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PubMed1988

Cytokeratin and vimentin intermediate filament proteins in benign and neoplastic prostatic epithelium.

Prostatic samples from 30 hyperplastic prostates and 61 prostatic adenocarcinomas were examined for vimentin and cytokeratins. The co-expression of cytokeratins and vimentin was found in all benign prostatic epithelium and in 83% of adenocarcinomas. Benign prostatic epithelium showed vimentin intermediate filaments distinctively distributed in the basal regions and as paranuclear sheaves along the long axis of the cell. This pattern of vimentin staining was seen in adenocarcinomas with low Gleason scores, whereas high-grade tumours showed intense diffuse perinuclear staining.

Adenocarcinoma↗
PubMedDate not supplied

Characterisation of a cell line from a human lung lymphosarcoma. Abundance of vimentin-type intermediate filaments.

A cell line (HCL82) was established from a human lung lymphosarcoma. Cells exhibited a stable phenotype and remained nearly diploid with a modal chromosome number of 45-48, showing no significant aberrations. Cultures consisted of single elongated cells and irregular colonies. Ultrastructurally, mitochondria, golgi complexes, and large bundles of intermediate filaments were well developed; some cells contained virus-like particles. Filaments were composed of vimentin identified by immunofluorescence and gel electrophoresis. Reaction with monoclonal antibody OKT4 suggested a close relationship to T-helper cells. Cells did grow at clonal density but did not form tumors in nude mice.

Animals↗
PubMed1986

Comparison of mouse and human keratin 18: a component of intermediate filaments expressed prior to implantation.

Keratin 18 is a type-I keratin that is found in a variety of simple epithelial tissues. In mice, the corresponding protein, called Endo B, is expressed at the 4- to 8-cell stage of mouse development and may be one of the first intermediate-filament proteins synthesized after fertilization. A cDNA clone for keratin 18, designated pK18, was isolated from a human placental cDNA library by hybridization with the mouse Endo-B probe. It was characterized by hybridization selection of RNA, translation, immunoprecipitation, Northern blotting, and sequence analysis. Synthetic T7 polymerase transcripts of the cDNA were indistinguishable in size from keratin-18 mRNA, suggesting that pK18 represents a full-length copy of the RNA. The cDNA insert is 1,428 nucleotides long and contains a single open reading frame of 1,342 nucleotides coding for 429 amino acids. The deduced amino acid sequence is 89.7% identical with that of Endo B. The only extensive difference between the two sequences is due to 9 additional amino acids being present in the last half of the N-terminal domain of keratin 18. The 38-nucleotide-long 3' noncoding region of the cDNA is 75% identical with the corresponding portion of Endo B. The 5' noncoding regions are 59% identical. The expression of keratin-18 mRNA was found to vary more than tenfold when HeLa cells and BeWo trophoblastic cells were compared.

Amino Acid Sequence↗
PubMed1988

Factors modulating filament formation by bovine glial fibrillary acidic protein, the intermediate filament component of astroglial cells.

Glial fibrillary acidic protein (GFAP) is soluble in low ionic strength solutions but shows a strong tendency toward assembly with increasing ionic strength as revealed by electron microscopy and turbidity measurements. Increasing K+, Na+, and Li+ concentrations cause an increase followed by a decrease in GFAP turbidity with a maximum at 200 mM, but their effects are much weaker than effects of divalent cations at the same ionic strength. Ca2+, Mg2+, Mn2+, and Ba2+ promote assembly at millimolar concentrations, and 10 microM Cu2+ causes rapid aggregation. The critical concentration for GFAP assembly was 0.08 +/- 0.04 mg/mL in 2 mM Tris-HCl, 60 mM KCl, and 1 mM CaCl2, pH 6.8. The Mr 38,000 rod domain of GFAP obtained by limited chymotryptic digestion is more soluble in 100 mM imidazole hydrochloride buffer, pH 6.8, than the intact molecule, and removal of the end pieces greatly reduces the ability of GFAP to form filaments. BNPS-skatole (2-[(2-nitrophenyl)sulfenyl]-3-methyl-3-bromoindolenine) treatment releases a Mr 30,000 N-terminus and a Mr 20,000 C-terminus. The Mr 30,000 polypeptide shows a higher affinity than the Mr 20,000 fragment for intact GFAP. Arginine and lysine at low concentrations slightly accelerate GFAP assembly, but above 100 mM both amino acids inhibit assembly. ATP, GTP, CTP, and UTP do not show significant effects on GFAP assembly. Dephosphorylation by alkaline phosphatase slightly reduces the assembly ability of GFAP, but phosphatase-treated GFAP still is assembly competent.

