Erythrophagocytosis induces heat shock protein synthesis by human monocytes-macrophages.

Exposure of cells to elevated temperatures and other environmental stresses results in the expression of specific genes encoding the so-called heat shock proteins (HSPs). Since exogenous H2O2 induces in human monocytes the synthesis of HSPs, and previous induction of HSPs protects these cells from oxidative injury, we investigated whether HSP synthesis was also induced during generation of reactive oxygen species by the phagocyte itself during phagocytosis. As a model system, we analyzed the effects of erythrophagocytosis on protein synthesis by the human premonocytic line U937, in which phagocytosis is induced during differentiation with 1,25-dihydroxyvitamin D3. Exposure to whole erythrocytes, but not to erythrocyte ghosts, induced in the phagocytic cells only the synthesis of the 70- and 83- to 90-kDa HSPs and a 32-kDa oxidation-related stress protein identical by partial peptide mapping to heme oxygenase. The radioprotective aminothiol N-(2'-mercaptoethyl)-1,3-propanediamine (WR-1065), which can substitute for glutathione as hydrogen donor, prevented this induction. These results suggest that oxygen free radicals generated in the presence of hemoglobin-derived iron and consecutive glutathione depletion are involved in induction of stress protein synthesis during erythrophagocytosis. HSPs synthesized during phagocytosis may play a role in the phagocyte's defense mechanisms and in protective immunity.     

Regulation of heat shock protein synthesis by gonadotropins in cultured granulosa cells

Primary cultures of granulosa cells can be stimulated to produce large amounts of progesterone by gonadotropins. This stimulation is associated with significant changes in the expression of several major proteins, as revealed by two-dimensional gel electrophoresis. These changes include a decrease in the synthesis of actin cytoskeleton proteins and an increase in the synthesis of a few abundant proteins, one of which is a mammalian heat shock protein, hsp90. Under culture conditions that have previously been shown to bring about the maturation of granulosa cells into progesterone-producing cells (i.e. treatment with gonadotropins or cAMP or by disrupting the actin cytoskeleton with cytochalasin), an increased synthesis of hsp90 could be demonstrated. Freshly isolated granulosa cells isolated from PMSG-treated animals synthesize hsp90 at a much higher level than cells isolated from diethylstilbestrol-treated rats. Kinetic studies have shown that granulosa cells isolated from diethylstilbestrol- or PMSG-treated rats synthesize high levels of hsp90 if maintained in culture in the presence of gonadotropins, but rapidly decrease hsp90 synthesis in the absence of gonadotropins and increase the synthesis of actin cytoskeleton proteins. Furthermore, in cells cultured for 48 h in the presence of cytochalasin-B followed by incubation for 24 h in the absence of the drug, the synthesis of hsp90 and several other proteins characteristic of mature granulosa cells decreased, while that of the actin cytoskeleton increased. In vitro translation assays and Northern blot analyses suggest that hsp90 synthesis in gonadotropin-stimulated cells may be regulated by mRNA translational efficiency. Taken together with recent findings in which hsp90 was identified in complex with cytoplasmic steroid receptors and the hormonal regulation of hsp90 content in target tissues, the results support the notion that hsp90 plays a role in the control of steroid hormone action.     

Recovery of protein synthesis after heat shock: prior heat treatment affects the ability of cells to translate mRNA.

A mild heat shock at 35 degrees C, which induces heat shock gene expression, greatly enhances survival and the recovery of protein synthesis in Drosophila cells after a higher temperature heat shock. The 35 degrees C treatment is also effective in preventing heat-induced developmental defects in pupae. We show here that the major larval mRNAs are present in approximately normal (25 degrees C) concentrations after a 40.1 degrees C heat shock whether or not the animals receive a pretreatment. This indicates that the pretreatment affects translation directly rather than messenger concentration. We also observe selective translation of heat shock messages and some 25 degrees C messages during recovery from heat shock.     

Inhibition of heat shock protein synthesis by heat-inducible antisense RNA.

