Molecular basis of class II PI3-kinase function

Lipids are important components of biological membranes that surround the cell and organelles inside the cell. Special lipids such as Phosphatidylinositol (PI) are not only responsible to be a building block of the membrane but also act as signaling molecules and denominators of membrane identity to control cell growth, survival, differentiation, migration and intracellular membrane dynamics among other functions. Depending on the modification state, like phosphorylation, they are changing its signaling potential and can only be found at certain locations inside the cell or membranes. Among the seven different phosphorylated Phosphatidylinositol (PIP) species found in mammals phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] arguably is the least understood, synthesized by class II PI 3-kinases (PI3KC2). Recent landmark studies from the host laboratory revealed that these kinases are regulating uptake of molecules into the cell (endocytosis) and are further reflecting the cellular nutrient status. Dysregulation of PI3KC2a-c is associated with diabetes and cancer but the mechanism that regulate PI3KC2a-c activity remain poorly understood. In my proposed research I will fill this important knowledge gap by capitalizing on the outstanding opportunities provided by the host lab to dissect the molecular basis of class II PI3K function. Specifically, I will build on reagents and experimental procedures recently established by the host lab to produce high amounts of pure and active PI3KC2 suitable for biochemical characterization and X-ray crystallography approaches. The availability of high amounts of soluble active PI3KC2 opens the door for the further biochemical, structural biological and functional characterization of this important class of enzymes. With the financial support of the Schrödinger-Stipend I aim to determine the structure and mechanism(s) of activation of PI3KC2a and PI3KC2b by using a variety of different molecular biological approaches, all of which are well established in host lab. Furthermore, over the last 8 years I obtained ample experience and training in protein crystallography that will help me to produce high quality protein crystals suitable to solve the structure of PI3KC2a- and b using X-ray diffraction experiments. Such 3D-structures will shed light on our understanding of PI3KC2a/b regulation and function in endocytosis and nutrient signaling and thereby pave the way for the pharmacological manipulation of these enzymes to establish novel avenues for the treatment of myotubular myopathy and, possibly, diabetes and cancer.

No additional funding sources recorded.