Banafshe Larijani : Cell Biophysics

Goals

We investigate the role of phosphoinositides both as second messengers and as modulators of membrane structure. Our objective is to demonstrate the effect of local synthesis of higher order phosphoinositides on the organisation and structural rearrangements of membranes. We suggest that localised augmentation of polyphosphoinositides will affect membrane structural dynamics, which will influence the targeting of effector proteins. This combination of altered membrane structure and phosphoinositide composition will lead to the unregulated protein-lipid interactions that may induce various types of cancers. Our studies lead to understanding more specifically the mechanisms which underlie proteo-lipid interactions in selected subcellular compartments such as the nuclear envelope and the plasma membrane. The effect of phosphoinositide metabolism on membrane dynamics will provide insight into how the change in their composition may affect local membrane structure and hence disrupt the molecular interactions that are not only central to targeting phosphoinositide-dependent proteins to specific compartments, but also to the correct formation of subcellular compartments. We use Förster resonance energy transfer (FRET) detected by fluorescence lifetime imaging microscopy (FLIM) to measure in situ and in vivo molecular interactions quantitatively. In conjunction with the development of single and multiple frequency and two-photon time domain FLIM, HPLC-Electrospray Ionisation - Tandem Mass Spectrometry (HPLC-ESI-MS/MS) for phospholipid and specifically phosphoinositides analysis, is used and developed in Cell Biophysics. Furthermore, to investigate in situ membrane dynamics of membrane compartments, novel applications of deuterium and phosphorous solid-state NMR spectroscopy are implemented in our laboratory.