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PubMed1989

Co-expression of cytokeratin and vimentin intermediate filament proteins in benign and neoplastic breast epithelium.

This paper identifies another neoplasm of epithelial origin which may express vimentin in addition to cytokeratins, thereby adding to the expanding list of tumours which demonstrate intermediate filaments (IFs) other than those of their reputed cell of origin. Twenty examples of benign breast disease and 66 carcinomas were examined for vimentin and cytokeratin IFs using an avidin-biotin-peroxidase complex technique. Co-expression of these IF proteins was found in 35 per cent of cases of benign breast tissue and in 60 per cent of the carcinomas. In 8 (16 per cent) of 50 cases of infiltrating ductal carcinoma, vimentin and cytokeratin immunostaining was observed in more than 60 per cent of the tumour cells. These carcinomas were predominantly of a high histological grade. In benign breast disease and well-differentiated carcinoma, vimentin was distributed in the basal and perinuclear regions of the cells, with sparing of the apical portions. In those cases in which large numbers of tumour cells expressed vimentin, cytoplasmic staining was diffuse, and often exhibited distinctive perinuclear and subplasmalemmal accentuation. We propose that a knowledge of the list of carcinomas which may co-express vimentin and cytokeratin IFs might be helpful in the assessment of undifferentiated tumours and metastatic deposits.

Breast↗

PubMed1999

Vimentin intermediate filament protein as differentiation marker of optic vesicle epithelium in the chick embryo.

For the study of the differentiation process of optic vesicle epithelium into neural retina, pigment epithelium and pars caeca retinae, vimentin intermediate filament protein in retinal epithelial cells was detected immunohistochemically in chick embryo at stages 11-21. In the late stage of optic vesicle development (stage 14), optic vesicle epithelium was classified into the following 3 different portions on the basis of vimentin staining intensity: latero-central epithelium under the lens placode, medio-central epithelium facing the latero-central epithelium, and peripheral epithelium connecting the latero-central and medio-central epithelia. Latero-central epithelium, the future neural retina, exhibited strongest staining of vimentin of the 3 portions. In contrast, medio-central epithelium, the future pigment epithelium, showed weakest staining. Moderate staining was observed in peripheral epithelium, the future pars caeca retinae. These differences in levels of vimentin expression were observed during optic cup formation. The present results clearly demonstrate that differentiation of retinal epithelium into neural retina, pigment epithelium and pars caeca retinae occurs in the late stage of the optic vesicle, and that retinal differentiation is reflected by the amount of vimentin in epithelial cells.

Animals↗

PubMed1983

Infection with vaccinia favors the selection of hybridomas synthesizing autoantibodies against intermediate filaments, one of them cross-reacting with the virus hemagglutinin.

Immunization of mice with lysates from infected cells and pure vaccinia virus generated hybridomas, a large fraction of which make autoantibodies binding to intermediate filaments (greater than IF) and vimentin. Antibodies that can be detected in preimmune mice as weakly binding to the cytoskeleton (greater than CS) are elevated in potency after immunization with either active or UV-inactivated pure vaccinia, suggesting that virus replication may not be obligatory for activation of greater than CS lymphocyte clones. Demonstration of a cross-reactivity of one IF monoclonal antibody with virally coded hemagglutinin, expressed at the surface, raises questions about the development of pathologic conditions associated with virus-mediated autoimmunity.

Animals↗

PubMed1982

Assembly of keratin onto PtK1 cytoskeletons: evidence for an intermediate filament organizing center.

Purified keratin, solubilized in 8 M of urea, was added to Triton X-100-extracted PtK1 cells in 5 mM PIPES buffer. The buffer conditions induced assembly of keratin filaments which appear to associate with nuclei of extracted cells. These keratin fibers extend beyond the original margin of the cells and frequently form bridges between adjacent cells. Electron microscopy shows that keratin filaments associate closely with the surface of the nucleus. We suggest that the site of association between keratin and the nucleus may represent an intermediate filament organizing center.

Animals↗

PubMed1993

ADP-ribosylation of the intermediate filament protein desmin and inhibition of desmin assembly in vitro by muscle ADP-ribosyltransferase.

Arginine-specific mono(ADP-ribosyl)transferase purified from rabbit skeletal muscle catalyzes stoichiometric ADP-ribosylation of the intermediate filament protein, desmin. In contrast, cholera toxin catalyzes a much lower level of ADP-ribosylation of desmin. Modification results in potent inhibition of desmin's ability to assemble into filaments. Phosphorylation of desmin by the catalytic subunit of cAMP dependent protein kinase is also inhibited by ADP-ribosylation. ADP-ribosylation site(s) are located within the N-terminal head domain of desmin.

ADP Ribose Transferases↗

PubMedDate not supplied

Transcriptional activation of an intermediate filament protein gene in mice with retinal dystrophy.

