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Masaki Inagaki - One of the best experts on this subject based on the ideXlab platform.
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Sphingolipids inhibit Vimentin-dependent cell migration.
Journal of cell science, 2015Co-Authors: Claire L. Hyder, Hidemasa Goto, Masaki Inagaki, John E Eriksson, Kati Kemppainen, Kimmo O. Isoniemi, Susumu Y. Imanishi, Elnaz Fazeli, Kid TörnquistAbstract:The sphingolipids, sphingosine 1-phosphate (S1P) and sphingosylphosphorylcholine (SPC), can induce or inhibit cellular migration. The intermediate filament protein, Vimentin, is an inducer of migration and a marker for epithelial-mesenchymal transition. Since keratin intermediate filaments are regulated by SPC, with consequences for cell motility, we wanted to determine whether Vimentin is regulated by sphingolipid signalling and if it is a determinant for sphingolipid-mediated functions. We observed that S1P and SPC induced phosphorylation of Vimentin on serine 71 (S71), with a corresponding reorganization of Vimentin filaments, in cancer cells whose migration S1P and SPC inhibited. These effects were sphingolipid signalling-dependent, as inhibition of either the S1P2 receptor or its downstream effector Rho-associated kinase (ROCK) cancelled the sphingolipid-induced effects on Vimentin organization and S71 phosphorylation. Furthermore, the anti-migratory effect of S1P and SPC could be prevented by expressing S71 phosphorylation-deficient Vimentin. In addition, we demonstrated using wild-type and Vimentin knockout mouse embryonic fibroblasts that the sphingolipid-mediated inhibition of migration is Vimentin-dependent. These results imply that the discovered sphingolipid-Vimentin signalling axis will exert brake and throttle functions in the regulation of cell migration.
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Vimentin-Ser82 as a memory phosphorylation site in astrocytes.
Genes to cells : devoted to molecular & cellular mechanisms, 2006Co-Authors: Takashi Oguri, Tomoya Yamaguchi, Ichiro Izawa, Akihito Inoko, Hiroshi Shima, Nariko Arimura, Naoyuki Inagaki, Kozo Kaibuchi, Kunimi Kikuchi, Masaki InagakiAbstract:In astrocytes, the PGF(2alpha) or ionomycin treatment induces the phosphorylation at Ser38 and Ser82 of Vimentin, a type III intermediate filament, by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). We found here that Vimentin phospho-Ser82 was dephosphorylated much slower than phospho-Ser38. Vimentin phospho-Ser38 was dephosphorylated quickly by purified PP1 catalytic subunit (PP1c) in vitro, whereas phospho-Ser82 was insensitive to PP1c. Because PP1c directly bound to Vimentin through a VxF motif (Val83-Asp84-Phe85), the PP1c active site appeared to be unable to approach phospho-Ser82, leading to the prolongation of the phosphorylation at Ser-82. In astrocytes, PP1calpha was in vivo associated with Vimentin filaments. The repetitive treatment by ionomycin at a short interval resulted in the sustained elevation of Ser82 phosphorylation, leading to the marked disassembly of Vimentin filaments. Taken together, these results suggest that Vimentin is a novel member of binding partner of PP1c in astrocytes, and Vimentin-Ser82 may act as a memory phosphorylation site.
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pkce mediated phosphorylation of Vimentin controls integrin recycling and motility
The EMBO Journal, 2005Co-Authors: Johanna Ivaska, Masaki Inagaki, Karoliina Vuoriluoto, Tuomas Huovinen, Ichiro Izawa, Peter J ParkerAbstract:PKCe controls the transport of endocytosed β1‐integrins to the plasma membrane regulating directional cell motility. Vimentin, an intermediate filament protein upregulated upon epithelial cell transformation, is shown here to be a proximal PKCe target within the recycling integrin compartment. On inhibition of PKC and Vimentin phosphorylation, integrins become trapped in vesicles and directional cell motility towards matrix is severely attenuated. In vitro reconstitution assays showed that PKCe dissociates from integrin containing endocytic vesicles in a selectively phosphorylated Vimentin containing complex. Mutagenesis of PKC (controlled) sites on Vimentin and ectopic expression of the variant leads to the accumulation of intracellular PKCe/integrin positive vesicles. Finally, introduction of ectopic wild‐type Vimentin is shown to promote cell motility in a PKCe‐dependent manner; alanine substitutions in PKC (controlled) sites on Vimentin abolishes the ability of Vimentin to induce cell migration, whereas the substitution of these sites with acidic residues enables Vimentin to rescue motility of PKCe null cells. Our results indicate that PKC‐mediated phosphorylation of Vimentin is a key process in integrin traffic through the cell.
