In vivo evaluation of GG2–GG1/A2 element activity in the insulin promoter region using the CRISPR–Cas9 system

The insulin promoter is regulated by ubiquitous as well as pancreatic β-cell-specific transcription factors. In the insulin promoter, GG2–GG1/A2–C1 (bases − 149 to − 116 in the human insulin promoter) play important roles in regulating β-cell-specific expression of the insulin gene. However, these events were identified through in vitro studies, and we are unaware of comparable in vivo studies. In this study, we evaluated the activity of GG2–GG1/A2 elements in the insulin promoter region in vivo. We generated homozygous mice with mutations in the GG2–GG1/A2 elements in each of the Ins1 and Ins2 promoters by CRISPR–Cas9 technology. The mice with homozygous mutations in the GG2–GG1/A2 elements in both Ins1 and Ins2 were diabetic. These data suggest that the GG2–GG1/A2 element in mice is important for Ins transcription in vivo.