Insights into early extracellular matrix evolution:: Spongin short chain collagen-related proteins are homologous to basement membrane type IV collagens and form a novel family widely distributed in invertebrates
Insights into early extracellular matrix evolution:: Spongin short chain collagen-related proteins are homologous to basement membrane type IV collagens and form a novel family widely distributed in invertebrates
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DOI：
10.1093/molbev/msl100
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发表时间：
2006-12-01
影响因子：
10.7
通讯作者：
Exposito, Jean-Yves
中科院分区：
文献类型：
--
作者：
Aouacheria, Abdel;Geourjon, Christophe;Exposito, Jean-Yves
胶原蛋白被认为是后生动物中最重要的分子创新之一。基底膜IV型胶原蛋白存在于所有真后生动物中，并且在Homoscleromorpha中发现，Homoscleromorpha是一种具有组织良好的上皮的海绵组，其可能代表动物进化期间组织分化的第一阶段。相比之下，海绵蛋白似乎是一种海绵特异性胶原蛋白，它可以完全替代无机骨架，例如众所周知的沐浴海绵。在淡水海绵Ephydatia mulleri，我们以前的特点是一个家庭的短链胶原蛋白，可能是海绵的主要成分。使用序列和结构为基础的方法相结合，我们提出了海绵短链胶原和IV型胶原的羧基末端非胶原NC 1结构域之间的远程同源性的证据。出乎意料的是，海绵蛋白短链胶原相关蛋白在非海绵动物中被检索到，这表明海绵蛋白相关的家族构成了IV型胶原家族的进化姐妹。祖先NC 1域的形成和海绵蛋白短链胶原蛋白相关和IV型胶原蛋白家族的分歧可能发生在parazoan-eumetazoan分裂之前，这是现存动物门中最早的分歧。基于NC 1结构域序列的分子遗传学表明海绵蛋白短链胶原相关和IV型胶原家族的不同进化历史，包括在蜕皮动物和脊椎动物的祖先中海绵蛋白短链胶原相关基因丢失。大多数无脊椎动物编码海绵蛋白短链胶原相关蛋白的事实提出了重要的问题，其成员可能的功能。考虑到胶原蛋白对动物结构和基质附着的重要性，这两个家族可能在动物多样化中发挥了至关重要的作用。
Collagens are thought to represent one of the most important molecular innovations in the metazoan line. Basement membrane type IV collagen is present in all Eumetazoa and was found in Homoscleromorpha, a sponge group with a well-organized epithelium, which may represent the first stage of tissue differentiation during animal evolution. In contrast, spongin seems to be a demosponge-specific collagenous protein, which can totally substitute an inorganic skeleton, such as in the well-known bath sponge. In the freshwater sponge Ephydatia mulleri, we previously characterized a family of short-chain collagens that are likely to be main components of spongins. Using a combination of sequence- and structure-based methods, we present evidence of remote homology between the carboxyl-terminal noncollagenous NC1 domain of spongin short-chain collagens and type IV collagen. Unexpectedly, spongin short-chain collagen-related proteins were retrieved in nonsponge animals, suggesting that a family related to spongin constitutes an evolutionary sister to the type IV collagen family. Formation of the ancestral NC1 domain and divergence of the spongin short-chain collagen-related and type IV collagen families may have occurred before the parazoan-eumetazoan split, the earliest divergence among extant animal phyla. Molecular phylogenetics based on NC1 domain sequences suggest distinct evolutionary histories for spongin short-chain collagen-related and type IV collagen families that include spongin short-chain collagen-related gene loss in the ancestors of Ecdyzosoa and of vertebrates. The fact that a majority of invertebrates encodes spongin short-chain collagen-related proteins raises the important question to the possible function of its members. Considering the importance of collagens for animal structure and substratum attachment, both families may have played crucial roles in animal diversification.