Dengue virus induced changes in Ca2+ homeostasis in human hepatic cells that favor the viral replicative cycle

Abstract

The role of Ca²⁺ during dengue virus (DENV) replication is unknown; thus, changes in Ca²⁺ homeostasis in DENV infected human hepatic HepG2 and Huh-7 cells were analyzed. Infected HepG2 cells, but not Huh-7 cells, showed a significant increase in plasma membrane permeability to Ca²⁺, while both cell lines showed marked reduced levels of Ca²⁺ stored in the endoplasmic reticulum. While the expression levels of STIM1 and ORAI1 showed no changes, STIM1 and ORAI1 were shown to co-localized in infected cells, indicating activation of the store-operated Ca²⁺ entry (SOCE) pathway. Finally, manipulation in the infected cells of the intra and extracellular Ca²⁺ levels by chelators (BAPTA-AM and EGTA), SOC inhibitor (SKF96365), IP3 Receptor antagonist (2APB) or increase of extracellular [Ca²⁺], significantly reduced DENV yield, but not vesicular stomatitis virus yield, used as a control. These results show that DENV infection alters cell Ca²⁺ homeostasis and that such changes favor viral replication.

Keywords: Ca(2+); Ca(2+) homeostasis; Dengue; Dengue virus; Hepatic cells; SOCE; STIM1/ORAI1.