The double-stranded RNA-binding protein PACT functions as a cellular activator of RIG-I to facilitate innate antiviral response.

Department of Biochemistry and State Key Laboratory for Liver Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.
Cell host & microbe (Impact Factor: 12.19). 04/2011; 9(4):299-309. DOI: 10.1016/j.chom.2011.03.007
Source: PubMed

ABSTRACT RIG-I, a virus sensor that triggers innate antiviral response, is a DExD/H box RNA helicase bearing structural similarity with Dicer, an RNase III-type nuclease that mediates RNA interference. Dicer requires double-stranded RNA-binding protein partners, such as PACT, for optimal activity. Here we show that PACT physically binds to the C-terminal repression domain of RIG-I and potently stimulates RIG-I-induced type I interferon production. PACT potentiates the activation of RIG-I by poly(I:C) of intermediate length. PACT also cooperates with RIG-I to sustain the activation of antiviral defense. Depletion of PACT substantially attenuates viral induction of interferons. The activation of RIG-I by PACT does not require double-stranded RNA-dependent protein kinase or Dicer, but is mediated by a direct interaction that leads to stimulation of its ATPase activity. Our findings reveal PACT as an important component in initiating and sustaining the RIG-I-dependent antiviral response.

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