SAFA facilitates chromatin opening of immune genes through interacting with anti-viral host RNAs

PLoS Pathog. 2022 Jun 3;18(6):e1010599. doi: 10.1371/journal.ppat.1010599. eCollection 2022 Jun.

Abstract

Regulation of chromatin structure and accessibility determines the transcription activities of genes, which endows the host with function-specific patterns of gene expression. Upon viral infection, the innate immune responses provide the first line of defense, allowing rapid production of variegated antiviral cytokines. Knowledge on how chromatin accessibility is regulated during host defense against viral infection remains limited. Our previous work found that the nuclear matrix protein SAFA surveilled viral RNA and regulated antiviral immune genes expression. However, how SAFA regulates the specific induction of antiviral immune genes remains unknown. Here, through integration of RNA-seq, ATAC-seq and ChIP-seq assays, we found that the depletion of SAFA specifically decreased the chromatin accessibility, activation and expression of virus induced genes. And mutation assays suggested that the RNA-binding ability of SAFA was essential for its function in regulating antiviral chromatin accessibility. RIP-seq results showed that SAFA exclusively bound with antiviral related RNAs following viral infection. Further, we combined the CRISPR-Cas13d mediated RNA knockdown system with ATAC-qPCR, and demonstrated that the binding between SAFA and according antiviral RNAs specifically mediated the openness of the corresponding chromatin and following robust transcription of antiviral genes. Moreover, knockdown of these associated RNAs dampened the accessibility of related genes in an extranuclear signaling pathway dependent manner. Interestingly, VSV infection cleaved SAFA protein at the C-terminus which deprived its RNA binding ability for immune evasion. Thus, our results demonstrated that SAFA and the interacting RNA products collaborated and remodeled chromatin accessibility to facilitate antiviral innate immune responses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antiviral Agents*
  • Chromatin / genetics
  • Host-Pathogen Interactions / genetics
  • Humans
  • Immunity, Innate / genetics
  • RNA, Viral
  • Virus Diseases*

Substances

  • Antiviral Agents
  • Chromatin
  • RNA, Viral

Grants and funding

This work was supported by the National Key Research and Development Program of China (2020YFA0707800 to YFP; 2016YFA0500300 to YFP), the National Natural Science Foundation of China (32000113 to CLL; 31570891 to YFP; 31872736 to YFP; 32022028 to YFP; 81991505 to YFP), Peking University Clinical + X (PKU2020LCXQ009 to YFP) and the Peking University Medicine Fund (PKU2020LCXQ009 to YFP). The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.