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21.
M. Kasper T. Reimann U. Hempel K.-W. Wenzel A. Bierhaus D. Schuh V. Dimmer G. Haroske M. Müller 《Histochemistry and cell biology》1997,109(1):41-48
Caveolin is a major structural protein of caveolae, also known as plasmalemmal vesicles, which are particularly abundant
in type I pneumocytes and capillary endothelial cells of lung parenchyma. Here we demonstrate that caveolin expression in
the alveolar epithelium of rats and mini pigs is strikingly downregulated after irradiation-induced lung injury. Indirect
immunoperoxidase staining with polyclonal anti-caveolin antibodies, confirmed by double fluorescence studies with type I cell-specific
monoclonal anti-cytokeratin antibodies or lectins, revealed a dramatic loss of caveolin immunoreactivity in type I pneumocytes.
In contrast, caveolin expression increased in endothelial cells. Immunoblotting of lung homogenates from normal and irradiated
rats using specific anti-caveolin antibodies confirmed the presence of caveolin in normal tissue and its marked decrease of
expression in fibrotic tissue. The loss of caveolin as an important structural protein of caveolae in alveolar epithelial
cells may be an early indicator of serious type I cell injury during fibrogenesis. The increase of caveolin immunoreactivity
in endothelia of blood vessels may indicate that different types of caveolae and/or different regulatory mechanisms of caveolin
expression exist.
Accepted: 28 May 1997 相似文献
22.
p-Nitrophenol conjugating activity associated with liver microsomal UDP-glucuronosyltransferase (EC 2.4.1.17) was purified 150- to 200-fold from cell-free homogenates. The purification scheme included solubilization with the nonionic detergent Lubrol WX, anion exchange chromatography at pH 6.0 and 7.5, and affinity chromatography with UDP-hexanolamine Sepharose 4B. The enzyme purified as a phospholipid-protein complex and was shown to consist of a single polypeptide chain of molecular weight 59,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Amino acid analysis indicated approximately 531 mol of amino acids/59,000 g of enzyme and a molar ratio of nonpolar to polar residues of 1.08. During fractionation, the enzyme displayed instability with such steps as gel filtration, dialysis, or ultrafiltration of dilute samples; however, upon adsorption to ion exchange resins or storage in concentrated form, the enzyme was reasonably stable. The active lipoprotein complex showed both size and charge heterogeneity as judged by gel filtration and electrofocusing. Three forms of the enzyme resolved by isoelectric focusing had isoelectric points which averaged pH 6.68, 6.56, and 6.31. Polypeptide compositions of these electrophoretically distinct phospholipid protein complexes were indistinguishable on the basis of sodium dodecyl sulfate-polyacryl-amide gel electrophoresis, suggesting that the charge heterogeneity may be the result of differences in the phospholipid content of the lipoprotein complex. 相似文献
23.
Graphical methods have traditionally been the principal means for estimation of parameters (e.g., affinity constants, cooperativity parameters, and concentrations of receptor sites) in enzymology and ligand-binding problems. The present report provides a review of these methods as well as new results, as applied to three coordinate systems popularly used in ligand-binding studies: vs [Bound]. vs [Free], and vs [Total]. We consider two extremely general models, the statistical mechanical model and the Adair model for equilibrium ligand binding. We also consider a very specialized case of receptor interaction wherein the equilibrium constannt of dissociation is linearly related to receptor occupancy. We collect previously described equations and derive new ones, to enable the user to estimate the parameters of the models in terms of relatively easily measurable graphical characteristics. We have evaluated the performance of these methods in representative cases using Monte Carlo studies. The results indicate the kind of precision and accuracy which can be obtained with typical experimental designs. Depending upon the magnitude of experimental error, the graphical methods can provide dependable values for the binding parameters. However, in general, the results obtained by the graphical methods should be regarded as reasonable initial estimates for further refinement by weighted nonlinear least-squares curve fitting. 相似文献
24.
25.
