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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The heat shock response in a transformed astrocyte line was compared with nontransformed astrocytes. The synthesis of HSP 68, the major inducible heat shock protein (HSP 68) was induced by a non-lethal 45 degrees C, 10 min heat shock. Although the incorporation of [35S]methionine into HSP 68 suggested that similar amounts of protein were being synthesized after heat shock, Western immunoblotting demonstrated striking differences in the HSP immunostaining between the two cell types. By one- and 'two-dimensional gel electrophoresis the major 68 kDa heat shock protein (HSP 68) was similar in both cell types. However, HSP 68 from heat shocked, transformed astrocytes did not immunostain with the monoclonal antibody, C-92, which is specific for the major inducible heat shock protein of HeLa cells. In contrast HSP 68 from heat shocked, nontransformed astrocytes immunostained quite well. A polyclonal antibody raised against the inducible 72 kDa heat shock protein of HeLa cells immunostained the HSP 68 from both astrocytes and transformed astrocytes. Analysis of the mRNA from the two cell types after heat shock revealed two bands of approximately 2.5 and 2.8 kb in astrocytes but only a single 2.5 kb band in the heat shocked transformed astroglia. These results suggest that structural differences in the HSP 68 may be present in the transformed astrocytes compared to the normal astrocytes.
Brain Res Mol Brain Res 1992 Jan
PMID:Characterization of the major 68 kDa heat shock protein in a rat transformed astroglial cell line. 131 2

We have previously reported that mineralocorticosteroid receptor (MR) is a 8-9 S heterooligomeric complex that includes the 90 kDa heat shock protein (hsp90). To elucidate how antagonist-receptor complexes are biologically inactive in terms of transcriptional regulation, we analyzed the binding of mineralocorticosteroid agonists and antagonists with MR and the ligand-induced transformation of its heterooligomeric structure. This study was performed in the cytosol of adrenalectomized rat kidney and of COS cells transiently transfected with human MR cDNA. Although aldosterone antagonists (SC9420 and RU26752) bind MR with the same affinity as aldosterone, they dissociate much more rapidly from the 8-9 S form of both rat and human MR than does aldosterone. Using sedimentation gradient analysis, we showed that the interaction between hsp90 and the steroid binding subunit of MR is highly dependent upon the nature of the steroid ligand since the binding of aldosterone antagonists results in an easy release of hsp90. We propose that both rapid dissociation of ligand and weakened hsp90-receptor interaction play a key role in the mechanism of mineralocorticosteroid antagonism. In the COS cell model, cortisol, described as a weak mineralocorticosteroid agonist, dissociates also more rapidly from human MR than does aldosterone. Our results suggest that ligand binding kinetics and ligand dependent modification in receptor structure are important modulators of MR function as a transcriptional regulatory factor.
J Steroid Biochem Mol Biol 1992 Mar
PMID:Differences between aldosterone and its antagonists in binding kinetics and ligand-induced hsp90 release from mineralocorticosteroid receptor. 131 85

We examined the effects of generalized seizures on heat shock protein (hsp) mRNA induction in the rat brain using in situ hybridization. Seizures induced by electroconvulsive shock, electrical or cocaine kindling caused a selective induction of the constitutive hsp 73 gene in the dentate gyrus. In these seizure paradigms, not thought to induce widespread tissue damage, neither the heat-inducible hsp 72 gene nor a member of the hsp 90 family (hsp 84) were induced. Hsp 73 may play a role in the adaptation and/or in the maintenance of dentate granule cell integrity following seizures.
Brain Res Mol Brain Res 1992 Mar
PMID:Induction of constitutive heat shock protein 73 mRNA in the dentate gyrus by seizures. 131 15

