RalB GTPase-Mediated Activation of the IκB Family Kinase TBK1 Couples Innate Immune Signaling to Tumor Cell Survival

Yuchen Chien, Sungchan Kim, Ron Bumeister, Yueh Ming Loo, Sung Won Kwon, Cynthia L. Johnson, Mirey G. Balakireva, Yves Romeo, Levy Kopelovich, Michael Gale, Charles Yeaman, Jacques H. Camonis, Yingming Zhao, Michael A. White

Research output: Contribution to journalArticlepeer-review

267 Scopus citations

Abstract

The monomeric RalGTPases, RalA and RalB are recognized as components of a regulatory framework supporting tumorigenic transformation. Specifically, RalB is required to suppress apoptotic checkpoint activation, the mechanistic basis of which is unknown. Reported effector proteins of RalB include the Sec5 component of the exocyst, an octameric protein complex implicated in tethering of vesicles to membranes. Surprisingly, we find that the RalB/Sec5 effector complex directly recruits and activates the atypical IκB kinase family member TBK1. In cancer cells, constitutive engagement of this pathway, via chronic RalB activation, restricts initiation of apoptotic programs typically engaged in the context of oncogenic stress. Although dispensable for survival in a nontumorigenic context, this pathway helps mount an innate immune response to virus exposure. These observations define the mechanistic contribution of RalGTPases to cancer cell survival and reveal the RalB/Sec5 effector complex as a component of TBK1-dependent innate immune signaling.

Original languageEnglish (US)
Pages (from-to)157-170
Number of pages14
JournalCell
Volume127
Issue number1
DOIs
StatePublished - Oct 6 2006

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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