kD Heat Shock Protein Research Articles

Deep Hypothermia Diminishes the Ischemic Induction of Heat-Shock Protein-72 mRNA in Piglet Brain

Expression of the 72-kD heat-shock protein (HSP72) has served as a useful indicator of ischemic stress after cerebral ischemia. Moderate hypothermia (30 degrees C) has been reported to block the induction of HSP72 after a brief episode of forebrain ischemia. The objective of the present study was to examine the effects of deep hypothermia (15 degrees C) on expression of HSP72 after a prolonged period of cerebral ischemia. Piglets 19 to 23 days old, were placed on cardiopulmonary bypass, and brain temperature was lowered to 23 degrees C (n = 9) or 15 degrees C (n = 9) before circulatory arrest for 1 hour. In an additional group of animals (n = 5), the temperature was lowered to 29 degrees C before arrest for 45 minutes. All animals were reperfused at 37 degrees C for 2 hours, and the regional expression of HSP72 mRNA was assessed using in situ hybridization. After ischemia at 15 degrees C, expression of HSP72 mRNA was limited to a few scattered regions of cerebral cortex; the percentage of cortex exhibiting HSP72 mRNA was 23 +/- 7% (mean +/- SEM). Ischemia at 23 degrees C triggered expression of HSP72 mRNA in a significantly larger portion of the cortex (68 +/- 8%, P < .001). Ischemia at 29 degrees C failed to induce substantial expression of HSP72 mRNA in the cerebral cortex. These results suggest that, relative to ischemia at 23 degrees C, deep hypothermia (15 degrees C) diminishes ischemic alterations leading to induction of HSP72 mRNA. The lack of cortical expression of HSP72 mRNA following ischemia at 29 degrees C may be secondary to inadequate recovery of energy metabolism.

Overexpression of the rat inducible 70-kD heat stress protein in a transgenic mouse increases the resistance of the heart to ischemic injury.

Myocardial protection and changes in gene expression follow whole body heat stress. Circumstantial evidence suggests that an inducible 70-kD heat shock protein (hsp70i), increased markedly by whole body heat stress, contributes to the protection. Transgenic mouse lines were constructed with a cytomegalovirus enhancer and beta-actin promoter driving rat hsp70i expression in heterozygote animals. Unstressed, transgene positive mice expressed higher levels of myocardial hsp70i than transgene negative mice after whole body heat stress. This high level of expression occurred without apparent detrimental effect. The hearts harvested from transgene positive mice and transgene negative littermates were Langendorff perfused and subjected to 20 min of warm (37 degrees C) zero-flow ischemia and up to 120 min of reflow while contractile recovery and creatine kinase efflux were measured. Myocardial infarction was demarcated by triphenyltetrazolium. In transgene positive compared with transgene negative hearts, the zone of infarction was reduced by 40%, contractile function at 30 min of reflow was doubled, and efflux of creatine kinase was reduced by approximately 50%. Our findings suggest for the first time that increased myocardial hsp70i expression results in protection of the heart against ischemic injury and that the antiischemic properties of hsp70i have possible therapeutic relevance.

Blood Pressure and Heat Shock Protein Expression in Response to Acute and Chronic Stress

We previously demonstrated that restraint and pharmacological agents that activate sympathetic nervous system activity induce expression of the 70-kD heat shock protein (HSP70) in major blood vessels. The magnitude and rapidity in which HSP70 is induced in the aorta suggest that it may play a salient role in the mechanical properties of vascular smooth muscle. Other investigators have reported that HSP70 inducibility is increased in genetically hypertensive animals. In this report, we have investigated the effects of acute and chronic (8-week) exposure to restraint and restraint in the presence of a randomized intermittent air jet on the development of hypertension and the induction of HSP70 in the aorta and adrenal glands of normotensive adult male Sprague-Dawley rats. Acute restraint or air jet resulted in a fivefold to sixfold increase in aortic HSP70 mRNA expression. Chronic exposure to restraint reduced the HSP70 response to acute restraint. In contrast, no adaptation of the HSP70 response to acute air jet was observed in aortas of chronically air jet-treated rats. In adrenal glands, HSP70 expression was reduced after chronic restraint and air jet, indicating that in this tissue, adaptation occurs to both stressors. There was no difference in HSP70 expression in unstressed rats that had been chronically exposed to restraint or air jet in either adrenal gland or aorta. A significant increase (P < .05) in systolic blood pressure developed in air jet-treated animals (120 +/- 3 mm Hg) but not in restrained rats (107 +/- 2 mm Hg) compared with unstressed controls (106 +/- 3 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of T cells recognizing self 60-kD heat shock protein can protect against experimental arthritis.

