scholarly journals Phosphorylation by Cdk1 induces Plk1-mediated vimentin phosphorylation during mitosis

2005 ◽  
Vol 171 (3) ◽  
pp. 431-436 ◽  
Author(s):  
Tomoya Yamaguchi ◽  
Hidemasa Goto ◽  
Tomoya Yokoyama ◽  
Herman Silljé ◽  
Anja Hanisch ◽  
...  
Keyword(s):  
Intermediate Filament ◽  
Rho Kinase ◽  
Direct Interaction ◽  
Enzyme Reaction ◽  
Aurora B ◽  
Intermediate Filament Protein ◽  
Cleavage Furrow ◽  
Filament Protein ◽  
Vimentin Filaments

Several kinases phosphorylate vimentin, the most common intermediate filament protein, in mitosis. Aurora-B and Rho-kinase regulate vimentin filament separation through the cleavage furrow-specific vimentin phosphorylation. Cdk1 also phosphorylates vimentin from prometaphase to metaphase, but its significance has remained unknown. Here we demonstrated a direct interaction between Plk1 and vimentin-Ser55 phosphorylated by Cdk1, an event that led to Plk1 activation and further vimentin phosphorylation. Plk1 phosphorylated vimentin at ∼1 mol phosphate/mol substrate, which partly inhibited its filament forming ability, in vitro. Plk1 induced the phosphorylation of vimentin-Ser82, which was elevated from metaphase and maintained until the end of mitosis. This elevation followed the Cdk1-induced vimentin-Ser55 phosphorylation, and was impaired by Plk1 depletion. Mutational analyses revealed that Plk1-induced vimentin-Ser82 phosphorylation plays an important role in vimentin filaments segregation, coordinately with Rho-kinase and Aurora-B. Taken together, these results indicated a novel mechanism that Cdk1 regulated mitotic vimentin phosphorylation via not only a direct enzyme reaction but also Plk1 recruitment to vimentin.

scholarly journals Fully functional, naturally occurring and C-terminally truncated variant human immunodeficiency virus (HIV) Vif does not bind to HIV Gag but influences intermediate filament structure

2001 ◽  
Vol 82 (3) ◽  
pp. 561-573 ◽  
Author(s):  
Tanja Henzler ◽  
Abdallah Harmache ◽  
Harald Herrmann ◽  
Herbert Spring ◽  
Marie Suzan ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Hela Cells ◽  
Intermediate Filament ◽  
Direct Interaction ◽  
Cellular Membrane ◽  
Intermediate Filament Protein ◽  
C Terminus ◽  
Filament Structure ◽  
Immunodeficiency Virus

A variant human immunodeficiency virus type 1 (HIV-1) vif gene, vifA45-2, which encodes a protein lacking 19 amino acids at the C terminus but which is fully functional in supporting HIV replication in non-permissive cells has been described previously. By employing newly generated anti-VifA45 serum, further properties of VifA45 and its full-length counterpart, VifA45open, in comparison to Vif from HIV strain BH10 are reported in permissive HeLa and COS-7 cells. The results obtained using confocal microscopic localization studies and in vitro binding assays do not support a requirement for the direct interaction of HIV Gag with Vif. Furthermore and in contrast to previous conclusions, detergent solubility analyses do not demonstrate a role for the C terminus of Vif in mediating localization to the fraction containing cellular membrane proteins. Localization of Vif from HIV strain BH10 to perinuclear aggregates in a small fraction (about 10%) of transfected HeLa cells has been previously reported. The intermediate filament protein vimentin colocalizes to these structures. In contrast, VifA45 and VifA45open form perinuclear aggregates in nearly all transfected HeLa cells; vimentin as well as the cytoskeletal-bridging protein plectin, but not the microtubular protein tubulin, become relocalized to these structures. Interestingly, in COS-7 cells, all of the functional Vif proteins tested (Vif from strain BH10, VifA45 and VifA45open) predominantly localize in the cytoplasm but still induce dramatic aggregation of vimentin and plectin, i.e. in these cells the respective Vif proteins are influencing intermediate filament structure in the absence of colocalization.

scholarly journals Suppression by antisense mRNA demonstrates a requirement for the glial fibrillary acidic protein in the formation of stable astrocytic processes in response to neurons.