Transcriptional activation of human heat shock protein (HSP) genes by heat shock or other stresses is regulated by the activation of a heat shock factor (HSF). Activated HSF posttranslationally acquires DNA-binding ability. We previously reported that quercetin and some other flavonoids inhibited the induction of HSPs in HeLa and COLO 320DM cells, derived from a human colon cancer, at the level of mRNA accumulation. In this study, we examined the effects of quercetin on the induction of HSP70 promoter-regulated chloramphenicol acetyltransferase (CAT) activity and on the binding of HSF to the heat shock element (HSE) by a gel mobility shift assay with extracts of COLO 320DM cells. Quercetin inhibited heat-induced CAT activity in COS-7 and COLO 320DM cells which were transfected with plasmids bearing the CAT gene under the control of the promoter region of the human HSP70 gene. Treatment with quercetin inhibited the binding of HSF to the HSE in whole-cell extracts activated in vivo by heat shock and in cytoplasmic extracts activated in vitro by elevated temperature or by urea. The binding of HSF activated in vitro by Nonidet P-40 was not suppressed by the addition of quercetin. The formation of the HSF-HSE complex was not inhibited when quercetin was added only during the binding reaction of HSF to the HSE after in vitro heat activation. Quercetin thus interacts with HSF and inhibits the induction of HSPs after heat shock through inhibition of HSF activation.
Mol Cell Biol 1992 Aug
PMID:Inhibition of the activation of heat shock factor in vivo and in vitro by flavonoids. 132 38

Mitochondria contain a nuclear-encoded heat shock protein, HSP60, which functions as a chaperonin in the post-translational assembly of multimeric proteins encoded by both nuclear and mitochondrial genes. We have isolated and sequenced full-length complementary DNAs coding for this mitochondrial chaperonin in Arabidopsis thaliana and Zea mays. Southern-blot analysis indicates the presence of a single hsp60 gene in the genome of A. thaliana. There is a high degree of homology at the predicted amino acid levels (43 to 60%) between plant HSP60s and their homologues in prokaryotes and other eukaryotes which indicates that these proteins must have similar evolutionarily conserved functions in all organisms. Northern- and western-blot analyses indicate that the expression of the hsp60 gene is developmentally regulated during seed germination. It is also heat-inducible. Developmental regulation of the (beta-subunit of F1-ATPase, an enzyme complex that is involved in the cyanide-sensitive mitochondrial electron transport system, indicates that imbibed embryos undergo rapid mitochondrial biogenesis through the early stages of germination. Based on the functional role of HSP60 in macromolecular assembly, these data collectively suggest that the presence of higher levels of HSP60 is necessary during active mitochondrial biogenesis, when the need for this protein is greatest in assisting the rapid assembly of the oligomeric protein structures.
Plant Mol Biol 1992 Mar
PMID:cDNA clones encoding Arabidopsis thaliana and Zea mays mitochondrial chaperonin HSP60 and gene expression during seed germination and heat shock. 134 37

It has recently been reported that incubation of avian progesterone receptors, mouse glucocorticoid receptors, or the viral tyrosine kinase pp60src with rabbit reticulocyte lysate reconstitutes their association with the 90 kDa heat shock protein, hsp90. The reassociation is thought to require unfolding of the steroid receptor or pp60src before hsp90 can bind. The unfoldase activity may be provided by hsp70, which is also present in the reconstituted receptor heterocomplex. In this paper we review evidence that hsp70 and hsp90 are associated in cytosolic heterocomplexes that contain a limited number of other proteins. From an analysis of known receptor-hsp interactions and a predicted direct interaction between hsp90 and hsp70 we have developed an admittedly very speculative model of glucocorticoid receptor unfolding and stabilization. One important feature of the model is that the receptor becomes attached to a heat shock protein heterocomplex rather than undergoing independent unfolding and stabilization events. The model requires that hsp70 and hsp90 bind directly to the receptor at independent sites. Importantly, the model accommodates the stoichiometry of 2 hsp90 per 1 molecule of receptor that has been assayed in the untransformed GR heterocomplex in cytosols prepared from hormone-free cells.
J Steroid Biochem Mol Biol 1992 Mar
PMID:A model of glucocorticoid receptor unfolding and stabilization by a heat shock protein complex. 137 96

Four distinct linear epitopes localized within species-specific sequences at the carboxy-terminal end of the 71 kDa heat shock protein of M. tuberculosis have been identified by scanning 94 overlapping peptides with 13 human sera. One epitope ("C") of entirely M. tuberculosis-specific core sequence (GEAGPG) has been found immunogenic in smear-negative tuberculosis, but not in non-tuberculous mycobacterial diseases. This peptide appears to be a valuable candidate for further serodiagnostic evaluation.
Mol Immunol 1992 Sep
PMID:Localisation of linear epitopes at the carboxy-terminal end of the mycobacterial 71 kDa heat shock protein. 137 82

