Changes In Heat Shock Protein Expression Research Articles

Thermal stress and mutation accumulation increase heat shock protein expression in Daphnia

Understanding the short- and long-term consequences of climate change is a major challenge in biology. For aquatic organisms, temperature changes and drought can lead to thermal stress and habitat loss, both of which can ultimately lead to higher mutation rates. Here, we examine the effect of high temperature and mutation accumulation on gene expression at two loci from the heat shock protein (HSP) gene family, HSP60 and HSP90. HSPs have been posited to serve as ‘mutational capacitors’ given their role as molecular chaperones involved in protein folding and degradation, thus buffering against a wide range of cellular stress and destabilization. We assayed changes in HSP expression across 5 genotypes of Daphnia magna, a sentinel species in ecology and environmental biology, with and without acute exposure to thermal stress and accumulated mutations. Across genotypes, HSP expression increased ~ 6× in response to heat and ~ 4× with mutation accumulation, individually. Both factors simultaneously (lineages with high mutation loads exposed to high heat) increased gene expression ~ 23×—much more than that predicted by an additive model. Our results corroborate suggestions that HSPs can buffer against not only the effects of heat, but also mutations—a combination of factors both likely to increase in a warming world.

Heat Shock Proteins in Vascular Diabetic Complications: Review and Future Perspective.

Heat shock proteins (HSPs) are a large family of proteins highly conserved throughout evolution because of their unique cytoprotective properties. Besides assisting protein refolding and regulating proteostasis under stressful conditions, HSPs also play an important role in protecting cells from oxidative stress, inflammation, and apoptosis. Therefore, HSPs are crucial in counteracting the deleterious effects of hyperglycemia in target organs of diabetes vascular complications. Changes in HSP expression have been demonstrated in diabetic complications and functionally related to hyperglycemia-induced cell injury. Moreover, associations between diabetic complications and altered circulating levels of both HSPs and anti-HSPs have been shown in clinical studies. HSPs thus represent an exciting therapeutic opportunity and might also be valuable as clinical biomarkers. However, this field of research is still in its infancy and further studies in both experimental diabetes and humans are required to gain a full understanding of HSP relevance. In this review, we summarize current knowledge and discuss future perspective.

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Objectives Heat shock proteins (HSPs) are induced in cells as a protective mechanism to cope with cellular stress. The activation of the heat shock response is mediated by heat shock transcription factor 1 (HSF1). HSFs (HSF1-4) bind to the promoter regions of target genes. HSF 1 exists in a complex with HSP40, HSP70 and HSP90 as inactive monomers; after stress HSF 1 is and trimerizes. We reported a spatial expression of HSPs in the placenta and that this is altered in pre-eclampsia (Abdulsid et al., 2013). Aims: To investigate whether expression of HSF-1 alters and may explain the changes in HSP expression. Methods Placental samples were obtained from 8 sites within each placenta: 4 equally spaced apart pieces were sampled from the inner, middle and outer zones of the placenta (Abdulsid et al., 2013). Non-labor, labor, labor pre-eclampsia and non-labor pre-eclampsia were studied. HSF 1 expression was investigated by Western blot analysis and real time PCR. Results Two HSF1 bands were observed which, according to the data sheet represent the phosphorylated 80 kDa and non-phosphorylated 65 kDa forms. HSF1; 65 kDa was significantly increased in both the pre-eclampsia non-labor and labor groups compared to the normal non-labor and labor groups at the inner zone (p = 0.04, p = 0.008 respectively). There was a significant decrease in 65 kDa HSF1 in labor pre-eclampsia compared to the control labor group at the middle zone (p = 0.004). There was no difference in the phosphorylated form of HSF1. No changes at the mRNA level were found when non-labor and labor pre-eclampsia were compared to control groups. When labor and non-labor groups were combined, there was a significant increase in pre-eclampsia compared to the normotensive groups at the inner and middle zones (p = 0.007, p = 0.02 respectively). Conclusions Changes in HSF1 expression occur during labor and pre-eclampsia but at different zones within the placenta. Disclosures A. Abdulsid: None. K. Hanretty: None. F. Lyall: None.

Modulation of heat shock proteins during macrophage differentiation

To evaluate the heat shock protein (HSP) variation during the differentiation and polarization of human macrophages. Gene expression analysis was investigated by real-time PCR from mRNA of human monocytes obtained from the buffy coats of healthy volunteers, polarized to classically activated macrophages (or M1), whose prototypical activating stimuli are interferon-gamma and lipopolysaccharide, and alternatively activated macrophages (or M2) obtained by interleukin-4 exposure. The modulation of HSPs at the transcriptomic levels was investigated using oligonucleotide microarray in the process of primary human monocyte-to-macrophage maturation and subsequent polarization into M1 or M2 cells. We found that 11 HSPs transcripts were modulated throughout monocyte-to-macrophage differentiation. Furthermore a considerable effect on HSP expression was detected in conjunction with the M1 polarizing condition. This affected 21 transcripts in M1 cells, with 6 of them significantly upregulated in comparison to unpolarized macrophages, whereas 15 were downregulated. Slight changes in HSPs expression were observed in M2 cells when compared to unpolarized macrophages. Under these circumstances only five transcripts were significantly modulated. Interestingly, HSPBAP1 was the only HSP significantly downregulated in both M1 and M2 conditions parallel to a significant up-regulation of its target HSPB1. Our study revealed that monocytes undergoing maturation differentially regulate the expression of several members of HSPs and that distinct patterns of HSP expression characterize the M1 and M2 effector stages of macrophage life.

