Constitutive expression of HSP 72 in swine heart

The role of heat shock proteins in inflammatory injury induced by cold stress in chicken hearts

The aim of this study was to investigate the effects of cold stress on the expression levels of heat shock proteins (Hsps90, 70, 60, 40, and 27) and inflammatory factors (iNOS, COX-2, NF-κB, TNF-α, and PTGEs) and oxidative indexes in hearts of chickens. Two hundred forty 15-day-old male chickens were randomly divided into 12 groups and kept at the temperature of 12 ± 1 °C for acute and chronic cold stress. There were one control group and five treatment groups for acute cold stress, three control groups, and three treatment groups for chronic cold stress. After cold stress, malondialdehyde level increased in chicken heart; the activity of superoxide dismutase and glutathione peroxidase in the heart first increased and then decreased. The inflammatory factors mRNA levels were increased in cold stress groups relative to control groups. The histopathological analysis showed that heart tissues were seriously injured in the cold stress group. Additionally, the mRNA levels of Hsps (70, 60, 40, and 27) increased significantly (P < 0.05) in the cold stress groups relative to the corresponding control group. Meanwhile, the mRNA level and protein expression of Hsp90 decreased significantly (P < 0.05) in the stress group, and showed a gradually decreasing tendency. These results suggested that the levels of inflammatory factors and Hsps expression levels in heart tissues can be influenced by cold stress. Hsps commonly played an important role in the protection of the heart after cold stress.

Hsp70 and HSF-1 expression is altered in the tissues of pigs transported for various periods of times

The aim of this study was to assess changes of Hsp70 and HSF-1 protein and mRNA expression in stress-sensitive organs of pigs during transportation for various periods of time. Twenty pigs were randomly divided into four groups (0 h, 1 h, 2 h, and 4 h of transportation). A significant increased activity of AST and CK was observed after 1 h and 2 h of transportation. Histopathological changes in the heart, liver, and stomach indicated that these organs sustained different degrees of injury. Hsp70 protein expression in the heart and liver of transported pigs did not change significantly while it increased significantly (p < 0.05) in the stomach. Hsp70 mRNA levels decreased significantly (p < 0.05) in the heart after 4 h of transportation. However, mRNA expression increased significantly in the liver after 1 (p < 0.05) and 4 h (p < 0.01) of transportation, and increased significantly in the stomach of the transported pigs after 1, 4 (p < 0.01), and 2 h (p < 0.05). HSF-1 levels were reduced at 1 and 4 h (p < 0.05) only in the hearts of transported pigs. These results indicate that Hsp70 mediates distinct stress-related functions in different tissues during transportation.

Expression and distribution of heat shock proteins in the heart of transported pigs

The expression and localization of four heat shock proteins (Hsp70, Hsp86, Hsp90, and Hsp27) were shown in the heart tissue of pigs transported for 6 h. Immunostaining detected the consistent presence of all Hsps in the pig myocardial cells under both transported and normal housing conditions. Immunohistochemical analysis revealed predominance of Hsp70 (significantly highest levels) and Hsp27 in the cytoplasm of myocardial cells. Hsp90 and Hsp86 were expressed both in the cytoplasm and in the nucleus, preferentially in the cytoplasm, of the myocardial cells. In view of their abundant and uniform distributions in the myocardial cells, the expression and distribution patterns of all detected Hsps within the myocardial cells, mostly limited to the cytoplasm, could be related to their chaperone function for cells with important special activities in this study. The identification of all four Hsps in the blood vessel endothelial cells possibly implies that endothelial cells react to ischemia and hypoxia by expressing Hsps. Immunoblot findings suggest that the level of all Hsps decreased in response to stress due to a 6 h journey. The decrease in Hsp levels in the myocardial cells may indicate that the transport stress may have overcharged the repair mechanisms of the cells. Whether this distinct depletion of Hsps contributes to an increased susceptibility to acute heart failure and the sudden death syndrome in transported pigs should be elucidated in future experiments.