NADPH-cytochrome P-450 oxidoreductase gene organization correlates with structural domains of the protein 总被引:7,自引:0,他引:7
cDNA clones to rat liver NADPH-cytochrome P-450 oxidoreductase were used to isolate genomic clones from a Wistar-Furth inbred rat genomic DNA library. Fifteen exons containing the coding region and 3'-nontranslated segment of the P-450 reductase gene were identified, spanning 20 kilobases of DNA contained in 3 lambda-Charon 35 clones. The organization of this single copy gene reveals a general correspondence between exons and structural domains of the protein, with the segment responsible for anchoring the reductase to the microsomal membrane and several segments involved in FMN, FAD, and NADPH binding encoded by discrete exons. 相似文献
26.
NADPH-cytochrome c oxidoreductase (EC 1.6.99.2) activity innate to rat liver nuclear envelope displays antigenic identity with the corresponding microsomal enzyme in a standard Ouchterlony double immunodiffusion test. As with the microsomal enzyme, the nuclear envelope enzyme is selectively released by restricted proteolysis and may be quantitatively isolated from the supernatant phase of the digest by immunoprecipitation. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the immunoprecipitates reveals that the oxidoreductase has a molecular weight of 72,000 regardless of its membrane of origin. Radial immunodiffusion titration demonstrates that nuclear envelope contains about one-third the level of NADPH-cytochrome c oxidoreductase (0.21%) as compared to microsomal membrane (0.71%) on a weight basis. By comparison, the specific activity of the nuclear envelope enzyme was half that of the microsomal enzyme. Turnover studies employing NaH14CO3 indicate that the half-lives for the nuclear envelope and microsomal enzymes are indistinguishable, each being approximately 55 h. 相似文献
27.
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29.
Toxoplasma gondii and mucosal immunity 总被引:34,自引:0,他引:34
Kasper L Courret N Darche S Luangsay S Mennechet F Minns L Rachinel N Ronet C Buzoni-Gatel D 《International journal for parasitology》2004,34(3):401-409
Toxoplasma gondii, an intracellular parasite infects the host through the oral route. Infection induces a cascade of immunological events that involve both the components of the innate and adaptative immune responses. Alteration of the homeostatic balance of infected intestine results in an acute inflammatory ileitis in certain strains of inbred mice. Both the infected enterocytes as well as the CD4 T cells from the lamina propria produce chemokines and cytokines that are necessary to clear the parasite whereas CD8 intraepithelial lymphocytes secrete transforming growth factor beta that reduces the inflammation. In this review, we describe the salient features of this complex network of interactions among the different components of the gut-associated lymphoid tissue cell population that are induced after oral infection with T. gondii. 相似文献
30.
Synaptic destabilization by neuronal Nogo-A 总被引:1,自引:0,他引:1
Aloy EM Weinmann O Pot C Kasper H Dodd DA Rülicke T Rossi F Schwab ME 《Brain Cell Biology》2006,35(2-3):137-157
Formation and maintenance of a neuronal network is based on a balance between plasticity and stability of synaptic connections.
Several molecules have been found to regulate the maintenance of excitatory synapses but nothing is known about the molecular
mechanisms involved in synaptic stabilization versus disassembly at inhibitory synapses. Here, we demonstrate that Nogo-A,
which is well known to be present in myelin and inhibit growth in the adult CNS, is present in inhibitory presynaptic terminals
in cerebellar Purkinje cells at the time of Purkinje cell-Deep Cerebellar Nuclei (DCN) inhibitory synapse formation and is
then downregulated during synapse maturation. We addressed the role of neuronal Nogo-A in synapse maturation by generating
several mouse lines overexpressing Nogo-A, starting at postnatal ages and throughout adult life, specifically in cerebellar
Purkinje cells and their terminals. The overexpression of Nogo-A induced a progressive disassembly, retraction and loss of
the inhibitory Purkinje cell terminals. This led to deficits in motor learning and coordination in the transgenic mice. Prior
to synapse disassembly, the overexpression of neuronal Nogo-A led to the downregulation of the synaptic scaffold proteins
spectrin, spectrin-E and β-catenin in the postsynaptic neurons. Our data suggest that neuronal Nogo-A might play a role in
the maintenance of inhibitory synapses by modulating the expression of synaptic anchoring molecules.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献