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J Virol. 2006 Dec;80(24):12332-42. Epub 2006 Oct 4.

RNA- and virus-independent inhibition of antiviral signaling by RNA helicase LGP2.

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  • 1Pancoe-ENH Research Pavilion, Northwestern University, 2200 Campus Drive, Evanston, IL 60208, USA.

Abstract

Antiviral innate immune responses can be triggered by accumulation of intracellular nucleic acids resulting from virus infections. Double-stranded RNA (dsRNA) can be detected by the cytoplasmic RNA helicase proteins RIG-I and MDA5, two proteins that share sequence similarities within a caspase recruitment domain (CARD) and a DExD/H box RNA helicase domain. These proteins are considered dsRNA sensors and are thought to transmit the signal to the mitochondrial adapter, IPS-1 (also known as MAVS, VISA, or CARDIF) via CARD interactions. IPS-1 coordinates the activity of protein kinases that activate transcription factors needed to induce beta interferon (IFN-beta) gene transcription. Another helicase protein, LGP2, lacks the CARD region and does not activate IFN-beta gene expression. LGP2 mRNA is induced by interferon, dsRNA treatments, or Sendai virus infection and acts as a feedback inhibitor for antiviral signaling. Results indicate that LGP2 can inhibit antiviral signaling independently of dsRNA or virus infection intermediates by engaging in a protein complex with IPS-1. Experiments suggest that LGP2 can compete with the kinase IKKi (also known as IKKepsilon) for a common interaction site on IPS-1. These results provide the first demonstration of protein interaction as an element of negative-feedback regulation of intracellular antiviral signaling by LGP2.

PMID:
17020950
[PubMed - indexed for MEDLINE]
PMCID:
PMC1676302
Free PMC Article
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