Age-related differences in skeletal muscle insulin signaling: the role of stress kinases and heat shock proteins

Aging is associated with an increase in insulin resistance in skeletal muscle, yet the underlying mechanism is not well established. We hypothesize that with aging, a chronic increase in stress kinase activation, coupled with a decrease in oxidative capacity, leads to insulin resistance in skeletal muscle. In aged (24 mo old) and young (3 mo old) Fischer 344 rats, 2-deoxyglucose uptake and insulin signaling [as measured by phosphorylation of insulin receptor substrate-1 (IRS-1), Akt (protein kinase B), and Akt substrate of 160 kDa (AS160)] decreased significantly with age. Activation of, c-Jun NH(2)-terminal kinase (JNK), glycogen serine kinase-3beta (GSK-3beta), and degradation of IkappaBalpha by the upstream inhibitor of kappa B kinase (IKKbeta), as measured by Western blot analysis, were increased with age in both soleus and epitrochlearis (Epi) muscles. However, much higher activation of these kinases in Epi muscles from young rats compared with soleus results in a greater effect of these kinases on insulin signaling in fast-twitch muscle with age. Heat shock protein (HSP) 72 expression and phosphorylation of HSP25 were higher in soleus compared with Epi muscles, and both parameters decreased with age. Age and fiber type differences in cytochrome oxidase activity are consistent with observed changes in HSP expression and activation. Our results demonstrate a significant difference in the ability of slow-twitch and fast-twitch muscles to respond to insulin and regulate glucose with age. A greater constitutive HSP expression and lower stress kinase activation may account for the ability of slow-twitch muscles to preserve the capacity to respond to insulin and maintain glucose homeostasis with age.

Novel Oxidative Stress-responsive Gene ERS25 Functions as a Regulator of the Heat-shock and Cell Death Response

Members of the yeast p24 family, including Emp24p and Erv25p, exist as heteromeric complexes that have been proposed to cycle between the endoplasmic reticulum (ER) and Golgi compartments. The specific functions and sites of action of p24 proteins are still unknown. Here we identified a human homolog of the yeast p24 family of proteins, named ERS25 (endoplasmic reticulum stress-response protein 25), and investigated its role in stress response. ERS25 is predicted to have an ER localization signal peptide, a GOLD (Golgi dynamics) domain, which is found in several eukaryotic Golgi and lipid-trafficking proteins, a coiled-coil region, and a transmembrane domain. We demonstrate that ERS25 is localized to the ER and is induced by ER-specific stress, heat shock, and oxidative stress. The selective induction of ERS25 by brefeldin A, but not tunicamycin, implicates the involvement of ERS25 in protein trafficking between the ER and the Golgi. Small interfering RNA-mediated inhibition of ERS25 results in a significant decrease in apoptosis as well as a reduction of reactive oxygen species induced by oxidative stress. Moreover, ERS25 depletion results in a significant increase in the levels of the ER chaperone HSP70 in response to heat-shock stress through increased levels of HSF-1. We also found that inhibition of ERS25 induction in response to heat shock enhanced the binding of HSP70 to Apaf-1, which is likely to interfere in stress-mediated apoptosis. Together, the data presented here demonstrate that ERS25 may play a critical role in regulation of heat-shock response and apoptosis.

The Heat Shock Response and Chaperones/Heat Shock Proteins in Brain Tumors: Surface Expression, Release, and Possible Immune Consequences

The heat shock response is a highly conserved "stress response" mechanism used by cells to protect themselves from potentially damaging insults. It often involves the upregulated expression of chaperone and heat shock proteins (HSPs) to prevent damage and aggregation at the proteome level. Like most cancers, brain tumor cells often overexpress chaperones/HSPs, probably because of the stressful atmosphere in which tumors reside, but also because of the benefits of HSP cytoprotection. However, the cellular dynamics and localization of HSPs in either stressed or unstressed conditions has not been studied extensively in brain tumor cells. We have examined the changes in HSP expression and in cell surface/extracellular localization of selected brain tumor cell lines under heat shock or normal environments. We herein report that brain tumor cell lines have considerable heat shock responses or already high constitutive HSP levels; that those cells express various HSPs, chaperones, and at least one cochaperone on their cell surfaces; and that HSPs may be released into the extracellular environment, possibly as exosome vesicular content. In studies with a murine astrocytoma cell line, heat shock dramatically reduces tumorigenicity, possibly by an immune mechanism. Additional evidence indicative of an HSP-driven immune response comes from immunization studies using tumor-derived chaperone protein vaccines, which lead to antigen-specific immune responses and reduced tumor burden in treated mice. The heat shock response and HSPs in brain tumor cells may represent an area of vulnerability in our attempts to treat these recalcitrant and deadly tumors.

