A photoactivatable Cre-loxP system for spatiotemporal genetic manipulation in mouse taste buds

Conventional genetic approaches, including global gene KO and conditional KO strategies such as the Cre-loxP system, have some limitations arising from systemic effects or insufficient temporal resolution. The recently developed photoactivatable Cre (PA-Cre) system may have a potential to improve spatiotemporal control of gene manipulation. In this study, we established and validated the feasibility of the PA-Cre system using taste buds as a model. We generated TRE-PA-Cre:R26-rtTA/tdTomato mice to evaluate blue-light-induced Cre recombinase activity. Through systematic optimization of illumination parameters, we found that a single session of blue-light-illumination resulted in limited recombination efficiency, whereas a multisession illumination strategy markedly increased recombination efficiency. To further assess the utility of the PA-Cre system for gene KO, we generated TRE-PA-Cre:R26-rtTA:Tas1r3-flox mice and targeted a taste-related gene Tas1r3. Genomic DNA quantitative PCR and reverse transcription-quantitative PCR both showed partial reductions in Tas1r3 at the DNA and mRNA levels, respectively. Behavioral assays further revealed a selective decrease in sensitivity to sweet and umami stimuli. Together, these findings demonstrate PA-Cre-mediated gene manipulation in taste buds and establish a practical optical activation paradigm, providing a high-spatiotemporal-resolution tool for investigating gene function in optically targeted regions.