The Protein Kinase C-Responsive Inhibitory Domain of CARD11 Functions in NF-κB Activation To Regulate the Association of Multiple Signaling Cofactors That Differentially Depend on Bcl10 and MALT1 for Association

Abstract

The activation of NF-κB by T-cell receptor (TCR) signaling is critical for T-cell activation during the adaptive immune response. CARD11 is a multidomain adapter that is required for TCR signaling to the IκB kinase (IKK) complex. During TCR signaling, the region in CARD11 between the coiled-coil and PDZ domains is phosphorylated by protein kinase Cθ (PKCθ) in a required step in NF-κB activation. In this report, we demonstrate that this region functions as an inhibitory domain (ID) that controls the association of CARD11 with multiple signaling cofactors, including Bcl10, TRAF6, TAK1, IKKγ, and caspase-8, through an interaction that requires both the caspase recruitment domain (CARD) and the coiled-coil domain. Consistent with the ID-mediated control of their association, we demonstrate that TRAF6 and caspase-8 associate with CARD11 in T cells in a signal-inducible manner. Using an RNA interference rescue assay, we demonstrate that the CARD, linker 1, coiled-coil, linker 3, SH3, linker 4, and GUK domains are each required for TCR signaling to NF-κB downstream of ID neutralization. Requirements for the CARD, linker 1, and coiled-coil domains in signaling are consistent with their roles in the association of CARD11 with Bcl10, TRAF6, TAK1, caspase-8, and IKKγ. Using Bcl10- and MALT1-deficient cells, we show that CARD11 can recruit signaling cofactors independently of one another in a signal-inducible manner.

SUPPLEMENTAL MATERIAL

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

ACKNOWLEDGMENTS

We thank V. Schowinsky for excellent technical assistance; M. Boldin, D. Baltimore, G. Nuñez, T. Kawai, S. Akira, and D. Goeddel for reagents; R. Lamason, S. Lew, V. Schowinsky, and J. McLellan for critical reading of the manuscript; and M. Meffert for helpful advice and discussions.

This work was supported by grant RSG-06-172-01-LIB from the American Cancer Society and funds from the Johns Hopkins Institute for Cell Engineering. J.L.P. is a recipient of a Kimmel Scholar Award from the Sidney Kimmel Foundation for Cancer Research and a Rita Allen Foundation Scholar.