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Fig. 5 Dissection of the lmo2 regulatory elements. (A) A 51-bp region from within the LG174 zebrafish promoter is 82% conserved with a 53-bp region in the fugu lmo2 locus. The three conserved ETS-factor binding sites (EBS) in this region are boxed. (B) Red triangles label EBS mutations. When EBS2 is mutated in LG174, strong expression is significantly decreased in ICM cells. When EBS1, EBS2, and EBS3 are mutated in the context of the entire 2.5-kb promoter, blood expression is normal, but endothelial expression is significantly reduced. When the region between -174 and -69 is removed from LG2.5 (called LG2.5Δ-170/-67), vascular expression is not seen, but blood expression is preserved. Removal of -174/+41 (LG2.5Δ-170/+41) resulted in no expression. (C) The transient expression pattern of LG2.5Δ-170/-67 at 24 and 36 hpf. At 24 hpf, the ICM is filled with EGFP+ cells (arrowhead) that are in circulation by 36 hpf. The inset shows blood cells (arrowhead) moving towards the heart at 36 hpf. No expression is seen in vascular endothelium at either stage. D shows the organization of lmo2 cis-elements.
Reprinted from Developmental Biology, 281(2), Zhu, H., Traver, D., Davidson, A.J., Dibiase, A., Thisse, C., Thisse, B., Nimer, S., and Zon, L.I., Regulation of the lmo2 promoter during hematopoietic and vascular development in zebrafish, 256-269, Copyright (2005) with permission from Elsevier. Full text @ Dev. Biol.