Trans-Golgi Network Remodeling by Microbial Factors

项目总结

PROJECT SUMMARY Eukaryotic trans-Golgi network (TGN) has been extensively studied for its role as the major sorting compartment and the center for terminal processing and modifications of newly synthesized proteins. While the TGN is known for its dynamic nature associated with the constant flux of traffic, whether its structures can be altered in microbe-eukaryote interactions and the subsequent consequences have remained elusive until recently. Our previous study has discovered that multiple microbial factors (e.g., bacterial antibiotics nigericin and gramicidin) are able to induce the disassembly of the TGN into vesicles. These dispersed TGN vesicles then serve as a signaling platform for the assembly and activation of the NLRP3 inflammasome. NLRP3 pathway induces proinflammatory cytokines, and its hyperactivation has been closely associated with a wide variety of human diseases, including autoimmune diseases, cancers, neurodegeneration, and metabolic disorders. Importantly, these stimuli do not affect the closely associated cis- and medial-Golgi, indicating that it is a tightly regulated reorganization event specifically targeting the TGN. Dissection of the detailed cellular and molecular basis has been challenging because these stimuli are either small molecules or nonribosomal peptides not encoded by genes. Recently, we have discovered two groups of microbial factors, i.e., pore- forming toxins from bacteria and viroporins from viruses, as highly specific TGN-dispersing stimuli. The protein nature of these stimuli has allowed us to easily track their translocation and genetically manipulate them to study the effects on TGN remodeling. In addition, we found evidence that TGN remodeling is not only important for inflammatory signaling, but also results in altered glycosylations. The ultimate goal of this MIRA R35 proposal is to use these protein microbial factors as tools to study the detailed mechanisms and functions of TGN remodeling. We will pursue three major questions: (1) What are the regions/motifs that are critical for these stimuli to remodel the TGN? Our identification of novel TGN dispersion peptide motifs will greatly facilitate future screening and identification of other TGN dispersion ligands in both microbes and eukaryotic organisms. (2) What eukaryotic factors (e.g., TGN-localized GTPases and golgin family proteins) are involved in TGN remodeling, and how conserved are their functions in other eukaryotic species such as yeast? (3) How does TGN remodeling affect various eukaryotic cellular processes, including inflammatory signaling and proteins modifications? Our proposed studies will help fill a critical knowledge gap on the mechanisms and functions of TGN remodeling, as well as providing invaluable insights into the rational design of innovative therapeutics to mitigate a wide range of human health problems.