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Phosphorylation by Cdk1 induces Plk1-mediated Vimentin phosphorylation during mitosis
Journal of Cell Biology, 2005Co-Authors: Tomoya Yamaguchi, Hidemasa Goto, Tomoya Yokoyama, Herman H W Silljé, Anja Hanisch, Andreas Uldschmid, Yasushi Takai, Takashi Oguri, Erich A. Nigg, Masaki InagakiAbstract: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.
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aurora b regulates the cleavage furrow specific Vimentin phosphorylation in the cytokinetic process
Journal of Biological Chemistry, 2003Co-Authors: Hidemasa Goto, Erich A. Nigg, Yoshihiro Yasui, Koh-ichi Nagata, Aie Kawajiri, Yasuhiko Terada, Masaaki Tatsuka, Masaki InagakiAbstract:Aurora-B is an evolutionally conserved protein kinase that regulates several mitotic events including cytokinesis. We previously demonstrated the possible existence of a protein kinase that phosphorylates at least Ser-72 on Vimentin, the most widely expressed intermediate filament protein, in the cleavage furrow-specific manner. Here we showed that Vimentin-Ser-72 phosphorylation occurred specifically at the border of the Aurora-B-localized area from anaphase to telophase. Expression of a dominant-negative mutant of Aurora-B led to a reduction of this Vimentin-Ser-72 phosphorylation. In vitro analyses revealed that Aurora-B phosphorylates Vimentin at approximately 2 mol phosphate/mol of substrate for 30 min and that this phosphorylation dramatically inhibits Vimentin filament formation. We further identified eight Aurora-B phosphorylation sites, including Ser-72 on Vimentin, and then constructed the mutant Vimentin in which these identified sites are changed into Ala. Cells expressing this mutant formed an unusually long bridge-like intermediate filament structure between unseparated daughter cells. We then identified important phosphorylation sites for the bridge phenotype. Our findings indicate that Aurora-B regulates the cleavage furrow-specific Vimentin phosphorylation and controls Vimentin filament segregation in cytokinetic process.
Hidemasa Goto - One of the best experts on this subject based on the ideXlab platform.
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Sphingolipids inhibit Vimentin-dependent cell migration.
Journal of cell science, 2015Co-Authors: Claire L. Hyder, Hidemasa Goto, Masaki Inagaki, John E Eriksson, Kati Kemppainen, Kimmo O. Isoniemi, Susumu Y. Imanishi, Elnaz Fazeli, Kid TörnquistAbstract:The sphingolipids, sphingosine 1-phosphate (S1P) and sphingosylphosphorylcholine (SPC), can induce or inhibit cellular migration. The intermediate filament protein, Vimentin, is an inducer of migration and a marker for epithelial-mesenchymal transition. Since keratin intermediate filaments are regulated by SPC, with consequences for cell motility, we wanted to determine whether Vimentin is regulated by sphingolipid signalling and if it is a determinant for sphingolipid-mediated functions. We observed that S1P and SPC induced phosphorylation of Vimentin on serine 71 (S71), with a corresponding reorganization of Vimentin filaments, in cancer cells whose migration S1P and SPC inhibited. These effects were sphingolipid signalling-dependent, as inhibition of either the S1P2 receptor or its downstream effector Rho-associated kinase (ROCK) cancelled the sphingolipid-induced effects on Vimentin organization and S71 phosphorylation. Furthermore, the anti-migratory effect of S1P and SPC could be prevented by expressing S71 phosphorylation-deficient Vimentin. In addition, we demonstrated using wild-type and Vimentin knockout mouse embryonic fibroblasts that the sphingolipid-mediated inhibition of migration is Vimentin-dependent. These results imply that the discovered sphingolipid-Vimentin signalling axis will exert brake and throttle functions in the regulation of cell migration.
