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Proximal upstream region of zebrafish bone morphogenetic protein 4 promoter directs heart expression of green fluorescent protein

We examined the activity of the bone morphogenetic protein 4 (BMP4) promoter in zebrafish embryos via transient and stable transgenic expression analyses in order to obtain a better understanding of the regulation of BMP4 tissue‐specific expression. Transient expression studies showed that the 9.0‐kb BMP4 promoter/upstream region drove green fluorescent protein (GFP) expression mainly in the heart. Deletion analyses indicated the existence of multiple regulatory elements in the 7.5‐kb BMP4 promoter/proximal upstream region. In addition, a coinjection experiment further demonstrated the 2.4‐kb Bgl II–Hind III DNA region contains major positive regulatory elements. In addition, stable transgenic lines were established to further confirm the heart‐specificity of this segment in BMP4 promoter. The results showed that GFP was mainly localized in the myocardium of developing ventricles of 48‐hpf (hours postfertilization), 72‐hpf, and 100‐hpf transgenic F1 embryos. Together, these results indicate that the 7.5‐kb BMP4 promoter/proximal upstream region specifically contains regulatory elements for BMP4 expression in the heart, while regulatory elements for other endogenous BMP4‐expressing tissues may reside in more distal regions and/or in introns. genesis 37:103–112, 2003. © 2003 Wiley‐Liss, Inc.