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  • 1
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    Online Resource
    Interaction of plakophilins with desmoplakin and intermediate filament proteins: an in vitro analysis
    The Company of Biologists ; 2000
    In:  Journal of Cell Science Vol. 113, No. 13 ( 2000-07-01), p. 2471-2483
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 113, No. 13 ( 2000-07-01), p. 2471-2483
    Abstract: Plakophilin 1 and 2 (PKP1, PKP2) are members of the arm-repeat protein family. They are both constitutively expressed in most vertebrate cells, in two splice forms named a and b, and display a remarkable dual location: they occur in the nuclei of cells and, in epithelial cells, at the plasma membrane within the desmosomal plaques. We have shown by solid phasebinding assays that both PKP1a and PKP2a bind to intermediate filament (IF) proteins, in particular to cytokeratins (CKs) from epidermal as well as simple epithelial cells and, to some extent, to vimentin. In line with this we show that recombinant PKP1a binds strongly to IFs assembled in vitro from CKs 8/18, 5/14, vimentin or desmin and integrates them into thick (up to 120 nm in diameter) IF bundles extending for several μm. The basic aminoterminal, non-arm-repeat domain of PKP1a is necessary and sufficient for this specific interaction as shown by blot overlay and centrifugation experiments. In particular, the binding of PKP1a to IF proteins is saturable at an approximately equimolar ratio. In extracts from HaCaT cells, distinct soluble complexes containing PKP1a and desmoplakin I (DPI) have been identified by coimmunoprecipitation and sucrose density fractionation. The significance of these interactions of PKP1a with IF proteins on the one hand and desmoplakin on the other is discussed in relation to the fact that PKP1a is not bound – and does not bind – to extended IFs in vivo. We postulate that (1) effective cellular regulatory mechanisms exist that prevent plakophilins from unscheduled IF-binding, and (2) specific desmoplakin interactions with either PKP1, PKP2 or PKP3, or combinations thereof, are involved in the selective recruitment of plakophilins to the desmosomal plaques.
    Type of Medium: Online Resource
    ISSN: 0021-9533 , 1477-9137
    URL: Article
    DOI: 10.1242/jcs.113.13.2471
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2000
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
    SSG: 12
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  • 2
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    Online Resource
    Expression of intermediate filament proteins during development of Xenopus laevis : I.cDNA clones encoding different forms of vimentin
    The Company of Biologists ; 1989
    In:  Development Vol. 105, No. 2 ( 1989-02-01), p. 279-298
    Details
    In: Development, The Company of Biologists, Vol. 105, No. 2 ( 1989-02-01), p. 279-298
    Abstract: To provide a basis for studies of the expression of genes encoding the diverse kinds of intermediate-filament (IF) proteins during embryogenesis of Xenopus laevis we have isolated and characterized IF protein cDNA clones. Here we report the identification of two types of Xenopus vimentin, Viml and Vim4, with their complete amino acid sequences as deduced from the cloned cDNAs, both of which are expressed during early embryogenesis. In addition, we have obtained two further vimentin cDNAs (Vim2 and 3) which are sequence variants of closely related Viml. The high evolutionary conservation of the amino acid sequences (Viml: 458 residues; Mr ∼ 52800; Vim4: 463 residues; Mr∼ 53500) to avian and mam malian vimentin and, to a lesser degree, to desmin from the same and higher vertebrate species, is emphasized, including conserved oligopeptide motifs in their head domains. Using these cDNAs in RNA blot and ribonu clease protection assays of various embryonic stages, we observed a dramatic increase of vimentin RNA at stage 14, in agreement with immunocytochemical results ob tained with antibody VIM-3B4. The significance of very weak mRNA signals detected in earlier stages is dis cussed in relation to negative immunocytochemical re sults obtained in these stages. The first appearance of vimentin has been localized to a distinct mesenchymal cell layer underlying the neural plate or tube, respect ively. The results are discussed in relation to programs of de novo synthesis of other cytoskeletal proteins in amphibian and mammalian development.
