Differential Expression of hsp70 Stress Proteins in Human Endothelial Cells Exposed to Heat Shock and Hydrogen Peroxide

Abstract

The potential role of oxidative stress conditions in the induction of heat shock proteins was studied in human umbilical vein endothelial cells. We compared the effects of temperature (43 to 45 degrees C), exposure to hydrogen peroxide (H2O2) and oxygen metabolites generated by the enzyme system hypoxanthine-xanthine oxidase (O2- plus H2O2), as well as exposure to 95% O2, on the expression of the major 70-kD heat shock proteins (hsp70). Northern blot analysis indicated that: (1) heat shock induced a rapid and marked increase in hsp70 mRNA levels that reached a maximum during recovery from a 30-min exposure to 45 degrees C; (2) treatment with a 5-mM H2O2 bolus or 50 mU/ml xanthine oxidase also increased hsp70 mRNA levels but to a lesser extent than heat shock (about 10 and 25 times less, respectively); (3) no change was detected after a 5-day exposure to 95% O2. Nuclear run on transcription data and kinetics of mRNA decay in the presence of actinomycin D indicated that the observed increase in hsp70 mRNA levels in both heat-shocked and H2O2-treated cells was mainly due to a transcriptional induction. The kinetics of hsp70 synthesis correlated with the accumulation of hsp70 mRNA. Two-dimensional gel electrophoresis and immunologic analysis of these heat shock proteins revealed a series of at least five distinct hsp70 isoforms induced in heat-shocked cells, whereas only a specific subset of these proteins, mainly one acidic isoform, was induced in very low amounts in response to H2O2 treatment. These results clearly indicate that the endothelial cell responses to oxidative stress and heat shock differ in both qualitative and quantitative terms in respect to hsp70 induction. They also suggest that the intensity of this response to oxidative stress conditions may vary depending on the nature of the oxidative challenge.

Heat Shock and Oxidative Stress-induced Exposure of Hydrophobic Protein Domains as Common Signal in the Induction ofhsp68

“…Expression of hsp68 was significantly stronger and faster induced by HS compared with OS as reported previously (34,52,53). In some previous studies no induction after OS was reported (9,54,55).…”

Homocysteine Induces Programmed Cell Death in Human Vascular Endothelial Cells through Activation of the Unfolded Protein Response

“…4A). Furthermore, Hsp70, which is highly induced by oxidative stress in human endothelial cells (24,35), was not induced by homocysteine. In contrast, Hsp70 was highly induced by hydrogen peroxide, and its induction was efficiently suppressed by pretreatment of cells with NAC (Fig.…”

Mitochondrial membrane potential: a novel biomarker of oxidative environmental stress.

“…HSPs are induced as an adaptive response on exposure to a variety of cellular injuries including oxidative damage. In particular, the cytosolic, inducible, 72 kDa HSP (Hsp70) is induced by oxidants both in vitro and in vivo (8)(9)(10), and its expression has been used as an indicative response to environmental stress and an interesting candidate as biomarkers of effect (11)(12)(13)(14). Optimal biomarkers would be biomarkers of exposure, which could provide the earliest, most upstream warning signs of environmental stress exposure.…”