The c-Jun N-terminal Kinase (JNK)-binding Protein (JNKBP1) Acts as a Negative Regulator of NOD2 Protein Signaling by Inhibiting Its Oligomerization Process

Samuel Jourdan,Yvette Habraken,Thomas A. Kufer,Jacques Piette,Marianne Fillet,Emmanuel Di Valentin,Sylvie Legrand-Poels,Edouard Louis,Catherine Sadzot,Aurore Lecat,Joan Somja,Philippe Delvenne

doi:10.1074/jbc.m112.355545

Abstract

NOD2 is one of the best characterized members of the cytosolic NOD-like receptor family. NOD2 is able to sense muramyl dipeptide, a specific bacterial cell wall component, and to subsequently induce various signaling pathways leading to NF-κB activation and autophagy, both events contributing to an efficient innate and adaptive immune response. Interestingly, loss-of-function NOD2 variants were associated with a higher susceptibility for Crohn disease, which highlights the physiological importance of proper regulation of NOD2 activity. We performed a biochemical screen to search for new NOD2 regulators. We identified a new NOD2 partner, c-Jun N-terminal kinase-binding protein 1 (JNKBP1), a scaffold protein characterized by an N-terminal WD-40 domain. JNKBP1, through its WD-40 domain, binds to NOD2 following muramyl dipeptide activation. This interaction attenuates NOD2-mediated NF-κB activation and IL-8 secretion as well as NOD2 antibacterial activity. JNKBP1 exerts its repressor effect by disturbing NOD2 oligomerization and RIP2 tyrosine phosphorylation, both steps required for downstream NOD2 signaling. We furthermore showed that JNKBP1 and NOD2 are co-expressed in the human intestinal epithelium and in immune cells recruited in the lamina propria, which suggests that JNKBP1 contributes to maintain NOD2-mediated intestinal immune homeostasis.

Highlights

These results show that Jun N-terminal kinase-binding protein 1 (JNKBP1) physically interacts with NOD2 and that this interaction is increased by muramyl dipeptide (MDP) treatment
In order to dissect the molecular mechanism by which JNKBP1 negatively modulates NOD2 signaling, we investigated the effect of JNKBP1 on NOD2 oligomerization and receptor-interacting protein 2 (RIP2) tyrosine phosphorylation
The N-terminal WD-40 domain of JNKBP1 is sufficient for its recruitment to NOD2, whereas both the N-terminal CARD1 and, to a lesser extent, the C-terminal leucine-rich repeats (LRRs) mediate the NOD2 binding to JNKBP1

Summary

Background

Significance: JNKBP1, by down-regulating NOD2 signaling, could contribute to maintaining intestinal immune homeostasis. NOD2 is able to sense muramyl dipeptide, a specific bacterial cell wall component, and to subsequently induce various signaling pathways leading to NF-␬B activation and autophagy, both events contributing to an efficient innate and adaptive immune response. We identified a new NOD2 partner, c-Jun N-terminal kinase-binding protein 1 (JNKBP1), a scaffold protein characterized by an N-terminal WD-40 domain. NOD2 (nucleotide-binding oligomerization domain-containing protein 2) has been the most studied member of the NLR family since the identification of NOD2 variants associated with a higher susceptibility for Crohn disease (CD) [3, 4]. We further provide details of the molecular mechanism underlying JNKBP1 function in NOD2 signaling

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION