Type III intermediate filaments in redox interplay: key role of the conserved cysteine residue.

Intermediate filaments (IFs) are cytoskeletal elements involved in mechanotransduction and in the integration of cellular responses. They are versatile structures and their assembly and organization are finely tuned by posttranslational modifications. Among them, type III IFs, mainly vimentin, have been identified as targets of multiple oxidative and electrophilic modifications. A characteristic of most type III IF proteins is the presence in their sequence of a single, conserved cysteine residue (C328 in vimentin), that is a hot spot for these modifications and appears to play a key role in the ability of the filament network to respond to oxidative stress. Current structural models and experimental evidence indicate that this cysteine residue may occupy a strategic position in the filaments in such a way that perturbations at this site, due to chemical modification or mutation, impact filament assembly or organization in a structure-dependent manner. Cysteine-dependent regulation of vimentin can be modulated by interaction with divalent cations, such as zinc, and by pH. Importantly, vimentin remodeling induced by C328 modification may affect its interaction with cellular organelles, as well as the cross-talk between cytoskeletal networks, as seems to be the case for the reorganization of actin filaments in response to oxidants and electrophiles. In summary, the evidence herein reviewed delineates a complex interplay in which type III IFs emerge both as targets and modulators of redox signaling.

The CD4+ T cell repertoire specific for citrullinated peptides shows evidence of immune tolerance.

Rheumatoid arthritis occurs most often in people who express HLA-DR molecules containing a five aa "shared epitope" in the ß chain. These MHCII molecules preferentially bind citrullinated peptides formed by posttranslational modification of arginine. Citrullinated peptide:HLA-DR complexes may act as arthritis-initiating neo-antigens for CD4+ T cells. Here, we used fluorophore-conjugated HLA-DR tetramers containing citrullinated peptides from human cartilage intermediate layer protein, fibrinogen, vimentin, or enolase 1 to track cognate CD4+ T cells. Immunization of HLA-DR transgenic mice with citrullinated peptides from vimentin or enolase 1 failed to cause any expansion of tetramer-binding cells, whereas immunization with citrullinated peptides from cartilage intermediate layer protein or fibrinogen elicited some expansion. The expanded tetramer-binding populations, however, had lower T helper 1 and higher regulatory T cell frequencies than populations elicited by viral peptides. These results indicate that HLA-DR-bound citrullinated peptides are not neo-antigens and induce varying degrees of immune tolerance that could pose a barrier to rheumatoid arthritis.

Vimentin single cysteine residue acts as a tunable sensor for network organization and as a key for actin remodeling in response to oxidants and electrophiles.

Cysteine residues can undergo multiple posttranslational modifications with diverse functional consequences, potentially behaving as tunable sensors. The intermediate filament protein vimentin has important implications in pathophysiology, including cancer progression, infection, and fibrosis, and maintains a close interplay with other cytoskeletal structures, such as actin filaments and microtubules. We previously showed that the single vimentin cysteine, C328, is a key target for oxidants and electrophiles. Here, we demonstrate that structurally diverse cysteine-reactive agents, including electrophilic mediators, oxidants and drug-related compounds, disrupt the vimentin network eliciting morphologically distinct reorganizations. As most of these agents display broad reactivity, we pinpointed the importance of C328 by confirming that local perturbations introduced through mutagenesis provoke structure-dependent vimentin rearrangements. Thus, GFP-vimentin wild type (wt) forms squiggles and short filaments in vimentin-deficient cells, the C328F, C328W, and C328H mutants generate diverse filamentous assemblies, and the C328A and C328D constructs fail to elongate yielding dots. Remarkably, vimentin C328H structures resemble the wt, but are strongly resistant to electrophile-elicited disruption. Therefore, the C328H mutant allows elucidating whether cysteine-dependent vimentin reorganization influences other cellular responses to reactive agents. Electrophiles such as 1,4-dinitro-1H-imidazole and 4-hydroxynonenal induce robust actin stress fibers in cells expressing vimentin wt. Strikingly, under these conditions, vimentin C328H expression blunts electrophile-elicited stress fiber formation, apparently acting upstream of RhoA. Analysis of additional vimentin C328 mutants shows that electrophile-sensitive and assembly-defective vimentin variants permit induction of stress fibers by reactive species, whereas electrophile-resistant filamentous vimentin structures prevent it. Together, our results suggest that vimentin acts as a break for actin stress fibers formation, which would be released by C328-aided disruption, thus allowing full actin remodeling in response to oxidants and electrophiles. These observations postulate C328 as a "sensor" transducing structurally diverse modifications into fine-tuned vimentin network rearrangements, and a gatekeeper for certain electrophiles in the interplay with actin.

