Efficient photoactivatable Dre recombinase for cell type-specific spatiotemporal control of genome engineering in the mouse.
                            
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                                CRY2/CIB1
                            
                                Magnets
                            
                                PhyB/PIF3
                            
                                VVD
                            
                            
                                
                                    HEK293T
                                
                            
                                
                                    HeLa
                                
                            
                                
                                    HEp-2
                                
                            
                                
                                    mouse in vivo
                                
                            
                                
                                    SH-SY5Y
                                
                            
                            
                                Nucleic acid editing
                            
                            
                            
                            
                            
                        
                        
                        
                        
                            Abstract:
                            Precise genetic engineering in specific cell types within an intact organism is intriguing yet challenging, especially in a spatiotemporal manner without the interference caused by chemical inducers. Here we engineered a photoactivatable Dre recombinase based on the identification of an optimal split site and demonstrated that it efficiently regulated transgene expression in mouse tissues spatiotemporally upon blue light illumination. Moreover, through a double-floxed inverted open reading frame strategy, we developed a Cre-activated light-inducible Dre (CALID) system. Taking advantage of well-defined cell-type-specific promoters or a well-established Cre transgenic mouse strain, we demonstrated that the CALID system was able to activate endogenous reporter expression for either bulk or sparse labeling of CaMKIIα-positive excitatory neurons and parvalbumin interneurons in the brain. This flexible and tunable system could be a powerful tool for the dissection and modulation of developmental and genetic complexity in a wide range of biological systems.