A 3 kb sequence from the mouse cellular retinoic-acid-binding protein gene upstream region mediates spatial and temporal LacZ expression in transgenic mouse embryos

A 3233 base pair (bp) sequence of the 5′-flanking region of the mouse cellular retinoic-acid-binding protein (CRABP) gene is determined. From this region, a 3 kb fragment located 150 bp upstream from the transcriptional initiation site is isolated and fused to a LacZ reporter sequence. Transgenic mouse embryos of this fusion gene show spatially and temporally specific expression of LacZ protein and the expression of this fusion gene at the RNA level is confirmed by RNAase protection assays, which detect specific fusion transcripts in RNA samples from tissues of transgenic mouse embryos. In contrast, transgenic mouse embryos of a shorter fusion gene containing only 583 bp from the same upstream region of the mouse CRABP gene fused to the same reporter sequence show no LacZ activities. Thus, it is concluded that the 3 kb sequence, but not the 583 bp sequence, of the mouse CRABP gene contains information for its temporally and spatially specific expression in mouse embryos.