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Phosphorylation by Cdk1 induces Plk1-mediated Vimentin phosphorylation during mitosis
Journal of Cell Biology, 2005Co-Authors: Tomoya Yamaguchi, Hidemasa Goto, Tomoya Yokoyama, Herman H W Silljé, Anja Hanisch, Andreas Uldschmid, Yasushi Takai, Takashi Oguri, Erich A. Nigg, Masaki InagakiAbstract: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.
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aurora b regulates the cleavage furrow specific Vimentin phosphorylation in the cytokinetic process
Journal of Biological Chemistry, 2003Co-Authors: Hidemasa Goto, Erich A. Nigg, Yoshihiro Yasui, Koh-ichi Nagata, Aie Kawajiri, Yasuhiko Terada, Masaaki Tatsuka, Masaki InagakiAbstract:Aurora-B is an evolutionally conserved protein kinase that regulates several mitotic events including cytokinesis. We previously demonstrated the possible existence of a protein kinase that phosphorylates at least Ser-72 on Vimentin, the most widely expressed intermediate filament protein, in the cleavage furrow-specific manner. Here we showed that Vimentin-Ser-72 phosphorylation occurred specifically at the border of the Aurora-B-localized area from anaphase to telophase. Expression of a dominant-negative mutant of Aurora-B led to a reduction of this Vimentin-Ser-72 phosphorylation. In vitro analyses revealed that Aurora-B phosphorylates Vimentin at approximately 2 mol phosphate/mol of substrate for 30 min and that this phosphorylation dramatically inhibits Vimentin filament formation. We further identified eight Aurora-B phosphorylation sites, including Ser-72 on Vimentin, and then constructed the mutant Vimentin in which these identified sites are changed into Ala. Cells expressing this mutant formed an unusually long bridge-like intermediate filament structure between unseparated daughter cells. We then identified important phosphorylation sites for the bridge phenotype. Our findings indicate that Aurora-B regulates the cleavage furrow-specific Vimentin phosphorylation and controls Vimentin filament segregation in cytokinetic process.
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Phosphorylation and reorganization of Vimentin by p21-activated kinase (PAK)
Genes to cells : devoted to molecular & cellular mechanisms, 2002Co-Authors: Hidemasa Goto, Kazushi Tanabe, Edward Manser, Louis Lim, Yoshihiro Yasui, Masaki InagakiAbstract:Background: Intermediate filament (IF) is one of the three major cytoskeletal filaments. Vimentin is the most widely expressed IF protein component. The Rho family of small GTPases, such as Cdc42, Rac and Rho, are thought to control the organization of actin filaments as well as other cytoskeletal filaments. Results: We determined if the Vimentin filaments can be regulated by p21-activated kinase (PAK), one of targets downstream of Cdc42 or Rac. In vitro analyses revealed that Vimentin served as an excellent substrate for PAK. This phosphorylated Vimentin lost the potential to form 10 nm filaments. We identified Ser25, Ser38, Ser50, Ser65 and Ser72 in the amino-terminal head domain as the major phosphorylation sites on Vimentin for PAK. The ectopic expression of constitutively active PAK in COS-7 cells induced Vimentin phosphorylation. Fibre bundles or granulates of Vimentin were frequent in these transfected cells. However, the kinase-inactive mutant induced neither Vimentin phosphorylation nor filament reorganization. Conclusion: Our observations suggest that PAK may regulate the reorganization of Vimentin filaments through direct Vimentin phosphorylation.
