Expression of heat shock protein 27 in developing and adult human kidney

Renal expression of Hsp27, 60, and 70 in cases of fatal hypothermia

Macromorphological findings can be missing in cases of fatal hypothermia when the agonal period is very short because of a large difference between environmental and core body temperatures. Expression of heat shock proteins (Hsps) increases under endogenous and exogenous cellular stresses such as thermal stress. These stress proteins can be revealed by immunohistochemical staining. Forty-five cases of death due to hypothermia and a control group of 100 deaths without any antemortem thermal stress were examined for Hsp27, 60, and 70 expression in renal tissue because renal tissue is sensitive to cellular stress. The results revealed no significant difference between Hsp27, 60, and 70 expression in both groups (28.8% positive staining in the study group and 19.0% positive staining in the control group), which is contradictory to a previous study on expression of Hsp70 in renal tissue in cases of fatal hypothermia. Hence, it is currently unclear whether immunohistochemical staining of Hsps supports a morphological diagnosis of fatal hypothermia.

Expression times for hsp27 and hsp70 as an indicator of thermal stress during death due to fire

The expression of heat shock proteins (hsps) increases in cases of hyperthermal cellular stress in order to protect cellular structures. Hsps can be visualized with immunohistochemical staining. We examined 48 cases of death from fire and excessive heat and a control group of 100 deaths without any perimortem thermal stress, measuring both the hsp27 and hsp70 expressions in myocardial, pulmonary, and renal tissues. The results revealed a correlation between hsp expression and survival time. Hsps are expressed rapidly within seconds or minutes after exposure to heat stress. In particular, hsp27 is expressed fast in high levels, whereas hsp70 expression is higher in the pulmonary and renal tissue of long-term survivors. In the myocardial tissue, hsp27 expression dominated in both short- and long-term survival. The expression pattern is strongly dependent on the organ structure and the survival time, which should be considered in future postmortem studies on hsps.

Heat shock proteins in the kidney

Heat shock proteins (Hsps) are essential to cell survival through their function as protein chaperones. The role they play in kidney health and disease is varied. Hsp induction may be either beneficial or detrimental to the kidney, depending on the specific Hsp, type of cell, and context. This review addresses the role of Hsps in the kidney, including during development, as osmoprotectants, and in various kidney disease models. Heat shock transcription factor, activated by a stress on renal cells, induces Hsp elaboration and separately regulates immune responses that can contribute to renal injury. Induced Hsps in the intracellular compartment are mostly beneficial in the kidney by stabilizing and restoring cell architecture and function through acting as protein chaperones. Intracellular Hsps also inhibit apoptosis and facilitate cell proliferation, preserving renal tubule viability after acute injury, but enhancing progression of cystic kidney disease and malignancy. Induced Hsps in the extracellular compartment, either circulating or located on outer cell membranes, are mainly detrimental through enhancing inflammation pathways to injury. Correctly harnessing these stress proteins promises the opportunity to alter the course of acute and chronic kidney disease.

Serum HSP27 is associated with medullary perfusion in kidney allografts

BACKGROUND

Heat shock protein 27 (HSP27) is a small HSP up-regulated in response to stress in the kidney. The relationship between HSP27 and intrarenal oxygenation in patients with native and transplant kidney disease is unknown.

METHODS

We compared HSP27 levels, intrarenal oxygenation measured by blood oxygen-level dependent (BOLD) imaging using R(2)* values, and perfusion determined by arterial spin labeling (ASL) magnetic resonance imaging (MRI), between patients with native and transplant kidney disease (n=28).

RESULTS

There were no statistical differences in mean age (53.9 vs. 47.1 years), kidney function (63.6 vs. 50.7 ml/min per 1.73 m(2)), mean arterial blood pressure (91.6 vs. 91.1 mm Hg), hematocrit (40.6% vs. 39.3%), diuretic or angiotensin-converting enzyme inhibitor use, serum or urine levels of hydrogen peroxide, nitric oxide, F(2) isoprostanes and HSP27 between native and transplant kidneys. BOLD-MRI studies demonstrated comparable patterns in intrarenal oxygen bioavailability (medullary R(2)* 18.1 vs. 18.3/s and cortical R(2)* 12 vs. 11.7/s, respectively). However, medullary perfusion was significantly lower in transplant kidneys (36.4 vs. 78.7 ml/100 g per minute, p=0.0002). There was a linear relationship between serum HSP27 concentrations and medullary perfusion in kidney allografts (HSP27 concentration [ng/mL] = 0.78 + 0.09 medullary perfusion, R(2)=0.43, p=0.01).

