The Endopos project started on May 2019 and the main results so far are:
1) BioID based proteomic screen identifying Rab11a, Rab11c (=Rab25) and Rab4 protein complexes followed by verification using an innovative Knocksideways technique and quantitative analysis.
2) We developed and optimized a novel approach allowing one-step CRISPR-Cas9 mediated targeted knock-ins resulting in conditional reversible gene knockouts/rescues ideal for fluorescent microscopy with the option to select cells by FACS sorting independent of traditional clonal methods. The rescue protein level is tunable and possible to control systematically (drug-based) or spatiotemporally (optogenetically) and is not limited to only active genes. Therefore, we were able to provide novel high-resolution colocalization data from simultaneous observation of endogenously fluorophore-tagged Rab11a/b with Rab25 positive vesicles inside live ovarian A2780 cancer cells where Rab25 is otherwise endogenously silenced. In addition, it allowed us to compare endogenous Rab11a, Rab11b and Rab25 expression kinetics (DNA accessibility for transcription), stability and dynamics of all protein coding isoforms at once and their direct effect on cell migration, proliferation and invasion.
3) In collaboration with Prof. Piehler’s lab (University of Osnabrück in Germany) we established magnetogenetic manipulation of endogenously tagged Rab25 (Rab11ab) endosomes by using GFP functionalized nanoparticles and by building home-made magnetic manipulator set-up including microinjection, perfusion system and extended heating chamber within the Bioimaging facility in Manchester. This system uses a state-of-the-art spinning disc microscope so we can image ovarian cancer cells at high spatial-temporal resolution and determine the effects of magnetogenetic manipulation of Rab11s on trafficking, signalling, actin dynamics and migration in living ovarian cancer cells. Our proof-of-concept experiments show how direct control of Rab25 positive endosomes can promote protrusions on demand and how these magnetically controlled endosomes allow ovarian cancer cell migrating in 3D environment to feel and respond to the magnetic field gradient.