Cytopathic effect of rotavirus NSP4 86-175 protein on rat cardiomyocytes and the possible mechanism / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the cytopathic effect of amino acids 86-175 of rotavirus non-structural protein 4 (NSP4 86-175) on rat cardiomyocytes and the possible mechanism. Methods:Rat H9C2 cardiomyocytes were treated with NSP4 86-175 protein. Changes in the growth and morphology of the cells were observed. The activity of LDH in the cell culture medium was detected. Fluo-3AM was used to label intracellular free calcium ions and the concentrations of calcium ions in rat cardiomyocytes with and without NSP4 86-175 treatment were detected by confocal laser microscopy. The expression of Bax, Bcl-2, caspase-3, 78 kDa glucose-regulated protein (GRP78), C/EBP homologous protein (CHOP) and caspase-12 at mRNA level was detected by real-time PCR. The expression of caspase-3, caspase-8, caspase-9, GRP78, CHOP and caspase-12 at protein level was detected by Western blot. Results:Normal cardiomyocytes showed a typical myoblast-like morphology, presenting as spindle-shaped cells with clear boundaries. Obvious cytopathic effect, vacuolar degeneration, shriveled and rounded cells, and cell fragmentation were observed after the treatment with purified NSP4 86-175 protein. The activity of LDH in cell culture medium was enhanced by NSP4 86-175 protein. NSP4 86-175 protein also enhanced the fluorescence of the calcium ions in rat cardiomyocytes, promoted cell apoptosis, up-regulated the expression of apoptotic factors including caspase-3, caspase-8, caspase-9 and Bax-2, and increased the expression of classical markers of endoplasmic reticulum stress such as GRP78, CHOP and caspase-12. Conclusions:NSP4 86-175 had a cytopathic effect on rat cardiomyocytes, which might be related to the induced intracellular calcium overload, endoplasmic reticulum stress, apoptosis and necrosis. These results might be used as theoretical reference for further study on rotavirus infection and myocardial injury.