Tissue-specific regulation of human alpha 1-antitrypsin gene expression in transgenic mice

The 5'-flanking sequence of the human alpha 1-antitrypsin (AAT) gene contains multiple cis-regulatory elements, including a distal enhancer and proximal sequences essential for its transcription in cultured hepatoma cells. To understand better the promoter specificity of the AAT gene in vivo, transgenic mice harboring the AAT-SV40 hybrid promoter or the natural AAT promoter fused to a reporter gene (CAT) were generated. Examination of CAT activity in various tissues indicated that the CAT gene was expressed primarily in the liver and also, to a lesser extent, in tissues known to express the AAT gene. In addition, the cis-acting elements of the human AAT gene were utilized to drive the transcription of the SV40 T antigen gene in transgenic mice. Hepatocellular malignancy was found in all founder animals examined, while sporadic occurrence of malignancy was also observed in stomach, pancreas, and kidney. These results verify that the 5'-flanking region of the human AAT gene contains cis-regulatory elements sufficient to confer tissue specificity in vivo.