CONCLUSIONS

Our study demonstrates that medullary perfusion is significantly lower in kidney allografts compared with native kidneys with comparable renal function. We further noted a direct association between serum HSP27 levels and medullary perfusion after transplantation. Additional studies are needed to examine the role of HSP27 as a biomarker of kidney disease progression.

Protein expression profiling in the spectrum of renal cell carcinomas

In this study, we aimed to evaluate the protein expression profile of a spectrum of renal cell carcinomas (RCC) to find potential biomarkers for disease onset and progression and therefore, prospective therapeutic targets. A 2D-gel based proteomic analysis was used to outline differences in protein levels among different subtypes of renal cell carcinomas, including clear cell carcinomas, papillary lesions, chromophobe tumors and renal oncocytomas. Spot pattern was compared to the corresponding normal kidney from the same patients and distinctive, differentially expressed proteins were characterized by mass spectrometry. Twenty-one protein spots were found differentially expressed between clear cell RCC and normal tissue and 38 spots were found expressed in chromophobe tumors. Eleven proteins were identified, with most differentially expressed -by fold change- between clear cell tumors and the corresponding normal tissue. Two of the identified proteins, Triosephosphate isomerase 1 (TPI-1) and Heat Shock protein 27 (Hsp27), were further validated in a separate set of tumors by immunohistochemistry and expression levels were correlated with clinicopathologic features of the patients. Hsp27 was highly expressed in 82% of the tumors used for validation, and all cases showed strong immunoreactivity for TPI-1. In both Hsp27 and TPI-1, protein expression positively correlated with histologic features of the disease. Our results suggest that the subjacent cytogenetic abnormalities seen in different histological types of RCC are followed by specific changes in protein expression. From these changes, Hsp27 and TPI-1 emerged as potential candidates for the differentiation and prognosis in RCC.

BOLD-MRI assessment of intrarenal oxygenation and oxidative stress in patients with chronic kidney allograft dysfunction

Blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) uses deoxyhemoglobin as an endogenous contrast agent for the noninvasive assessment of tissue oxygen bioavailability. We hypothesized that intrarenal oxygenation was impaired in patients with chronic allograft nephropathy (CAN). Ten kidney-transplant recipients with CAN and nine healthy volunteers underwent BOLD-MRI. Medullary R2* (MR2*) and cortical R2* (CR2*) levels (measures directly proportional to tissue deoxyhemoglobin levels) were determined alongside urine and serum markers of oxidative stress (OS): hydrogen peroxide (H(2)O(2)), F(2)-isoprostanes, total nitric oxide (NO), heat shock protein 27 (HSP27), and total antioxidant property (TAOP). Mean MR2* and CR2* levels were significantly decreased in CAN (increased local oxyhemoglobin concentration) compared with healthy volunteers (20.7 +/- 1.6 vs. 23.1 +/- 1.8/s, P = 0.03 and 15.9 +/- 1.9 vs. 13.6 +/- 2.3/s, P = 0.05, respectively). There was a significant increase in serum and urine levels of H(2)O(2) and serum HSP27 levels in patients with CAN. Conversely, urine NO levels and TAOP were significantly increased in healthy volunteers. Multiple linear regression analyses showed a significant association between MR2* and CR2* levels and serum/urine biomarkers of OS. BOLD-MRI demonstrated significant changes in medullary and cortical oxygen bioavailability in allografts with CAN. These correlated with serum/urine biomarkers of OS, suggesting an association between intrarenal oxygenation and OS.

