The role of SNAREs in post-Golgi trafficking.

The inside of a cell is organized into a series of compartments (organelles) with each organelle having a defined function. Once a protein has been made or modified in one organelle, its function or activity is often required somewhere else. The cell therefore has to transport the protein to the site where it is needed, this is accomplished by packaging the proteins into a small lipid bound packages (vesicles) that brake off from one organelle and fuse with another. The aim of my research is to understand how these vesicles know with which organelles they should fuse. This research will increase our fundamental understanding of how cells function and may give insight into how defects in these processes cause diseases.

One of the most fundamental unresolved questions in cell biology is how cells manage to preserve the organization and integrity of the endocytic and exocytic systems, while maintaining the transport of lipids and proteins between these specialized organelles. Proteins and lipids are transported between these organelles via small membrane bound transport vesicles, which bud from one compartment and fuse with another, thereby delivering their contents. The targeting and fusion of these vesicles with membranes is regulated in part by the specific interactions of a family of molecules known as SNAREs. In mammalian cells there are at least 38 SNAREs, each one being localized to a different compartment and involved in a subset of transport pathways. The aim of my research is to functionally define the SNAREs involved in Trans Golgi Network (TGN) to endosome and TGN to cell surface transport, by inhibiting SNARE function in combination with quantitative transport assays. To achieve this, I have generated a library of antibodies and siRNAs specific to 14 post-Golgi SNAREs and will use them in combination with flow cytometry based assays for measuring post-TGN trafficking. I also plan to identify the function of the vesicle SNARE VAMP4, by characterizing a VAMP4 knock out mouse that I am currently having generated. The proposed research will provide insight into how specificity is achieved in membrane transport and may also provide a framework for better understanding diseases caused by defects in membrane trafficking to lysosome and lysosome related organelles.