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Protein kinases required for segregation of Vimentin filaments in mitotic process
Oncogene, 2001Co-Authors: Yoshihiro Yasui, Hidemasa Goto, Edward Manser, Seiya Matsui, Koh-ichi Nagata, Masaki InagakiAbstract:Vimentin, one of type III intermediate filament (IF) proteins, is expressed not only in mesenchymal cells but also in most types of tumor cells. In the present study, we introduced several types of Vimentin mutated at putative phosphorylation sites in its amino-terminal head domain into type III IF-negative T24 cells. Site-specific mutation induced the formation of an unusually long bridge-like IF structure between the unseparated daughter cells, although these mutants formed the filament network similar to wild type in interphase cells. Together with sites phosphorylated by Rho-kinase and protein kinase C (PKC), Vimentin-Ser72, which can not be phosphorylated by any known Vimentin kinase, was one of the mutation sites essential for this phenotype. We further demonstrated that Vimentin-Ser72 was phosphorylated specifically at the cleavage furrow during cytokinesis. These observations suggest the existence of a novel protein kinase responsible for Vimentin filament separation through the cleavage furrow-specific Vimentin phosphorylation. We propose that Rho-kinase, PKC, and an unidentified Vimentin-Ser72 kinase may play important roles in Vimentin filament separation during cytokinesis.
Dolores Pérez-sala - One of the best experts on this subject based on the ideXlab platform.
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Effects of oxidants and electrophiles on Vimentin assembly
Free Radical Biology and Medicine, 2018Co-Authors: Andreia Mónico, Sofia Duarte, María A. Pajares, Dolores Pérez-salaAbstract:The intermediate filament protein Vimentin constitutes a critical sensor for electrophiles and oxidative stress in mesenchymal cells. The structure of the Vimentin network structure is altered by lipoxidation, although the mechanisms involved are not completely understood. Here, we have studied the response of Vimentin to oxidation and lipoxidation, both in vitro and in cells. Electrophilic lipids including 15d-PGJ2 and HNE bind to isolated Vimentin in vitro, whereas the oxidant diamide induces disulfide bond formation. Requirement for the presence of the cysteine residue differs among these modifications. Interestingly, pre-incubation of Vimentin with these agents disrupts NaCl-induced filament formation, whereas NaCl polymerized-Vimentin appears to be more resistant to filament disruption by electrophiles and oxidants. These observations suggest that (lip)oxidative modifications of soluble Vimentin subunits would be more deleterious than modification of polymerized Vimentin. Therefore, we are exploring the interplay between Vimentin lipoxidation and dynamics in cells. These studies will contribute to understand the implications of Vimentin in pathophysiological processes associated with oxidative stress.
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Vimentin gets a new glow from zinc.
Oncotarget, 2015Co-Authors: Dolores Pérez-sala, Clara L. Oeste, Francisco J. Sánchez-gómezAbstract:Intermediate filaments are important beams in cell architecture. Keratin filaments, neurofilaments, the constituents of the nuclear lamina and the Vimentin network are examples of these structures, which confer mechanical resistance to cells and at the same time are flexible and dynamic. Vimentin is an intermediate filament protein expressed in mesenchymal cells. Leading-edge research in the last decade has shown that besides its structural purpose, Vimentin plays other important roles in cell homeostasis, including promoting the correct position and function of organelles, the interaction with and regulation of signaling proteins, and a bidirectional cross-talk with other cytoskeletal structures [1, 2]. In addition, Vimentin plays a leading role in numerous pathophysiological processes including epithelial mesenchymal transition, infection, autoimmune disease, and wound healing. In spite of many years of excellent research in this field [1, 3], Vimentin still conceals some secrets. The structure of this coiled-coil protein has not been fully characterized and its mode of assembly in cells is incompletely understood. Although many stimuli have been identified that promote Vimentin disassembly, less is known about the induction of Vimentin filaments polymerization or elongation. Thus, in some aspects, Vimentin is still a mysterious protein, compared to the building blocks of other cytoskeletal structures such as tubulin in microtubules or actin in microfilaments. This 55 kDa protein possesses a single cysteine residue, cys328. In recent work we have shown that this residue is a remarkable