Regulation of the Deubiquitinating Enzyme CYLD by IκB Kinase Gamma-Dependent Phosphorylation

Abstract

Tumor suppressor CYLD is a deubiquitinating enzyme (DUB) that inhibits the ubiquitination of key signaling molecules, including tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2). However, how the function of CYLD is regulated remains unknown. Here we provide evidence that inducible phosphorylation of CYLD is an important mechanism of its regulation. Under normal conditions, CYLD dominantly suppresses the ubiquitination of TRAF2. In response to cellular stimuli, CYLD undergoes rapid and transient phosphorylation, which is required for signal-induced TRAF2 ubiquitination and activation of downstream signaling events. Interestingly, the CYLD phosphorylation requires IκB kinase gamma (IKKγ) and can be induced by IKK catalytic subunits. These findings suggest that CYLD serves as a novel target of IKK and that the site-specific phosphorylation of CYLD regulates its signaling function.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://mcb.asm.org/.

ACKNOWLEDGMENTS

We thank M. Karin and I. M. Verma for reagents and the Sun lab members for fruitful discussion. We also thank the Core Facility of Hershey Medical Center for oligonucleotide synthesis and DNA sequencing analyses.

This work was supported by research grants from the National Institutes of Health to S.-C.S (CA094922 and AI45045) and M.Z (AI45045) and the Four Diamond Fund at Penn State Children's Hospital to M.Z.W.R. was supported by a predoctoral/postdoctoral training grant (5 T32CA60395-09) from the National Institutes of Health.