STAG2 deficiency induces interferon responses via cGAS-STING pathway and restricts virus infection

Siyuan Ding,Harry B Greenberg,Kevin F Brulois,Ningguo Feng,Yaw Shin Ooi,David A Solomon,Lili Ren,Bin Li,Jonathan Diep,Xingnan Li,Linda L Yasukawa,Xin Wang,Jan E Carette,Calvin J Kuo

doi:10.1038/s41467-018-03782-z

Abstract

Cohesin is a multi-subunit nuclear protein complex that coordinates sister chromatid separation during cell division. Highly frequent somatic mutations in genes encoding core cohesin subunits have been reported in multiple cancer types. Here, using a genome-wide CRISPR-Cas9 screening approach to identify host dependency factors and novel innate immune regulators of rotavirus (RV) infection, we demonstrate that the loss of STAG2, an important component of the cohesin complex, confers resistance to RV replication in cell culture and human intestinal enteroids. Mechanistically, STAG2 deficiency results in spontaneous genomic DNA damage and robust interferon (IFN) expression via the cGAS-STING cytosolic DNA-sensing pathway. The resultant activation of JAK-STAT signaling and IFN-stimulated gene (ISG) expression broadly protects against virus infections, including RVs. Our work highlights a previously undocumented role of the cohesin complex in regulating IFN homeostasis and identifies new therapeutic avenues for manipulating the innate immunity.

Highlights

Background vs selectionMockMocVk5-STAG2 α-GAPDH WT STAG2 –/– (***P ≤ 0.001)immunity-associated host factors
Paralleling the results of STAG2 deficiency, we found that etoposide treatment, which induced chromosome instability and increased γH2AX levels (Supplementary Fig. 5C), activated STAT1 phosphorylation and IFNstimulated gene (ISG) expression (Supplementary Figs. 5C and 5D)
Our results indicated that small interfering RNA (siRNA) silencing of either cGAS or STING led to a significant decrease in IFN expression in STAG2−/− HT-29 cells (Supplementary Fig. 6A), whereas knockdown of MAVS had a minimal effect (Supplementary Fig. 6B)

Summary

Introduction

It was interesting that the replication of RV was highly restricted by the absence of several key components of the nuclear cohesin complex, even though RV replication is thought to take place exclusively in the cytoplasm[7]. To further examine this fascinating phenotype, we first validated the screen results by knocking out STAG2 in Caco-2 and T84 cells, both human colonic cancer-derived epithelial cell lines (Supplementary Fig. 1A). Complete STAG2 deletion was confirmed by both western blot and Sanger sequencing (Supplementary Fig. 1C) These cells did not exhibit severe defects in survival or proliferation Besides the bovine RV NCDV strain, we tested additional human and animal RV strains and they were all reduced in the absence of STAG2 (Supplementary Fig. 3A)

Methods

Results

Conclusion