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Abstract
The p53 tumour suppressor protein is regulated by ubiquitin-mediated proteasomal degradation. In normal cells p53 is constitutively ubiquitylated by the Mdm2 ubiquitin ligase. When the p53 response is activated by stress signals p53 levels rise due to inhibition of this degradative pathway. Here we show that p53 is modified by the small ubiquitin-like protein SUMO-1 at a single site, K386, in the C-terminus of the protein. Modification in vitro requires only SUMO-1, the SUMO-1 activating enzyme and ubc9. SUMO-1 and ubiquitin modification do not compete for the same lysine acceptor sites in p53. Overexpression of SUMO-1 activates the transcriptional activity of wild-type p53, but not K386R p53 where the SUMO-1 acceptor site has been mutated. The SUMO-1 modification pathway therefore acts as a potential regulator of the p53 response and may represent a novel target for the development of therapeutically useful modulators of the p53 response.
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52
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Garrido C, Bruey JM, Fromentin A, Hammann A, Arrigo AP, Solary E. HSP27 inhibits cytochrome c-dependent activation of procaspase-9. FASEB J 1999; 13:2061-70. [PMID: 10544189 DOI: 10.1096/fasebj.13.14.2061] [Citation(s) in RCA: 359] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have previously shown that the small heat shock protein HSP27 inhibited apoptotic pathways triggered by a variety of stimuli in mammalian cells. The present study demonstrates that HSP27 overexpression decreases U937 human leukemic cell sensitivity to etoposide-induced cytotoxicity by preventing apoptosis. As observed for Bcl-2, HSP27 overexpression delays poly(ADP-ribose)polymerase cleavage and procaspase-3 activation. In contrast with Bcl-2, HSP27 overexpression does not prevent etoposide-induced cytochrome c release from the mitochondria. In a cell-free system, addition of cytochrome c and dATP to cytosolic extracts from untreated cells induces the proteolytic activation of procaspase-3 in both control and bcl-2-transfected U937 cells but fails to activate procaspase-3 in HSP27-overexpressing cells. Immunodepletion of HSP27 from cytosolic extracts increases cytochrome c/dATP-mediated activation of procaspase-3. Overexpression of HSP27 also prevents procaspase-9 activation. In the cell-free system, immunodepletion of HSP27 increases LEDH-AFC peptide cleavage activity triggered by cytochrome c/dATP treatment. We conclude that HSP27 inhibits etoposide-induced apoptosis by preventing cytochrome c and dATP-triggered activity of caspase-9, downstream of cytochrome c release.
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Affiliation(s)
- C Garrido
- INSERM U517, Groupe Biologie et Thérapie des Cancers (JE 515), Faculty of Medicine and Pharmacy, 21033 Dijon, France.
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53
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Abstract
The family of glutathione peroxidases comprises four distinct mammalian selenoproteins. The classical enzyme (cGPx) is ubiquitously distributed. According to animal, cell culture and inverse genetic studies, its primary function is to counteract oxidative attack. It is dispensible in unstressed animals, and accordingly ranks low in the hierarchy of glutathione peroxidases. The gastrointestinal isoenzyme (GI-GPx) is most related to cGPx and is exclusively expressed in the gastrointestinal tract. It might provide a barrier against hydroperoxides derived from the diet or from metabolism of ingested xenobiotics. The extreme stability in selenium deficiency ranks this glutathione peroxidase highest in the hierarchy of selenoproteins and points to a more vital function than that of cGPx. Plasma GPx (pGPx) behaves similar to cGPx in selenium deficiency. It is directed to extracellular compartments and is expressed in various tissues in contact with body fluids, e.g., kidney, ciliary body, and maternal/fetal interfaces. It has to be rated as an efficient extracellular antioxidant device, though with low capacity because of the limited extracellular content of potential thiol substrates. Phospholipid hydroperoxide glutathione peroxidase (PHGPx), originally presumed to be a universal antioxidant enzyme protecting membrane lipids, appears to have adopted a variety of specific roles like silencing lipoxygenases and becoming an enzymatically inactive structural component of the mitochondrial capsule during sperm maturation. Thus, all individual isoenzymes are efficient peroxidases in principle, but beyond their mere antioxidant potential may exert cell- and tissue-specific roles in metabolic regulation, as is evident for PHGPx and may be expected for others.