Exogenous Vimentin Supplementation Transiently Affects Early Steps during HPV16 Pseudovirus Infection.

Understanding and modulating the early steps in oncogenic Human Papillomavirus (HPV) infection has great cancer-preventative potential, as this virus is the etiological agent of virtually all cervical cancer cases and is associated with many other anogenital and oropharyngeal cancers. Previous work from our laboratory has identified cell-surface-expressed vimentin as a novel HPV16 pseudovirus (HPV16-PsVs)-binding molecule modulating its infectious potential. To further explore its mode of inhibiting HPV16-PsVs internalisation, we supplemented it with exogenous recombinant human vimentin and show that only the globular form of the molecule (as opposed to the filamentous form) inhibited HPV16-PsVs internalisation in vitro. Further, this inhibitory effect was only transient and not sustained over prolonged incubation times, as demonstrated in vitro and in vivo, possibly due to full-entry molecule engagement by the virions once saturation levels have been reached. The vimentin-mediated delay of HPV16-PsVs internalisation could be narrowed down to affecting multiple steps during the virus' interaction with the host cell and was found to affect both heparan sulphate proteoglycan (HSPG) binding as well as the subsequent entry receptor complex engagement. Interestingly, decreased pseudovirus internalisation (but not infection) in the presence of vimentin was also demonstrated for oncogenic HPV types 18, 31 and 45. Together, these data demonstrate the potential of vimentin as a modulator of HPV infection which can be used as a tool to study early mechanisms in infectious internalisation. However, further refinement is needed with regard to vimentin's stabilisation and formulation before its development as an alternative prophylactic means.

Selection and Characterization of Vimentin-Binding Aptamer Motifs for Ovarian Cancer.

The application of aptamers in biomedicine is emerging as an essential technology in the field of cancer research. As small single-stranded DNA or RNA ligands with high specificity and low immunogenicity for their targets, aptamers provide many advantages in cancer therapeutics over protein-based molecules, such as antibodies. Vimentin is an intermediate filament protein that is overexpressed in endothelial cells of cancerous tissue. High expression levels of vimentin have been associated with increased capacity for migration and invasion of the tumor cells. We have selected and identified thioated aptamers with high specificity for vimentin using human ovarian cancer tissues. Tentative binding motifs were chosen for two vimentin aptamers based on predicted secondary structures. Each of these shorter, tentative binding motifs was synthesized, purified, and characterized via cell binding assays. Two vimentin binding motifs with high fidelity binding were selected and further characterized via cell and tissue binding assays, as well as flow cytometric analysis. The equilibrium binding constants of these small thioated aptamer constructs were also determined. Future applications for the vimentin binding aptamer motifs include conjugation of the aptamers to synthetic dyes for use in targeted imaging and therapy, and ultimately more detailed and precise monitoring of treatment response and tumor progression in ovarian pathology.

Identification of the Molecular Basis of Nanocurcumin-Induced Telocyte Preservation within the Colon of Ulcerative Colitis Rat Model.

