Search results for "Pore complex"
showing 10 items of 24 documents
Applications of Super Resolution Expansion Microscopy in Yeast
2021
Super-resolution microscopy includes multiple techniques in optical microscopy that enable sub-diffraction resolution fluorescence imaging of cellular structures. Expansion microscopy (EXM) is a method of physical expansion to obtain super-resolution images of a biological sample on conventional microscopy. We present images of yeast organelles, applying the combination of super-resolution and ExM techniques. When preparing pre-expanded samples, conventional methods lead to breakage of dividing yeast cells and difficulties in studying division-related proteins. Here, we describe an improved sample preparation technique that avoids such damage. ExM in combination with Airyscan and structured…
Caspase-8 prevents sustained activation of NF-kappaB in monocytes undergoing macrophagic differentiation.
2006
Abstract Caspases have demonstrated several nonapoptotic functions including a role in the differentiation of specific cell types. Here, we show that caspase-8 is the upstream enzyme in the proteolytic caspase cascade whose activation is required for the differentiation of peripheral-blood monocytes into macrophages. On macrophage colony-stimulating factor (M-CSF) exposure, caspase-8 associates with the adaptor protein Fas-associated death domain (FADD), the serine/threonine kinase receptor-interacting protein 1 (RIP1) and the long isoform of FLICE-inhibitory protein FLIP. Overexpression of FADD accelerates the differentiation process that does not involve any death receptor. Active caspase…
Differential functions of calpain 1 during epithelial cell death and adipocyte differentiation in mammary gland involution
2014
Calpains become activated in the mammary gland early during weaning, cleaving several proteins located mainly in the cell membrane, but also in other organelles such as lysosomes, mitochondria and nuclei. By immunofluorescence and Western blot analysis, we have demonstrated the nuclear translocation of calpain-1 and calpain-2, together with the cleavage of several cytoplasmic nucleoporins in epithelial cells of the lobulo-alveolar compartment. In vivo and in vitro calpain inhibition prevented this nucleoporin degradation. In addition, calpain-1 was also present in the nucleus of non-epithelial mammary tissue cells, concomitant with adipocyte re-differentiation. Calpain-1 was internalized wi…
Studies on protein kinases involved in regulation of nucleocytoplasmic mRNA transport
1988
The rate of energy-dependent nucleoside triphosphatase (NTPase)-mediated nucleocytoplasmic translocation of poly(A)-containing mRNA [poly(A)+mRNA] across the nuclear envelope is thought to be regulated by poly(A)-sensitive phosphorylation and dephosphorylation of nuclear-envelope protein. Studying the phosphorylation-related inhibition of the NTPase, we found that phosphorylation of one polypeptide of rat liver envelopes by endogenous NI- and NII-like protein kinase was particularly sensitive to poly(A). This polypeptide (106 kDa) was also phosphorylated by nuclear-envelope-bound Ca2+-activated and phospholipid-dependent protein kinase (protein kinase C). Activation of kinase C by tumour-pr…
Down-regulation of Glutathione and Bcl-2 Synthesis in Mouse B16 Melanoma Cells Avoids Their Survival during Interaction with the Vascular Endothelium
2003
B16 melanoma (B16M) cells with high GSH content show high metastatic activity. However, the molecular mechanisms linking GSH to metastatic cell survival are unclear. The possible relationship between GSH and the ability of Bcl-2 to prevent cell death was studied in B16M cells with high (F10) and low (F1) metastatic potential. Analysis of a Bcl-2 family of genes revealed that B16M-F10 cells, as compared with B16M-F1 cells, overexpressed preferentially Bcl-2 (approximately 5.7-fold). Hepatic sinusoidal endothelium-induced B16M-F10 cytotoxicity in vitro increased from approximately 19% (controls) to approximately 97% in GSH-depleted B16M-F10 cells treated with an antisense Bcl-2 oligodeoxynucl…
The liquid state of FG-nucleoporins mimics permeability barrier properties of nuclear pore complexes
2019
Nuclear pore complexes form a permeability barrier in vivo that regulates nucleocytoplasmic transport. Here, the authors present a microfluidic device that couples rapid liquid–liquid phase separation of nucleoporins with direct optical interrogation. Freshly formed liquid nucleoporin droplets mimic permeability barrier properties of NPCs.
Insights into mRNP biogenesis provided by new genetic interactions among export and transcription factors.
2012
Abstract Background The various steps of mRNP biogenesis (transcription, processing and export) are interconnected. It has been shown that the transcription machinery plays a pivotal role in mRNP assembly, since several mRNA export factors are recruited during transcription and physically interact with components of the transcription machinery. Although the shuttling DEAD-box protein Dbp5p is concentrated on the cytoplasmic fibrils of the NPC, previous studies demonstrated that it interacts physically and genetically with factors involved in transcription initiation. Results We investigated the effect of mutations affecting various components of the transcription initiation apparatus on the…
Reorganization of Nuclear Pore Complexes and the Lamina in Late-Stage Parvovirus Infection
2015
Article
Evidence for a direct interaction of Rev protein with nuclear envelop mRNA-translocation system.
1991
The interaction of the Rev protein from human immunodeficiency virus type 1 (HIV-1) with the nucleocytoplasmic mRNA-transport system was investigated. In gel-shift assay, the recombinant Rev protein used in this study selectively bound to the Rev-responsive element (RRE) region of HIV-1 env-specific RNA. Nitrocellulose-filter-binding studies and Northern/Western-blotting experiments revealed an association constant of approximately 1 x 10(10) M-1. The Rev protein also strongly bound to isolated nuclear envelopes from H9 cells, containing the poly(A)-binding site (= mRNA carrier) and the nucleoside triphosphatase (= NTPase), which are thought to be involved in nuclear export of poly(A)-rich …
Rtp1p Is a Karyopherin-Like Protein Required for RNA Polymerase II Biogenesis
2013
The assembly and nuclear transport of RNA polymerase II (RNA pol II) are processes that require the participation of many auxiliary factors. In a yeast genetic screen, we identified a previously uncharacterized gene, YMR185w (renamed RTP1), which encodes a protein required for the nuclear import of RNA pol II. Using protein affinity purification coupled to mass spectrometry, we identified interactions between Rtp1p and members of the R2TP complex. Rtp1p also interacts, to a different extent, with several RNA pol II subunits. The pattern of interactions is compatible with a role for Rtp1p as an assembly factor that participates in the formation of the Rpb2/Rpb3 subassembly complex and its bi…