Effect of thermal stress on early and late passaged mouse lens epithelial cells

Cataract is an age related disease of protein aggregation. It has been suggested that aging affects the cells ability to protect protein integrity. The protein integrity, which is essential for cellular homeostasis, is maintained by a complex system of refolding or degradation of damaged proteins. The heat shock proteins (hsps) are the major contributors in the maintenance of protein integrity. The heat shock transcription factor (HSF-1) is the master regulator of all hsp synthesis in response to stress. This investigation examined the role of HSF-1 in the regulation of hsp synthesis in early and late passaged alphaTN-4 cells. Data collected in this study revealed that the nucleotide sequence of HSF-1 mRNA obtained from early and late passaged alphaTN-4 cells were identical. When early and late passaged cell were exposed to thermal stress, their hsp expression were also similar. HSP-40 expression was detected after 2 h of heat stress, whereas HSP-70 and low molecular weight heat shock protein alphabeta crystallin showed significantly increased synthesis 18 h post heat stress. The late passaged alphaTN-4 cells ability to upregulate hsps in response to heat stress could be due to its high replicative activities. The data presented here suggests a relationship between the presence of functional HSF-1 and sustained proliferative activities of the late passaged alphaTN-4 cell.

Insulin induces myocardial protection and Hsp70 localization to plasma membranes in rat hearts

Insulin induces the expression of the 70-kDa heat shock protein (Hsp70) in rat hearts. In this study, we examined insulin- and heat shock-treated hearts for improved contractile recovery after 30 min of ischemia, activation of the heat shock transcription factor, and localization of the Hsp70 in relation to dystrophin and α-tubulin. Adult male Sprague-Dawley rats were assigned to groups: 1) control, 2) sham control, 3) insulin injected (200 μU/g body wt), 4) heat shock treated (core body temperature 42°C for 15 min), and 5) heat shock and insulin treated. Six hours later, hearts were isolated for Langendorff perfusion to determine cardiac function, or myocardial tissues were collected and prepared for either electrophoretic mobility shift assay, Western blot analysis, or immunofluorescence microscopy. Insulin treatment with 6 h of recovery enhances postischemic myocardial recovery of contractile function and increases Hsp70 expression through activation of the heat shock transcription factor. Insulin-treated hearts had elevated levels of Hsp70, particularly in the membrane fraction. In contrast, heat-shocked hearts had elevated levels of Hsp70 in the cytosol, membrane, and pellet fractions. After insulin treatment, Hsp70 was mostly colocalized to the plasma membrane with dystrophin. In contrast, after heat shock, Hsp70 was localized mostly between cardiomyocytes in apparent vascular or perivascular elements. The localization of Hsp70 is dependent on the inducing stimuli of either heat shock or insulin treatment. The cell membrane versus vascular localization of Hsp70 suggests the interesting possibility of functionally distinct roles for Hsp70 in the heart, whether induced by insulin or heat shock treatment.

Cold stress does not induce stress proteins SP 25 and SP 72 in rat skeletal muscle

Cryotherapy is a common treatment for musculoskeletal injuries, yet the mechanism(s) underlying its effects remain unclear. Since cryotherapeutic treatment often involves temperatures that are known to induce the protective stress proteins (SPs), we determined whether SP 25 and SP 72 expression was altered following a 20-min cold stress to the hindlimb muscles of Sprague-Dawley rats. The right hindlimb of anesthetized animals was placed in an ice bath until muscle temperature decreased to either 8.4 +/- 0.4 degrees C or 19.7 +/- 0.3 degrees C for 20 min. After a 24-h recovery, the white and red gastrocnemius, plantaris, soleus, extensor digitorum longus, and tibialis anterior muscles from both legs were removed and rapidly frozen in liquid nitrogen. Portions of the muscles were homogenized and SP 25 and SP 72 content was assessed by SDS-PAGE/Western blot analyses. Quantification of SP 25 and SP 72 by densitometric scanning of blots demonstrated no significant increases in SP 25 or SP 72 content in any of the muscles exposed to either the 8 or the 20 degrees C cold stress compared to muscles from the unstressed contralateral limbs. These results suggest that a 20-min cold stress of 8 degrees C or 20 degrees C does not increase muscle SP 25 or SP 72 content.