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54
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Berengian AR, Parfenova M, Mchaourab HS. Site-directed spin labeling study of subunit interactions in the alpha-crystallin domain of small heat-shock proteins. Comparison of the oligomer symmetry in alphaA-crystallin, HSP 27, and HSP 16.3. J Biol Chem 1999; 274:6305-14. [PMID: 10037719 DOI: 10.1074/jbc.274.10.6305] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Site-directed spin labeling was used to investigate quaternary interactions along a conserved sequence in the alpha-crystallin domain of alphaA-crystallin, heat-shock protein 27 (HSP 27), and Mycobacterium tuberculosis heat-shock protein (HSP 16.3). In previous work, it was demonstrated that this sequence in alphaA-crystallin and HSP 27 forms a beta-strand involved in subunit contacts. In this study, the symmetry and geometry of the resulting interface were investigated. For this purpose, the pattern of spin-spin interactions was analyzed, and the number of interacting spins was determined in alphaA-crystallin and HSP 27. The results reveal a 2-fold symmetric interface consisting of two beta-strands interacting near their N termini in an antiparallel fashion. Remarkably, subunit interactions along this interface persist when the alpha-crystallin domains are expressed in isolation. Because this domain in alphaA-crystallin forms dimers and tetramers, it is inferred that interactions along this interface mediate the formation of a basic dimeric unit. In contrast, in HSP 16.3, spin-spin interactions are observed at only one site near the C terminus of the sequence. Furthermore, cysteine substitutions at residues flanking the N terminus resulted in the dissociation of the oligomeric structure. Analysis of the spin-spin interactions and size exclusion chromatography indicates a 3-fold symmetric interface. Taken together, our results demonstrate that subunit interactions in the alpha-crystallin domain of mammalian small heat-shock proteins assemble a basic building block of the oligomeric structure. Sequence divergence in this domain results in variations in the size and symmetry of the quaternary structure between distant members of the small heat-shock protein family.
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Affiliation(s)
- A R Berengian
- National Biomedical ESR Center, Biophysics Research Institute, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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55
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McMillan Carr V, Morimoto RI, Farbman AI. Development and further characterization of a small subclass of rat olfactory receptor neurons that shows immunoreactivity for the HSP70 heat shock protein. J Comp Neurol 1999. [DOI: 10.1002/(sici)1096-9861(19990215)404:3<375::aid-cne7>3.0.co;2-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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56
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Punyiczki M, Fésüs L. Heat shock and apoptosis. The two defense systems of the organism may have overlapping molecular elements. Ann N Y Acad Sci 1998; 851:67-74. [PMID: 9668607 DOI: 10.1111/j.1749-6632.1998.tb08978.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Stress response and apoptosis are two interrelated end points of the defense systems of living organisms. The molecular elements of the two have strong influences on each other. Ceramide formation and signal-induced phosphorylation cascades may be critical in determining the final fate of cells exposed to environmental changes.
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Affiliation(s)
- M Punyiczki
- Department of Biochemistry and Molecular Biology, University Medical School of Debrecen, Hungary.
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57
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Préville X, Schultz H, Knauf U, Gaestel M, Arrigo AP. Analysis of the role of Hsp25 phosphorylation reveals the importance of the oligomerization state of this small heat shock protein in its protective function against TNFα- and hydrogen peroxide-induced cell death. J Cell Biochem 1998. [DOI: 10.1002/(sici)1097-4644(19980615)69:4<436::aid-jcb5>3.0.co;2-o] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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58
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Zheng J, Luo W, Tanzer ML. Aggrecan synthesis and secretion. A paradigm for molecular and cellular coordination of multiglobular protein folding and intracellular trafficking. J Biol Chem 1998; 273:12999-3006. [PMID: 9582335 DOI: 10.1074/jbc.273.21.12999] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Each globular domain of exported multiglobular proteins putatively undergoes chaperone surveillance in the endoplasmic reticulum lumen. It is difficult to visualize how surveillance of multiple globular domains might be orchestrated and regulated. Aggrecan core protein has been used as a prototype for this problem by examining transfection of informative constructs into Chinese hamster ovary cells. The salient results are as follows: 1) aggrecan's N-terminal G1 domain is minimally secreted, and its flanking Golgi reporter sites are not decorated with glycsoaminoglycan chains; in contrast, its C-terminal G3 domain is readily secreted with flanking GAG chains, and G3 also facilitates G1 secretion; 2) G3 but not G1 can be intracellularly cross-linked to chaperone Hsp25; 3) G3 and Hsp25 remain noncovalently bound and are secreted together when G3 is situated N-terminal to its normal location; 4) exon 15, which encodes the center of G3's C-lectin subdomain, is necessary and sufficient for G3 secretion. A model is proposed in which Hsp25 piggybacks onto nascent G3 in the cytosol during a translocational pause and enters the ER lumen with G3, and once G3 properly folds, Hsp25 releases G3 and recycles to the nucleus while G3 continues to the Golgi stacks, providing passage for the entire core protein.