We show that antisense RNAs transcribed from genes that are stably integrated into the genome can be used to inhibit the expression of an endogenous cellular gene. Drosophila tissue culture cells were stably transformed with a gene encoding a heat-inducible RNA complementary to the message for hsp26, one of the small heat shock proteins. These cells produced much less hsp26 after heat shock than did untransformed cells. The inhibition was highly specific: expression of the closely related heat shock proteins hsp22, hsp23, and hsp28 was unaffected. By varying the copy number of the antisense gene, the degree of inhibition was varied over a broad range. Reducing the rate of hsp26 synthesis did not appear to affect the synthesis of any other protein during either heat shock or recovery.     

Alpha-crystallin/small heat shock protein has autokinase activity.

The alpha-crystallins (alpha A and alpha B) are major water-soluble proteins of the transparent eye lens that are expressed in a variety of tissues and can function as molecular chaperones. alpha B-crystallin is also a small heat shock protein associated with numerous degenerative diseases and abnormal growth patterns. Previous experiments have shown that alpha A-and alpha B-crystallin are phosphorylated on specific serine residues by a cAMP-dependent pathway. Here we provide evidence that either total bovine alpha-crystallin or its isolated polypeptides can autophosphorylate serine by a cAMP-independent mechanism in the presence of Mg2+ and [gamma-32P]ATP; the autophosphorylated products isoelectrically focus with the authentic phosphorylated forms of the alpha-crystallin polypeptides. Thus, the alpha A- and alpha B-crystallin/small heat shock protein polypeptides are enzyme-crystallins which may be involved in metabolic pathways important for the development, maintenance, or pathology of the lens and other tissues.     

Short-chain fatty acids induce intestinal epithelial heat shock protein 25 expression in rats and IEC 18 cells

BACKGROUND & AIMS: Because short-chain fatty acids (SCFAs) and heat shock proteins (hsps) confer protection to intestinal epithelia cells (IECs), we studied whether SCFAs modulate IEC hsp expression. METHODS: Hsp 25, hsp72, and hsc73 protein expression in rat intestinal tissues and IEC-18 cells were determined by Western blot and immunohistochemistry. Cell survival under conditions of oxidant stress (monochloramine) was determined using (51)Cr release in hsp25 cDNA anti-sense and sense-transfected cells expressing minimal and increased hsp25, respectively. RESULTS: Butyrate induces a time- and concentration-dependent increase in hsp25, but not hsp72 or hsc73, protein expression in rat IEC-18 cells but not 3T3 fibroblasts. Other SCFAs, including the poorly metabolized isobutyate, also induced selective expression of hsp25. Butyrate treatment significantly improved the ability of IEC-18 cells to withstand oxidant (monochloramine) injury. This effect could be blocked in cells in which hsp25 induction by butyrate was blocked by stable hsp25 antisense transfection. Additionally, hsp25-transfected overexpressing IEC-18 cells showed increased resistance to monochloramine. In vivo, increasing dietary fiber increased colonic, but not proximal, ileal hsp25 while having no effect on hsp72 or hsc73 expression. CONCLUSIONS: SCFAs, the predominant anions of colonic fluid derived from bacterial flora metabolism of luminal carbohydrates, protect IECs against oxidant injury, an effect mediated in part by cell-specific hsp25 induction.     

Identification of heat shock protein 27 as a radioresistance-related protein in nasopharyngeal carcinoma cells

Purpose

To identify the proteins involved in radioresistance in nasopharyngeal cancer (NPC) cells.

Methods

Sublethal ionizing radiation was applied to establish a radioresistant NPC cell line from its parental NPC cell line CNE1. Clonogenic survival assay, cell growth assay and flow cytometry analysis were used to examine the difference of radiosensitivity in the radioresistant CNE1 cells (CNE1-IR) and control CNE1 cells. Comparative proteomics was performed to identify the differential proteins in the two cell lines. Association of HSP27, one of upregulated proteins in CNE1-IR cells, with NPC cell radioresistance was selected for further investigation using antisense oligonucleotides (ASOs), clonogenic survival assay, Hoechst 33258 staining of apoptotic cells and MTT assay of cell viability.