Heat shock protein 27: its potential role in vascular disease

Heat shock proteins are molecular chaperones that have an ability to protect proteins from damage induced by environmental factors such as free radicals, heat, ischaemia and toxins, allowing denatured proteins to adopt their native configuration. Heat shock protein-27 (Hsp27) is a member of the small Hsp (sHsp) family of proteins, and has a molecular weight of approximately 27 KDa. In addition to its role as a chaperone, it has also been reported to have many additional functions. These include effects on the apoptotic pathway, cell movement and embryogenesis. In this review, we have focused on its possible role in vascular disease.

Hsp27 Expression Coincides with Epidermal Stratification during Human Epidermal Morphogenesis

Heat shock protein 27 (Hsp27), apart from its protective function in response to stress, is implicated in the regulation of cell growth, differentiation and apoptosis. Data on the expression of Hsp27 in the developing human epidermis are sparse and partially conflicting. Thus, the purpose of the present study was to investigate Hsp27 expression during the morphogenesis of human epidermis. Skin biopsies and dispase-separated epidermal sheets obtained from 7 human embryos (7 and 8 weeks estimated gestational age, EGA), from 79 human fetuses (9-23 weeks EGA) and from 10 healthy adult volunteers were investigated by immunohistochemistry and Western blotting, respectively. The earliest detection of Hsp27 expression was found by immunohistochemistry at the 12th week EGA (basal and intermediate layer) and by Western blotting at the 9th week EGA. From the 16th to the 23rd week EGA immunoreactivity was not detectable in the basal layer, whereas in the overlying layers it revealed a differentiation-related pattern. The simultaneous onset of epidermal stratification and Hsp27 expression (9th week EGA) and the alterations of the latter in the subsequent stages of development, suggest that this stress protein may be involved in the molecular events underlying human epidermal morphogenesis.

Heat Shock Protein 27 in Chronic Allograft Nephropathy: A Local Stress Response

BACKGROUND

Heat shock protein (HSP) 27 plays a cytoprotective role through its antioxidant, antiapoptotic, and actin-stabilizing properties during cell stress. The authors hypothesized that HSP27 is involved in chronic allograft nephropathy (CAN), a chronic state of inflammation and stress.

METHODS

The authors used the Fisher 344-to-Lewis model of CAN. Transplants were performed in 3-month-old recipient rats. HSP27 mRNA and protein levels were determined using semiquantitative polymerase chain reaction, microarray (stress-toxicity, GEArray) analyses, gene sequencing, immunoblotting, and immunohistochemical analyses at 10 days and 6 months posttransplant. P38 mitogen-activated protein kinase (MAPK), manganese (Mn) superoxide dismutase (SOD), copper-zinc (CuZn) SOD, FasL, Bax, hypoxia-inducible factor (HIF)-1alpha, and CD3 lymphocytes were studied in parallel as selective biomarkers of oxidative stress (OS), apoptosis, hypoxia, and graft-infiltrating immune cells.

RESULTS

Six months after transplantation, kidney allografts displayed histologic and functional features of CAN, including tubular atrophy, interstitial fibrosis, glomerulosclerosis, and increased proteinuria and serum creatinine levels. HSP27 mRNA and protein levels in CAN were reduced by 50% and 85%, respectively (P=0.04). Immunohistochemical analyses revealed a "shift" in HSP27 from the medulla to the cortex in allografts with CAN. Bax, phosphorylated p38-MAPK, HIF-1alpha, and MnSOD followed a parallel relocation pattern. CD3 lymphocyte density and tubular FasL expression were also greater in the cortex of allografts with CAN. Time-course analyses revealed that most of these changes were present as early as 10 days posttransplant.

CONCLUSIONS

The shift of HSP27 from the medulla to the cortex, combined with greater CD3, p38-MAPK, Bax, FasL, HIF-1alpha, and MnSOD immunoreactivity in this area of the kidney, likely represents an allograft-level response to CAN-related OS-hypoxia.