sensor for oxidative stress [4]. Mutating this residue numbs the responsiveness of the Vimentin network to oxidants and electrophilic compounds, attenuating its remodeling and making it somehow “resistant” to these aggressions [4, 5]. However, this mutant does not keep up with Vimentin's demanding tasks in various cellular processes and shows limited performance in the expansion of the Vimentin network after cell plating, in achieving the appropriate distribution of cytoplasmic organelles such as lysosomes, and in forming aggresomes upon inhibition of proteasomal degradation or extensive oxidative damage. While studying the mechanisms underlying the requirement for cys328 for optimal Vimentin function, we found that Vimentin binds zinc [4]. We think that this is an unprecedented, exciting finding for this protein, which may turn the spot-light on some previously dim features in this field. Zinc is the transition metal most frequently found as a cofactor in proteins [6]. Zinc binding to proteins may serve regulatory or structural roles, either by promoting specific conformations, sustaining catalytic activity or stabilizing oligomeric associations. In vitro, Vimentin avidly binds zinc with high affinity, and submillimolar zinc reversibly promotes Vimentin polymerization inducing the formation of Vimentin bundles. Zinc binding to Vimentin is suprastoichiometric, which suggests that it involves multiple electrostatic interactions likely due to the polyelectrolyte nature of the protein [3]. In cells, zinc availability has a strong impact on Vimentin function. Zinc reversibly regulates the assembly of fluorescent GFP-Vimentin constructs in Vimentin-deficient cells. Moreover, whereas pharmacological zinc chelation alters the Vimentin network, genetic zinc deficiency is associated with increased Vimentin susceptibility to further zinc depletion or oxidative stress, together with a lower proportion of polymerized Vimentin and a thinner appearance of filaments, and these alterations are alleviated by zinc supplementation. Interestingly, cellular imaging with the fluorescent zinc probe, zinquin, lights-up portions of Vimentin bundles, indicating that zinc interacts with Vimentin in cells. Although the interaction of zinc with other cytoskeletal proteins has been reported, the affinity of Vimentin appears to be much higher based on the behavior of the purified proteins. If such an efficient binding takes place in cells, Vimentin could behave as a zinc reservoir, or as a zinc-sequestering agent. Moreover, the stimulating possibility exists that the interaction between zinc and Vimentin has reciprocal outcomes, that is, zinc may regulate Vimentin, but Vimentin could also play an important role in cellular zinc homeostasis. In light of our findings it would be tempting to speculate that Vimentin can fulfil this role through a direct interaction with zinc. Figure 1 Vimentin subunits associate to form filaments Although the precise structural features of the Vimentin-zinc interaction have not been elucidated, we may picture zinc atoms as staples that reversibly stabilize filaments at specific places. Zinc can be incorporated into proteins in Zn-clusters, often of tetrahedral geometry, in which a zinc atom is coordinated by four ligands, most frequently involving sulfur from cysteine, nitrogen from histidine and/or oxygen from carboxylic residues [7]. In addition, zinc could interact with Vimentin through electrostatic interactions, as it has been described for other divalent cations such as calcium or magnesium [3]. These possibilities are not mutually exclusive. The fact that the cys328 Vimentin mutant appears to be resistant to zinc-deficiency indicates that this residue plays a role in the effects of zinc through direct or indirect mechanisms. Besides the complex interactions between zinc binding and redox regulation of cysteine residues, zinc may affect overall cellular status by interacting with transcription factors or other zinc binding proteins. The pathophysiological implications of these findings are far-reaching. Besides the broad implications of Vimentin in disease, zinc deficiency is extremely frequent, due to various pathologies but, above all, to insufficient dietary intake. Symptoms of this condition may include dermatitis, impaired wound healing, diarrhea, and cognitive alterations. Our findings raise the possibility that defective Vimentin, or hypothetically, intermediate filament function, may underlie some of these alterations [4]. Therefore, we believe that they introduce a new perspective from which to revisit some concepts in this field.
Francisco J. Sánchez-gómez - One of the best experts on this subject based on the ideXlab platform.
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Vimentin gets a new glow from zinc.
