Molecular evidence for an activator-inhibitor mechanism in development of embryonic feather branching
Molecular evidence for an activator-inhibitor mechanism in development of embryonic feather branching
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DOI：
10.1073/pnas.0500781102
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发表时间：
2005-08-16
影响因子：
11.1
通讯作者：
Prum, RO
中科院分区：
文献类型：
--
作者：
Harris, MP;Williamson, S;Prum, RO
形态复杂性的发育基础一直是发育和进化生物学的核心问题。羽毛提供了一个独特的系统来分析复杂的形态新奇的发展。在这里，我们描述了音刺猬（Shh）和骨形态发生蛋白2（BMP 2）信号之间的相互作用在羽毛倒钩脊形态发生。我们表明，激活剂-抑制剂模型的Shh和Bmp 2信号在管状羽毛上皮细胞是足够的，以解释最初形成的一个分生模式的倒钩脊和观察到的变化，倒钩形态发生在小鸡纳塔尔下来的羽毛。实证检验支持该模型的假设，即在羽毛外胚层，Shh（激活剂）上调其自身的转录和Bmp 2（抑制剂），而Bmp 2信号下调Shh的表达。更复杂的模型，将第二个激活剂和背/腹极化的激活剂信号的修改可以产生所有的倒钩形态发生模式的生长过程中观察到的更复杂的分支pennaceous羽毛：新的倒钩脊的形成，螺旋状的增长，倒钩脊融合。羽毛形态发生和进化的综合模型表明，羽毛结构的羽毛胚芽的基底上皮细胞中的Shh和Bmp 2信号之间的激活-抑制剂相互作用的建立。随后，pennaceous羽毛结构的发展，通过整合的倒钩脊形态与第二，本地抑制剂和背/腹信号梯度内的羽毛。该模型与古生物学证据相一致，即羽毛状羽毛是原始的羽毛状羽毛。
The developmental basis of morphological complexity remains a central question in developmental and evolutionary biology. Feathers provide a unique system to analyze the development of complex morphological novelties. Here, we describe the interactions between Sonic hedgehog (Shh) and bone morphogenetic protein 2 (Bmp2) signaling during feather barb ridge morphogenesis. We demonstrate that activator-inhibitor models of Shh and Bmp2 signaling in the tubular feather epithelium are sufficient to explain the initial formation of a meristic pattern of barb ridges and the observed variation in barb morphogenesis in chick natal down feathers. Empirical tests support the assumptions of the model that, within the feather ectoderm, Shh (activator) up-regulates its own transcription and that of Bmp2 (inhibitor), whereas Bmp2 signaling down-regulates Shh expression. More complex models incorporating a second activator and dorsal/ventral polarized modification of activator signaling can produce all of the barb morphogenesis patterns observed during the growth of more complex branched pennaceous feathers: new barb ridge formation, helical growth, and barb ridge fusion. An integrated model of feather morphogenesis and evolution suggests that plumulaceous feather structure evolved by the establishment of activator-inhibitor interactions between Shh and Bmp2 signaling in the basal epithelium of the feather germ. Subsequently, pennaceous feather structure evolved through the integration of barb ridge morphogenesis with a second, local inhibitor and a dorsal/ventral signal gradient within the feather. The model is congruent with paleontological evidence that plumulaceous feathers are primitive to pennaceous feathers.