Expression of antisense RNA against eukaryotic translation initiation factor 4E (eIF-4E) in HeLa cells causes a reduction in the levels of both eIF-4E and eIF-4 gamma (p220) and a concomitant decrease in the rates of both cell growth and protein synthesis (De Benedetti, A., Joshi-Barve, S., Rinker-Schaffer, C., and Rhoads, R. E. (1991) Mol. Cell Biol. 11, 5435-5445). The synthesis of most proteins in the antisense RNA-expressing cells (AS cells) is decreased, but certain proteins continue to be synthesized. In the present study, we identified many of these as stress-inducible or heat shock proteins (HSPs). By mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by reactivity with monoclonal antibodies generated against human HSPs, four of these were shown to be HSP 90, HSP 70, HSP 65, and HSP 27. The steady-state levels of HSP 90, 70, and 27 were elevated in relation to total protein in AS cells. Pulse labeling and immunoprecipitation indicated that HSP 90 and HSP 70 were synthesized more rapidly in AS cells than in control cells. The accelerated synthesis of HSPs in the AS cells was not due, however, to increased mRNA levels; the levels of HSP 90 and 70 mRNAs either remained the same or decreased after induction of antisense RNA expression. Actin mRNA, a typical cellular mRNA, was found on high polysomes in control cells but shifted to smaller polysomes in AS cells, as expected from the general decrease in translational initiation caused by eIF-4E and eIF-4 gamma depletion. HSP 90 and 70 mRNAs showed the opposite behavior; they were associated with small polysomes in control cells but shifted to higher polysomes in AS cells. These results demonstrate that HSP mRNAs have little or no requirement in vivo for the cap-recognition machinery and suggest that these mRNAs may utilize an alternative, cap-independent mechanism of translational initiation.
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PMID:Preferential translation of heat shock mRNAs in HeLa cells deficient in protein synthesis initiation factors eIF-4E and eIF-4 gamma. 140 Apr 17

In order to investigate the humoral immune response against Entamoeba histolytica a lambda ZapII cDNA library was constructed from trophozoites of the pathogenic E. histolytica strain SFL-3. The library was screened with serum IgG from a patient with invasive amoebiasis. Forty-nine immunopositive lambda clones were isolated and partial sequences from the inserts were obtained. By comparison of the sequences with the merged database MIPSX from the Martinsried Institute for Protein Sequences we were able to identify homologous proteins for 36 of the clones. Twenty-six of the clones encoded intracellular proteins, among these, the major part (16 clones) were highly homologous to the eukaryotic 70-kDa heat shock proteins (Hsps). The open reading frame of one complete clone encodes a protein of 656 amino acid residues of 71.5 kDa which has 69.8% sequence identity with the human Hsp70 protein. In a larger screening experiment only 3 out of 12 patients detected with their IgG the phage which expressed the 70-kDa heat shock protein(s).
Mol Biochem Parasitol 1992 Sep
PMID:Humoral immune response against a 70-kilodalton heat shock protein of Entamoeba histolytica in a group of patients with invasive amoebiasis. 143 58

We have isolated a full length cDNA that encodes a heat shock protein, hsp90, from a rat brain library and present the nucleotide sequence and deduced amino acid sequence. Comparison of the entire nucleotide sequence with mouse hsp84 and human hsp90 beta cDNAs reveal sequence similarities of 92 and 87%, respectively. The coding region of 2172 nucleotides corresponds to a polypeptide chain of 724 amino acids. Comparison with mouse hsp84 and human hsp90 beta amino acid sequences indicates a similarity of 97%, respectively. Characterization of the constitutive expression of this cDNA both by RNA blot hybridization and immunoblotting, reveals that it is expressed in all rat tissues examined. Hsp90 has been shown to form a transient complex with steroid hormone receptors. In order to further elucidate the role of hsp90 in the endocrine response of cells, we have examined the effects of dexamethasone and RU38486 on the level of hsp90 mRNA in a system in which glucocorticoids down-regulate glucocorticoid receptor mRNA levels. In this system, a subtle but reproducible approx. 2-fold decrease in hsp90 mRNA levels is observed after 48 h treatment with dexamethasone.
J Steroid Biochem Mol Biol 1992 Sep
PMID:Cloning and regulation by glucocorticoid receptor ligands of a rat hsp90. 152 42


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