B islet cells of pancreas are the site of expression of the human insulin gene in transgenic mice.

Transgenic mouse lines carrying the human insulin gene were previously shown to express it in pancreas but not in other tissues. The present study reports evidence that the expression of the transgene is restricted to a single category of cells. Immunofluorescence staining of frozen pancreas sections showed that the human C-peptide was present in pancreatic islets only, and more precisely in the B cells of the islets. Human insulin transcripts were initiated correctly in mouse pancreas at the same site as in human pancreas. Three different transgenic lines with different insertion sites and various copy numbers of the human insulin transgene had the same high levels of the transgene transcripts corresponding to a well-balanced contribution in insulin gene expression.