Heat shock proteins HSP27 and HSP70 in unilateral obstructed kidneys

Unilateral ureteropelvic junction obstruction (UPJO), a condition involving injury to the kidney, leads to vasoconstriction, macrophage infiltration, oxidative stress, and tubulointerstitial fibrosis. In the present study we analyzed in 22 children, the impact of UPJO on expression of HSP27 and HSP70 and related the changes to renal function and duration of obstruction. Kidney function was evaluated, and renal biopsies were obtained for immunohistochemical and western blot analyses at the time of surgery. Kidney tissue from 5 children of similar age, removed because of various malignancies, was used as control. Increased HSP27, with an expression pattern related to the duration of the obstruction, was noted in proximal tubules (PTs), cortical collecting ducts (CCDs), and medullary collecting ducts. Strong HSP27 staining in cytoplasm and nuclei of these segments appeared in children with kidney obstruction for 2.1+/-0.41 years. HSP70 showed a close spatial expression pattern with that of HSP27. The increased staining of HSP70 in PTs and CCDs was related to the decreased glomerular filtration rate. The constitutive/cognate form of HSP70 (HSC72) was absent. These results support the concept that HSP27 and HSP70 are involved in the adaptive response of the human kidney to congenital UPJO.

Heat shock proteins in the genitourinary system

Heat shock proteins are ubiquitous molecules that are expressed in all living organisms in response to stress. They have two specific roles: protection against cell damage and modulation of the immune response. Recent studies have dramatically increased our knowledge and understanding of the role of heat shock proteins in the genitourinary system. This review uses a Medline approach to examine the current literature.

Differential expression of a novel gene in response to hsp27 and cell differentiation in human keratinocytes

The 27 kDa heat shock protein (hsp27) is expressed in keratinocytes in a differentiation-related pattern. Keratinocyte differentiation involves a coordinated program of expression and interaction of specific differentiation-related genes and proteins. To investigate the functional role of hsp27 in these processes we used a differential display approach to identify genes that might be regulated by the expression of hsp27 in human keratinocytes. mRNA was extracted from the human squamous carcinoma cell line A431 and a subclone stably transfected with human hsp27. Reverse transcriptase differential display polymerase chain reaction was performed using one base anchored oligo-dT and arbitrary primers. Differentially expressed genes were confirmed by northern blot analysis and further characterized by sequencing. Their expression in human skin and other tissues was investigated by northern blot and in situ hybridization. Out of five fragments detected with the initial reverse transcriptase differential display polymerase chain reaction screen one could be confirmed by northern blot to be downregulated in hsp27-overexpressing A431. This mRNA (G24) is not only downregulated by overexpression of hsp27 in A431 but also during differentiation in normal human keratinocytes in culture and in situ, situations where hsp27 is known to be induced. According to sequence analysis G24 represents a novel gene that does not code for a protein and thus might belong to the growing family of noncoding RNAs. These results not only demonstrate for the first time that overexpression of hsp27 by gene transfer is associated with regulation of gene expression but also reveal a novel differentiation-associated gene in human keratinocytes.

Small heat shock proteins expression in rat kidneys treated with cyclosporine A alone and combined with melatonin

Small heat shock proteins (sHSPs) are cytoskeletal chaperones constitutively expressed in the normal kidney but enhanced with beneficial roles during adverse stimuli. Cyclosporine A is an immunosuppressive drug with major adverse side effect such as severe nephrotoxicity. Among possible mechanisms of cyclosporine A-induced renal damage, oxidative stress and cytoskeletal damage have been suggested. Melatonin has been successfully used as antioxidant against many renal diseases. This in vivo study was performed to shed light on the protective effect of melatonin against cyclosporine A-induced renal alterations. We treated rats with cyclosporine A alone, or combined with melatonin, and with melatonin alone (as controls) for 40 days and analysed the renal abundance and distribution of two sHSPs, HSP25 and alpha B-crystallin. These data were correlated with the histopathological effects of the treatments. Cyclosporine A induced insoluble isoforms that moved to soluble fractions after melatonin coadministration as in controls. After cyclosporine A treatment, an intense signal for sHSPs was found within the glomeruli, nucleus and cytoplasm of cortical tubules, collecting ducts and vascular wall. After melatonin supply, the staining was faint, limited to the cytoplasm of cortical tubules, similar to controls. Both fibrosis and tubular alterations significantly decreased after melatonin coadministration. In conclusion, HSP25 and alpha B-crystallin are overexpressed in the rat kidney treated with cyclosporine A but are similar to controls after combined melatonin. This could be a consequence of the cytoprotective effect of melatonin in this nephrotoxic model so that a beneficial sHSPs response is unnecessary.

