O‐GlcNAcylation Stabilizes Nod2, an Innate Immune Receptor Involved in Crohn's Disease

Abstract

Nucleotide‐binding oligomerization domain2 (Nod2) is an intracellular receptor that can sense bacterial components, such as, Muramyl dipeptide (MDP). MDP is a peptidoglycan fragment from bacterial cell wall that can activate NF‐kB, a transcriptional factor that can induce the production of various inflammatory molecules. Nod2 mutations have been linked to Crohn's disease with a decreased ability to activate NF‐kB. Recently, using the classic cycloheximide stabilization assay, we demonstrated that Nod2 variants have a lower half‐life compared to wild type Nod2 in cells. To further characterize this protein, the objective of this study is to determine if Nod2 is post‐translationally modified. O‐GlcNAcylation is a post translational modification in which the O‐GlcNAc transferase (OGT) transfers N‐acetylglucosamine (GlcNAc) from UDP‐GlcNAc to selected serine and threonine residues of a target protein. As GlcNAc is a major component of peptidoglycan of bacterial cell wall and a large amount of GlcNAc is released from bacterial cell wall during cell wall remodeling, we hypothesized that Nod2 could be O‐GlcNAcylated. Preliminary data show that wild type Nod2 and Nod2 variants are O‐GlcNAcylated. In addition, increasing the O‐GlcNAcylation level can increase the half‐life of wild type Nod2 or Nod2 variants. In future experiments, we will determine which residue of Nod2 is O‐GlcNAcylated and investigate if this modification affects Nod2 mediated NF‐kB pathway in wild type Nod2 or Nod2 variants.Funding of this project is provided by University of Delaware.