Results

Radioresistant NPC cell line CNE1-IR derived from its parental cell line CNE1 was established. Thirteen differential proteins in the CNE1-IR and CNE1 cells were identified by proteomics, and differential expression of HSP27, one of identified proteins, was selectively confirmed by western blot. Inhibition of HSP27 expression by HSP27 ASOs decreased clonogenic survival and cell viability and increased cell apoptosis of CNE1-IR cells after irradiation, that is, enhanced radiosensitivity of CNE1-IR cells.

Conclusion

The data suggest that HSP27 is a radioresistant protein in NPC cells, and its upregulation may be involved in the NPC radioresistance.     

Vaccination against autoimmune mouse diabetes with a T-cell epitope of the human 65-kDa heat shock protein.

Insulin-dependent diabetes mellitus is caused by autoimmune destruction of the insulin-producing beta cells resident in the pancreatic islets. We recently discovered that the pathogenesis of diabetes in NOD strain mice was associated with T-cell reactivity to an antigen cross-reactive with a mycobacterial 65-kDa heat shock protein. To identify peptide epitopes critical to the insulin-dependent diabetes mellitus of NOD mice, we studied the specificities of helper T-cell clones capable of causing hyperglycemia and diabetes. We now report the identification of a functionally important peptide within the sequence of the human variant of the 65-kDa heat shock protein molecule. T-cell clones recognizing this peptide mediate insulitis and hyperglycemia. Alternatively, the T cells can be attenuated and used as therapeutic T-cell vaccines to abort the diabetogenic process. Moreover, administration of the peptide itself to NOD mice can also down-regulate immunity to the 65-kDa heat shock protein and prevent the development of diabetes. Thus, T-cell vaccination and specific peptide therapy are feasible in spontaneous autoimmune diabetes.     

Functional interaction of heat shock protein GroEL with an RNase E-like activity in Escherichia coli.

The highly specific endoribonuclease activities of RNase E (which processes ribosomal 9S RNA into p5S RNA) and RNase K (which initiates decay of the ompA mRNA) are inferred to play a central role in RNA processing and mRNA decay in Escherichia coli. In vivo both activities are affected by a conditional mutation of the ams/rne gene that seems to be complemented at nonpermissive temperatures by a fragment of the groEL gene. Analysis of the relationship between the two nucleases and the heat shock protein revealed that GroEL interacts functionally with an RNase E-like activity but not with an RNase K activity, a groEL mutation affected 9S RNA processing but not ompA mRNA cleavage, RNase E activity could be precipitated with an antibody against GroEL, and a highly purified GroEL preparation contained RNase E activity but not RNase K activity. When purifying RNase E activity, we obtained a preparation containing two major proteins of 60 and 17 kDa. The size and the N-terminal sequence identified the 60-kDa protein as GroEL.     

Decreased expression of heat shock protein 70 mRNA and protein after heat treatment in cells of aged rats.

The effect of aging on the induction of heat shock protein 70 (HSP70)-encoding gene expression by elevated temperatures was studied in cultures of lung- or skin-derived fibroblasts from young (5 mo) and old (24 mo) male Wistar rats. Although the kinetics of the heat shock response were found to be similar in the two age groups, we observed lower levels of induction of HSP70 mRNA and HSP70 protein in confluent primary lung and skin fibroblast cultures derived from aged animals. Additional experiments with freshly excised lung tissue showed a similar age-related decline in the heat-induced expression of HSP70.     

