Elucidation of cell secretion: pancreas led the way

Secretion is a basic process in all cells and is required for several important functions such as neurotransmission, the secretion of digestive juices from the exocrine pancreas and the release of hormones from endocrine and neuroendocrine cells. Due to these important functions, the mechanism of cell secretion has been intensely investigated for over half a century. However, it is only in the last decade, with the discovery of a new cellular structure, the 'porosome' or 'fusion pore', and the elucidation of SNARE-induced membrane fusion, that has finally provided us with an understanding of cell secretion at the molecular level. The 'porosome', a supramolecular structure at the cell plasma membrane, was first discovered in the exocrine pancreas, and subsequently in endocrine/neuroendocrine cells and in neurons. The structure and dynamics of the 'porosome' in live cells at nanometer resolution and in real-time, its composition and functional reconstitution in lipid membrane, have all been determined. These findings have fundamentally changed our understanding of cell secretion and provide a clear understanding of this highly regulated process in cells.