Lewis rats are susceptible to several forms of experimental arthritis-induced using heat-killed Mycobacterium tuberculosis (adjuvant arthritis, or AA), streptococcal cell walls, collagen type II, and the lipoidal amine CP20961. Prior immunization with the mycobacterial 65-kD heat shock protein (hsp65) was reported to protect against AA, and other athritis models not using M. tuberculosis, via a T cell-mediated mechanism. Hsp65 shares 48% amino acid identity with mammalian hsp60, which is expressed at elevated levels in inflamed synovia. Several studies have reported cross-reactive T cell recognition of mycobacterial hsp65 and self hsp60 in arthritic and normal individuals. We previously described nine major histocompatibility complex class II-restricted epitopes in mycobacterial hsp65 recognized by Lewis rat T cells. Of these only one, covering the 256-270 sequence, primed for cross-reactive T cell responses to the corresponding region of rat hsp60. Here we have tested each hsp65 epitope for protective activity by immunizing rats with synthetic peptides. A peptide containing the 256-270 epitope, which induced cross-reactive T cells, was the only one able to confer protection against AA. Similarly, administration of a T cell line specific for this epitope protected against AA. Preimmunization with the 256-270 epitope induced T cells that responded to heat-shocked syngeneic antigen-presenting cells, and also protected against CP20961-induced arthritis, indicating that activation of T cells, recognizing an epitope in self hsp60 can protect against arthritis induced without mycobacteria. Therefore, in contrast to the accepted concept that cross-reactive T cell recognition of foreign and self antigens might induce aggressive autoimmune disease, we propose that cross-reactivity between bacterial and self hsp60 might also be used to maintain a protective self-reactive T cell population. This discovery might have important implications for understanding T cell-mediated regulation of inflammation.

Juvenile chronic arthritis: T cell reactivity to human HSP60 in patients with a favorable course of arthritis.

Synovial fluid and peripheral blood mononuclear cell proliferative responses to the 60-kD human heat shock protein (HSP60) were studied in 23 patients with juvenile chronic arthritis (JCA) and 7 non-JCA control patients. All patients showed active arthritis at the time of study. The patients were divided into two groups according to the presence (group A) or absence (group B) of T lymphocyte reactivity to human HSP60. We show that reactivity to human HSP60 is primarily, though not exclusively, occurring in patients with a remitting course of disease, i.e., the subgroup of HLA-B27 negative JCA patients with an oligoarticular onset. Immunohistochemical analysis of HSP expression in synovial membranes showed a significantly higher intensity of staining in JCA patients than in non-JCA controls. The results suggest that, in accordance with the earlier observation made in experimental models, T lymphocyte reactivity to human HSP60 in this subgroup of JCA patients may be part of T cell regulatory mechanisms that control the development of arthritis.

Immunohistochemical detection of estrogen receptor in invasive human breast cancer: correlation with heat shock proteins, pS2 and oncogene products.

The authors immunohistochemically studied the expression of the estrogen receptor (ER), 27-kD heat shock protein (HSP27) and pS2 in 118 invasive primary human breast cancers. Positive nuclear staining of the ER was detected in 64% of the cases and was closely correlated with the biochemical assay (p < 0.0001). ER-positive tumors were significantly decreased with tumor size and stage (p < 0.001 each), but not with lymph node status. Positivity of the ER was correlated with the cytoplasmic expression of HSP27 (p < 0.005), pS2 (not significant) and HSP70 (not significant). ER negativity was significantly correlated with the expression of p53, epidermal growth factor receptor (EGFR) and c-erbB-2 (p < 0.05 each). Thus, it was concluded that ER-positive breast carcinomas, relatively small in size, preferentially expressed HSP27, HSP70 and pS2 and that ER-negative tumors, relatively large in size, were predisposed to express p53, EGFR and c-erbB-2.

Histological and subcellular distribution of 65 and 70 kD heat shock proteins in experimental nephrotoxic injury.

