RIG-I Detects Kaposi's Sarcoma-Associated Herpesvirus Transcripts in a RNA Polymerase III-Independent Manner.

Yugen Zhang,Joseph A Duncan,Piotr A Mieczkowski,Dirk P Dittmer,Kurtis M Host,Blossom Damania,William G Fusco,Michael J Imperiale

doi:10.1128/mbio.00823-18

Yugen Zhang, Joseph A Duncan + Show 6 more

Open Access

https://doi.org/10.1128/mbio.00823-18

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Journal: mBio	Publication Date: Jul 3, 2018
Citations: 41	License type: CC BY 4.0

Affiliation: University of North Carolina at Chapel Hill

Abstract

ABSTRACTRetinoic acid-inducible gene I (RIG-I) is a cytosolic pathogen recognition receptor that initiates the innate immune response against many RNA viruses. We previously showed that RIG-I restricts Kaposi's sarcoma-associated herpesvirus (KSHV) reactivation (J. A. West et al., J Virol 88:5778–5787, 2014, https://doi.org/10.1128/JVI.03226-13). In this study, we report that KSHV stimulates the RIG-I signaling pathway in a RNA polymerase (Pol) III-independent manner and subsequently induces type I interferon (IFN) responses. Knockdown or inhibition of RNA Pol III had no effect on beta interferon (IFN-β) induction by KSHV. By using high-throughput sequencing of RNA isolated by cross-linking immunoprecipitation (HITS-CLIP) approach, we identified multiple KSHV regions that give rise to RNA fragments binding to RIG-I, such as ORF810420-10496, Repeat region (LIR1)119059-119204, and ORF2543561-43650. The sequence dissimilarity between these fragments suggests that RIG-I detects a particular structure rather than a specific sequence motif. Synthesized ORF810420-10496 RNA stimulated RIG-I-dependent but RNA Pol III-independent IFN-β signaling. In summary, several KSHV RNAs are sensed by RIG-I in a RNA Pol III-independent manner.

Highlights

IMPORTANCE Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi’s sarcoma, primary effusion lymphoma, and multicentric Castleman’s disease
We wanted to determine whether Retinoic acid-inducible gene I (RIG-I) could sense Kaposi’s sarcoma-associated herpesvirus (KSHV/HHV8) and whether this was by a Pol III-dependent or -independent mechanism
The role of RNA Pol III was probed by using iSLK.219 cells transfected with small interfering RNA (siRNA) targeting Pol III (POLR3A) or RIG-I, followed by the addition of doxycycline for 72 h to reactivate the virus

Summary

Introduction

IMPORTANCE Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi’s sarcoma, primary effusion lymphoma, and multicentric Castleman’s disease. Retinoic acid-inducible gene I (RIG-I), a cytosolic RNA helicase sensor, plays a significant role in the induction of type I interferon responses following viral infection. We identified multiple RNA regions in KSHV as potential virus ligands that bind to RIG-I and stimulate RIG-Idependent but RNA Pol III-independent IFN-␤ signaling. RIG-I has previously been shown to be involved in sensing DNA viruses in a RNA polymerase (Pol) III-dependent manner. Adenovirus induces IFN-␤ expression in a RNA polymerase III-dependent manner through activation of RIG-I [22]. Sensing of the herpesvirus, herpes simplex virus 1 (HSV-1/HHV1), seems to occur by RNA polymerase III-independent mechanisms [20, 24, 25], suggesting that among the large DNA viruses, multiple pathways can give rise to RIG-I substrates. We wanted to determine whether RIG-I could sense Kaposi’s sarcoma-associated herpesvirus (KSHV/HHV8) and whether this was by a Pol III-dependent or -independent mechanism

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