Photoactivatable Cre recombinase 3.0 for in vivo mouse applications.
                            
                                blue
                            
                            
                                CRY2/CIB1
                            
                                FKF1/GI
                            
                                iLID
                            
                                Magnets
                            
                            
                                
                                    HEK293T
                                
                            
                                
                                    isolated MEFs
                                
                            
                                
                                    mouse in vivo
                                
                            
                                
                                    mouse neural progenitor cells
                                
                            
                            
                            
                            
                            
                            
                        
                        
                        
                        
                            Abstract:
                            Optogenetic genome engineering tools enable spatiotemporal control of gene expression and provide new insight into biological function. Here, we report the new version of genetically encoded photoactivatable (PA) Cre recombinase, PA-Cre 3.0. To improve PA-Cre technology, we compare light-dimerization tools and optimize for mammalian expression using a CAG promoter, Magnets, and 2A self-cleaving peptide. To prevent background recombination caused by the high sequence similarity in the dimerization domains, we modify the codons for mouse gene targeting and viral production. Overall, these modifications significantly reduce dark leak activity and improve blue-light induction developing our new version, PA-Cre 3.0. As a resource, we have generated and validated AAV-PA-Cre 3.0 as well as two mouse lines that can conditionally express PA-Cre 3.0. Together these new tools will facilitate further biological and biomedical research.