    Type of Medium: Online Resource
    ISSN: 0950-1991 , 1477-9129
    URL: Article
    DOI: 10.1242/dev.105.2.279
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 1989
    detail.hit.zdb_id: 2007916-3
    SSG: 12
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  • 3
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    Online Resource
    A dominant vimentin mutant upregulates Hsp70 and the activity of the ubiquitin-proteasome system, and causes posterior cataracts in transgenic mice
    The Company of Biologists ; 2008
    In:  Journal of Cell Science Vol. 121, No. 22 ( 2008-11-15), p. 3737-3746
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 121, No. 22 ( 2008-11-15), p. 3737-3746
    Abstract: Vimentin is the main intermediate filament (IF) protein of mesenchymal cells and tissues. Unlike other IF–/– mice, vimentin–/– mice provided no evidence of an involvement of vimentin in the development of a specific disease. Therefore, we generated two transgenic mouse lines, one with a (R113C) point mutation in the IF-consensus motif in coil1A and one with the complete deletion of coil 2B of the rod domain. In epidermal keratins and desmin, point mutations in these parts of the α-helical rod domain cause keratinopathies and desminopathies, respectively. Here, we demonstrate that substoichiometric amounts of vimentin carrying the R113C point mutation disrupted the endogenous vimentin network in all tissues examined but caused a disease phenotype only in the eye lens, leading to a posterior cataract that was paralleled by the formation of extensive protein aggregates in lens fibre cells. Unexpectedly, central, postmitotic fibres became depleted of aggregates, indicating that they were actively removed. In line with an increase in misfolded proteins, the amounts of Hsp70 and ubiquitylated vimentin were increased, and proteasome activity was raised. We demonstrate here for the first time that the expression of mutated vimentin induces a protein-stress response that contributes to disease pathology in mice, and hypothesise that vimentin mutations cause cataracts in humans.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.030312
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2008
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
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  • 4
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    Lamin aggregation is an early sensor of porphyria-induced liver injury
    The Company of Biologists ; 2013
    In:  Journal of Cell Science
    Details
    In: Journal of Cell Science, The Company of Biologists
    Abstract: Oxidative liver injury during steatohepatitis results in aggregation and transglutaminase-2 (TG2)-mediated crosslinking of the keratin cytoplasmic intermediate filament proteins (IFs) to form Mallory-Denk body (MDB) inclusions. The effect of liver injury on lamin nuclear IFs is unknown, though lamin mutations in several human diseases result in lamin disorganization and nuclear shape changes. We tested the hypothesis that lamins undergo aggregation during oxidative liver injury using two MDB mouse models: (i) feeding the porphyrinogenic drug 3, 5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) and, (ii) mice that harbor a mutation in ferrochelatase (fch), which converts protoporphyrin-IX to heme. Dramatic aggregation of lamin A/C and B1 was noted in the livers of both models in association with changes in lamin organization and nuclear shape as determined by immunostaining and electron microscopy. The lamin aggregates sequester other nuclear proteins including transcription factors and ribosomal and nuclear pore components into high molecular weight complexes, as determined by mass-spectrometry and confirmed biochemically. Lamin aggregate formation is rapid and precedes keratin aggregation in fch livers, and is seen in liver explants of patients with alcoholic cirrhosis. Exposure of cultured cells to DDC, protoporphyrin-IX or N-methyl-protoporphyrin, or incubating purified lamins with protoporphyrin-IX also results in lamin aggregation. In contrast, lamin aggregation is ameliorated by TG2 inhibition. Therefore, lamin aggregation is an early sensor of porphyria-associated liver injury and may serve to buffer oxidative stress. The nuclear shape and lamin defects associated with porphyria phenocopy the changes seen in laminopathies and could result in transcriptional alterations due to sequestration of nuclear proteins.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.123026
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2013
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
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  • 5
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    Deleterious assembly of mutant p.S143P lamin A/C causes ER stress in familial dilated cardiomyopathy
    The Company of Biologists ; 2016
    In:  Journal of Cell Science
    Details
    In: Journal of Cell Science, The Company of Biologists
    Abstract: Mutation of the LMNA gene, encoding nuclear lamin A/C, is a common cause of familial dilated cardiomyopathy (DCM). Among Finnish DCM patients, the founder mutation c.427T & gt;C (p.S143P) is the most frequently reported genetic variant. Here we show that p.S143P lamin A/C is more nucleoplasmic and soluble than wild type lamin A/C and accumulates into large intranuclear aggregates in a fraction of cultured patient fibroblasts as well as in cells ectopically expressing either FLAG- or GFP-tagged p.S143P lamin A. In fluorescence loss in photobleaching (FLIP) experiments, non-aggregated EGFP-tagged p.S143P lamin A is significantly more dynamic. In in vitro association studies p.S143P lamin A failed to form appropriate filament structures but instead assembled into disorganized aggregates similar to those observed in patient cell nuclei. A whole genome expression analysis revealed an elevated unfolded protein response (UPR) in p.S143P lamin A/C expressing cells. Additional endoplasmic reticulum (ER) stress induced by tunicamycin reduced the viability of mutant lamin expressing cells further. In summary, p.S143P lamin A/C affects normal lamina structure and influences the cellular stress response, homeostasis and viability.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.184150
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2016