The cellular distribution of 65 and 70 kD heat shock proteins (HSPs) was studied in the normal rat kidney and after acute tubular necrosis (ATN) induced by inorganic mercury (HgCl2). In the normal kidney the 65 kD HSP was found in the cytoplasm of podocytes and proximal convoluted tubules, whereas the 70 kD HSP was located in nuclei and cytoplasm of podocytes, cortical convoluted, and collecting tubules. The distribution of both HSPs along ATN changed as a function of time. In the early phase, before evidence of histological damage, both HSPs were found in the pielocaly ceal epithelium and medullary collecting tubules. During the necrotic phase, HSPs coexisted with sites of severe damage (i.e. cortical tubules). With immunoelectron microscopy damaged cells showed an abundance of 65 kD HSP-I in mitochondria, as well as in chromatin and nucleoli, while 70 kD HSP-I was overexpressed in the cytoplasm, mito chondria, lysosomes, cytoskeleton, chromatin, and nucleoli, and coincided with urinary excretion of HSPs. In the postregenerative phase, the distribution of HSPs was similar to that found in the normal kidney. HSPs of 65 and 70 kD were encountered constitutionally and their immunolabeling is correlated with the magnitude of cell injury.

Differential Distribution of 70-kD Heat Shock Protein in Atherosclerosis

Smooth muscle cell death may contribute to necrotic plaque rupture and subsequent thromboembolus. Stress-induced synthesis of heat-shock proteins (HSPs) normally protects cells from death, but vascular HSPs may become insufficient as cytotoxicity increases in advanced plaques. To determine whether vascular HSP content is altered near necrosis, we compared 70-kD HSP (HSP70) distribution between fibrotic and necrotic plagues in immunostained carotid endarterectomy specimens. Average levels of HSP70 immunoreactivity were compared by video densitometry between fibrotic and necrotic plaques or between their underlying media. Both necrotic plaques and their underlying media contained significantly more HSP70 staining than did fibrotic tissues. To test whether cellular HSP70 correlated with resistance to toxicity in vitro, aortic smooth muscle cells (aSMCs) were heat shocked to induce endogenous HSPs or given 2 to 50 micrograms/mL purified HSP70. Cells were then serum deprived or exposed to 12 to 96 mumol/L cholestanetriol (C3ol) or 25-hydroxycholesterol, and survival was determined. Cellular HSP70 content was assayed by immunoblotting, and protein synthesis was monitored by 35S radiolabeling. Serum deprivation inhibited general protein synthesis but induced HSP70; C3ol exposure inhibited both overall protein and HSP70 synthesis, including post-heat shock. Induction of endogenous HSPs or 10 micrograms/mL exogenous HSP70 improved viability of serum-deprived cells (P < .05 and P < .01, respectively), while only exogenous HSP70 protected against C3ol (P < .002). The results suggest that insufficient HSP70 accumulates in aSMCs residing near necrosis to protect against plaque toxicity; aSMC death might then occur, allowing resident macrophages to degrade and destabilize the matrix, leading to rupture.

Immunocytochemical observation of the 90 KD heat shock protein (HSP90): high expression in primordial and pre-meiotic germ cells of male and female rat gonads.

We used immunocytochemistry to detect the 90 KD major heat shock protein (HSP90), a potential regulator of gene expression, during male and female rat gonad development. In the Day 13.0 post-coital (dpc) fetal gonad, strong immunoreactivity to anti-HSP90 antibody was shown in the cytoplasm of primordial germ cells (PGCs). Other somatic cells in the gonad showed only faint reactivity. During testicular development, strong immunostaining was observed in the cytoplasm of embryonic germ cells and in spermatogonia and spermatocytes of the pre-pubertal testis. In adult testis reactivity of spermatogonia and pachytene spermatocytes was strong but reactivity of post-meiotic spermatogenic cells, i.e., secondary spermatocytes and spermatids, was extremely reduced. During ovarian development, immunostaining was also observed in the oogonia and the oocytes of pre-pubertal ovary. However, the staining of oocytes was reduced with the development of primordial follicles during the first week after birth. This study revealed that HSP90 is highly expressed in PGCs and continues to be expressed in both male and female pre-meiotic germ cells. The HSP90 accumulation may be essential for both male and female mammalian pre-meiotic germ cells.

