A transgenic pig model expressing a ZsGreen1 reporter across an extensive array of tissues

ABSTRACT Background The advent of genetically engineered pig production has revealed a wide array of opportunities to enhance both biomedical and agricultural industries. One powerful method to develop these models is transgenesis; however, selection of a suitable promoter to drive transgene expression is critical. The cytomegalovirus (CMV) promoter is the most commonly used viral promoter as it robustly drives transgene expression in a ubiquitous nature. However, recent reports suggest that the level of CMV promoter activity is tissue-dependent in the pig. Therefore, the objective of this study was to quantify the activity of the CMV promoter in a wide range of porcine tissues. Swine harboring a CMV-ZsGreen1 transgene with a single integration site were utilized for this study. Thirty five tissue samples were collected from neonatal hemizygous (n = 3) and homozygous (n = 3) transgenic piglets and analyzed for ZsGreen1 abundance via immunoblot. Results ZsGreen1 was detected in all tissues examined; however, quantification revealed that ZsGreen1 protein levels were tissue-specific. Within organs of the digestive system, for example, ZsGreen1 was most abundant in the salivary gland, moderately produced in the esophagus and levels were lowest in the stomach. Interestingly, abundance of ZsGreen1 also differed within organ. For instance, levels were highest in the right ventricle compared with other chambers of the heart. There was no effect of transgene dose as ZsGreen1 expression patterns were similar between homozygous and hemizygous piglets. Conclusions Ultimately, these results elucidate the tissue-specific activity of the CMV promoter in the neonatal pig. Moreover, this model can serve as a useful tool for research applications requiring reporter gene activity in mammalian organs.