Recognition efficiency of the hepatitis B virus polyadenylation signals is tissue specific in transgenic mice

The hepatitis B virus genome contains a unique polyadenylation (TATAAA) signal which is differentially utilized in the formation of the various hepatitis B virus transcripts. A head-to-tail multiple-copy insertion of a viral fragment comprising the viral enhancer, the X promoter, the X open reading frame, and the viral poly(A) signal in transgenic mice allowed us to monitor tissue-specific differences in the expression of transcripts initiating from the X promoter. These transcripts are efficiently processed at the first polyadenylation site in the liver, while in the kidney, the brain, and the testis, a portion of the transcripts covers two copies of the transgene, since only the second polyadenylation site is properly recognized. As discussed in this article, this observation suggests a tissue-specific distribution of cellular factors involved in polyadenylation.