Regulation of Linear Ubiquitin Chain Assembly Complex by Caspase-Mediated Cleavage of RNF31

Abstract

Cell death and survival signaling pathways have opposed but fundamental functions for various cellular processes and maintain cell homeostasis through cross talk. Here we report a novel mechanism of interaction between these two pathways through the cleavage of RNF31 by caspases. RNF31, a component of the linear ubiquitin chain assembly complex (LUBAC), regulates cell survival by inducing linear ubiquitination of NF-κB signaling components. We found that RNF31 is cleaved under apoptosis conditions through various stimulations. The effector caspases caspase 3 and caspase 6 are responsible for this event, and aspartates 348, 387, and 390 were identified as target sites for this cleavage. Cleavage of RNF31 suppressed its ability to activate NF-κB signaling; thus, mutation of cleavage sites inhibited the induction of apoptosis by treatment with tumor necrosis factor alpha (TNF-α). Our findings elucidate a novel regulatory loop between cell death and the survival signal and may provide guidance for the development of therapeutic strategies for cancers through the sensitization of tumor cells to death-inducing drugs.

ACKNOWLEDGMENTS

We thank Vishva Dixit (Genentech Corporation) for providing anti-linear ubiquitin antibodies.

This work was partially supported by grant R01AI116722 from the National Institutes of Health (NIH) to X.L. and a pilot grant from the Center for Inflammation and Cancer (CIC) in the University of Texas MD Anderson Cancer Center to X.L.

We declare no conflict of interest.

D.J., M.B., X.Z., and X.L. designed experiments; D.J. and Y.T. performed experiments; J.J. contributed new reagents; D.J. and X.L. analyzed the data and wrote the manuscript.