Animals↗
PubMed1985

Site specificity in vimentin-membrane interactions: intermediate filament subunits associate with the plasma membrane via their head domains.

Fragments of vimentin, generated by chemical or enzymatic cleavages, were analyzed for their capacity to bind to human inverted erythrocyte membrane vesicles. Only peptides comprising the amino-terminal head domain of vimentin molecules were competent in associating with the membranes. In vitro studies also demonstrated that isolated ankyrin (the major vimentin acceptor site on the membrane) binds to an oligomeric species of vimentin and prevents the formation of characteristic 10-nm filaments. These data, taken together with the observation that the NH2-terminal end of vimentin is implicated in the polymerization process (Traub, P., and C. Vorgias, J. Cell Sci., 1983, 63:43-67), imply that intermediate filaments may contact the membrane in an end-on fashion, using the exposed head domains of their terminal subunits.

Animals↗
PubMed1997

Expression of the smooth-muscle proteins alpha-smooth-muscle actin and calponin, and of the intermediate filament protein desmin are parameters of cardiomyocyte maturation in the prenatal rat heart.

BACKGROUND: Coexpression of alpha- and beta-myosin heavy chain (MHC) is a characteristic of the primary myocardial tube. To establish if the smooth-muscle proteins alpha-smooth-muscle actin (alpha-SMA) and calponin, and the intermediate filament protein, desmin, contribute to the specific functional properties of these early cardiomyocytes, we studied their spatiotemporal expression pattern. METHODS: Sections of prenatal and neonatal Wistar rats were stained with antibodies against alpha- and beta-MHC, alpha-SMA, calponin, and desmin. RESULTS: The expression of alpha-SMA and calponin in embryonic cardiomyocytes increases to reach its highest level at ED14. Subsequently, these proteins gradually disappear, beginning in the interventricular septum (IVS) and followed successively by the compact myocardium of the left ventricle, the right ventricle, and the central atrium. Expression of alpha-SMA persists longer in the ventricular conduction system, making it a convenient marker for the ventricular conduction system of the fetal rat. Desmin becomes expressed one day later than alpha-SMA, but also reaches its peak at ED14, suggesting that a relatively high concentration is required to form mature sarcomeres. CONCLUSIONS: The results indicate that alpha-SMA, calponin, and desmin are involved in the myofibrillar development in rat heart. The presence of spatiotemporal differences in the expression of these proteins reveals regional differences in the developmental timing of cardiomyocyte maturation. The maturation process extends from the compact myocardium in the IVS to the left and right ventricular free walls, whereas the atrioventricular junction, the ventricular trabeculae, and developing ventricular conduction system show a relatively slow maturation. Smooth-muscle proteins may contribute to the slow shortening speed that is characteristic of the embryonic myocardium.

Actins↗
PubMed1985

Amino acid sequences of mouse and human epidermal type II keratins of Mr 67,000 provide a systematic basis for the structural and functional diversity of the end domains of keratin intermediate filament subunits.

From the nucleotide sequences of specific cDNA clones, we present partial amino acid sequences (75-90% of the total) of 67-kDa type II keratin subunits expressed in terminally differentiating mouse and human epidermis. Analysis of the sequence information reveals that their secondary structures conform to the pattern common for all intermediate filament (IF) subunits. Together with the previously published sequence of the mouse 59-kDa type I keratin (Steinert, P. M., Rice, R. H., Roop, D. R., Trus, B. L., and Steven, A. C. (1983) Nature 302, 794-800) these data allow us to make comparisons between two keratins which are coexpressed in an epithelial cell type and which coassemble into the same IF. Moreover, these comparisons suggest a systematic plan for the general organization of the end domains of other keratin subunits. We postulate that each end domain consists of a set of subdomains which are distributed with bilateral symmetry with respect to the central alpha-helical domain. Type II (but not type I) keratins contain short globular sequences, H1 and H2, immediately adjacent to the central domain, that have been conserved in size and sequence and which account for most of the difference in mass between coexpressed type II and type I keratins. These are flanked by subdomains V1 and V2 that are highly variable in both length and sequence, often contain tandem peptide repeats, and are conspicuously rich in glycines and/or serines. At the termini are strongly basic subdomains (N and C, respectively) that are variable in sequence. Among keratins of a given type, their variability in mass appears to reside in the size of their V1 and V2 subdomains. However, coexpressed type I and type II keratins have generally similar V1 and/or V2 sequences. By virtue of the ease with which large portions of these subdomain sequences can be removed from intact keratin IF by limited proteolysis, we hypothesize that they lie on the periphery of the IF where they participate in interactions with other constituents of epithelial cells.