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
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  • 6
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    The dynamic properties of intermediate filaments during organelle transport
    The Company of Biologists ; 2009
    In:  Journal of Cell Science Vol. 122, No. 16 ( 2009-08-15), p. 2914-2923
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 122, No. 16 ( 2009-08-15), p. 2914-2923
    Abstract: Intermediate filament (IF) dynamics during organelle transport and their role in organelle movement were studied using Xenopus laevis melanophores. In these cells, pigment granules (melanosomes) move along microtubules and microfilaments, toward and away from the cell periphery in response to α-melanocyte stimulating hormone (α-MSH) and melatonin, respectively. In this study we show that melanophores possess a complex network of vimentin IFs which interact with melanosomes. IFs form an intricate, honeycomb-like network that form cages surrounding individual and small clusters of melanosomes, both when they are aggregated and dispersed. Purified melanosome preparations contain a substantial amount of vimentin, suggesting that melanosomes bind to IFs. Analyses of individual melanosome movements in cells with disrupted IF networks show increased movement of granules in both anterograde and retrograde directions, further supporting the notion of a melanosome-IF interaction. Live imaging reveals that IFs, in turn, become highly flexible as melanosomes disperse in response to α-MSH. During the height of dispersion there is a marked increase in the rate of fluorescence recovery after photobleaching of GFP-vimentin IFs and an increase in vimentin solubility. These results reveal a dynamic interaction between membrane bound pigment granules and IFs and suggest a role for IFs as modulators of granule movement.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.046789
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2009
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
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  • 7
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    Online Resource
    Expression of intermediate filament proteins during development of Xenopus laevis: II. Identification and molecular characterization of desmin
    The Company of Biologists ; 1989
    In:  Development Vol. 105, No. 2 ( 1989-02-01), p. 299-307
    Details
    In: Development, The Company of Biologists, Vol. 105, No. 2 ( 1989-02-01), p. 299-307
    Abstract: During embryogenesis of avian and mammalian species the formation of intermediate filaments (IFs) containing desmin is characteristic for myogenesis. In view of important differences of patterns of IF protein expression in embryogenic pathways of amphibia on the one hand and birds and mammals on the other, we have decided to study the expression of desmin during early embryogenesis of Xenopus laevis by cDNA hybridization and antibody reactions. Here we describe the isolation of a cDNA clone encoding Xenopus desmin and the deduced amino acid sequence (458 residues; Mr52800) which displays a very high degree of conservation during vertebrate evolution from Xenopus to chicken and hamster, with a similar degree of sequence divergence between all three species compared. In addition, we have noted, by both cDNA-hybrid-selection-translation and immunoblotting of cytoskeletal proteins a second desmin-related polypeptide of Mr∼49000. RNA (Northern) blot analyses show the occurrence of three different desmin mRNAs (1 · 9, 2 · 6 and 3 · 0kb) which seem to represent different polyadenylation sites, displaying quantitative differences in different kinds of muscle tissues. During embryogenesis, desmin mRNA has first been detected in stage-14 embryos and then increases drastically to high levels at stage 18 and thereafter. Immunofluorescence microscopy using desmin-specific antibodies shows that this synthesis of desmin is restricted to somite tissue. The embryonic time course of synthesis of desmin and desmin mRNA is discussed in relation to those of other muscle proteins.
    Type of Medium: Online Resource
    ISSN: 0950-1991 , 1477-9129
    URL: Article
    DOI: 10.1242/dev.105.2.299
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 1989
    detail.hit.zdb_id: 2007916-3
    SSG: 12
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  • 8
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    Online Resource
    Monoclonal antibody to a 43 000 M r surface protein of a human leukaemia cell line (thp-1) crossreacts with the fibroblast intermediate filament protein vimentin
    The Company of Biologists ; 1985
    In:  Journal of Cell Science Vol. 73, No. 1 ( 1985-02-01), p. 87-103
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 73, No. 1 ( 1985-02-01), p. 87-103
    Abstract: Monoclonal antibodies were produced against surface antigens of live cells from a human acute monocytic leukaemia cell line (THP-1). One clone, VIC-C2, when assayed by immunofluor-sscence microscopy, brightly stained the surface of THP-1 cells and the cytoplasm of Langerhans cells, fibroblasts and melanocytes in sections of human skin. The immunoreactive cytoplasmic structures were filamentous and resembled intermediate filaments. By double immunofluorescence microscopy using VIC-C2 and polyclonal antibodies to vimentin, the VIC-C2 antigen was shown to be located on intermediate filaments of cultured fibroblasts and to follow these filaments during various drug-induced rearrangements. As demonstrated by immunoprecipitation, antibody gel overlay and immunoblotting of two-dimensional polyacrylamide gels, VIC-C2 recognized two different antigens in extracts of THP-1 cells: one of Mr = 43000 and pl = 7, the other of Mr = 57000. In extracts from various cultured fibroblast cells only the 57 000Mr antigen was detected. This 57000AL protein was identified as vimentin by immunoblotting of rat glioma C6 cytoskeletons on two-dimensional gels. When vimentin was digested with chymotrypsin, only fragments containing parts of both helical rod pieces and the connecting non-helical spacer-region were strongly antigenic, whereas the helical rods alone were only weakly crossreactive. Moreover, immunoprecipitation revealed that VIC-C2 preferentially reacted with native compared to denatured vimentin.
