Characterization of the mouse carbonic anhydrase II gene promoter

This work characterizes a 250-base pair (bp) fragment of the mouse carbonic anhydrase II (CAII) gene as an efficient but not cell-specific promoter. This fragment contains multiple consensus cis regulatory regions that interact in a complex fashion to regulate transcriptional activity from the promoter. Truncated fragments of the 250-bp promoter retain transcriptional activity. The 90-bp 5' "GC"-rich portion of the promoter can direct transcription independently from the consensus TATA box and also contains a silencer that diminishes transcription from the 3' 160-bp portion of the CAII promoter as well as from the SV40 promoter. There are two nonconsensus dual functioning Ap2-like elements on the promoter that are essential for core promoter activity and cAMP-mediated increases in transcription of the gene. A nuclear protein of approximately 65 kDa binds to these elements and is present in nuclear extracts of nonstimulated and forskolin-stimulated NIH-3T3 cells. I conclude that these nonconsensus Ap2-like elements and their cognitive binding protein play a major role in the expression of the CAII gene.