BACKGROUND: Telocytes (TCs) are a distinct type of interstitial cells that play a vital role in the pathogenesis of ulcerative colitis and colonic tissue hemostasis. The aim of this study was to examine the effect of nanocurcumin (NC) on the morphometric and immunohistochemical characterization of TCs in the ulcerative colitis (UC) rat model. METHODS: Forty rats were randomly divided into control, NC, UC, and UC+NC groups. At the end of the experiment, the colon was dissected and prepared for histopathological and immunohistochemical assessment. Tissue homogenates were prepared for real-time PCR assessment of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and transforming growth factor-beta (TGF-ß) gene expression. Our results revealed extensive mucosal damage with inflammatory cell infiltration, significant reduction of CD34, and vimentin immunostained TCs in the colon of the UC group with significant elevation of expression of IL-6, TNF-α, and TGF-ß. The UC+NC-treated group revealed significant elevation of TC count compared to the UC group besides, a significant reduction of the three gene expression. CONCLUSION: NC successfully targeted the colonic tissue, improved the mucosal lesion, preserve TCs distribution, and count through its anti-inflammatory and fibrinolytic properties.

Clinical verification of vimentin/EpCAM immunolipid magnetic sorting system in monitoring CTCs in arterial and venous blood of advanced tumor.

BACKGROUND: Circulating tumor cells (CTCs) are the dominant factor leading to tumor metastasis. This study aims to investigate the effect of disparate sources of CTCs on the treatment and prognosis of patients with advanced tumors by analyzing the number and gene mutations change of CTCs in arterial and venous blood in patients with advanced tumors. RESULTS: A CTCs sorting system was constructed based on Vimentin-immunolipid magnetic balls (Vi-IMB) and EpCAM immunolipid magnetic balls (Ep-IMB). Results showed that the prepared Ep-IMB and Vi-IMB had lower cytotoxicity, better specificity and sensitivity. The number of arterial CTCs was higher than that of venous CTCs, with a statistically significant difference (P < 0.05). Moreover, the prognosis of the low positive group of total CTCs in arterial blood and venous blood was higher than that of the high positive group, with a statistical significance (P < 0.05). The genetic testing results showed that the targeted drug gene mutations in tissues, arterial CTCs and venous CTCs showed a complementary trend, indicating that there was heterogeneity among different tumor samples. CONCLUSIONS: CTCs in blood can be efficiently captured by the CTCs sorting system based on Vi-LMB/Ep-LMB, and CTCs detection in arterial blood can be utilized to more accurately evaluate the prognosis and predict postoperative progress. It is further confirmed that tumor samples from disparate sources are heterogeneous, providing a reference basis for gene mutation detection before clinical targeted drug treatment, and the detection of CTCs in arterial blood has more potential clinical application value. TRIAL REGISTRATION: The Ethics Committee of Putuo Hospital, PTEC-A-2019-18-1. Registered 24 September 2019.

New GFAP splice isoform (GFAPµ) differentially expressed in glioma translates into 21 kDa N-terminal GFAP protein.

The glial fibrillary acidic protein (GFAP) is a type III intermediate filament (IF) protein that is highly expressed in astrocytes, neural stem cells, and in gliomas. Gliomas are a heterogeneous group of primary brain tumors that arise from glia cells or neural stem cells and rely on accurate diagnosis for prognosis and treatment strategies. GFAP is differentially expressed between glioma subtypes and, therefore, often used as a diagnostic marker. However, GFAP is highly regulated by the process of alternative splicing; many different isoforms have been identified. Differential expression of GFAP isoforms between glioma subtypes suggests that GFAP isoform-specific analyses could benefit diagnostics. In this study we report on the differential expression of a new GFAP isoform between glioma subtypes, GFAPµ. A short GFAP transcript resulting from GFAP exon 2 skipping was detected by RNA sequencing of human glioma. We show that GFAPµ mRNA is expressed in healthy brain tissue, glioma cell lines, and primary glioma cells and that it translates into a ~21 kDa GFAP protein. 21 kDa GFAP protein was detected in the IF protein fraction isolated from human spinal cord as well. We further show that induced GFAPµ expression disrupts the GFAP IF network. The characterization of this new GFAP isoform adds on to the numerous previously identified GFAP splice isoforms. It emphasizes the importance of studying the contribution of IF splice variants to specialized functions of the IF network and to glioma research.

