Project description:Sirt6 acts as a negative regulator of FcεRI signaling cascade in mast cells by suppressing PTPRC transcription. Activation of Sirt6 may therefore represent a promising and novel therapeutic strategy for anaphylaxis.
Project description:Wnt signaling plays a central role in development, adult tissue homeostasis and cancer. Several steps in the canonical Wnt/b-catenin signaling cascade are regulated by ubiquitylation, a protein modification that influences the stability, subcellular localization or protein-protein interactions of target proteins. To identify novel regulators of the Wnt/b-catenin pathway, we performed RNAi screens in C. elegans and human tissue culture cells and identified the HECT domain containing ubiquitin ligase eel-1/Huwe1 as a negative regulator of Wnt signaling. Huwe1 functions cell autonomously in signal-receiving cells and genetically acts upstream of b-catenin. Mechanistically, Huwe1 binds to and ubiquitylates the cytoplasmic Wnt pathway component Dishevelled (Dvl) in a Wnt3a and CK1e dependent manner. Huwe1 mediated ubiquitylation does not target Dvl for degradation. Instead, we found that Huwe1 decreases Dvl signaling by inhibiting Dvl multimerization. We conclude that Huwe1 is part of an evolutionarily conserved negative feedback loop in the Wnt/b-catenin pathway
Project description:Toll-like receptor 4 (TLR4) plays a pivotal role in the host response to lipopolysaccharide (LPS), a major cell wall component of Gram-negative bacteria. Here we elucidated whether the endocytic adaptor protein Disabled-2 (Dab2) that is abundantly expressed in the macrophages plays a role in LPS-stimulated TLR4 signaling and trafficking. Molecular analysis and transcriptome profiling of the RAW264.7 macrophage-like cells expressing short-hairpin RNA of Dab2 revealed that Dab2 mainly regulated LPS-stimulated TRIF-dependent, but not MyD88-dependent TLR4 signaling. Consequently, knockdown of Dab2 augmented TRIF-dependent interferon regulatory factor 3 activation and the expression for the subsets of inflammatory cytokines and interferon-inducible genes. We further delineated that Dab2 acted as a “clathrin sponge” and sequestered clathrin from TLR4/MD2 complex in the resting stage of macrophages. Clathrin was released from Dab2 and associated with TLR4 to facilitate the internalization of TLR4/MD2 complex together with the bound ligand from the cell surface upon LPS stimulation. Dab2 thereby functions as a negative immune regulator of TLR4 endocytosis and signaling, supporting a novel role of Dab2-associated regulatory circuit in the control of inflammatory response of macrophage to endotoxin.
Project description:We performed high throughput RNA sequencing at preadipocyte (D0) and differentiated adipocyte (D7) of primary brown preadipocyte and found that Kruppel-like factor 16 (KLF11) gene that was downregulated in D7 was a novel negative regulator of adipogenesis.