Analysis of Fibroblast growth factor 15 cis-elements reveals two conserved enhancers which are closely related to cardiac outflow tract development
Analysis of Fibroblast growth factor 15 cis-elements reveals two conserved enhancers which are closely related to cardiac outflow tract development
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DOI：
10.1016/j.mod.2006.07.002
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发表时间：
2006-09
影响因子：
2.6
通讯作者：
H. Saitsu;K. Shiota;M. Ishibashi
中科院分区：
文献类型：
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作者：
H. Saitsu;K. Shiota;M. Ishibashi
成纤维细胞生长因子15（Fgf 15）在发育中的小鼠中枢神经系统和咽弓中表达。fgf 15突变小鼠表现出心脏流出道的缺陷，可能是因为心脏神经嵴细胞的异常行为。在这项研究中，我们研究了顺式元件的FGF 15基因的瞬时转基因分析，使用lacZ作为报告。我们确定了两个增强子：一个在后脑/脊髓中定向lacZ表达，另一个在后中脑（pmb）、菱形节1（r1）和咽上皮中定向lacZ表达。有趣的是，与这两个小鼠增强子高度同源的人类基因组区域显示出与转基因小鼠胚胎中的小鼠几乎相同的增强子活性，表明这两个增强子在人类和小鼠之间是保守的。我们还发现，小鼠和人类pmb/r1增强子可以调节lacZ在鸡胚胎中的表达，几乎相同的方式在小鼠胚胎中。我们发现，该增强子的lacZ表达域通过异位Fgf 8b表达而扩展，这表明该增强子受Fgf 8信号转导的调节。此外，Fgf 15的过度表达导致峡部/r1中Fgf 8表达的上调。这些结果表明，Fgf 15和Fgf 8之间存在一个互惠的正向调节峡部/R1。与FGF 15突变体中的心脏流出道缺陷一起，在后脑/脊髓和咽上皮中的增强子的保守性表明人FGF 19（FGF 15的直系同源物）参与心脏神经嵴细胞的早期发育和分布，并且是先天性心脏缺陷的候选基因之一。
Fibroblast growth factor 15 (Fgf15) is expressed in the developing mouse central nervous system and pharyngeal arches. Fgf15 mutant mice showed defects of the cardiac outflow tract probably because of aberrant behavior of the cardiac neural crest cells. In this study, we examined cis-elements of the Fgf15 gene by transient transgenic analysis using lacZ as a reporter. We identified two enhancers: one directed lacZ expression in the hindbrain/spinal cord and the other in the posterior midbrain (pmb), rhombomere1 (r1) and pharyngeal epithelia. Interestingly, human genomic regions which are highly homologous to these two mouse enhancers showed almost the same enhancer activities as those of mice in transgenic mouse embryos, indicating that the two enhancers are conserved between humans and mice. We also showed that the mouse and human pmb/r1 enhancer can regulate lacZ expression in chick embryos in almost the same way as in mouse embryos. We found that the lacZ expression domain with this enhancer was expanded by ectopic Fgf8b expression, suggesting that this enhancer is regulated by Fgf8 signaling. Moreover, over-expression of Fgf15 resulted in up-regulation of Fgf8 expression in the isthmus/r1. These findings suggest that a reciprocal positive regulation exists between Fgf15 and Fgf8 in the isthmus/r1. Together with cardiac outflow tract defects in Fgf15 mutants, the conservation of enhancers in the hindbrain/spinal cord and pharyngeal epithelia suggests that human FGF19 (ortholog of Fgf15) is involved in early development and the distribution of cardiac neural crest cells and is one of the candidate genes for congenital heart defects.