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Affiliation(s)
- J Zheng
- Department of Biostructure and Function, School of Dental Medicine, University of Connecticut Health Center, Farmington, Connecticut 06030-3705, USA
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59
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Kretz-Remy C, Bates EE, Arrigo AP. Amino acid analogs activate NF-kappaB through redox-dependent IkappaB-alpha degradation by the proteasome without apparent IkappaB-alpha phosphorylation. Consequence on HIV-1 long terminal repeat activation. J Biol Chem 1998; 273:3180-91. [PMID: 9452429 DOI: 10.1074/jbc.273.6.3180] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We report here that amino acid analogs, which activate hsp70 promoter, are powerful transcriptional activators of human immunodeficiency virus 1 (HIV-1) long terminal repeat (LTR), an activation which was impaired when the two kappaB sites present in the LTR were mutated or deleted. Amino acid analogs also stimulated the transcription of a kappaB-controlled reporter gene. Upon treatment with amino acid analogs, the two NF-kappaB subunits (p65 and p50), which are characterized by a relatively long half-life, redistributed into the nucleus where they bound to kappaB elements. This phenomenon, which began to be detectable after 1 h of treatment, was concomitant with the degradation of the short lived inhibitory subunit IkappaB-alpha by the proteasome. However, contrasting with other NF-kappaB inducers that trigger IkappaB-alpha degradation through a phosphorylation step, amino acid analogs did not change IkappaB-alpha isoform composition. Antioxidant conditions inhibited amino acid analog stimulatory action toward NF-kappaB. This suggests that aberrant protein conformation probably generates a pro-oxidant state that is necessary for IkappaB-alpha proteolysis by the proteasome. Moreover, this activation of NF-kappaB appeared different from that mediated by endoplasmic reticulum overload as it was not inhibited by calcium chelation.
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Affiliation(s)
- C Kretz-Remy
- Laboratoire du Stress Cellulaire, Centre de Génétique Moléculaire et Cellulaire, CNRS-UMR 5534, Université Claude Bernard Lyon-I, 69622 Villeurbanne Cedex, France
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60
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The Heat Shock Response and Tissue Protection. DELAYED PRECONDITIONING AND ADAPTIVE CARDIOPROTECTION 1998. [DOI: 10.1007/978-94-011-5312-6_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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61
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Abstract
Mucins are widely distributed in mucous secretion fluids or are associated with plasma membranes. Up to now 9 genes of epithelial mucins have been identified, distributed over five chromosomes. Superposed on the genetic diversity, each type of mucin displays heterogeneity in oligosaccharide composition, including the terminal sugar residues. On top of that there is variation between individuals brought about by blood group antigens. Heterogeneity is further incited by the degree of sulfation. This tremendous structural heterogeneity endows mucin molecules with properties suggestive for a multifunctional role. The major biological function assigned to mucins is still the protection of tissues covered by the mucous gel. Current knowledge on the specific biological functions of the sulfate residues is fragmentary and periphrastic. Glycosylation including sulfation appears to be subject to modification under pathological conditions. There is evidence that sulfation rate-limits bacterial degradation of mucins. Moreover, accumulating data focus towards their involvement in recognition phenomena. Sulfate residues on blood group related structures provoke specific epitopes for selective interaction with microorganisms e.g. Helicobacter pylori. A distinct class of mucins acts as ligands for selectins, crucial in cellular recognition processes like cellular homing of lymphocytes. Whereas in earlier days mucins were only seen as water-binding molecules, protecting the underlying mucosa against harmful agents, the current picture of these molecules is characterized by the selective interaction with their environment, including epithelial-, and endothelial cells and microorganisms, thereby regulating a great number of biological processes. However, the specific role of sulfate remains to be further elucidated.