    Type of Medium: Online Resource
    ISSN: 0021-9533 , 1477-9137
    URL: Article
    DOI: 10.1242/jcs.73.1.87
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 1985
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
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  • 9
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    Altering lamina assembly identifies lamina-dependent and -independent functions for A-type lamins
    The Company of Biologists ; 2015
    In:  Journal of Cell Science
    Details
    In: Journal of Cell Science, The Company of Biologists
    Abstract: Lamins are intermediate filament proteins forming a fibrous meshwork, called nuclear lamina, between the inner nuclear membrane and peripheral heterochromatin of metazoan cells. The assembly and incorporation of lamin A/C into the lamina as well as their various functions are still not well understood. Here, we employed designed ankyrin repeat proteins (DARPins) as novel experimental tools for lamin research. We screened for DARPins that specifically bind lamin A/C, interfere with lamin assembly in vitro, and with incorporation of lamin A/C into the native lamina in living cells. Selected DARPins inhibit lamin assembly and delocalize A-type lamins to the nucleoplasm without modifying lamin expression levels or amino acid sequence. Using these lamin binders we demonstrate the importance of proper integration of lamin A/C into the lamina for nuclear mechanical properties and nuclear envelope integrity. Finally, our study provides evidence for cell-type specific differences in lamin functions.
    Type of Medium: Online Resource
    ISSN: 1477-9137 , 0021-9533
    URL: Article
    DOI: 10.1242/jcs.171843
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2015
    detail.hit.zdb_id: 219171-4
    detail.hit.zdb_id: 1483099-1
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  • 10
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    Online Resource
    Vimentin in a cold-water fish, the rainbow trout: highly conserved primary structure but unique assembly properties
    The Company of Biologists ; 1996
    In:  Journal of Cell Science Vol. 109, No. 3 ( 1996-03-01), p. 569-578
    Details
    In: Journal of Cell Science, The Company of Biologists, Vol. 109, No. 3 ( 1996-03-01), p. 569-578
    Abstract: We have isolated from a rainbow trout (Oncorhynchus mykiss) spleen cDNA library a clone coding for vimentin. The deduced amino acid sequence reveals a high degree of identity with vimentin from carp (81%), frog (71%), chick and human (73% each). Large stretches in the central αhelical rod are identical within all four classes of vertebrates, but in 17 residues spread over the entire rod, the two fish differ distinctly from the tetrapod species. In addition, in the more diverged non-helical head domain, a nonapeptide motif previously shown to be important for regular filament formation is conserved. Recombinant trout vimentin assembles into bona fide filaments in vitro, with a temperature optimum between 18 and 24°C. Above 27°C, however, filament assembly is abruptly abolished and short filaments with thickened ends as well as structures without typical intermediate filament appearance are formed. This distinguishes its assembly properties significantly from amphibian, avian and mammalian vimentin. Also in vivo, after cDNA transfection into vimentin-free mammalian epithelial cells, trout vimentin does not form typical intermediate filament arrays at 37°C. At 28°C, and even more pronounced at 22°C, the vimentin-positive material in the transfected cells is reorganized in the perinuclear region with a partial fibrillar appearance, but typical intermediate filament arrays are not formed. Together with immunoblotting and immunolocalization data from trout tissues, where vimentin is predominantly found in glial and white blood cells, we conclude that vimentin is indeed important in its filamentous form in fish and other vertebrates, possibly fulfilling cellular functions not directly evident in gene targeting experiments carried out in mice.
    Type of Medium: Online Resource
    ISSN: 0021-9533 , 1477-9137
    URL: Article
    DOI: 10.1242/jcs.109.3.569
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 1996
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