Ischemic preconditioning: lack of delayed protection against skeletal muscle ischemia-reperfusion

We investigated the ability of ischemic preconditioning to induce expression of heat shock protein 70 (Hsp 70) and/or to increase muscle survival after ischemia-reperfusion in the rat hind limb. Ischemic preconditioning regimens tested were; 1 x 5 min of ischemia, 4 x 5 min of ischemia interrupted by 10 min of reperfusion, 1 x 10 min of ischemia or 2 x 10 min of ischemia interrupted by 15 min of reperfusion. Western blot analysis revealed only a modest induction of Hsp 70 at 24 h after preconditioning using the latter two protocols of 1 x 10 min of ischemia or 2 x 10 min. Used at 24 h prior to prolonged ischemia, neither protocol improved muscle survival measured at 24 h after reperfusion. In conclusion, ischemic preconditioning did not produce delayed protection from ischemia-reperfusion in this model and the study suggests that ischemic preconditioning is not a useful protective strategy against skeletal muscle necrosis in the long-term.

Differential expression of stress proteins in rat myocardium after free wheel or treadmill run training

High-intensity treadmill exercise increases the expression of a cardioprotective, inducible 72-kDa stress protein (SP72) in cardiac muscle. This investigation examined whether voluntary free wheel exercise training would be sufficient to confer a similar response. Male Sprague-Dawley rats were randomly assigned to either treadmill (TM-Tr) or free wheel (FW-Tr) training groups. By the end of the 8-wk training period, TM-Tr animals ran 1 h/day, 5 days/wk up a 10% grade, covering a distance of 8,282 m/wk. FW-Tr rats ran, on average, 5,300 m/wk, with one-third of the animals covering distances similar to those for the TM-Tr group. At the time of death, hearts of trained and caged sedentary control (Sed) animals were divided into left (LV) and right (RV) ventricles. Citrate synthase activity and the relative immunoblot contents of SP72, SP73 (the constitutive isoform of the SP70 family), and a 75-kDa mitochondrial chaperone (SP75) were subsequently determined. LV and RV did not differ on any measure, and SP73, SP75, and citrate synthase were not affected by training. Cardiac SP72 levels were elevated over fourfold in both ventricles of TM-Tr compared with RV of FW-Sed rats. Despite the animals having run a similar total distance, cardiac SP72 content in FW-Tr rats was not different from that in Sed animals. These data indicate that voluntary exercise training is insufficient to elicit an elevation of SP72 in rat heart and suggest that exercise intensity may be a critical factor in evoking the cardioprotective SP72 response.

Heat shock protein 72 production in liver tissue after experimental total hepatic inflow occlusion

BACKGROUND

The pathogenesis of hepatic ischaemia-reperfusion injury is incompletely understood. This study examined the effects of reperfusion with congested portal blood on ischaemia-reperfusion injury of the liver following Pringle's manoeuvre, as monitored by heat shock protein (HSP) 72 production in rat liver tissue.

METHODS

Rats were randomized to three groups. In group 1 hepatic ischaemia with portal congestion was induced by Pringle's manoeuvre for 15 min; in group 2 Pringle's manoeuvre was applied for 15 min with an extracorporeal portasystemic shunt; and in group 3 the superior mesenteric vein was occluded for 15 min. The production of HSP72 in liver tissue was measured by Western blotting at 48 h after each intervention. Conventional parameters for hepatic function were examined at 1, 3 and 48 h after reperfusion.

RESULTS

There was marked HSP72 expression in group 1, but not in group 2 or 3, showing that a combination of liver ischaemia and reperfusion of congested portal blood is required to induce strong expression of HSP72 in the tissue. On the other hand, biochemical parameters were raised equally in both groups 1 and 2, reflecting a similar degree of ischaemic hepatocyte injury.

CONCLUSION

The additional stress impact of temporary portal occlusion upon ischaemia-reperfusion injury of the liver was clearly detected by in situ hepatic HSP72 production in this study.