Amino Acid Sequence↗
PubMed1985

Monoclonal antibody to intermediate filaments of cytokeratin type. I. Drug studies and reactivity with cultured cells and tissue sections.

Establishment of a mouse-mouse hybridoma and partial characterization of IgM monoclonal antibody (M-04) identifying cytoplasmic filamentous structures is described. Immunofluorescence performed on a panel of various cultured human cell types as well as on frozen sections of normal and tumour tissues revealed specificity of M-04 antibody for cells of epithelial origin. Using MCF-7 cell line as a model, staining patterns of microtubules, microfilaments and M-04-target filaments in untreated cells were compared with those pretreated with Colcemid and Cytochalasin B. From both differential staining of various cell types and the results of drug studies it is concluded that monoclonal antibody M-04 binds to intermediate filaments of cytokeratin type. Furthermore, restricted expression of M-04 target determinant among epithelial tissues is suggested from the lack of reaction in stratified skin epithelium.

Animals↗
PubMed1979

Intermediate filaments in hyaline material in alcoholic liver disease (Mallory bodies) and in cultured hepatoma cells.

Antibodies specific for cytoskeletal intermediate (10 nm) filaments reacted both with the hyaline deposits in alcoholic liver disease (Mallory bodies) and with perinuclear hyaline material of cultured hepatoma cells used as a model for hyaline formation in vitro. Our results suggest that disorganization and accumulation of intermediate filaments is an important step in the pathogenesis of alcoholic liver injury.

Animals↗
PubMed1984

Keratin intermediate filaments bear antigenic determinants for stratum corneum antibodies.

Stratum corneum (SC) antibodies are directed against antigens in the SC of the epidermis and are known to occur in all normal human sera. They have been shown by indirect immunofluorescence to be frequently associated with upper cytoplasmic (U-Cyt) antibodies. We have recently identified keratin intermediate filaments (KIF) as antigens for U-Cyt antibodies. In this study we investigated whether KIF also bear antigenic sites for SC antibodies. Normal human sera that contained SC and/or U-Cyt antibodies by indirect immunofluorescence were studied. Using immunoblot techniques 3 selected sera were shown to bind to high-molecular-weight (HMW) KIF proteins which had been extracted from 2 different epidermal cell preparations, that is, human callus or epidermis from which the SC had been removed by tape-stripping. The 3 test sera were absorbed on KIF which had been reconstituted in vitro from urea extracts from both epidermal substrates. As shown by indirect immunofluorescence, the SC and U-Cyt antibodies of all 3 sera were absorbed out with KIF from callus and with KIF from epidermis without SC. Immunoblot experiments, which are more sensitive than indirect immunofluorescence, demonstrated the absorption of anti-KIF protein antibodies of the 3 test sera on callus KIF and 2 of the sera on KIF obtained from epidermis without SC. This was shown by the lack of staining of the respective HMW KIF proteins with the postabsorption sera. With the third serum a marked reduction of antibody binding was found after absorption on KIF from epidermis without SC. These data indicate that KIF bear antigenic sites for SC antibodies.

Absorption↗
PubMedDate not supplied

Expression of vimentin intermediate filament in human odontoblast.

BACKGROUND: Vimentin (57 Kda) is a cytoskeletal protein. Odontoblasts contain vimentin and it seems that this protein may function to keep the organelles and the nucleus in a definite place. However little is known about vimentin in the cytoskeleton of odontoblast processes. The purpose of the present study was, therefore to immunolocalize vimentin intermediate filament in odontoblast body and process in order to clarify the distribution of this cytoskeletal element. METHODS: 12 extracted intact premolars, from children, were used in the present study. Each specimen was decalcified in EDTA. Each tissue portion was embedded in paraffin. On sections a monoclonal anti-vimentin antibody was applied. The immunoreaction was visualized by ABC technique. RESULTS: Vimentin was expressed in the cell body and cell process of odontoblasts, however with a different immunolabeling pattern related to the topographical area of observations. In odontoblast cell bodies vimentin showed a perinuclear and cytoplasmatic staining. In the very initial portion of odontoblast process immunoreaction products for vimentin were observed in the core of the process. In the middle zone of dentin vimentin immunoreactions products also showed a granular and cross-bridge arrangements, and also, vimentin was also detected under the plasma membrane, at the periphery of the odontoblast process. Nearby the dentino-enamel junction vimentin immunolabeling was appreciated, mainly under the plasma membrane. CONCLUSIONS: On the basis of vimentin distribution in the odontoblast process it seems plausible to assume that this IF vimentin is important in forming a flexible scaffold essential for structuring cytoplasm.

Child↗