Mechanical and Non-Mechanical Functions of Filamentous and Non-Filamentous Vimentin.

Intermediate filaments (IFs) formed by vimentin are less understood than their cytoskeletal partners, microtubules and F-actin, but the unique physical properties of IFs, especially their resistance to large deformations, initially suggest a mechanical function. Indeed, vimentin IFs help regulate cell mechanics and contractility, and in crowded 3D environments they protect the nucleus during cell migration. Recently, a multitude of studies, often using genetic or proteomic screenings show that vimentin has many non-mechanical functions within and outside of cells. These include signaling roles in wound healing, lipogenesis, sterol processing, and various functions related to extracellular and cell surface vimentin. Extracellular vimentin is implicated in marking circulating tumor cells, promoting neural repair, and mediating the invasion of host cells by viruses, including SARS-CoV, or bacteria such as Listeria and Streptococcus. These findings underscore the fundamental role of vimentin in not only cell mechanics but also a range of physiological functions. Also see the video abstract here https://youtu.be/YPfoddqvz-g.

Vimentin S-glutathionylation at Cys328 inhibits filament elongation and induces severing of mature filaments in vitro.

Vimentin intermediate filaments are a significant component of the cytoskeleton in cells of mesenchymal origin. In vivo, filaments assemble and disassemble and thus participate in the dynamic processes of the cell. Post-translational modifications (PTMs) such as protein phosphorylation regulate the multiphasic association of vimentin from soluble complexes to insoluble filaments and the reverse processes. The thiol side chain of the single vimentin cysteine at position 328 (Cys328) is a direct target of oxidative modifications inside cells. Here, we used atomic force microscopy, electron microscopy and a novel hydrogen-deuterium exchange mass spectrometry (HDex-MS) procedure to investigate the structural consequences of S-nitrosylation and S-glutathionylation of Cys328 for in vitro oligomerisation of human vimentin. Neither modification affects the lateral association of tetramers to unit-length filaments (ULF). However, S-glutathionylation of Cys328 blocks the longitudinal assembly of ULF into extended filaments. S-nitrosylation of Cys328 does not hinder but slows down the elongation. Likewise, S-glutathionylation of preformed vimentin filaments causes their extensive fragmentation to smaller oligomeric species. Chemical reduction of the S-glutathionylated Cys328 thiols induces reassembly of the small fragments into extended filaments. In conclusion, our in vitro results suggest S-glutathionylation as a candidate PTM for an efficient molecular switch in the dynamic rearrangements of vimentin intermediate filaments, observed in vivo, in response to changes in cellular redox status. Finally, we demonstrate that HDex-MS is a powerful method for probing the kinetics of vimentin filament formation and filament disassembly induced by PTMs.

Selection of Aptamers Against Vimentin for Isolation and Release of Circulating Tumor Cells Undergoing Epithelial Mesenchymal Transition.

Circulating tumor cells (CTCs) undergoing epithelial mesenchymal transition (EMT) play an essential role in metastasis and have a better correlation with poor disease outcomes, but the most current affinity-based enrichment methods rely on targeting epithelial markers, which are less effective in capturing CTCs undergoing EMT. Herein, we identified and optimized an aptamer (ZY5C) sequence with high binding affinity and specificity against cell surface vimentin (CSV), which is overexpressed on the post-EMT CTCs. Not only can the hairpin-structured ZY5C aptamer specifically recognize a number of cancer cells with native CSV expression, but it can also bind to CSV expressed on EMT-cells. The Kd value of the ZY5C aptamer against CSV-positive T24 cells was found to be 38 ± 4 nM. Using the evolved ZY5C aptamer and multivalent ZY5C aptamer-functionalized chip, we were able to isolate CTCs from the blood of adenocarcinoma, sarcoma, and carcinosarcoma patients. Overall, this ZY5C aptamer and isolation method bring a fresh approach to CTCs analysis, which not only detects CTCs from nonepithelial origin, but also provides an efficient way to in-depth study the role of post-EMT CTCs in clinical application and metastasis mechanisms.

