Rotavirus NSP4 interacts with H9c2(2-1) cells in vitro, elevates intracellular Ca levels and can become cytotoxic: a possible mechanism for extra-intestinal pathogenesis.

Rotavirus (RV) is the predominant cause of infantile gastroenteritis with multiple pathogenic factors, among which enterotoxin NSP4 is the most significant factor. NSP4 has been shown to induce elevation of the intracellular calcium concentration, alteration of the cytoskeleton organization, and cytopathic effect among other processes. However, increasing evidence suggests that RVs can escape from the gastrointestinal tract and invade other organs and tissues to cause extra-intestinal diseases. In this study, we investigated whether NSP4 has a pathogenic effect on extra-intestinal cells and examined possible molecular mechanisms in vitro. Our results showed that NSP4 has important functions in increasing intracellular Ca concentration, altering actin cytoskeleton organization and inducing cellular damage in H9c2(2-1) cells. Blockade of the integrin α2 receptor using a specific antibody attenuated the increase of intracellular Ca concentration and alleviated the observed cytopathic effects, suggesting that integrin α2 may be a receptor for NSP4. Collectively, these results indicate that extracellular NSP4 can induce elevation of the intracellular Ca concentration, cause cytotoxic changes, and disrupt the actin cytoskeleton in H9c2(2-1) cells, which may constitute a possible mechanism for RV extra-intestinal pathogenesis.