Perinatal expression of heat-shock protein 27 in brain regions and nonneural tissues of the piglet

Important stressful events occur at birth or within the few hours that follow this event. To unravel a possible involvement of stress proteins, it is important to determine their levels of expression. Expression of HSP27 protein was determined by Western blotting in several nonneural tissues and in brain regions of the developing pig (fetal to adult). Maximum levels of expression were observed in heart, liver, and lung. In kidney, the expression was reduced during the first hours of life. Brain parts included whole brain, cerebellum, cortex, hippocampus, hypothalamus, and striatum. HSP27 immunogenicity was observed in all the brain regions studied. In whole brain, cerebellum, cortex, hippocampus, and hypothalamus extracts, the levels of HSP27 were decreased during the first hours of age (4 h to 2 d). In striatum, levels of expression were very low--if detectable--during the early postnatal days of life. Changes in environmental parameters, like temperature and/or hypoxia can be possibly related to differential expressions of HSPs, which can result in severe adverse developmental outcomes. The results are discussed in terms of using the newborn piglet as a model to study different forms of stress on the heat-shock protein postnatal expression.

Molecular chaperones in the kidney: distribution, putative roles, and regulation

Molecular chaperones are intracellular proteins that prevent inappropriate intra- and intermolecular interactions of polypetide chains. A specific group of highly conserved molecular chaperones are the heat shock proteins (HSPs), many of which are constitutively expressed but most of which are inducible by diverse (in some cases specific) stress factors. HSPs, either alone or in cooperation with "partner" chaperones, are involved in cellular processes as disparate as correct folding and assembly of proteins, transport of proteins to specific intracellular locations, protein degradation, and preservation and restructuring of the cytoskeleton. The characteristic distribution of individual HSPs in the kidney, and their response to different challenges, suggests that a number of HSPs may fulfill specific, kidney-related functions. HSP72 and the osmotic stress protein 94 (Osp94) appear to participate in the adaptation of medullary cells to high extracellular salt and urea concentrations; the small HSPs (HSP25/27 and crystallins) may be involved in the function of mesangial cells and podocytes and contribute to the volume-regulatory remodeling of the cytoskeleton in medullary cells during changes in extracellular tonicity. HSP90 contributes critically to the maturation of steroid hormone receptors and may thus be a critical determinant of the aldosterone sensitivity of specific renal epithelial cells. Certain HSPs are also induced in various pathological states of the kidney. The observation that the expression of individual HSPs in specific kidney diseases often displays characteristic time courses and intrarenal distribution patterns supports the idea that HSPs are involved in the recovery but possibly also in the initiation and/or maintenance phases of these disturbances.

The concept of glomerular self-defense

The balance between local offense factors and defense machinery determines the fate of tissue injury: progression or resolution. In glomerular research, the most interest has been on the offensive side, for example, the roles of leukocytes, platelets, complement, cytokines, eicosanoids, and oxygen radical intermediates. There has been little focus on the defensive side, which is responsible for the attenuation and resolution of disease. The aim of this review is to address possible mechanisms of local defense that may be exerted during glomerular injury. Cytokine inhibitors, proteinase inhibitors, complement regulatory proteins, anti-inflammatory cytokines, anti-inflammatory eicosanoids, antithrombotic molecules, and extracellular matrix proteins can participate in the extracellular and/or cell surface defense. Heat shock proteins, antioxidants, protein phosphatases, and cyclin kinase inhibitors may contribute to the intracellular defense. This article outlines how the glomerulus, when faced with injurious cells or exposed to pathogenic mediators, defends itself via the intrinsic machinery that is brought into play in resident glomerular cells.

