AUTHOR=Wen Chunxia , Yu Yufeng , Gao Chengfeng , Qi Xian , Cardona Carol J. , Xing Zheng 

TITLE=RIPK3-Dependent Necroptosis Is Induced and Restricts Viral Replication in Human Astrocytes Infected With Zika Virus

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 11 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2021.637710

DOI=10.3389/fcimb.2021.637710

ISSN=2235-2988

ABSTRACT=Apoptosis, pyroptosis and necroptosis are regulated processes of cell death which could be crucial for pathogenicity and resistance in hosts infected by viruses. Zika virus (ZIKV) is a mosquito-borne flavivirus, which infects humans and could cause neurological disorders. Neural developmental disorders and microcephaly could occur in infected fetus. Several types of nervous cells have been reported to be susceptible to ZIKV infection. Human astrocytes play important roles in neuronal nutritional support and defense. In this study, we show that astrocytes were susceptible to ZIKV infection and underwent progressive cell death with viral RNA and proteins detected after infection. In infected astrocytes we detected no cleavage or activation of pro-caspase-3 and pro-caspase-1 or apoptotic substrates and increased secretion of interleukin (IL)-1 or IL-18 did not occur, which therefore ruled out the occurrence of apoptosis or pyroptosis in ZIKV-infected astrocytes. We detected, however, an increase of phosphorylated receptor-interacting serine/threonine-protein kinase (RIPK)1, RIPK3, and mixed lineage kinase domain-like (MLKL) protein, indicating that a programmed necrosis, or necroptosis, was induced in infected astrocytes. The phosphorylation and cell death could be inhibited in the cells pre-treated with GSK872, an inhibitor of RIPK3, while inhibition of RIPK1 with an inhibitor, Necrostatin-1, had no effect, suggesting that ZIKV-induced necroptosis was RIPK1-independent in astrocytes. In line with this finding, the inhibition of RIPK1 had no effect on phosphorylation of MLKL. We showed evidence that MLKL phosphorylation was RIPK3-dependent and ZBP-1, which could stimulate RIPK3, was upregulated in ZIKV-infected astrocytes. Finally, we demonstrated that in GSK872-pre-treated astrocytes, viral replication increased significantly, which indicates that necroptosis could be protective against viral replication in astrocytes. Our finding that astrocytes uniquely underwent necroptosis in response to ZIKV infection provides insightful knowledge and helps us better understand the viral pathogenesis in the central nervous system infected with ZIKV.