Regulation by heat shock protein 27 of osteocalcin synthesis in osteoblasts

We have previously reported that various stimuli, including sphingosine 1-phosphate, are able to induce heat shock protein (HSP) 27 in osteoblast-like MC3T3-E1 cells. However, the precise role of HSP27 in bone metabolism has not been satisfactory clarified. In this study, we investigated the effect of HSP27 on osteocalcin synthesis induced by bone morphogenetic protein (BMP)-4 or T? in these cells. In MC3T3-E1 cells, pretreatment with sphingosine 1-phosphate, sodium arsenite, or heat stress caused the attenuation of osteocalcin synthesis induced by BMP-4 or T? with concurrent HSP27 induction. To further investigate the effect of HSP27, we established stable HSP27-transfected cells. The osteocalcin synthesis was significantly reduced in the stable HSP27-transfected MC3T3-E1 cells and normal human osteoblasts compared with empty-vector transfected cells. On the other hand, anisomycin, a p38 MAPK activator, caused the phosphorylation of HSP27 in both sphingosine 1-phosphate-stimulated untransfected MC3T3-E1 cells and HSP27-transfected MC3T3-E1 cells. An immunofluorescence microscopy study showed that the phosphorylated HSP27 induced by anisomycin concentrated perinuclearly in these cells, in which it colocalized with the endoplasmic reticulum. We also established stable mutant-HSP27-transfected cells. Osteocalcin synthesis induced by either BMP-4 or T? was markedly suppressed in the nonphosphorylatable HSP27-overexpressing MC3T3-E1 cells compared with the phosphomimic HSP27-overexpressing cells. In contrast, the matrix mineralization was more obvious in nonphosphorylatable HSP27-overexpressing cells than that in phosphomimic HSP27-overexpressing cells. Taken together, these results strongly suggest that unphosphorylated HSP27 has an inhibitory effect on osteocalcin synthesis, but has a stimulatory effect on mineralization, in osteoblasts.     

Alpha B-crystallin is a small heat shock protein.

Sequence similarity between alpha B-crystallin and small heat shock proteins (HSPs) has prompted us to investigate whether alpha B-crystallin expression is induced by heat shock. Indeed, accumulation of alpha B-crystallin was detected immunologically in NIH 3T3 cells after incubation at elevated temperatures and after addition of Cd2+ or sodium arsenite to these cells. Two-dimensional gel electrophoresis revealed identity between alpha B-crystallin from eye lenses and from heat-treated fibroblasts. The promoter of the alpha B-crystallin gene was fused to the bacterial chloramphenicol acetyltransferase gene and was shown to confer heat inducibility on this reporter gene in transient transfection assays. A perfect heat shock element within the promoter region is likely to mediate this response. Small HSPs and alpha B-crystallin were shown to share the following two physical properties: (i) they form supramolecular structures with sedimentation values around 17 S and (ii) they are associated with the nucleus at high temperatures and are localized in the cytoplasm under normal conditions. We conclude that alpha B-crystallin has to be considered a member of the class of small HSPs.     

Isolation and functional analysis of a human 70,000-dalton heat shock protein gene segment.

A human 70-kDa heat shock protein (hsp70) gene segment has been isolated. The segment contains 3.15 kilobase pairs (kbp) of 5' nontranscribed sequence, an RNA leader of 119 bp, and a protein-coding region of 741 bp. The human protein sequence shows a high degree of homology to hsp70 sequences from other species. Expression experiments in Xenopus oocytes and mammalian cells indicate that a region that includes only 105 bp of 5' nontranscribed sequence contains all elements required for the efficient heat-controlled expression of the human gene. Two adjacent identical sequence elements, which are partly homologous to the Drosophila "heat shock consensus" sequence, are located 57 to 76 bp upstream from the capping site. Interestingly, the capping site itself is flanked by inverted repeat sequences.     

Axonal transport of a heat shock protein in the rabbit visual system.

Intraocular injection of [35S]methionine was used to demonstrate the pronounced induction of a 74-kDa heat shock protein in the rabbit retina after a 3 degrees C increase in body temperature was generated by intravenous administration of D-lysergic acid diethylamide. Two-dimensional polyacrylamide gel electrophoresis and fluorography revealed that the induced heat shock protein underwent axonal transport from retinal ganglion cells into the optic nerve and subsequently down the contralateral optic tract to synaptic termini in the visual projection area. Since the heat shock protein took more than 8 days to move down the optic nerve to the superior colliculus, it is transported by slow rather than by fast axonal transport.     

