by RanGTP. P446L-imp-beta, like normal importin-beta, binds some types of the nucleoporins that have been known to be required for NE assembly at the end of mitosis. It appears that the inhibitory effect of P446L-imp-beta on NE assembly is caused by sequestering some of the nucleoporins required for NE assembly to the MTs.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1078/0171-9335-00324 | DOI Listing |
Mol Biol Cell
September 2025
Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
The ESCRT machinery mediates membrane remodeling in fundamental cellular processes including cytokinesis, endosomal sorting, nuclear envelope reformation, and membrane repair. Membrane constriction and scission is driven by the filament-forming ESCRT-III complex and the AAA-ATPase VPS4. While ESCRT-III-driven membrane scission is generally established, the mechanisms governing the assembly and coordination of its twelve mammalian isoforms in cells remain poorly understood.
View Article and Find Full Text PDFNat Rev Mol Cell Biol
September 2025
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA.
The defining property of eukaryotic cells is the storage of heritable genetic material in a nuclear compartment. For eukaryotic cells to carry out the myriad biochemical processes necessary for their function, macromolecules must be efficiently exchanged between the nucleus and cytoplasm. The nuclear pore complex (NPC) - which is a massive assembly of ~35 different proteins present in multiple copies totalling ~1,000 protein subunits and architecturally conserved across eukaryotes - establishes a size-selective channel for regulated bidirectional transport of folded macromolecules and macromolecular assemblies across the nuclear envelope.
View Article and Find Full Text PDFEmerg Microbes Infect
September 2025
State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, and College of Veterinary Medicine, Jilin University, Changchun 130062, China.
Enveloped viruses rely on matrix proteins for structural integrity and lifecycle progression. Matrix protein 1 (M1) is the most abundant structural protein of influenza A virus (IAV), playing a multifaceted role in viral uncoating, polymerase activity, vRNA transcription and replication, and assembly and budding. The M1 protein not only interacts with host cells but also regulates viral morphogenesis, thereby influencing viral transmissibility and pathogenicity.
View Article and Find Full Text PDFBMB Rep
September 2025
Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon 16499; Department of Biomedical Sciences, The Graduate School of Ajou University, Suwon 16499; BK21 R&E Initiative for Advanced Precision Medicine, Ajou University School of Medicine, Suwon 16499, Korea.
Altered nuclear morphology, one of the characteristics of cancer cells, is often indicative of tumor prognosis. While reactive oxygen species (ROS) are known to induce nuclear morphology changes, mechanisms underlying these effects remain elusive, particularly regarding nuclear assembly. We hypothesized that mitotic cells might exhibit increased susceptibility to ROSinduced nuclear deformation due to the dynamic nature of nuclear envelope during mitosis, i.
View Article and Find Full Text PDFPlant Cell
September 2025
Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
Communication between cellular organelles is essential for mounting effective innate immune responses. The transport of organelles to pathogen penetration sites and their assembly around the host membrane, which delineates the plant-pathogen interface, are well-documented. However, whether organelles associate with these specialized interfaces, and the extent to which this process contributes to immunity, remain unknown.
View Article and Find Full Text PDF