The Structural Function of Nestin in Cell Body Softening is Correlated with Cancer Cell Metastasis.

Intermediate filaments play significant roles in governing cell stiffness and invasive ability. Nestin is a type VI intermediate filament protein that is highly expressed in several high-metastatic cancer cells. Although inhibition of nestin expression was shown to reduce the metastatic capacity of tumor cells, the relationship between this protein and the mechanism of cancer cell metastasis remains unclear. Here, we show that nestin softens the cell body of the highly metastatic mouse breast cancer cell line FP10SC2, thereby enhancing the metastasis capacity. Proximity ligation assay demonstrated increased binding between actin and vimentin in nestin knockout cells. Because nestin copolymerizes with vimentin and nestin has an extremely long tail domain in its C-terminal region, we hypothesized that the tail domain functions as a steric inhibitor of the vimentin-actin interaction and suppresses association of vimentin filaments with the cortical actin cytoskeleton, leading to reduced cell stiffness. To demonstrate this function, we mechanically pulled vimentin filaments in living cells using a nanoneedle modified with vimentin-specific antibodies under manipulation by atomic force microscopy (AFM). The tensile test revealed that mobility of vimentin filaments was increased by nestin expression in FP10SC2 cells.

Vimentin disruption by lipoxidation and electrophiles: Role of the cysteine residue and filament dynamics.

The intermediate filament protein vimentin constitutes a critical sensor for electrophilic and oxidative stress, which induce extensive reorganization of the vimentin cytoskeletal network. Here, we have investigated the mechanisms underlying these effects. In vitro, electrophilic lipids, including 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and 4-hydroxynonenal (HNE), directly bind to vimentin, whereas the oxidant diamide induces disulfide bond formation. Mutation of the single vimentin cysteine residue (Cys328) blunts disulfide formation and reduces lipoxidation by 15d-PGJ2, but not HNE. Preincubation with these agents differentially hinders NaCl-induced filament formation by wild-type vimentin, with effects ranging from delayed elongation and increased filament diameter to severe impairment of assembly or aggregation. Conversely, the morphology of vimentin Cys328Ser filaments is mildly or not affected. Interestingly, preformed vimentin filaments are more resistant to electrophile-induced disruption, although chemical modification is not diminished, showing that vimentin (lip)oxidation prior to assembly is more deleterious. In cells, electrophiles, particularly diamide, induce a fast and drastic disruption of existing filaments, which requires the presence of Cys328. As the cellular vimentin network is under continuous remodeling, we hypothesized that vimentin exchange on filaments would be necessary for diamide-induced disruption. We confirmed that strategies reducing vimentin dynamics, as monitored by FRAP, including cysteine crosslinking and ATP synthesis inhibition, prevent diamide effect. In turn, phosphorylation may promote vimentin disassembly. Indeed, treatment with the phosphatase inhibitor calyculin A to prevent dephosphorylation intensifies electrophile-induced wild-type vimentin filament disruption. However, whereas a phosphorylation-deficient vimentin mutant is only partially protected from disorganization, Cys328Ser vimentin is virtually resistant, even in the presence of calyculin A. Together, these results indicate that modification of Cys328 and vimentin exchange are critical for electrophile-induced network disruption.

