Pancreatic expression of human insulin gene in transgenic mice

We have investigated the possibility of obtaining integration and expression of a native human gene in transgenic mice. An 11-kilobase (kb) human chromosomal DNA fragment including the insulin gene (1430 base pairs) was microinjected into fertilized mouse eggs. This fragment was present in the genomic DNA of several developing animals. One transgenic mouse and its progeny were analyzed for expression of the foreign gene. Synthesis and release of human insulin was revealed by detection of the human C-peptide in the plasma and urine. Human insulin mRNA was found in pancreas but not in other tissues. These findings indicate that the 11-kb human DNA fragment carries the sequences necessary for tissue-specific expression of the insulin gene and the human regulatory sequences react to homologous signals in the mouse.