Zika virus non-structural protein NS2A mediated endoplasmic reticulum stress through interacting with Sarco/endoplasmic reticulum Ca2+-ATPase 2.

Zika virus (ZIKV) infection of neuronal cells leads to endoplasmic reticulum (ER) stress, which is one of the key causes of neuronal damage. However, how ZIKV mediates ER stress has not been fully understood. Here, we observed that ZIKV infection of astrocytes elevated Sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) expression, increased intracellular Ca²⁺ concentration, and upregulated ER stress-related genes. SERCA2 was identified to regulate Ca²⁺ homeostasis and ER stress during ZIKV infection through both knockdown and overexpression of SERCA2 in astrocytes. Furthermore, ZIKV NS2A interacted with SERCA2 and increased the expression of SERCA2, disrupted Ca²⁺ homeostasis, and induced ER stress in astrocytes. After the knockdown of SERCA2 expression, Ca²⁺ homeostasis and ER stress were significantly mitigated in astrocytes expressing NS2A. Additionally, pTMS1-2 and pTMS4-5 of NS2A interacted with SERCA2 and regulated Ca²⁺ homeostasis and ER stress. ZIKV infection of the brains of BALB/c neonatal mice also elevated expression of SERCA2 and ER stress-related genes. Furthermore, SERCA2 expression facilitated ZIKV replication. These results suggested that ZIKV NS2A mediates ER stress through its interaction with SERCA2, providing new insights into the pathogenic mechanism of ZIKV and the development of anti-ZIKV therapies.

Importance: Zika virus (ZIKV) infection induces intracellular Ca²⁺ imbalance and endoplasmic reticulum (ER) stress. However, the molecular mechanisms involved in it remain unknown. Here we reported, for the first time, that ZIKV infection increased the expression of Sarco/endoplasmic reticulum Ca²⁺-ATPase 2 (SERCA2), which plays a crucial role in regulating Ca²⁺ homeostasis and ER stress. Furthermore, ZIKV NS2A was found to interact with SERCA2, contributing to the regulation of Ca²⁺ homeostasis and ER stress during ZIKV infection. And ZIKV NS2A pTMS1-pTMS2 and pTMS4-pTMS5 were the specific sites that interacted with SERCA2. These findings elucidate that the interaction between NS2A and SERCA2 is responsible for the regulation of the upstream signaling pathway of ER stress mediated by ZIKV infection. Additionally, the expression of SERCA2 promoted ZIKV proliferation, indicating that SERCA2 may serve as a potential target for anti-ZIKV therapies.