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NOD2 contributes to the innate immune response and to the homeostasis of the intestinal mucosa. In response to its bacterial ligand, NOD2 interacts with RICK and activates the NF-κB and MAPK pathways, inducing gene transcription and synthesis of proteins required to initiate a balanced immune response. Mutations in NOD2 have been associated with an increased risk of Crohn’s Disease (CD), a disabling inflammatory bowel disease (IBD). Because NOD2 signaling plays a key role in CD, it is important to further characterize the network of protein interacting with NOD2. Using yeast two hybrid (Y2H) screens, we identified new NOD2 interacting proteins (NIP). The primary interaction was confirmed by coimmunoprecipitation and/or bioluminescence resonance energy transfer (BRET) experiments for 11 of these proteins (ANKHD1, CHMP5, SDCCAG3, TRIM41, LDOC1, PPP1R12C, DOCK7, VIM, KRT15, PPP2R3B, and C10Orf67). These proteins are involved in diverse functions, including endosomal sorting complexes required for transport (ESCRT), cytoskeletal architecture and signaling regulation. Additionally, we show that the interaction of 8 NIPs is compromised with the 3 main CD associated NOD2 mutants (R702W, G908R and 1007fs). Furthermore, to determine whether these NOD2 protein partners could be encoded by IBD susceptibility genes, a transmission disequilibrium test (TDT) was performed on 101 single nucleotide polymorphisms (SNPs) and the main corresponding haplotypes in genes coding for 15 NIPs using a set of 343 IBD families with 556 patients. Overall this work did not increase the number of IBD susceptibility genes but extends the NOD2 protein interaction network and suggests that NOD2 interactome and signaling depend upon the NOD2 mutation profile in CD. [ABSTRACT FROM AUTHOR]

Abstract: The functions of Src family kinases are tightly regulated through Src homology (SH) domain-mediated protein–protein interactions. We previously reported the biophysical characteristics of the apoptosis-linked gene 2-interacting protein X (Alix) in complex with the haemopoietic cell kinase (Hck) SH3 domain. In the current study, we have combined ITC, NMR, SAXS and molecular modeling to determine a 3D model of the complex. We demonstrate that Hck SH3 recognizes an extended linear proline-rich region of Alix. This particular binding mode enables Hck SH3 to sense a specific non-canonical residue situated in the SH3 RT-loop of the kinase. The resulting model helps clarify the mechanistic insights of Alix–Hck interaction. Structured summary of protein interactions: Hck physically interacts with SAM68 by two hybrid ( View interaction ) FynR96I physically interacts with Alix by two hybrid ( View interaction ) Hck binds to Alix by pull down ( View interaction ) Fyn physically interacts with SAM68 by two hybrid ( View interaction ) Hck and Alix bind by nuclear magnetic resonance ( View interaction ) FynR96I and Alix bind by isothermal titration calorimetry (View Interaction: 1 , 2 ) FynR96I and Alix bind by nuclear magnetic resonance ( View interaction ) FynR96I binds to Alix by pull down ( View interaction ) Hck physically interacts with Alix by two hybrid ( View interaction ) FynR96I and Alix bind by x ray scattering ( View interaction ) Hck physically interacts with NEF by two hybrid ( View interaction ) FynR96I physically interacts with NEF by two hybrid ( View interaction ) [Copyright &y& Elsevier]