An ancient gene network is co-opted for teeth on old and new jaws.
An ancient gene network is co-opted for teeth on old and new jaws.
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DOI：
10.1371/journal.pbio.1000031
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发表时间：
2009-02-10
期刊：
影响因子：
9.8
通讯作者：
Streelman JT
中科院分区：
文献类型：
--
作者：
Fraser GJ;Hulsey CD;Bloomquist RF;Uyesugi K;Manley NR;Streelman JT
脊椎动物的齿系起源于5亿多年前无颌鱼类的后咽。随着颚口类（有颚脊椎动物）的进化，牙齿在口颚上发育，并帮助建立了这一谱系在陆地和海洋中的统治地位。口腔颌骨的出现是促进，在一定程度上，缺乏HOX基因的表达，在第一，最前面的，咽arch. Much后来在进化的时间，硬骨鱼进化出一种新的牙齿颌骨在咽部，第一个脊椎动物牙齿的位置。为了研究牙列的进化模块性，我们询问口腔和咽部牙齿的发育是否使用共同或独立的基因调控途径。首先，我们发现牙齿数量与马拉维湖（东非）的慈鲷鱼的口腔和咽部颌骨相关，提示牙齿启动的共同调控机制。令人惊讶的是，我们发现，慈鲷咽齿发育在一个密集的HOX基因表达的区域。因此，牙齿数量的调节是保守的，尽管不同的发展环境的口腔和咽颌;咽颌占据hox阳性，内胚层网站，和口腔颌开发hox阴性地区与外胚层细胞的贡献。接下来，我们研究了牙齿形成的牙齿基因网络的表达，其中大多数基因在两个不同的颌骨部位都有类似的分布。这些基因包括外胚层发育不良途径的成员eda和edar，它们在口腔和咽部牙齿的形成过程中表达相同。总之，这些数据表明，无颌脊椎动物的咽齿在口颌、口齿和外胚层附属物起源之前就利用了一个古老的基因网络。第一个脊椎动物的牙列可能出现在hox阳性的内胚层环境中，并表达了包括外胚层发育不良途径基因在内的遗传程序。这个古老的调节回路被增选和修改的牙齿在口腔颌骨的第一个有颌脊椎动物，并随后部署为颚包围牙齿的新咽颚。我们的数据突出了颌骨和牙齿在脊椎动物历史上共同进化时的惊人模块性。我们利用这种多样性来推断第一颗牙齿及其所有后代共有的核心牙齿基因网络。在进化过程中，牙齿起源于古代和灭绝的无颌鱼类的咽部深处。后来，随着硬骨鱼的进化，牙齿出现在口腔中，就像大多数现在的脊椎动物一样，尽管一些活着的鱼类在后咽部保留了牙齿。我们整合比较形态学，古生物学和分子生物学来推断第一齿列的遗传控制。我们确定Hox基因作为一个古老的牙齿基因调控电路的重要组成部分，并查明随后的修改，这个基因网络，伴随着牙齿的口腔颌骨的演变。此外，我们强调了一组在所有牙齿的构建中保守的基因，无论位置和血统如何。这个核心的牙齿基因网络在进化上是必不可少的：大自然似乎从来没有创造过没有它的牙齿，一个共同的基因调控回路控制着所有牙齿的发育，从5亿年前无颌鱼类喉咙里的原始牙齿，到现代脊椎动物的门牙和臼齿。
Vertebrate dentitions originated in the posterior pharynx of jawless fishes more than half a billion years ago. As gnathostomes (jawed vertebrates) evolved, teeth developed on oral jaws and helped to establish the dominance of this lineage on land and in the sea. The advent of oral jaws was facilitated, in part, by absence of hox gene expression in the first, most anterior, pharyngeal arch. Much later in evolutionary time, teleost fishes evolved a novel toothed jaw in the pharynx, the location of the first vertebrate teeth. To examine the evolutionary modularity of dentitions, we asked whether oral and pharyngeal teeth develop using common or independent gene regulatory pathways. First, we showed that tooth number is correlated on oral and pharyngeal jaws across species of cichlid fishes from Lake Malawi (East Africa), suggestive of common regulatory mechanisms for tooth initiation. Surprisingly, we found that cichlid pharyngeal dentitions develop in a region of dense hox gene expression. Thus, regulation of tooth number is conserved, despite distinct developmental environments of oral and pharyngeal jaws; pharyngeal jaws occupy hox-positive, endodermal sites, and oral jaws develop in hox-negative regions with ectodermal cell contributions. Next, we studied the expression of a dental gene network for tooth initiation, most genes of which are similarly deployed across the two disparate jaw sites. This collection of genes includes members of the ectodysplasin pathway, eda and edar, expressed identically during the patterning of oral and pharyngeal teeth. Taken together, these data suggest that pharyngeal teeth of jawless vertebrates utilized an ancient gene network before the origin of oral jaws, oral teeth, and ectodermal appendages. The first vertebrate dentition likely appeared in a hox-positive, endodermal environment and expressed a genetic program including ectodysplasin pathway genes. This ancient regulatory circuit was co-opted and modified for teeth in oral jaws of the first jawed vertebrate, and subsequently deployed as jaws enveloped teeth on novel pharyngeal jaws. Our data highlight an amazing modularity of jaws and teeth as they coevolved during the history of vertebrates. We exploit this diversity to infer a core dental gene network, common to the first tooth and all of its descendants. During evolution, teeth originated deep in the pharynx of ancient and extinct jawless fishes. Later, with the evolution of bony fish, teeth appeared in the mouth, as in most current vertebrates, although some living fishes retain teeth in the posterior pharynx. We integrate comparative morphology, paleontology, and molecular biology to infer the genetic control of the first dentition. We identify Hox genes as important components of an ancient dental gene-regulatory circuit and pinpoint subsequent modifications to this gene network that accompanied the evolution of toothed oral jaws. Furthermore, we highlight a set of genes conserved in the construction of all teeth, regardless of location and lineage. This core dental gene network is evolutionarily essential: nature appears never to have made a dentition without it. A common gene regulatory circuit controls the development of all dentitions, from the original teeth in the throats of jawless fishes half a billion years ago, to the incisors and molars of modern vertebrates.
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影响因子：
64.8
作者：
Cohn, MJ
通讯作者：
Cohn, MJ
影响因子：
7
作者：
Drögemüller, C;Distl, O;Leeb, T
通讯作者：
Leeb, T
影响因子：
2.9
作者：
Borday-Birraux, V;Van der Heyden, C;Sire, JY
通讯作者：
Sire, JY
DOI：
10.1002/jez.b.21182
发表时间：
2008-06-15
影响因子：
2.2
作者：
Graham, Anthony
通讯作者：
Graham, Anthony
DOI：
10.1002/jez.b.21183
发表时间：
2007-12-15
影响因子：
2.2
作者：
Debiais-Thibaud, Melanie;Borday-Birraux, Veronique;Laurenti, Patrick
通讯作者：
Laurenti, Patrick