Long Non-Coding MALAT1 Functions as a Competing Endogenous RNA to Regulate Vimentin Expression by Sponging miR-30a-5p in Hepatocellular Carcinoma.

BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) has a high morbidity as well as mortality and is believed to be one of the most prevalent cancers worldwide. The long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is involved in numerous cancers, including HCC. This study aimed to explore the role of MALAT1 in HCC progression. METHODS: The expression levels of MALAT1 and Vimentin in HCC tissues and relative pair-matched adjacent normal liver tissues were analyzed by RT-PCR, and immunohistochemistry. Using bioinformatics analysis and dual-luciferase assay, we examined the correlation between MALAT1 and miR-30a-5p. Dual-luciferase assay and western blotting suggested that Vimentin was a target of miR-30a-5p. A wound healing assay and transwell assays were employed to determine the effect of MALAT1 and miR-30a-5p on cell migration and invasion in HCC. RESULTS: Our data demonstrated that the levels of MALAT1 and Vimentin were upregulated in HCC tissues and that miR-30a-5p was a direct target of MALAT1. Silenced MALAT1 and overexpressed miR-30a-5p each inhibited cell migration and invasion. Additionally, dual-luciferase assay and western blotting demonstrated that MALAT1 could competitively sponge miR-30a-5p and thereby regulate Vimentin. CONCLUSION: Our data suggest that MALAT1 acts as an oncogenic lncRNA that promotes HCC migration and invasion. Therefore, the MALAT1-miR-30a-5p-Vimentin axis is a potential therapeutic target and molecular biomarker in HCC.

A vimentin binding small molecule leads to mitotic disruption in mesenchymal cancers.

Expression of the transcription factor FOXC2 is induced and necessary for successful epithelial-mesenchymal transition, a developmental program that when activated in cancer endows cells with metastatic potential and the properties of stem cells. As such, identifying agents that inhibit the growth of FOXC2-transformed cells represents an attractive approach to inhibit chemotherapy resistance and metastatic dissemination. From a high throughput synthetic lethal screen, we identified a small molecule, FiVe1, which selectively and irreversibly inhibits the growth of mesenchymally transformed breast cancer cells and soft tissue sarcomas of diverse histological subtypes. FiVe1 targets the intermediate filament and mesenchymal marker vimentin (VIM) in a mode which promotes VIM disorganization and phosphorylation during metaphase, ultimately leading to mitotic catastrophe, multinucleation, and the loss of stemness. These findings illustrate a previously undescribed mechanism for interrupting faithful mitotic progression and may ultimately inform the design of therapies for a broad range of mesenchymal cancers.

Precise epitope determination of the anti-vimentin monoclonal antibody V9.

Vimentin is a type III intermediate filament protein that is typically expressed in mesenchymal cells. Overexpression of vimentin is frequently observed in several types of cancer and is often associated with epithelial­to­mesenchymal transition. It was recently reported that the serum vimentin level is significantly elevated in colon and liver tumors. Therefore, a more sensitive vimentin detection system may be useful for cancer screening and early detection. The V9 mouse monoclonal antibody (mAb), which recognizes the human vimentin protein, is widely used in routine pathology to identify mesenchymal cells using immunohistochemical analysis. Although it has been suggested that the epitope of the V9 mAb is located within the C­terminal region of vimentin, the precise amino acid sequence that it recognizes has not yet been identified. In the present study, we constructed several deletion mutants of the vimentin protein and examined their reactivity with the V9 mAb to accurately map its epitope. We confirmed that its epitope resides in the C­terminal region of vimentin, between amino acids 392­466. Additionally, cross­species comparison of amino acid sequence alignment of vimentin, as well as site­directed mutagenesis, revealed that one residue, the asparagine at position 417, is critical for antibody binding. Using smaller vimentin fragments ranging in length from 9 to 13 residues, each containing this critical asparagine, we determined that the minimal residues required for V9 mAb recognition of human vimentin are the thirteen amino acid residues at positions 411-423 (411ISLPLPNFSSLNL423).

