Regulation of endogenous transmembrane receptors through optogenetic Cry2 clustering.
                            
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                                CRY2/CRY2
                            
                            
                                
                                    HEK293T
                                
                            
                                
                                    NIH/3T3
                                
                            
                                
                                    rat hippocampal NSCs
                                
                            
                            
                                Signaling cascade control
                            
                                Control of cytoskeleton / cell motility / cell shape
                            
                            
                            
                            
                            
                        
                        
                        
                        
                            Abstract:
                            Transmembrane receptors are the predominant conduit through which cells sense and transduce extracellular information into intracellular biochemical signals. Current methods to control and study receptor function, however, suffer from poor resolution in space and time and often employ receptor overexpression, which can introduce experimental artefacts. We report a genetically encoded approach, termed Clustering Indirectly using Cryptochrome 2 (CLICR), for spatiotemporal control over endogenous transmembrane receptor activation, enabled through the optical regulation of target receptor clustering and downstream signalling using noncovalent interactions with engineered Arabidopsis Cryptochrome 2 (Cry2). CLICR offers a modular platform to enable photocontrol of the clustering of diverse transmembrane receptors including fibroblast growth factor receptor (FGFR), platelet-derived growth factor receptor (PDGFR) and integrins in multiple cell types including neural stem cells. Furthermore, light-inducible manipulation of endogenous receptor tyrosine kinase (RTK) activity can modulate cell polarity and establish phototaxis in fibroblasts. The resulting spatiotemporal control over cellular signalling represents a powerful new optogenetic framework for investigating and controlling cell function and fate.