Genetically encoded fluorescent biosensors for live cell imaging of lipid dynamics.

Fluorescence imaging provides a powerful technique to visualize spatiotemporal dynamics of biomolecules in living cells, if fluorescent biosensors for the relevant biomolecules become available. Here I describe a fluorescent biosensor for a lipid second messenger, phosphatidylinositol 3,4,5-triphosphate (PI(3,4,5)P3). The biosensor overcomes limitations of existing methods for the lipid analysis and allows us to pinpoint that the PI(3,4,5)P3 concentrations are increasing and/or decreasing not only at the plasma membrane but also at organelle membranes, such as the Golgi apparatus membranes and endoplasmic reticulum membranes. The present biosensor has also been shown to be applicable to a variety of lipid second messengers, including diacylglycerol and phosphatidylinositol 3,4-bisphosphate.