Comparable processing of beta-lactoglobulin pre-mRNA in cell culture and transgenic mouse models.

Eukaryotic pre-mRNAs undergo a variety of post-transcriptional modifications, including the removal of intronic sequences by splicing, leading to creation of a functional mRNA. We have compared the processing of transcripts generated from ovine beta-lactoglobulin gene constructs in stably transfected cells and in transgenic mice. In both the in vitro and in vivo model systems the removal of the middle two introns resulted in the inefficient splicing of the downstream, terminal intron. This intron-containing transcript was detected in the cytoplasmic RNA fraction. Thus, the initial in vitro analysis in cell lines of minigene constructs destined for expression in transgenic animals may provide a rapid and reliable indicator of the processing efficiency of the pre-mRNA produced by the construct in vivo. This is in contrast to the apparent limitations of in vitro systems in the analysis of transcription regulatory elements required for transgene expression.