Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Intermediate Filaments”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,639 records · Page 91Linked to original sources
PubMed1998

Expression of a wool intermediate filament keratin transgene in sheep fibre alters structure.

Alteration of the protein composition of the wool fibre via transgenesis with sheep wool keratin and keratin associated protein (KAP) genes may lead to production of fibre types with improved processing and wearing qualities. Using this approach, we have demonstrated that high level cortical-specific expression of a wool type II intermediate filament (IF) keratin gene, K2.10, leads to marked alterations in both the microstructure and macrostructure of the wool fibres, which have higher lustre and reduced crimp. Analysis of mRNA found reduced levels of transcripts from endogenous cortical type I (p < 0.05) and type II (p < 0.01) keratin IF genes and from the KAP8 (p < 0.001) and KAP2 (p < 0.01) gene families. Examination of protein composition revealed an altered ratio in the keratin type II protein family of the wool fibre cortex. Whilst the over-expressed K2.10 transgene product constituted the majority of keratin type II IF protein, it appeared unable to form heterodimers with much of the expressed endogenous keratin type I IF. In comparison with non-transgenic sheep, fewer IF microfibrils were visible in the cortical cells of fibres from transgenics. The combined effect on fibre structure was disruption of the formation of orthocortical and paracortical cells in the fibre cortex, a factor which could account for the reduction in fibre crimp. No effects upon transcript or protein levels, or fibre microstructure or macrostructure were observed in transgenic sheep expressing the transgene at lower levels, indicating that subtle changes to the gene expression profile in sheep wool follicles can be tolerated. The data here also illustrate that control over endogenous transcript levels in the cortex results when factors acting on the endogenous keratin type I, keratin type II and KAP gene sequences are sequestered by the active K2.10 transgene locus. Moreover, interference to a transcriptional hierarchy shared by keratin and KAP genes may occur prior to establishment of the orthocortical and paracortical compartments of the follicle cortex, at the level of the chromatin.

Animals↗
PubMed1983

Microfilaments and intermediate filaments in epithelial cells transformed by murine sarcoma or leukemia viruses.

The murine epithelial cell line MMC-E was used to study changes in the cytoskeletal organization associated with viral transformation of epithelial cells by two different viruses. The cells were transformed with Moloney mouse sarcoma virus (MSV) or murine leukemia virus (MuLV). The expression of actin, myosin and of intermediate filament proteins in the cells was then studied. In MMC-E cells actin and myosin were organized as belt-like structures at the edges of the border cells of the cell islands and also circumferentially in the cells inside the islands. The major change after transformation was the decrease of the actomyosin containing belt extending from cell to cell at the borders of the cell islands. Both MMC-E cells and the MSV-transformed cells contained keratin as a juxtanuclear granular aggregate whereas the MuLV-transformed cells showed bright fibrillar arrays of keratin. Both virus-transformed cell lines showed enhanced vimentin-specific fluorescence and analysis of their cytoskeletal polypeptides confirmed the result. Similar molecular forms of keratin polypeptides were seen in all cells by immunoblotting. Viral transformation of MMC-E epithelial cells thus leads to different changes in their cytoskeletal organization depending on the transforming viral or cellular gene.

Actin Cytoskeleton↗
PubMed1983

Organization of intermediate filaments in ciliated cells from quail oviduct.

When ciliated cortices were isolated from oviducts of laying quail, the demembranated cortices remained associated with the cell nucleus. The organization of the material linking the nucleus to the apical cell surface has been observed by electron microscopy in ciliated cells in situ and characterized by HRP immunocytochemistry. A well developed network of prekeratin intermediate filaments attached to the desmosomes creates a basket surrounding the nucleus. Furthermore, prekeratin filaments are associated with the striated rootlets of basal bodies.

Animals↗
PubMed1984

Remarkable conservation of structure among intermediate filament genes.

Using a cloned cDNA complementary to a portion of the mRNA for the 50 kd human epidermal keratin, we have screened a human genomic library and have isolated and sequenced the gene encoding this keratin. A comparison of the keratin gene with the very distantly related vimentin gene has enabled us to explore the relation between the evolutionary conservation of structure in intermediate filament (IF) subunits and the conservation of structure in IF genes. Our results reveal that not only the secondary structure of the IF proteins, but also the structural skeleton of their genes, has been maintained throughout evolution. These characteristics have persisted despite considerable flexibility in both protein and nucleic acid sequence. Surprisingly, although the positions of the introns within these two genes are highly conserved, they do not seem to correspond to the boundaries of the structural domains common to all IF subunits.

Amino Acid Sequence↗
PubMed1993

Nonspecific cytotoxic cells in fish: antigenic cross-reactivity of a function associated molecule with the intermediate filament vimentin.

