The E3 ligase TRIM56 is a host restriction factor of Zika virus and depends on its RNA-binding activity but not miRNA regulation, for antiviral function

Yang, Darong; Li, Nan L.; Wei, Dahai; Liu, Baoming; Guo, Fang; Elbahesh, Husni; Zhang, Yunzhi; Zhou, Zhi; Chen, Guo-Yun; Li, Kui

To this end, we investigated the impact of TRIM56 on ZIKV infection in 293T-derived cells deficient in Dicer expression thus lacking the biogenesis of miRNAs [33] . First, we confirmed the Dicer deficiency phenotype in two clonal cell lines (referred to as No-Dice (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19) (20) and ) by showing the absence of miR-92a and miR-21 expression, as opposed to control 293T (referred to as 293T-WT) cells (Fig 6A) . It should be noted that total small RNA deep sequencing analysis had shown these two Dicer-knockout 293T cell lines were deficient in miRNA expression globally, as opposed to 293T-WT cells, in a previous study [33] . Our miRNA qPCR data thus confirmed the reported phenotype of these cells. Next, we wondered if Dicer deficiency affected ZIKV fitness in these 293T-derived cells. Although No-Dice (2-20) cells were slightly impaired for supporting intracellular ZIKV RNA replication ( Fig 6B) and progeny virus production (Fig 6C) , No-Dice (4-25) cells permitted ZIKV propagation at efficiencies comparable to 293T-WT cells (Fig 6B and 6C) . These data suggest that host miRNAs are not essential for ZIKV replication. In subsequent experiments, we utilized No-Dice (4-25) and 293T-WT cells for comparison to dissect the possible role of host miRNAs in the anti-ZIKV action of TRIM56.