Immune Pathogenesis of Asymptomatic Chlamydia trachomatis Infections in the Female Genital Tract

Chlamydia trachomatis (CT) infections of the female genital tract, although frequently asymptomatic, are a major cause of fallopian-tube occlusion and infertility. Early stage pregnancy loss may also be due to an unsuspected and undetected CT infection. In vitro and in vivo studies have demonstrated that this organism can persist in the female genital tract in a form undetectable by culture. The mechanism of tubal damage as well as the rejection of an embryo may involve an initial immune sensitization to the CT 60 kD heat shock protein (HSP), followed by a reactivation of HSP-sensitized lymphocytes in response to the human HSP and the subsequent release of inflammatory cytokines. The periodic induction of human HSP expression by various microorganisms or by noninfectious mechanisms in the fallopian tubes of women sensitized to the CT HSP may eventually result in tubal scarring and occlusion. Similarly, an immune response to human HSP expression during the early stages of pregnancy may interfere with the immune regulatory mechanisms required for the maintenance of a semiallogeneic embryo.

Interaction of heat shock protein (hsp90) with the cytoskeleton: potential implication in intracellular transport

In this article we will summarize the details concerning the association of 90kD heat shock protein (hsp90) with cytoskeletal structures and we will discuss the potential involvement of these interactions in the translocation of steroid hormone receptors to the cell nucleus. In cultured mammalian cells hsp90 has been found to be colocalized with both microtubules and cytokeratin intermediate filaments, whereas no association with actin filaments and vimentin intermediate filaments has been established. The colocalization of hsp90 with microtubules and cytokeratin in intact cells rises the possibility that cytoskeletal structures could serve as rails for the direct movement of the steroid hormone receptor via association-dissociation with hsp90 molecules from the cytoplasmic site of synthesis to the nuclear site of action. Biomedical Reviews 1994; 3: 27-37.

CDNA cloning and efficient mitochondrial import of pre-mtHSP70 from rat liver.

Members of the 70-kD heat shock protein family have been found in all free-living organisms investigated and in major compartments of eukaryotic cells where they are essential to a wide range of functions, including protein folding and targeting. We have isolated a mitochondrial homolog (mtHSP70) from rat liver using ATP agarose affinity chromatography. Its identity was confirmed on the basis of immunological analysis and Ca(2+)-dependent autophosphorylation. Using protein sequence obtained from the amino termius and nine endo Lys-C peptide fragments, we have employed oligonucleotides to isolate a full-length cDNA clone. The open reading frame encodes a protein of 679 amino acids and calculated M(r) 73,913 daltons. The sequence has a high degree of identity with other members of the HSP70 family, including Escherichia coli DnaK (51%), Saccharomyces cerevisiae SSC1p (65%), the constitutive cytosolic HSP70 from rat, HSC70 (46%), and the rat endoplasmic reticulum isoform, BiP, (49%). The cDNA encodes a precursor protein with a 46-amino-acid signal peptide that is absent from the protein isolated from rat liver. The protein also shows a high degree of identity (98%) with a protein isolated from mouse and human tissues (PBP74, Domanico et al., 1993; mortalin, Wadhwa et al., 1993a; CSA, Michikawa et al., 1993a); however, the intracellular localization of these proteins is uncertain. We show that the precursor of mtHSP70 is efficiently imported into isolated mitochondria from rat liver and processed from 74 kD to the mature 69-kD protein.

Phylogenetic analysis of 70 kD heat shock protein sequences suggests a chimeric origin for the eukaryotic cell nucleus

