Project A05

Lipid-Mediated Activation of Protein Kinases During Cell Polarization

The correct targeting of kinases to subdomains of the plasma membrane and their subsequent controlled activation is a crucial prerequisite for numerous cellular processes, including cell polarity, cell-cell adhesion, cell migration and signal transduction. We have recently identified phosphatidic acid (PA) to be essential for the activation of the Liver Kinase B1 (LKB1) in Drosophila and mammalian cells. We will use in vitro experiments combined with mammalian cell culture models and Drosophila in vivo experiments to investigate the detailed mechanisms of LKB1 activation by phospholipids at cellular interfaces and their impact on cell polarity and signaling. We aim to establish phospholipid-biosensors in polarized Drosophila tissues as well as mammalian cells in order to visualize the formation of phospholipid microdomains in the plasma membrane and the subsequent localization and activation of LKB1 to these microdomains, by applying super-resolution microscopy. Furthermore, two different phosphorylation events of LKB1 by phospholipid-activated kinases will be characterized regarding their temporal and spatial distribution as well as their functionality in the context of cell polarity and signal transduction.