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Affiliation(s)
- A V Nieuw Amerongen
- Dept. of Oral Biochemistry, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands
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62
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Mehlen P, Mehlen A, Godet J, Arrigo AP. hsp27 as a switch between differentiation and apoptosis in murine embryonic stem cells. J Biol Chem 1997; 272:31657-65. [PMID: 9395507 DOI: 10.1074/jbc.272.50.31657] [Citation(s) in RCA: 172] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Small stress proteins are developmentally regulated and linked to cell growth and differentiation. The early phase of murine embryonic stem (ES) cell differentiation, characterized by a gradual growth arrest, is accompanied with hsp27 transient accumulation. This differentiation process also correlated with changes in hsp27 phosphorylation and oligomerization. The role of hsp27 was investigated in ES clones stably transfected with murine or human hsp27 genes, placed in sense or antisense orientation. Several clones were obtained that either underexpressed endogenous murine hsp27 or overexpressed murine or human hsp27. Maintained undifferentiated, these clones showed similar growth rates. We report here that hsp27 constitutive overexpression enhanced the differentiation-mediated decreased rate of ES cell proliferation but did not alter morphological changes. In contrast, hsp27 underexpression, which attenuated cell growth arrest, induced differentiation abortion because of an overall cell death by apoptosis. Recently, we showed that hsp27 interfered with cell death probably because of its ability to modulate intracellular glutathione. hsp27 accumulation during ES cell differentiation was also correlated with an increase in glutathione, which was attenuated by hsp27 down-expression. Hence, hsp27 transient expression seems essential for preventing differentiating ES cells from undergoing apoptosis, a switch that may be redox regulated.
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Affiliation(s)
- P Mehlen
- Laboratoire du Stress Cellulaire, Centre de Génétique Moléculaire et Cellulaire, CNRS UMR-5534, Université Claude Bernard Lyon-I, 69622 Villeurbanne Cédex, France
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63
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Mehlen P, Hickey E, Weber LA, Arrigo AP. Large unphosphorylated aggregates as the active form of hsp27 which controls intracellular reactive oxygen species and glutathione levels and generates a protection against TNFalpha in NIH-3T3-ras cells. Biochem Biophys Res Commun 1997; 241:187-92. [PMID: 9405255 DOI: 10.1006/bbrc.1997.7635] [Citation(s) in RCA: 180] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The mammalian small stress protein hsp27 is an oligomeric phosphoprotein which interferes with the cell death induced by several stimuli. In that sense, we and others have recently shown that human hsp27 expression induced cellular protection against tumor necrosis factor (TNFalpha), a protection which depends on the ability of hsp27 to decrease the level of reactive oxygen species and increase that of glutathione. Here, we have analyzed unphosphorylatable mutants of human hsp27 in which serines 15, 78, and 82 were replaced by alanines, glycines, or aspartic acids. Depending on the amino acid which was used to substitute the serine sites, a different pattern of hsp27 structural organization was observed. Alanine substitution generated large hsp27 aggregates while glycine and aspartic acid did the reverse. Hence, these phosphorylatable serine residues can be considered as key elements affecting hsp27 structural organization. Only the large aggregates of hsp27 were able to modulate reactive oxygen species and glutathione and generated cellular protection against TNFalpha. Moreover, using drugs that modulate the intracellular level of glutathione, we show that an increase in glutathione by itself was sufficient to generate large hsp27 structures while the reverse was observed in the case of glutathione deprivation.