1991 ◽  
Vol 112 (6) ◽  
pp. 1205-1213 ◽  
Author(s):  
D E Weinstein ◽  
M L Shelanski ◽  
R K Liem
Keyword(s):  
Glial Fibrillary Acidic Protein ◽  
Cell Lines ◽  
Intermediate Filament ◽  
Neuronal Cell ◽  
Acidic Protein ◽  
Intermediate Filament Protein ◽  
Astrocytoma Cell ◽  
Filament Protein ◽  
U251 Cells

The glial fibrillary acidic protein (GFAP) is a glial-specific intermediate filament protein, which is expressed in astrocytes in the central nervous system, as well as in astrocytoma cell lines. To investigate the function of GFAP, we have studied the human astrocytoma cell line, U251, which constitutively expresses GFAP and vimentin in the same 10-nm filaments. These cells respond to neurons in vitro in the same way as primary astrocytes: they withdraw from the cell cycle, support neuronal cell survival and neurite outgrowth, and they extend complex, GFAP-positive processes. To determine the role of GFAP in these responses, we have specifically suppressed its expression by stably transfecting the U251 cells with an antisense GFAP construct. Two stable antisense cell lines from separate transfections were isolated and were shown to be GFAP negative by Northern and Western blot analyses, and by immunofluorescence studies. The antisense cell lines were inhibited in their ability to extend significant glial processes in response to neurons. In culture with primary neurons, the average increase in process length of the U251 cells was nearly 400%, as compared to only 14% for the antisense transfectants. The other neuron induced responses of astrocytes, i.e., proliferative arrest and neuronal support, were not affected in these cell lines. These data support the conclusion that the glial-specific intermediate filament protein, GFAP, is required for the formation of stable astrocytic processes in response to neurons.

scholarly journals Regulation of GFAP Expression

ASN NEURO ◽  
2021 ◽  
Vol 13 ◽  
pp. 175909142098120
Author(s):  
Michael Brenner ◽  
Albee Messing
Keyword(s):  
Transcription Factors ◽  
Histone Methylation ◽  
Intermediate Filament ◽  
Genetic Manipulation ◽  
Direct Interaction ◽  
Intermediate Filament Protein ◽  
Its Gene ◽  
Gfap Expression ◽  
Experimental Findings ◽  
Filament Protein

Expression of the GFAP gene has attracted considerable attention because its onset is a marker for astrocyte development, its upregulation is a marker for reactive gliosis, and its predominance in astrocytes provides a tool for their genetic manipulation. The literature on GFAP regulation is voluminous, as almost any perturbation of development or homeostasis in the CNS will lead to changes in its expression. In this review, we limit our discussion to mechanisms proposed to regulate GFAP synthesis through a direct interaction with its gene or mRNA. Strengths and weaknesses of the supportive experimental findings are described, and suggestions made for additional studies. This review covers 15 transcription factors, DNA and histone methylation, and microRNAs. The complexity involved in regulating the expression of this intermediate filament protein suggests that GFAP function may vary among both astrocyte subtypes and other GFAP-expressing cells, as well as during development and in response to perturbations.

scholarly journals Artemisinins target the intermediate filament protein vimentin for human cytomegalovirus inhibition

2020 ◽  
Vol 295 (44) ◽  
pp. 15013-15028 ◽  
Author(s):  
Sujayita Roy ◽  
Arun Kapoor ◽  
Fei Zhu ◽  
Rupkatha Mukhopadhyay ◽  
Ayan Kumar Ghosh ◽  
...  
Keyword(s):  
Intermediate Filament ◽  
Hcmv Infection ◽  
Intermediate Filament Protein ◽  
Biological Assays ◽  
Human Foreskin Fibroblasts ◽  
Hcmv Replication ◽  
Human Cmv ◽  
Filament Protein