Expression of the small heat shock protein HSP 27 in developing human skin

The 27 kDa heat shock protein (HSP 27) is expressed in keratinocytes of the upper epidermal layers, and recent evidence suggests that this protein is involved in the regulation of epidermal differentiation. The expression of HSP 27 was investigated in developing human skin by immunohistochemistry utilizing a specific monoclonal antibody. We used formalin-fixed, paraffin-embedded tissue of abdominal skin obtained from 34 human fetuses ranging between 13 and 30 weeks estimated gestational age (EGA). We found that HSP 27 is not expressed in keratinocytes until week 14 EGA. At this stage staining is observed in the periderm and the upper intermediate cells but not in hair germs. During further development, HSP 27 expression correlates with increasing epidermal differentiation, i.e. shedding of the periderm and beginning of keratinization. HSP 27 expression is confined to the upper cell layers and sparse basal cells. In hair follicles, HSP 27 can be detected in the innermost cell layer of the outer root sheath and in keratinocytes of the bulge identical to what is observed in adult skin. The hair papilla, matrix cells and sebaceous glands are negative for HSP 27 and remain so during further development. In eccrine sweat glands of the 24th week EGA, HSP 27 is confined to the superficial cell layer of the sweat ducts. In the present report we demonstrate differentiation-related expression of HSP 27 in developing human skin. Further in vitro studies will address the molecular function of HSP 27 in epidermal differentiation and development.

Heat shock proteins in renal injury and recovery

Heat shock proteins, or stress proteins, are molecular chaperones responsible for protein processing and protection against cellular injury through the prevention of inappropriate peptide interactions. The distribution of individual stress proteins varies between regions of the kidney and within subcellular compartments both in normal and pathological conditions. Novel molecular chaperones have been identified in renal medullary cells which are unique, among mammalian cells, in routinely facing osmotic stress. Heat shock proteins can participate in renal injury as antigenic targets, but their primary role is beneficial, and these proteins may function by interacting with the cytoskeleton to protect against and assist recovery from cellular injury.

Expression of MT-3 mRNA in human kidney, proximal tubule cell cultures, and renal cell carcinoma

The human metallothionein 3 (MT-3) gene has recently been identified and characterized as a brain-specific MT having growth inhibitory activity for neuronal cells. One objective of the present study was to determine if MT-3 is brain-specific or also present in the renal system, a site for chronic toxicity due to heavy metal exposure. Using RT-PCR methodology, MT-3 mRNA was shown to be expressed in the human renal system at levels below mRNA for the beta-actin gene. MT-3 mRNA was shown to be expressed in all samples obtained from both the developing and adult renal systems, from 20 weeks of fetal age to 72 years. Cultures of human proximal tubule (HPT) cells were used to determine if MT-3 mRNA expression is influenced by metal exposure. Exposure of HPT cells to either Zn2+ or Cd2+ resulted in an early (within 24 h), but unsustained increase in MT-3 mRNA. The demonstration of MT-3 mRNA expression in the kidney indicates that MT-3 may play an important early role in the response of the cell to metal exposure. MT-3 mRNA expression was also examined in tissues and cells from three cases of renal cell carcinoma. MT-3 was found to be expressed in all three cases at levels similar to those found for normal kidney, providing evidence that MT-3 mRNA expression is not altered in this cancer.

Expression of heat shock protein 27 in adult human third molar dental pulp

This study is the first to define the expression of hsp 27 in the pulp of the adult human third molar. Using a monoclonal antibody against human hsp 27, immunoreactivity was demonstrated in the odontoblasts, odontoblast processes, pulp fibroblasts, and smooth muscle and endothelial cells of vessel walls. Nerves were negative. Pulp fibroblasts were characterized by cytoplasmic staining and variable nuclear staining. Odontoblasts also displayed consistent cytoplasmic staining and variable nuclear staining. Western, Northern, and RT-PCR analysis confirmed the expression of hsp 27 mRNA and protein. Hsp 27 was also shown to be present in both the unphosphorylated and phosphorylated isoforms. In general, nuclear localization and phosphorylation of hsp 27 has been correlated with cells responding to stress or other stimuli. This study demonstrates that pulp from a single human third molar provides sufficient material to support a detailed molecular analysis of gene expression.