PICCORO: A technique for manipulating the activity of transcription factors with blue light

The ability to modulate transcription factor activity is critically important for deciphering many cellular and developmental processes. Light is an attractive signal for artificially controlling transcription factor activity because it has high spatial and temporal precision. Several light-switchable technologies have been developed to control gene expression negatively or positively. Although these systems allow spatiotemporal control of transcription, the target gene must be placed downstream of a specific promoter, which is time consuming and applicable to a limited number of genes at the same time. On the other hand, we recently developed a technique for manipulation of transcription factor activity with blue light, termed PixD complex-dependent control (PICCORO) using the bacterial blue-light photoreceptor PixD. This method has the advantage of controlling transcription factor activity at the posttranslational level. Using this method, we were able to control activity of the chimeric dominant-negative transcription factor No tail (Ntl) in zebrafish with blue light. Here we describe the mechanism of PICCORO action and a detailed protocol to apply the technique for controlling other transcription factors.