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Affiliation(s)
- P Mehlen
- Centre de Génétique Moléculaire et Cellulaire, Université Claude Bernard LYON-I, Villeurbanne, F-69622, France
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64
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Konishi H, Matsuzaki H, Tanaka M, Takemura Y, Kuroda S, Ono Y, Kikkawa U. Activation of protein kinase B (Akt/RAC-protein kinase) by cellular stress and its association with heat shock protein Hsp27. FEBS Lett 1997; 410:493-8. [PMID: 9237690 DOI: 10.1016/s0014-5793(97)00541-3] [Citation(s) in RCA: 209] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Protein kinase B (PKB, also named as Akt or RAC-protein kinase), that is activated by cellular stress such as heat shock and hyperosmotic treatment, was revealed to be activated by oxidative stress and by chemical stressors of CdCl2 and NaAsO2 by measuring the activity of the enzyme immunoprecipitated from the transfected COS-7 cells. Upon stress treatment, a 30-kDa phosphoprotein was co-immunoprecipitated with PKB from the cells metabolic labeled with [32P]orthophosphate. The phosphoprotein was identified as Hsp27, a small heat shock protein, by immunoblot analysis and co-immunoprecipitation. The association of Hsp27 was specific to PKB as the heat shock protein was not co-immunoprecipitated with other protein kinases such as protein kinase C and PKN. When the cells were treated with H2O2, PKB was activated gradually and the association of Hsp27 with PKB increased concurrently with the enhancement of PKB activity. In heat-shocked cells, activation of PKB and the association of Hsp27 were detected immediately after the treatment, and the association of the heat shock protein decreased while PKB kept stimulated activity when the cells were further incubated at 37 degrees C. These results suggest that Hsp27 is involved in the activation process of PKB in the signal transduction pathway of various forms of stress.
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Affiliation(s)
- H Konishi
- Biosignal Research Center, Kobe University, Japan
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65
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Mehlen P, Schulze-Osthoff K, Arrigo AP. Small stress proteins as novel regulators of apoptosis. Heat shock protein 27 blocks Fas/APO-1- and staurosporine-induced cell death. J Biol Chem 1996; 271:16510-4. [PMID: 8663291 DOI: 10.1074/jbc.271.28.16510] [Citation(s) in RCA: 488] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Small stress protein expression enhances the survival of mammalian cells exposed to numerous injuries that induce necrotic cell death. The cell surface receptor Fas/APO-1 and its ligand have been recently identified as important mediators of apoptosis. Here, we show that constitutive expression of human heat shock protein (hsp)27 in murine L929 cells blocks Fas/APO-1-mediated cell death. Expression of human hsp27 prevented anti-APO-1-induced DNA fragmentation and morphological changes. These results strongly suggest that human hsp27 acts as a cellular inhibitor of Fas/APO-1-induced apoptosis. We also report that the expression of small stress proteins from different species, such as human hsp27, Drosophila Dhsp27, or human alphaB-crystallin, confers resistance to apoptotic cell death induced by staurosporine, a protein kinase C inhibitor. Hence, small stress proteins are novel regulators that are able to block apoptosis induced by different pathways.
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Affiliation(s)
- P Mehlen
- Laboratoire du Stress Cellulaire, Centre de Génétique Moléculaire et Cellulaire, CNRS UMR-5534, Université Claude Bernard Lyon-I, 69622 Villeurbanne, France
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66
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Hoch B, Lutsch G, Schlegel WP, Stahl J, Wallukat G, Bartel S, Krause EG, Benndorf R, Karczewski P. HSP25 in isolated perfused rat hearts: localization and response to hyperthermia. Mol Cell Biochem 1996; 160-161:231-9. [PMID: 8901478 DOI: 10.1007/bf00240054] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent investigations concentrate on the correlation between the myocardial expression of the inducible 70-kDa heat shock protein (HSP70i) by different stress conditions and its possible protective effects. Only few studies have focused on the involvement of small heat shock proteins in this process. We analyzed the location of the small heat shock protein HSP25 in isolated cardiomyocytes as well as its location and induction in isolated perfused hearts of rats. By immunofluorescence microscopy HSP25 was found to colocalize with actin in the I-band of myofibrils in cardiomyocytes of isolated perfused hearts as well as in isolated neonatal and adult cardiomyocytes. Hyperthermic perfusion of isolated hearts for 45 min resulted in modulation of different parameters of heart function and in induction of HSP25 is constitutively expressed even in normothermic perfused (44-46 degrees C) were lethal with respect to the contractile function of the hearts. Compared to control hearts perfused at 37 degrees C, significant increases during hyperthermic perfusion at 42 degrees C and 43 degrees C were obtained for heart rate, contraction velocity and relaxation velocity. In response to hyperthermia at 43 degrees C and after subsequent normothermic perfusion for 135 min at 37 degrees C, left to control values immediately after the period of heat treatment. HSP25 is constitutively expressed even in normothermic perfused hearts as shown by Western blotting. Hyperthermia increased the content of HSP25 only in the left ventricular tissue. In contrast, HSP70i was strongly induced in all analyzed parts of the myocardium (left ventricle, right ventricle, septum). Our findings suggest a differential regulation of HSP25 and HSP70i expression in response to hyperthermia in isolated perfused hearts. The constitutively expressed HSP25 seems to be located adjacent to the myofibrils which implies a specific role of this protein even under unstressed conditions for the contractile function of the myocardium.