Background: The evolutionary relationships between archaebacteria, eubacteria and eukaryotic cells are of central importance in biology. The current view is that each of these three groups of organisms constitutes a monophyletic domain, and that eukaryotic cells have evolved from an archaebacterial ancestor. Recent studies on a number of highly conserved protein sequences do not, however, support this view and raise important questions concerning the evolutionary relationships between all extant organisms, particularly regarding the origin of eukaryotic cells.Results We have used sequences of 70 kD heat shock protein (hsp70) — the most conserved protein found to date in all species — to examine the evolutionary relationship between various species. We have obtained two new archaebacterial hsp70 sequences from the species, Thermoplasma acidophilum and Halobacterium cutirubrum. A global comparison of hsp70 sequences, including our two new sequences, shows that all known archaebacterial homologs share a number of sequence signatures with the Gram-positive group of bacteria that are not found in any other prokaryotic or eukaryotic species. In contrast, the eukaryotic homologs are shown to share a number of unique sequence features with the Gram-negative bacteria that are not present in any archaebacteria. Detailed phylogenetic analyses of hsp70 sequences strongly support a specific evolutionary relationship between archaebacteria and Gram-positive bacteria on the one hand, and Gram-negative bacteria and eukaryotes on the other. The phylogenetic analyses also indicate a polyphyletic branching of archaebacteria within the Gram-positive species. The possibility that the observed relationships are due to horizontal gene transfers can be excluded on the basis of sequence characteristics of different groups of homologs.Conclusion Our results do not support the view that archaebacteria constitute a monophyletic domain, but instead suggest a close evolutionary linkage between archaebacteria and Gram-positive bacteria. Furthermore, in contrast to the presently accepted view, eukaryotic hsp70s show a close and specific relationship to those from Gram-negative species. To explain the phylogenies based on different gene sequences, a chimeric model for the origin of the eukaryotic cell nucleus involving fusion between an archaebacterium and a Gram-negative eubacterium is proposed. Several predictions from the chimeric model are discussed.

T Cell Epitop Mapping of the Synthetic Peptides Derived from the Mycobacterial and Human 60–65 kD Heat Shock Proteins in Recurrent Oral Ulceration

T Cell Epitop Mapping of the Synthetic Peptides Derived from the Mycobacterial and Human 60–65 kD Heat Shock Proteins in Recurrent Oral Ulceration

Phosphorylated HSP27 Associates With the Activation-Dependent Cytoskeleton in Human Platelets

AbstractThe three prominently phosphorylated 29-kD proteins in thrombin-activated human platelets are forms of the mammalian 27-kD heat-shock protein (HSP27). Though the function of HSP27 is not yet known, its phosphorylation is highly correlated with platelet secretion, and recent evidence in nonhematopoietic cells suggests that HSP27 regulates cortical actin filament assembly. Therefore, the subcellular location and phosphorylation state of HSP27 in resting and thrombin-activated platelets was studied. Platelets were fractionated by established Triton X-100 lysis methods followed by differential centrifugation to obtain the 14,000g fraction (low-speed cytoskeleton), 100,000g fraction (membrane skeleton), and the 100,000g supernatant fraction containing soluble cytosolic proteins. In resting platelets, HSP27 was present principally in the 100,000g supernatant fraction. Platelet activation with thrombin led to translocation of the majority of HSP27 to the low-speed cytoskeleton. This association was reversible by DNase, supporting the idea that HSP27 is a specific component of the actin cytoskeleton. Immunofluorescence studies similarly showed HSP27 is cytoplasmic in resting platelets but colocalizes with actin in fully spread, glass-activated platelets. Immunoprecipitation studies showed a small amount of constitutively phosphorylated HSP27 in resting platelets, but phosphorylation of the majority of HSP27 after thrombin activation. After activation, virtually all phosphorylated HSP27 was found in the low-speed cytoskeletal fraction, and each of the three phosphorylated forms of HSP27 were present by two-dimensional autoradiography. Furthermore, in time-course studies, the phosphorylation of HSP27 occurred just before localization of HSP27 to the low-speed pellet. These results show that, after platelet activation, HSP27 is first phosphorylated and then translocated from the cytoplasm to the assembling cytoskeleton, and suggest that HSP27 phosphorylation may be important to the binding of HSP27 to cytoskeletal components and the cytoskeletal rearrangements characteristic of platelet activation.

Hypertension, aging, and myocardial synthesis of heat-shock protein 72.