Oncotarget, 2015Co-Authors: Dolores Pérez-sala, Clara L. Oeste, Francisco J. Sánchez-gómezAbstract:Intermediate filaments are important beams in cell architecture. Keratin filaments, neurofilaments, the constituents of the nuclear lamina and the Vimentin network are examples of these structures, which confer mechanical resistance to cells and at the same time are flexible and dynamic. Vimentin is an intermediate filament protein expressed in mesenchymal cells. Leading-edge research in the last decade has shown that besides its structural purpose, Vimentin plays other important roles in cell homeostasis, including promoting the correct position and function of organelles, the interaction with and regulation of signaling proteins, and a bidirectional cross-talk with other cytoskeletal structures [1, 2]. In addition, Vimentin plays a leading role in numerous pathophysiological processes including epithelial mesenchymal transition, infection, autoimmune disease, and wound healing. In spite of many years of excellent research in this field [1, 3], Vimentin still conceals some secrets. The structure of this coiled-coil protein has not been fully characterized and its mode of assembly in cells is incompletely understood. Although many stimuli have been identified that promote Vimentin disassembly, less is known about the induction of Vimentin filaments polymerization or elongation. Thus, in some aspects, Vimentin is still a mysterious protein, compared to the building blocks of other cytoskeletal structures such as tubulin in microtubules or actin in microfilaments. This 55 kDa protein possesses a single cysteine residue, cys328. In recent work we have shown that this residue is a remarkable sensor for oxidative stress [4]. Mutating this residue numbs the responsiveness of the Vimentin network to oxidants and electrophilic compounds, attenuating its remodeling and making it somehow “resistant” to these aggressions [4, 5]. However, this mutant does not keep up with Vimentin's demanding tasks in various cellular processes and shows limited performance in the expansion of the Vimentin network after cell plating, in achieving the appropriate distribution of cytoplasmic organelles such as lysosomes, and in forming aggresomes upon inhibition of proteasomal degradation or extensive oxidative damage. While studying the mechanisms underlying the requirement for cys328 for optimal Vimentin function, we found that Vimentin binds zinc [4]. We think that this is an unprecedented, exciting finding for this protein, which may turn the spot-light on some previously dim features in this field. Zinc is the transition metal most frequently found as a cofactor in proteins [6]. Zinc binding to proteins may serve regulatory or structural roles, either by promoting specific conformations, sustaining catalytic activity or stabilizing oligomeric associations. In vitro, Vimentin avidly binds zinc with high affinity, and submillimolar zinc reversibly promotes Vimentin polymerization inducing the formation of Vimentin bundles. Zinc binding to Vimentin is suprastoichiometric, which suggests that it involves multiple electrostatic interactions likely due to the polyelectrolyte nature of the protein [3]. In cells, zinc availability has a strong impact on Vimentin function. Zinc reversibly regulates the assembly of fluorescent GFP-Vimentin constructs in Vimentin-deficient cells. Moreover, whereas pharmacological zinc chelation alters the Vimentin network, genetic zinc deficiency is associated with increased Vimentin susceptibility to further zinc depletion or oxidative stress, together with a lower proportion of polymerized Vimentin and a thinner appearance of filaments, and these alterations are alleviated by zinc supplementation. Interestingly, cellular imaging with the fluorescent zinc probe, zinquin, lights-up portions of Vimentin bundles, indicating that zinc interacts with Vimentin in cells. Although the interaction of zinc with other cytoskeletal proteins has been reported, the affinity of Vimentin appears to be much higher based on the behavior of the purified proteins. If such an efficient binding takes place in cells, Vimentin could behave as a zinc reservoir, or as a zinc-sequestering agent. Moreover, the stimulating possibility exists that the interaction between zinc and Vimentin has reciprocal outcomes, that is, zinc may regulate Vimentin, but Vimentin could also play an important role in cellular zinc homeostasis. In light of our findings it would be tempting to speculate that Vimentin can fulfil this role through a direct interaction with zinc. Figure 1 Vimentin subunits associate to form filaments Although the precise structural features of the Vimentin-zinc interaction have not been elucidated, we may picture zinc atoms as staples that reversibly stabilize filaments at specific places. Zinc can be incorporated into proteins in Zn-clusters, often of tetrahedral geometry, in which a zinc atom is coordinated by four ligands, most frequently involving sulfur from cysteine, nitrogen from histidine and/or oxygen from carboxylic residues [7]. In addition, zinc could interact with Vimentin through electrostatic interactions, as it has been described for other divalent cations such as calcium or magnesium [3]. These possibilities are not mutually exclusive. The fact that the cys328 Vimentin mutant appears to be resistant to zinc-deficiency indicates that this residue plays a role in the effects of zinc through direct or indirect mechanisms. Besides the complex interactions between zinc binding and redox regulation of cysteine residues, zinc may affect overall cellular status by interacting with transcription factors or other zinc binding proteins. The pathophysiological implications of these findings are far-reaching. Besides the broad implications of Vimentin in disease, zinc deficiency is extremely frequent, due to various pathologies but, above all, to insufficient dietary intake. Symptoms of this condition may include dermatitis, impaired wound healing, diarrhea, and cognitive alterations. Our findings raise the possibility that defective Vimentin, or hypothetically, intermediate filament function, may underlie some of these alterations [4]. Therefore, we believe that they introduce a new perspective from which to revisit some concepts in this field.