Superficial vimentin mediates DENV-2 infection of vascular endothelial cells.

Damage to vascular endothelial cells (VECs) is a critical hallmark of hemorrhagic diseases caused by dengue virus (DENV). However, the precise molecular event involved in DENV binding and infection of VECs has yet to be clarified. In this study, vimentin (55 kDa) was identified to be involved in DENV-2 adsorption into VECs. This protein is located on the surface of VECs and interacts with DENV-2 envelope protein domain III (EDIII). The expression level of the superficial vimentin on VECs was not affected by viral infection or siRNA interference, indicating that the protein exists in a particular mode. Furthermore, the rod domain of the vimentin protein mainly functions in DENV-2 adsorption into VECs. Molecular docking results predicted several residues in vimentin rod and DENV EDIII; these residues may be responsible for cell-virus interactions. We propose that the superficial vimentin could be a novel molecule involved in DENV binding and infection of VECs. DENV EDIII directly interacts with the rod domain of vimentin on the VEC surface and thus mediates the infection.

Epithelial cell migration requires the interaction between the vimentin and keratin intermediate filaments.

Epithelial migration plays a central role in development, wound repair and tumor metastasis, but the role of intermediate filament in this important event is unknown. We showed recently that vimentin coexists in the same cell with keratin-KRT14 at the leading edge of the migrating epidermal cells, and knockdown of vimentin impaired colony growth. Here we demonstrate that vimentin co-localizes and co-immunoprecipitates with keratin-KRT14, and mutations in the -YRKLLEGEE- sequence of vimentin significantly reduced migration of the keratinocytes. Our data demonstrates that keratinocyte migration requires the interaction between vimentin and keratins at the -YRKLLEGEE- sequence at the helical 2B domain of vimentin. These findings have broad implications for understanding the roles of vimentin intermediate filaments in normal and neoplastic epithelial cells.

Par-4 secretion: stoichiometry of 3-arylquinoline binding to vimentin.

Advanced prostate tumors usually metastasize to the lung, bone, and other vital tissues and are resistant to conventional therapy. Prostate apoptosis response-4 protein (Par-4) is a tumor suppressor that causes apoptosis in therapy-resistant prostate cancer cells by binding specifically to a receptor, Glucose-regulated protein-78 (GRP78), found only on the surface of cancer cells. 3-Arylquinolines or "arylquins" induce normal cells to release Par-4 from the intermediate filament protein, vimentin and promote Par-4 secretion that targets cancer cells in a paracrine manner. A structure-activity study identified arylquins that promote Par-4 secretion, and an evaluation of arylquin binding to the hERG potassium ion channel using a [(3)H]-dofetilide binding assay permitted the identification of structural features that separated this undesired activity from the desired Par-4 secretory activity. A binding study that relied on the natural fluorescence of arylquins and that used the purified rod domain of vimentin (residues 99-411) suggested that the mechanism behind Par-4 release involved arylquin binding to multiple sites in the rod domain.

Malignant peripheral nerve sheath tumour in a sow.

Nodular lung lesions in swine are frequently due to abscesses or granulomatous pneumonia. Although tumours are rarely reported in modern pig farming, they should be considered as a differential diagnosis when nodular lung lesions are found. A first-parity sow exhibiting respiratory signs was euthanized. Several whitish firm nodules, not encapsulated, ranging in diameter from 0.5 to 5 cm were present in all lung lobes. Microscopically, the nodules were composed of dense neoplastic cells, mainly in Antoni types A and B patterns, infiltrative and with development of emboli. All neoplastic cells stained positively by immunohistochemistry for vimentin and S-100 protein, with variable immunostaining for glial fibrillary acidic protein and stained negative for cytokeratin. Based on the gross, histological and immunohistochemical features, the tumor was diagnosed as malignant peripheral nerve sheath tumour.