The Lyl1 promoter proximal region drives expression in hematopoietic and endothelial cells. (A) Synplot28 graphical representation of a Multi-LAGAN29 multiple sequence alignment of vertebrate Lyl1 loci where Hs is Homo sapiens, Cf is Canis familiaris, Bt is Bos taurus, Mm is Mus musculus, and Rn is Rattus norvegicus. Coding and noncoding exons are highlighted in red and pink, respectively. Repetitive sequences are indicated by light blue shading. The base pair numbering along the horizontal axis includes gaps introduced by the alignment program. The segment of the homology profile shaded in green corresponds to the Lyl1 proximal promoter fragment used to generate transgenic mice. (B) The Lyl1 promoter region is active in transgenic mice. Shown is a representative E11.5 transgenic embryo expressing lacZ under control of the Lyl1 proximal promoter region (wholemount view, left; histologic sections, right). Endothelial staining discernible from wholemount analysis was confirmed by analysis of a blood vessel (ET = endothelium). Staining was also observed in round hematopoietic cells in the fetal liver (FL), clusters of round cells attached to the ventral wall of the dorsal aorta (DA), and the endocardium (EC). (C) The Lyl1 proximal promoter region functions as an enhancer in transgenic mice. Shown is a representative E11.5 transgenic embryo where the Lyl1 proximal promoter region drives lacZ expression from the SV40 minimal promoter (wholemount view, left; histologic sections, right). The staining pattern was similar to that observed in Figure 1B. The arrowhead indicates a β-galactosidase–positive cell with megakaryocyte morphology.
