Previously, we proposed a dual control mechanism for the regulation of the heat shock response in mammalian cells: a positive control mediated by the heat shock transcription factor HSF1 and a negative control mediated by the constitutive heat shock element-binding factor (CHBF). To study the physiological role of CHBF in the regulation of heat shock response, we purified CHBF to apparent homogeneity and showed it to be identical to the Ku autoantigen, a heterodimer consisting of 70-kDa (Ku-70) and 86-kDa (Ku-80) polypeptides. To study further the functional significance of Ku/CHBF in the cellular response to heat shock, we established rodent cell lines that stably and constitutively overexpressed one or both subunits of the human Ku protein, and examined the thermal induction of hsp70 and other heat shock proteins in these Ku-overexpressing cells. We show that expression of the human Ku-70 and Ku-80 subunits jointly or of the Ku-70 subunit alone specifically inhibits heat-induced hsp70 expression. Conversely, expression of human Ku-80 alone does not have this effect. Thermal induction of other heat shock proteins in all of the Ku-overexpressing cell lines appears not to be significantly affected, nor is the state of phosphorylation or the DNA-binding ability of HSF1 affected. These findings support a model in which hsp70 expression is controlled by a second regulatory factor in addition to the positive activation of HSF1. The Ku protein, specifically the Ku-70 subunit, is involved in the regulation of hsp70 gene expression.Cells and organisms respond to heat shock and a number of other environmental stresses by rapidly increasing the level of transcription of heat shock genes and the translation of their messages, leading to an elevated cellular level of the heat shock proteins (hsps). Among these proteins, hsp70 has been implicated in playing a key role in the cellular response to heat shock. Many recent studies suggest that one of the functions of hsp70 is to protect cells from thermal damage (3,17,21,29,30,44,45,53) by maintaining the native state and proper folding of cellular proteins under physiological stress (5,8,19,56), and/or by facilitating the restoration of certain cellular functions (37,48,57).In recent years, extensive studies of the mammalian heat shock transcription factor HSF1 have implicated this protein as a key positive regulatory factor in the heat shock response (1, 33-35, 59, 67). Although the importance of HSF1 in the regulation of mammalian hsp70 expression is well-established, recent data indicate that activation of HSF1 is not sufficient for the induction of hsp70 gene expression (36,39,43). Studies from our laboratory and others suggest the existence of an additional regulatory factor or factors (18,36). Experiments with extracts of control and heat-shocked cells demonstrated that rodent cells may contain two different heat shock element (HSE)-binding factors: in addition to HSF1, there appears to be a constitutive HSE-binding factor (CHBF) (22,36).Analysis of these two factors in ...

Objective: To investigate the protective mechanism of zinc finger protein A20 over-expression in acute myocardial infarction (AMI) rats. Methods: Forty-five Sprague Dawley (SD) rats were randomly divided into sham group, model group and observation group. The model and observation groups were injected with normal saline and pcDNA3.1-A20 plasmid in the pre-operative 24 hour, respectively. The AMI model was established by ligating the left anterior descending coronary arteries of the model group and the observation group. The sham group were only treated with left anterior descending coronary artery threading but not ligation. The levels of A20 messenger ribonucleic acids (mRNA) and protein were detected by, reverse transcription polymerase chain reaction (RT-PCR) and Western blot. The levels of tumour necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6) proteins in the peripheral blood were detected by the enzyme-linked immunosorbent assay (ELISA). The myocardial infarct size was analysed by triphenyl tetrazolium (TTC) staining. Results: Compared with the sham group, the levels of A20 mRNA and protein in the myocardium of the model and observation groups were significantly increased; the level in observation group was significantly higher than that of model group (p < 0.05). Compared with sham group, the level of nuclear factor-κB (NF-κB) p65 protein in the myocardium of the model and observation groups was activated into the nucleus, and NF-κB p65 protein in the nucleus in the observation group was significantly lower than that of the model group (p < 0.05). Compared with the sham group, the levels of TNF-α and IL-6 proteins in the peripheral blood in the model and observation groups were significantly increased (p < 0.05). The myocardial infarct size was significantly increased in the model and observation groups (p < 0.05), while the myocardial infarct size in the observation group was significantly decreased compared with the model group (p < 0.05). Conclusion: Zinc finger protein A20 can significantly inhibit the inflammatory injury and cell apoptosis process in AMI rats, which may be related to its inhibition of the expression and activation of nuclear transcription factor NF-κB.

Our present study investigates the cellular and molecular inflammatory events in male albino rat arterial injury. Male albino rats were subjected to longitudinal incision and carotid artery clamping for the duration of 45 days. Heat shock protein (HSP) 27, HSP70, HSP47 and Nuclear Factor kappa B (NF-κB) expressions were determined by qPCR and Western blot method. The morphology of vessel wall alteration was studied by the light microscopy. The expression of NF-κB was found to be increased after ten days of carotid artery injury. The qPCR and Western blot analysis showed elevation in HSP47, HSP27, and HSP70 expression, ten days following the surgical injury. The neointima-formation and the media layer discontinuity were evidenced by light microscopy. The dendritic-like cells were in close contact with the lymphocytes. Our study reports that the surgical injury induces an inflammatory response through the increased NF-κB and HSPs expression.