Sebé-Pedrós Arnau, Ruiz-Trillo Iñaki
Departament de Genítica; Facultat de Biologia; Av. Diagonal 645 Universitat de Barcelona; Barcelona, Spain.
Commun Integr Biol. 2010 Sep;3(5):475-7. doi: 10.4161/cib.3.5.12603.
The integrin-mediated adhesion machinery is the primary cell-matrix adhesion mechanism in Metazoa. The integrin adhesion complex, which modulates important aspects of the cell physiology, is composed of integrins (alpha and beta subunits) and several scaffolding and signaling proteins. Integrins appeared to be absent in all non-metazoan eukaryotes so-far analyzed, including fungi, plants and choanoflagellates, the sister-group to Metazoa. Thus, integrins and, therefore, the integrin-mediated adhesion and signaling mechanism was considered a metazoan innovation. Recently, a broad comparative genomic analysis including new genome data from several unicellular organisms closely related to fungi and metazoans shattered previous views. The integrin adhesion and signaling complex is not specific to Metazoa, but rather it is present in apusozoans and holozoan protists. Thus, this important signaling and adhesion system predated the origin of Fungi and Metazoa, and was subsequently lost in fungi and choanoflagellates. This finding suggests that cooption played a more important role in the origin of Metazoa than previously believed. Here, we hypothesize that the integrin adhesome was ancestrally involved in signaling.
整合素介导的黏附机制是后生动物中主要的细胞-基质黏附机制。整合素黏附复合体由整合素（α和β亚基）以及多种支架蛋白和信号蛋白组成，它调节细胞生理学的重要方面。在目前已分析的所有非后生动物真核生物中，包括真菌、植物和领鞭毛虫（后生动物的姐妹类群），似乎都不存在整合素。因此，整合素以及整合素介导的黏附与信号传导机制被认为是后生动物的一项创新。最近，一项广泛的比较基因组分析，包括来自几种与真菌和后生动物密切相关的单细胞生物的新基因组数据，打破了以往的观点。整合素黏附与信号复合体并非后生动物所特有，而是存在于顶复合门原生生物和全养型原生生物中。因此，这个重要的信号传导和黏附系统在真菌和后生动物起源之前就已存在，随后在真菌和领鞭毛虫中丢失。这一发现表明，在后生动物起源过程中，功能获得比之前认为的发挥了更重要的作用。在此，我们假设整合素黏附体在进化上最初参与信号传导。