Nonspecific cytotoxic cells (NCC) in fish may lyse tumor cells and protozoan parasites in a similar fashion as their mammalian NK counterparts. Previous studies have shown that recognition and binding by NCC may be mediated by a receptor. In the present study the putative receptor or function-associated molecule (FAM) on NCC was shown to contain antigenic cross-reactivity with the mammalian intermediate filament vimentin. This was accomplished by comparing the specificity of anti-FAM monoclonal antibody 5C6 with commercially available anti-vimentin mabs V9 and 13.2 and with a polyclonal anti-vimentin antiserum. Tissue distribution studies indicated that the anti-vimentin antibodies bound to significantly fewer (< 50%) anterior kidney, spleen, kidney, and brain cells than mab 5C6. These mabs, however, produced inhibition of NCC lysis of IM-9 target cells. Conditions of mab incubation (with NCC) which were previously shown to modulate NCC cytotoxicity by 5C6 also produced large increases in NCC lysis of IM-9 targets in the presence of mabs V9 and 13.2. The determinant(s) recognized by these antibodies is present on the cell membrane. Microscopic examination of nonpermeabilized or acetone-treated and antibody-stained cells demonstrated that acetone permeabilization produced a 28-32% increase in staining (due to intracellular binding) compared to the staining of viable cells. Biochemical analysis of the cross-reactive antigens was done using analytical 2D SDS-PAGE and Western blot experiments. Mab 5C6 detected a 32- to 35-kDa protein (pI 6.3-6.5) in NCC extracts. Anti-vimentin mab 13.2 recognized a 57-kDa vimentin protein which had a relatively broad pI range (pH 6.3-6.7). Mab 13.2 also cross-reacted (in the same Western blot) with the NCC receptor protein (pI = pH 6.3-6.5). These data indicate that the FAM on NCC/NK cells contain vimentin-like antigenic determinants which may function in target cell binding.

Animals↗
PubMed1983

Coexpression of keratin- and vimentin-type intermediate filaments in human metastatic carcinoma cells.

Metastatic tumor cells of epithelial origin present in effusions from human serous cavity fluids (ascites or pleural fluid) were examined for their intermediate-sized filament types by using antibodies to keratin, vimentin, and desmin in the indirect immunofluorescence technique. Solid epithelial tumors (both primary carcinomas and their metastases) contain keratin intermediate-sized filaments exclusively. However, when these cells are present in ascitic or pleural fluid, they also express vimentin, which occurs in a fibrillar organization. The possible effects of this additional, but temporary, cytoskeleton on metastatic growth or aggressiveness (or both) are discussed.

Carcinoma↗
PubMed1985

Antibody against T lymphoblastic leukemia-associated antigen (3-40) identifies vimentin and keratin intermediate filaments in normal cells.

Antibody 3-40 defines a 35- to 40-kd surface antigen present on T lymphoblastic leukemia (T-ALL) cells that is absent on normal hematopoietic cells (Naito et al, Blood 62:852, 1983). Using immunoblot analysis of cytoskeletal proteins and indirect immunofluorescence of cell lines treated with various cytoskeletal inhibitors, in this report we have demonstrated that antibody 3-40 also identifies vimentin intermediate filaments (IMF) within the HSB-2 (T-ALL) cell line as well as in normal thymocytes, peripheral blood mononuclear cells, and human and rodent fibroblast cell lines. Cross-reactivity with several keratin subclasses was demonstrated in both human and rodent epithelial cell lines, human thymus, and skin. In addition, we have shown that antibody 3-40 defined a 39-kd intracellular IMF-associated protein in HSB-2 cells, epithelial and fibroblast cell lines. This IMF-associated protein may be selectively expressed on the surface of human T cells during malignant transformation.

Animals↗
PubMed1985

Loop arrays in mouse brain demonstrated with antisera to cytokeratins and monoclonal antibodies to several classes of intermediate filaments: strain differences and developmental expression.

Some monoclonal antibodies raised against mouse brain antigens display a novel loop array apparently localized within the cytoplasm of neurons in fresh frozen sections of adult mouse brain. By indirect immunofluorescence, these loops are detectable in the cerebral cortex, thalamus, brainstem, and are particularly striking in association with pyramidal neurons of the hippocampus. The loops are also seen with polyclonal antibodies to the cytokeratin class of intermediate filaments. The antibodies which react with these loops also react with ependymal cells. Western blot analysis of crude insoluble cytoskeletal components of mouse brain with antibodies of cytokeratins confirm the presence of reactive bands in the range of 40-60 kdalton, appropriate in molecular weight for this class of cytoskeletal filaments. This evidence suggests that the loops share antigenic determinants with non-neural cytokeratins. During development, immunoreactive structures are first seen as small punctate or curvilinear profiles, which change into a loop array at approximately 14 days postnatal age in several mouse strains. However, in 8 of 15 different mouse strains, these immature punctate profiles remain without morphological alteration to loops throughout adult age. The F1 crosses between strains with and without the loops develop loops, but on average they are of smaller size than in the positive parent.