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Affiliation(s)
- B Hoch
- Max Delbrück Centre for Molecular Medicine, Dept. Molecular Cardiology, Berlin-Buch, Germany
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67
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Mehlen P, Kretz-Remy C, Préville X, Arrigo AP. Human hsp27, Drosophila hsp27 and human alphaB-crystallin expression-mediated increase in glutathione is essential for the protective activity of these proteins against TNFalpha-induced cell death. EMBO J 1996; 15:2695-706. [PMID: 8654367 PMCID: PMC450205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Expression of small stress proteins (shsp) enhances the survival of mammalian cells exposed to heat or oxidative injuries. Recently, we have shown that the expression of shsp from different species, such as human hsp27, Drosophila hsp27 or human alphaB-crystallin protected murine L929 cells against cell death induced by tumor necrosis factor (TNFalpha), hydrogen peroxide or menadione. Here, we report that, in growing L929 cell lines, the presence of these shsp decreased the intracellular level of reactive oxygen species (ROS). shsp expression also abolished the burst of intracellular ROS induced by TNFalpha. Several downstream effects resulting from the TNFalpha-mediated ROS increment, such as NF-kappaB activation, lipid peroxidation and protein oxidation, were inhibited by shsp expression. We also report that the expression of these different shsp raised the total glutathione level in both L929 cell lines and transiently transfected NIH 3T3-ras cells. This phenomenon was essential for the shsp-mediated decrease in ROS and resistance against TNFalpha. Our results therefore suggest that the protective activity shared by human hsp27, Drosophila hsp27 and human alphaB-crystallin against TNFalpha-mediated cell death and probably other types of oxidative stress results from their conserved ability to raise the intracellular concentration of glutathione.
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Affiliation(s)
- P Mehlen
- Laboratoire du Stress Cellulaire, Centre de Génétique Moléculaire etCellulaire, CNRS-UMR-5534, France
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68
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Kretz-Remy C, Mehlen P, Mirault ME, Arrigo AP. Inhibition of I kappa B-alpha phosphorylation and degradation and subsequent NF-kappa B activation by glutathione peroxidase overexpression. J Cell Biol 1996; 133:1083-93. [PMID: 8655581 PMCID: PMC2120847 DOI: 10.1083/jcb.133.5.1083] [Citation(s) in RCA: 216] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We report here that both kappa B-dependent transactivation of a reporter gene and NF-kappa B activation in response to tumor necrosis factor (TNF alpha) or H2O2 treatments are deficient in human T47D cell transfectants that overexpress seleno-glutathione peroxidase (GSHPx). These cells feature low reactive oxygen species (ROS) levels and decreased intracellular ROS burst in response to TNF alpha treatment. Decreased ROS levels and NF-kappa B activation were likely to result from GSHPx increment since these phenomena were no longer observed when GSHPx activity was reduced by selenium depletion. The cellular contents of the two NF-kappa B subunits (p65 and p50) and of the inhibitory subunit I kappa B-alpha were unaffected by GSHPx overexpression, suggesting that increased GSHPx activity interfered with the activation, but not the synthesis or stability, of Nf-kappa B. Nuclear translocation of NF-kappa B as well as I kappa B-alpha degradation were inhabited in GSHPx-overexpressing cells exposed to oxidative stress. Moreover, in control T47D cells exposed to TNF alpha, a time correlation was observed between elevated ROS levels and I kappa B-alpha degradation. We also show that, in growing T47D cells, GSHPx overexpression altered the isoform composition of I kappa B-alpha, leading to the accumulation of the more basic isoform of this protein. GSHPx overexpression also abolished the TNF alpha-mediated transient accumulation of the acidic and highly phosphorylated I kappa B-alpha isoform. These results suggest that intracellular ROS are key elements that regulate the phosphorylation of I kappa B-alpha, a phenomenon that precedes and controls the degradation of this protein, and then NF-kappa B activation.
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Affiliation(s)
- C Kretz-Remy
- Centre National de la Recherche Scientifique Unité Mixte de Recherche Université Claude Bernard Lyon-I, France
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