Abstract: Autoregulatory systems that have been implemented to control the expression and activity of Cast 3d, including the activity of Cast 3d in vivo, thereby reducing collateral damage in cells at off-target sites (e.g., non-target messenger RNA transcripts. The autoregulatory system is in the form of a nucleic acid molecule comprising a zinc finger binding site, a promoter, and a nucleotide sequence encoding a Cast 3d fusion protein, and a transcriptional repressor domain, and wherein the Cast 3d fusion protein binds to the zinc finger binding site and represses transcription of the nucleotide sequence encoding the Cast 3d fusion protein.