Dale D. Tang - One of the best experts on this subject based on the ideXlab platform.
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Reorganization of the Vimentin Network in Smooth Muscle.
Journal of engineering and science in medical diagnostics and therapy, 2019Co-Authors: Dale D. Tang, Guoning Liao, Brennan D. GerlachAbstract:Vimentin intermediate filaments (IFs) link to desmosomes (intercellular junctions) on the membrane and dense bodies in the cytoplasm, which provides a structural base for intercellular and intracellular force transmission in smooth muscle. There is evidence to suggest that the Vimentin framework plays an important role in mediating smooth muscle mechanical properties such as tension and contractile responses. Contractile activation induces Vimentin phosphorylation at Ser-56 and Vimentin network reorientation, facilitating contractile force transmission among and within smooth muscle cells. p21-activated kinase 1 and polo-like kinase 1 catalyze Vimentin phosphorylation at Ser-56, whereas type 1 protein phosphatase dephosphorylates Vimentin at this residue. Vimentin filaments are also involved in other cell functions including migration and nuclear positioning. This review recapitulates our current knowledge how the Vimentin network modulates mechanical and biological properties of smooth muscle.
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Critical role of Vimentin phosphorylation at Ser-56 by p21-activated kinase in Vimentin cytoskeleton signaling.
The Journal of biological chemistry, 2006Co-Authors: Amy M. Spinelli, Ruping Wang, Yana Anfinogenova, Harold A. Singer, Dale D. TangAbstract:Phosphorylation and spatial reorganization of the Vimentin network have been implicated in mediating smooth muscle contraction, cell migration, and mitosis. In this study, stimulation of cultured smooth muscle cells with 5-hydroxytryptamine (5-HT) induced PAK1 phosphorylation at Thr-423 (an indication of p21-activated kinase (PAK) activation). Treatment with PAK led to disassembly of wild-type (but not mutant S56A) Vimentin filaments as assessed by an in vitro filament assembly assay. Furthermore, stimulation with 5-HT resulted in the dissociation of Crk-associated substrate (CAS; an adapter protein associated with smooth muscle force development) from cytoskeletal Vimentin. Expression of mutant S56A Vimentin in cells inhibited the increase in phosphorylation at Ser-56 and in the ratios of soluble to insoluble Vimentin (an index of Vimentin disassembly) and the dissociation of CAS from cytoskeletal Vimentin in response to 5-HT activation compared with cells expressing wild-type Vimentin. Because CAS may be involved in PAK activation, PAK phosphorylation was evaluated in cells expressing the S56A mutant. Expression of mutant S56A Vimentin depressed PAK phosphorylation at Thr-423 induced by 5-HT. Expression of the S56A mutant also inhibited the spatial reorientation of Vimentin filaments in cells in response to 5-HT stimulation. Our results suggest that Vimentin phosphorylation at Ser-56 may inversely regulate PAK activation possibly via the increase in the amount of soluble CAS upon agonist stimulation of smooth muscle cells. Additionally, Vimentin phosphorylation at this position is critical for Vimentin filament spatial rearrangement elicited by agonists.