We are interested in understanding neuronal interactions that regulate expression of specific genes in glial cells in the nervous system. In the normal mouse retina, the glial intermediate filament protein (GFAP) is not detectable in Müller cells, the predominant glial cells in the retina. Photoreceptor degeneration resulting from retinal degeneration (rd) mutation or environmental light damage, however, leads to the appearance of GFAP in Müller cells. We have investigated the mechanism underlying GFAP accumulation in these retinas. Western blotting analysis, steady-state mRNA level comparisons, and nuclear run-on assays show that transcription of the GFAP gene is activated in these retinas. In situ hybridizations with retinal sections and solitary Müller cells establish that GFAP mRNA levels are elevated in Müller cells. These results show that disruption of neuron-glia interactions resulting from photoreceptor degeneration leads to activation of the GFAP gene in glial cells of mice with retinal dystrophy. The functional significance of this glial response and the need for GFAP expression remain to be understood.

Animals↗

PubMed1987

Intermediate filament expression in small cell lung cancer; poor correlation to in vitro data.

A panel of monoclonal antibodies, detecting different intermediate sized filament proteins, was prospectively applied on all specimens derived from S.C.L.C. patients attending our clinic in 1985. Reactivity with the antibodies was subsequently correlated to clinical data. The results indicate a heterogeneous pattern of reactivity of the assessed antibodies. However this heterogeneity is not a straightforward extension of the intermediate sized filament expression in SCLC cell lines.

Antibodies, Monoclonal↗

PubMedDate not supplied

Changes in the cytokeratin intermediate filament cytoskeleton associated with Mallory body formation in mouse and human liver.

Mouse and human extracted liver tissue were examined by indirect immunofluorescent staining and transmission electron microscopy in order to study the alteration of cytokeratin intermediate filaments associated with Mallory body formation. Frozen sections of griseofulvin-fed mouse liver and human liver of primary biliary cirrhosis and primary sclerosing cholangitis were extracted by Triton X-100 and nuclease. Indirect immunofluorescent staining was performed by using anticow hoof keratin antibody for mouse liver and anti-human epidermal keratin antibody (AE1 and AE3) for human liver. Transmission electron microscopy was also performed on extracted and critical point-dried samples. The griseofulvin-fed mouse hepatoma cells showed four different types of altered staining pattern based on the indirect immunofluorescent staining of the cytoplasm and Mallory bodies: Type I--cytoplasm(+), Mallory body(-); Type II--cytoplasm(+), Mallory body(+); Type III--cytoplasm(-), Mallory body(+), and Type IV--cytoplasm(-), Mallory body(-). Types I and III were predominant, however, some hepatoma cells which contain Mallory bodies revealed bright cytoplasmic staining (Type II). The nuclear rims were strongly stained. In human liver, AE1 stained Mallory bodies and the bile duct epithelium intensely, but did not stain normal hepatocytes. AE3 mainly stained Mallory bodies and normal hepatocytes, but also stained bile duct epithelium weakly. Indirect immunofluorescent staining for human liver showed the same staining patterns as found in mouse liver, except that Type IV was not observed. Although many hepatocytes which contained Mallory bodies did not react with either of these two antibodies (Type III), some of the hepatocytes were stained, not only with AE3, but also with AE1 (Type II).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

Are cross-bridging structures involved in the bundle formation of intermediate filaments and the decrease in locomotion that accompany cell aging?

Five different fibroblast strains derived from donors of a wide range of ages were used for investigation of senescence-associated changes in the organization of intermediate filaments (IFs) and the activity of cell locomotion. Results of immunofluorescence microscopy demonstrate that, in large and flat in vitro aged fibroblasts, vimentin-containing IFs are distributed as unusually organized large bundles. Electron microscopic examination shows that these large bundles are indeed composed of filaments of 8-10 nm. Such a profile of large bundles is rarely seen in young fibroblasts whose IFs are usually interdispersed among microtubules. Within the large filament bundles of senescent fibroblasts, cross-bridge-like extensions are frequently observed along the individual IFs. Immunogold labeling with antibody to one of the cross-bridging proteins, p50, further illustrates the abundance of interfilament links within the IF bundles. The senescence-related increase in interfilament association was also supported by the results of co-precipitation between vimentin and an associated protein of 50,000 D. Time-lapse cinematographic studies of cell locomotion reveal that accompanying aging, fibroblasts have a significantly reduced ability to translocate across a solid substratum. These results led me to suggest that the increased interfilament links via cross-bridges may in part contribute to the mechanism that orchestrates the formation of large filament bundles. The presence of enormous bundles in the cytoplasm may physically impede the efficiency of locomotion for these nondividing cells.

Aging↗

PubMed1986