Changes of Heat Shock Proteins and Actin Induced by Oxiative Stress in Cultured H9c2 Cell Line

ABSTRACT

BACKGROUND AND OBJECTIVE: Even though they are identified on the basis of their induction by elevated temperatures, heat shock proteins are induced by various stimuli. Such inducers include viral infection, exposure to ethanol, sodium arsenite, steroid hormones and heavy metals. They become involved under pathological conditions, such as anoxia/ischemia, reperfusion injury and oxidative stress in the heart. In this research, the cellular damages and changes of Hsp25 and alphaB crytallin were investigated under oxidative stress induced H2O2 treatment in a cultured cardiomyoblast cell line, H9c2. MATERIALS AND METHODS: The morphological changes of the H9c2, and the distributions of Hsp25 and alphaB crytallin, were examined with phase-contrast, confocal and electron microscopy. The levels of Hsp25 and alphaB crytallin expressions within the cells were also checked. RESULTS: After exposure to a low concentration (10 micrometer) of H2O2, the amounts of Hsp25 and alphaB crytallin were increased more than in the control and heat shock groups. They were particularly localized in the perinuclear region and along the actin filament. When exposed to a high concentration (more than 100 micrometer) of H2O2, many cells developed apoptotic features, such as vacuolization, blebbing and apoptotic body formations. The amounts of Hsp25 and alphaB crytallin were decreased more than in the control group. However, a weak reaction in the perinuclear region and along the actin filaments still remained when observed under confocal microscopy. CONCLUSION: These results suggest that the elevation of the expressions of Hsp25 and alphaB crytallin were dependent on the concentration of H2O2. Additionally, the redistribution of these small Hsps is closely associated with the actin filaments, as well as the nuclei. Therefore, much more research will be essential for the elucidation of roles of Hsp25 and alphaB crytallin in oxidative stress, such as ischemia or ischemic-reperfusion injury.