Origin of animal epithelia: insights from the sponge genome
Origin of animal epithelia: insights from the sponge genome
复制标题
DOI：
10.1111/j.1525-142x.2010.00445.x
复制
发表时间：
2010-11-01
影响因子：
2.9
通讯作者：
Degnan, Bernard M.
中科院分区：
文献类型：
--
作者：
Fahey, Bryony;Degnan, Bernard M.
上皮组织是一种关键的后生动物细胞类型，为构建多样的动物身体结构提供了基本的结构单位。从历史上看，上皮组织层次的结构被认为仅限于真后生动物，而对多孔动物所描述的大多数细胞层缺乏上皮细胞的任何保守的超微结构特征。现在，通过利用来自寻常海绵纲的澳大利亚厚皮海绵（Amphimedon queenslandica）的基因组信息，我们确定了双侧对称动物中决定上皮细胞极性或编码特殊上皮连接和细胞外基质结构成分的基因的直系同源物。澳大利亚厚皮海绵拥有大多数双侧对称动物上皮极性和黏着连接基因的直系同源物，但很少或没有紧密连接、分隔连接或基膜基因。为了将这一信息置于进化背景中，我们将这些分析扩展到各种真菌、领鞭毛虫（Monosiga brevicollis）、扁盘动物（Trichoplax adhaerens）和刺胞动物（Nematostella vectensis）的完整基因组。结果表明，大多数“上皮”基因起源于后生动物或真后生动物谱系，只有两个基因，即Par - 1和Discs large，早于领鞭毛虫 - 后生动物的分化。我们通过追踪组成结构域和结构域组合的起源，进一步探索了这些基因各自的进化机制。一般来说，据推测在当代双侧对称动物中发现的结构域配置在后生动物进化早期就已经进化，并且与现代刺胞动物、扁盘动物和寻常海绵动物代表中存在的结构域配置相同或相似。
Epithelial tissues are a key metazoan cell type, providing a basic structural unit for the construction of diverse animal body plans. Historically, an epithelial grade of organization was considered to be restricted to the Eumetazoa, with the majority of cell layers described for Porifera lacking any of the conserved ultrastructural characteristics of epithelia. Now with the use of genomic information from the demosponge, Amphimedon queenslandica, we identify orthologs of bilaterian genes that determine epithelial cell polarity or encode components of specialized epithelial junctions and extracellular matrix structures. Amphimedon possesses orthologs of most bilaterian epithelial polarity and adherens junction genes but few or no tight junction, septate junction, or basal lamina genes. To place this information in an evolutionary context, we extended these analyses to the completed genomes of various fungi, the choanoflagellate, Monosiga brevicollis, the placozoan, Trichoplax adhaerens, and the cnidarian, Nematostella vectensis. The results indicate that the majority of "epithelial" genes originated in metazoan or eumetazoan lineages, with only two genes, Par-1 and Discs large, antedating the choanoflagellate-metazoan split. We further explored the mechanism of evolution for each of these genes by tracking the origin of constituent domains and domain combinations. In general, domain configurations found in contemporary bilaterians are inferred to have evolved early in metazoan evolution and are identical or similar to those present in representatives of modern cnidarians, placozoans, and demosponges.