Circulating heat shock protein and heat shock protein antibody levels in established hypertension

OBJECTIVE: Serum Hsp60 and anti-Hsp65 antibody levels are raised in subjects with borderline hypertension, and there is an association between circulating Hsp60 levels and early atherosclerosis. Given the recognized relationship between hypertension and atherosclerosis, this study determined heat shock protein and heat shock protein antibody levels in subjects with established hypertension. METHODS: Samples from 111 men with hypertension were obtained from the European Lacidipine study on Atherosclerosis and samples from 75 normotensive controls were taken from a population-screening programme (diastolic pressure, 95 and 80 mmHg, respectively). Hsp60, Hsp70 and anti-human Hsp60, anti-human Hsp70 and anti-mycobacterial Hsp65 antibody levels were measured by enzyme immunoassay. Intima-media thickness (I-M) and the presence of carotid atherosclerosis were determined by ultrasonography. RESULTS: Hsp60, Hsp70 and anti-Hsp60 antibody levels in hypertension were similar to those in normotensive controls, whereas anti-Hsp70 and anti-Hsp65 antibody levels were elevated ( 0.001). Hsp60 levels and atherosclerosis were not associated. Anti-Hsp70 and anti-Hsp65 antibody levels were both associated with hypertension, independently of age, smoking habits and blood lipids. CONCLUSIONS: This study demonstrates elevated levels of selected heat shock protein antibodies in subjects with hypertension. Although the association between heat shock protein antibody levels and human cardiovascular stress/disease appears to be robust, the relationship of the latter with heat shock protein levels is more complex. Further studies are required before the factors inducing, and the clinical significance of, circulating heat shock proteins can be evaluated.     

The 60-kDa heat shock protein regulates energy rearrangement and protein synthesis to promote proliferation of multiple myeloma cells

To investigate the cellular mechanisms of multiple myeloma (MM), we used liquid chromatography-tandem mass spectrometry for proteomics analysis of CD138⁺ plasma cells from patients with MM and healthy controls. We found that the 60-kDa heat shock protein (HSP60, also known as HSPD1) was significantly upregulated in myeloma cells. HSP60 is an important chaperone protein that regulates the homeostasis of mitochondrial proteins and maintains mitochondrial function. Knockdown (KD) of HSP60 in myeloma cells resulted in inhibition of proliferation and reduced the quality of the mitochondria. Mitochondrial stress tests showed that HSP60 KD inhibited glycolysis and mitochondrial activity. Metabolomics showed a decrease in glycolysis and tricarboxylic acid cycle metabolites, and inhibited the formation of creatine and phosphocreatine by the reaction of S-adenosylmethionine (SAM) with amino acids mediated by demethyladenosine transferase 1, mitochondrial (TFB1M) and reduced energy storage substances. Moreover, HSP60 silencing influenced the synthesis of ribonucleotides and nicotinamide adenine dinucleotide phosphate (NADPH) by the pentose phosphate pathway to inhibit cell proliferation. HSP60 KD inhibited 5' adenosine monophosphate-activated protein kinase (AMPK), which inhibited the key enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), effecting the metabolism of fatty acids by inhibiting malonyl-coenzyme A. Our data suggest that reduced HSP60 expression alters metabolic reprogramming in MM, inhibits tumour progression and reduces mitochondrial-dependent biosynthesis, suggesting that HSP60 is a potential therapeutic target for MM treatment.     

Prevention of autoimmune lysis by T cells with specificity for a heat shock protein by antisense oligonucleotide treatment.

T lymphocytes with specificity for the bacterial heat shock protein (hsp) 60 recognize stressed host cells, thus possibly promoting pathogenesis of certain infectious and autoimmune diseases. Here, we show that autoimmune destruction of stressed Schwann cells and macrophages by cytotoxic T lymphocytes raised against mycobacterial hsp60 can be inhibited by the use of hsp60-specific antisense oligodeoxynucleotides (A-ODNs). The inhibitory effect of hsp60 A-ODNs was specific because lysis of murine cytomegalovirus-infected host cells by virus-specific cytotoxic lymphocytes was not affected. Immunoblot analysis and immunoprecipitation studies suggest that different forms of stress increase hsp60 synthesis in Schwann cells and that this neosynthesis is reduced by hsp60 A-ODNs. These findings (i) provide evidence for participation of endogenous hsp60 in the recognition of stressed host cells by mycobacterial hsp60-crossreactive T cells and (ii) suggest the feasibility of inhibiting autoimmune reactions by target-cell treatment with specific A-ODNs.