The antimalarial agents artemisinins inhibit cytomegalovirus (CMV) in vitro and in vivo, but their target(s) has been elusive. Using a biotin-labeled artemisinin, we identified the intermediate filament protein vimentin as an artemisinin target, validated by detailed biochemical and biological assays. We provide insights into the dynamic and unique modulation of vimentin, depending on the stage of human CMV (HCMV) replication. In vitro, HCMV entry and viral progeny are reduced in vimentin-deficient fibroblasts, compared with control cells. Similarly, mouse CMV (MCMV) replication in vimentin knockout mice is significantly reduced compared with controls in vivo, confirming the requirement of vimentin for establishment of infection. Early after HCMV infection of human foreskin fibroblasts vimentin level is stable, but as infection proceeds, vimentin is destabilized, concurrent with its phosphorylation and virus-induced calpain activity. Intriguingly, in vimentin-overexpressing cells, HCMV infection is reduced compared with control cells. Binding of artesunate, an artemisinin monomer, to vimentin prevents virus-induced vimentin degradation, decreasing vimentin phosphorylation at Ser-55 and Ser-83 and resisting calpain digestion. In vimentin-deficient fibroblasts, the anti-HCMV activity of artesunate is reduced compared with controls. In summary, an intact and stable vimentin network is important for the initiation of HCMV replication but hinders its completion. Artesunate binding to vimentin early during infection stabilizes it and antagonizes subsequent HCMV-mediated vimentin destabilization, thus suppressing HCMV replication. Our target discovery should enable the identification of vimentin-binding sites and compound moieties for binding.

The Binding in Vitro of Modified LDL to the Intermediate Filament Protein Vimentin

2000 ◽  
Vol 267 (1) ◽  
pp. 49-53 ◽  
Author(s):  
Anne K. Heidenthal ◽  
Peter C. Weber ◽  
Friedrich Lottspeich ◽  
Nina Hrboticky
Keyword(s):  
Intermediate Filament ◽  
Intermediate Filament Protein ◽  
Modified Ldl ◽  
Filament Protein

scholarly journals The molecular architecture of vimentin filaments

2021 ◽  
Author(s):  
Matthias Eibauer ◽  
Miriam S. Weber ◽  
Yagmur Turgay ◽  
Suganya Sivagurunathan ◽  
Robert D. Goldman ◽  
...  
Keyword(s):  
Intermediate Filament ◽  
Electron Tomography ◽  
Helical Axis ◽  
Intermediate Filament Protein ◽  
Molecular Architecture ◽  
Cellular Functions ◽  
Intrinsically Disordered ◽  
Filament Protein ◽  
Polypeptide Chains ◽  
Vimentin Filaments

Intermediate filaments are integral components of the cytoskeleton in metazoan cells. Due to their specific viscoelastic properties they are principal contributors to flexibility and tear strength of cells and tissues. Vimentin, an intermediate filament protein expressed in fibroblasts and endothelial cells, assembles into ~11 nm thick biopolymers, that are involved in a wide variety of cellular functions in health and disease. Here, we reveal the structure of in-situ polymerized vimentin filaments to a subnanometer resolution by applying cryo-electron tomography to mouse embryonic fibroblasts grown on electron microscopy grids. We show that vimentin filaments are tube-like assemblies with a well-defined helical symmetry. Their structure is comprised of five octameric, spring-like protofibrils harboring 40 vimentin polypeptide chains in cross-section. The protofibrils are connected by the intrinsically disordered head and helix 1A domains of vimentin. Individual filaments display two polymerization states characterized by either the presence or absence of a luminal density along the helical axis. The structure of vimentin filaments unveils the generic building plan of the intermediate filament superfamily in molecular details.

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