Physical and functional interaction between A20 and ATG16L1-WD40 domain in the control of intestinal homeostasis

Karolina Slowicka,Ioanna Petta,Inmaculada Serramito-Gómez,Geert Van Loo,Riet De Rycke,Emilio Boada-Romero,Savvas N Savvides,Saskia Lippens,Felipe X Pimentel-Muiños,Hanna K Vikkula,Arne Martens,Mozes Sze,Eef Parthoens,Andy Wullaert,Lars Vereecke

doi:10.1038/s41467-019-09667-z

Abstract

Prevention of inflammatory bowel disease (IBD) relies on tight control of inflammatory, cell death and autophagic mechanisms, but how these pathways are integrated at the molecular level is still unclear. Here we show that the anti-inflammatory protein A20 and the critical autophagic mediator Atg16l1 physically interact and synergize to regulate the stability of the intestinal epithelial barrier. A proteomic screen using the WD40 domain of ATG16L1 (WDD) identified A20 as a WDD-interacting protein. Loss of A20 and Atg16l1 in mouse intestinal epithelium induces spontaneous IBD-like pathology, as characterized by severe inflammation and increased intestinal epithelial cell death in both small and large intestine. Mechanistically, absence of A20 promotes Atg16l1 accumulation, while elimination of Atg16l1 or expression of WDD-deficient Atg16l1 stabilizes A20. Collectively our data show that A20 and Atg16l1 cooperatively control intestinal homeostasis by acting at the intersection of inflammatory, autophagy and cell death pathways.

Highlights

Prevention of inflammatory bowel disease (IBD) relies on tight control of inflammatory, cell death and autophagic mechanisms, but how these pathways are integrated at the molecular level is still unclear
In order to characterize the physiological function of the ATG16L1 WD40 domain of ATG16L1 (WDD), we developed a proteomics approach to identify proteins able to interact with this region
Many of the IBD-associated genes identified so far are involved in the regulation of innate immune responses and intestinal epithelial functions

Summary

Introduction

Prevention of inflammatory bowel disease (IBD) relies on tight control of inflammatory, cell death and autophagic mechanisms, but how these pathways are integrated at the molecular level is still unclear. We show that the anti-inflammatory protein A20 and the critical autophagic mediator Atg16l1 physically interact and synergize to regulate the stability of the intestinal epithelial barrier. Genome wide association studies (GWAS) have identified more than 200 genes associated with IBD, many of which are involved in the regulation of innate immune responses and intestinal epithelial functions, including A20 and ATG16L12,4–6. Generally linked to inflammation, NF-κB activation in intestinal epithelial cells (IECs) is essential for regulating important protective mechanisms including maintaining gut barrier integrity by inducing antiapoptotic proteins, antimicrobial peptides, and mucins[3,7,8,9]. IECspecific deletion of A20 was shown to sensitize mice to experimental colitis and TNF toxicity, due to increased epithelial apoptosis, identifying A20 as a crucial barrier protective factor, indispensable for maintaining intestinal barrier integrity during inflammatory stress[12,14].

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Conclusion