Importance of the stress response in acid-induced mucosal injury in opossum esophagus

Recent studies suggest that oxidative stress occurs during the development of reflux esophagitis. Changes in heat shock protein (HSP) expression have been observed in patients and in animal models of gastrointestinal disease, although the esophagus has largely been ignored. Aim: To study changes in antioxidant enzyme levels and HSP expression following the induction of esophegitis and after one week of recovery in anesthetized opossums. Methods: The esophagus was pertused intraluminally for 45 minutes on each of 3 consecutive days with either 0.9% saline (NS) (n = 6; control) or 100 mM HCI (n = 6). 24 hours later, the esophagus was excised and samples were removed from distal, middle and proximal sites (1-3, 5-7 and 9-11 cm above the LES, respectively). An additional group of recovery animals (n = 4) was also perfused repeatedly with acid, but was then allowed 7 days to recover prior to tissue removal. Myeloperoxidase (MPO) activity (index of naatrophil accumulation) and mucocal levels of the antioxidant enzymes glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) were determined spectrophotomatrically for each sample, while mucocal HSP 60, 72 and 90 were examined using western blot. Results: Repeated acid exposure caused significant increases in MPO activity (p<O.O01, p<O.O01, p<O.01), GPx levels (p<O.OB, p<O.O01, p<O.O01) and HSP 90 (p<O.05, p<O.O01, p<O.01) at all 3 sites, compared to controls (p values listed for distal, middle and proximal sites, respectively). No changes in SOD or CAT were found at any site. HSP 72 was found to be significantly decreased (p<O.01, p<O.01) at the distal and middle sites after acid, but no change occurred at the proximal site. HSP 60 content was significantly increased (p<O.05) at the proximal site only. In recovery animals, MPO activity, antioxidant enzyme levels and HSP content were not different from controls at any site. Conclusions: Repeated intraluminal acid exposure induces marked esophageal inflammation that is accompanied by oxidative stress and differential changes in HSP expression, all of which are relatively short-lived it no further exposure occurs. It is not known if the changes in antioxidant status and HSP expression are related. Similar stress responses may also occur in patients chronically challenged with refluxed gastric contents and could play a role in the pathogenesis of gastroesophageal reflux disease.

Enhanced expression of heat shock proteins in leukocytes from trauma patients.

Heat shock proteins (HSPs) play essential roles as molecular chaperones in cells to assist in the repair of degenerated proteins. The expression of HSPs in polymorphonuclear leukocytes (PMNLs) following insult has not been delineated. The objective of this study was to clarify the serial changes in HSP expression in PMNLs from trauma patients. Fifty severely injured patients (mean Injury Severity Score of 31.8 +/- 10.8) and 17 healthy volunteers were included as study subjects. Blood samples were serially obtained at three time points: days 0 to 1, days 2 to 5, and days 6 to 14 after the trauma event. We measured expressions of HSP27, HSP60, HSP70, and HSP90 in permeabilized PMNLs by flow cytometry using a monoclonal antibody generated against each HSP and fluorescein isothiocyanate-conjugated antimouse immunoglobulins as secondary reagents. We also evaluated the expression of HSP70 mRNA in PMNLs by Northern blot hybridization and the expression of HSP70 in PMNLs by fluorescence microscopy. Expressions of HSP27, HSP70, and HSP90 in PMNLs from trauma patients were significantly greater than in PMNLs from healthy volunteers in all three periods (days 0-1, days 2-5, and days 6-14). The expression of HSP60 in PMNLs from trauma patients was significantly greater than normal expression on days 2 to 5 and days 6 to 14. The values for HSP27, HSP60, and HSP70 on days 2 to 5 were significantly higher than those on days 0 to 1. The expression of HSP70 mRNA in PMNLs was significantly enhanced for as long as 2 weeks after trauma compared with that in normal volunteers. Severe trauma causes demonstrated enhanced expression of HSPs in PMNLs during the acute phase. This enhanced expression of HSPs may regulate PMNL functions.

Expression of heat shock proteins in squamous cell carcinoma of the tongue: an immunohistochemical study.

Twenty-four specimens of squamous cell carcinoma of the tongue were immunostained for heat shock proteins (HSPs) to reveal differences in stainability among normal epithelium, dysplasia and carcinoma and to clarify the prognostic significance of HSPs in comparison with survival period, clinical stage, lymph node metastasis, histological grade, and p53 immunostaining. Normal epithelium was positively stained in the suprabasal layer for HSP60 and HSP70, but was negative for HSP27 and HSP90. Dysplastic lesions were positive for HSP27, HSP70 and HSP90, but stained variously for HSP60. In squamous cell carcinoma, the cytoplasm of suprabasal tumor cells was often positive for HSP27 and HSP90 (18/24, 17/24, respectively). Although HSP immunohistochemistry has revealed changes in HSP expression during tumorigenesis of squamous epithelium of the tongue, there was no correlation between HSP staining and survival period, stage, lymph node metastasis, histological grade or p53 immunostaining.