Animals↗
PubMed1985

The intermediate filament protein desmin in cardiac and skeletal muscle from normal and dystrophic (BIO 14.6) hamsters.

Electrophoretic separation on polyacrylamide gels of polypeptides extracted from skeletal and cardiac muscle of BIO 14.6 dystrophic, carrier, and random-bred normal hamsters demonstrates similar quantities and electrophoretic mobility of a protein having a relative mass of 52 000 daltons (apparent isoelectric point 6.2) from all sources examined; we have tentatively identified this protein as the intermediate filament protein desmin. Reaction of such separated polypeptides transferred to nitrocellulose blots with antibodies raised against this protein fails to show immunological differences in this 52 000 dalton protein in cardiac and skeletal muscle from normal and dystrophic animals. Indirect immunofluorescence analysis of skeletal myofibrils from 30-to 60-day normal and dystrophic animals shows no differences in Z-line staining when immunoglobulins from anti-alpha-actinin serum are used as primary antibodies. Immunoglobulins from the putative anti-desmin serum also produce Z-line staining of skeletal myofibrils from normal animals, but fail to bind to the Z-lines of some skeletal myofibrils from dystrophic hamsters.

Animals↗
PubMed1983

Distinctions between gap junctions and sites of intermediate filament attachment in the leech C.N.S.

Freeze-fracture studies on the nerve cord of the leech Hirudo medicinalis reveal that the plasma membranes of various cells, including glial and muscle cells, contain at least two distinct types of aggregated intramembrane particles, identified as hemidesmosomes and gap junctions. Hemidesmosomes consist of angular particles irregularly arranged in circular or elongate patches in external leaflets (E-faces), and are associated with a bundle of intermediate filaments extending into the cytoplasm. Hemidesmosomes of specific axons abut on extracellular space at openings in the surrounding glial sheath. Gap junctions are patches of rounder particles in cytoplasmic leaflets (P-faces) and are more uniformly spaced; they have a corresponding array of pits in the complementary E-face. Gap junctions connect processes of adjacent smooth muscle cells, and apparently interconnect glial processes. Thus, different types of cells in the leech C.N.S. have similar intramembrane specializations. Moreover, the hemidesmosomes and gap junctions might, on superficial examination, be confused.

Animals↗
PubMed2005

The intermediate filament protein vimentin is a new target for epigallocatechin gallate.

Epigallocatechin gallate (EGCG) is the major active polyphenol in green tea. Protein interaction with EGCG is a critical step in the effects of EGCG on the regulation of various key proteins involved in signal transduction. We have identified a novel molecular target of EGCG using affinity chromatography, two-dimensional electrophoresis, and mass spectrometry for protein identification. Spots of interest were identified as the intermediate filament, vimentin. The identification was confirmed by Western blot analysis using an anti-vimentin antibody. Experiments using a pull-down assay with [3H]EGCG demonstrate binding of EGCG to vimentin with a Kd of 3.3 nm. EGCG inhibited phosphorylation of vimentin at serines 50 and 55 and phosphorylation of vimentin by cyclin-dependent kinase 2 and cAMP-dependent protein kinase. EGCG specifically inhibits cell proliferation by binding to vimentin. Because vimentin is important for maintaining cellular functions and is essential in maintaining the structure and mechanical integration of the cellular space, the inhibitory effect of EGCG on vimentin may further explain its anti-tumor-promoting effect.

Amino Acid Sequence↗
PubMed1982

Alveolar rhabdomyosarcoma. Demonstration of the muscle type of intermediate filament protein, desmin, as a diagnostic aid.

Three cases of soft-tissue sarcomas with the characteristic histologic features of alveolar rhabdomyosarcoma, but lacking cytoplasmic cross-striations, were studied ultrastructurally and immunohistochemically to confirm the diagnosis and evaluate the histogenesis. The results showed that it was not possible to judge the skeletal muscle derivation of the cells at the ultrastructural level. However, immunohistochemically, the results of every case were positive for desmin-the muscle type of the intermediate filament protein. The results suggest that demonstration of desmin may be a helpful adjunct tool in the diagnosis of poorly differentiated alveolar rhabdomyosarcomas.

Adolescent↗