We determined the temperature-induced synthesis of the 72-kD heat-shock protein (hsp72) in hearts of normotensive and spontaneously hypertensive rats (SHR) subjected to whole-body hyperthermia (42.0 +/- 0.5 degrees C for 15 minutes). The animals were studied at three different ages: young (2 months), adult (6 months), and old (18 months). The hsp72 was determined by Western blot analysis using a monoclonal antibody. The results were calculated densitometrically as a percentage of a commercial standard. Young SHR responded to hyperthermic stress with increased synthesis of hsp72 compared with age-matched normotensive rats (298.8 +/- 70.0% versus 88.3 +/- 25.5%). This trend was maintained in adult rats (118.1 +/- 31.0% versus 54.8 +/- 21.3%) but not in old rats (65.3 +/- 29.4% versus 43.6 +/- 15.1%). Aging caused a reduction of hsp72 expression in response to hyperthermic stress in both SHR (4.6-fold) and normotensive rats (twofold). These data show that hearts of young and adult SHR respond to heat shock with enhanced synthesis of hsp72. This abnormal response, attenuated by aging, is independent of the presence and degree of hypertension or hypertrophy and is potentially linked to the genetic determination of the disease.

T lymphocyte response to 70-kD heat shock proteins in multiple sclerosis, in tuberculosis and in healthy individuals

T lymphocyte response to 70-kD heat shock proteins in multiple sclerosis, in tuberculosis and in healthy individuals

Small subclass of rat olfactory neurons with specific bulbar projections is reactive with monoclonal antibodies to the HSP70 heat shock protein.

As part of a study of turnover of rat olfactory receptor neurons we have been examining immunohistochemical expression of members of the 70 kD heat shock protein (HSP70) family in the olfactory epithelium. Expression of HSP70 family members is up-regulated in many cells following exposure to physiologically stressing conditions. Because dying neurons are likely to undergo some sort of physiological stress before the onset of frank degeneration, we hoped that anti-HSP70 monoclonal antibodies would prove to be useful markers for early stages of olfactory neuron cell death. Two anti-human HSP70 monoclonal antibodies were used, Mabs 2A4 and 3a3. Two-dimensional gel electrophoresis/western blot analysis indicates that these Mabs are reactive with the HSC70 and HSP70 members of the rat HSP70 family. Immunohistological observations show that both Mabs are strongly reactive with a widely dispersed subpopulation of olfactory receptor neurons. Morphological, immunohistological, and autoradiographic birthdating analyses demonstrate that reactive cells are fully mature receptor neurons. Their reactivity, however, does not appear to be stress-related. More significantly, axons of reactive neurons show intense anti-2A4 reactivity. This has allowed us to trace these axons to their target glomeruli in the olfactory bulb, demonstrating that the reactive neurons project to just one to two glomeruli on either side of each bulb via consistent and predictable pathways. This is the first subpopulation of olfactory receptor neurons to be traced to such a small number of glomeruli. Given this extremely small number, it seems likely that the reactive receptor cell subpopulation serves some specific olfactory function. In addition, axonal 2A4 reactivity should also prove useful in defining the relative roles of receptor neurons and glomeruli in the establishment of epithelial-glomerular connections.

Activation of heat-shock transcription factor by graded reductions in renal ATP, in vivo, in the rat.

Renal ischemia results in both a profound fall in cellular ATP and a rapid induction of the 70 kD heat-shock protein family, HSP-70. The present studies examined the relationship between cellular ATP and induction of the stress response in renal cortex. Cellular ATP, continuously monitored by in vivo 31P-NMR spectroscopy, was reduced and maintained at specific, stable levels in renal cortex by partial aortic occlusion for 45 min. Activation of heat-shock transcription factor (HSF) was detected by gel retardation assay and transcription was confirmed by Northern analysis. Activation of HSF was not present, and HSP-70 mRNA induction did not occur when ATP levels were maintained above 60% preocclusion (control) levels. Reduction in cortical ATP levels to 35-50% preocclusion values resulted in HSF activation and low-level expression of inducible HSP-70 mRNA. Cellular ATP of 20-25% control values resulted in a greater level of HSF activation and subsequent HSP-70 mRNA elaboration. HSF was activated at the end of 15 min of total occlusion. The studies indicate that a 50% reduction in cellular ATP in the renal cortex must occur before the stress response is detectable, that reduction of ATP below 25% control levels produces a more vigorous response, and that reperfusion is not required for initiation of a heat-shock response in the kidney. Cellular ATP, or the metabolic consequences associated with ATP depletion, may be a threshold factor for initiation of a stress response in the kidney.

Induction of 72-kD heat shock protein in cultured human malignant melanoma cells and their heat sensitivity

Induction of 72-kD heat shock protein in cultured human malignant melanoma cells and their heat sensitivity