Activated cAMP receptors switch encystation into sporulation
Activated cAMP receptors switch encystation into sporulation
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DOI：
10.1073/pnas.0901617106
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发表时间：
2009-04-28
影响因子：
11.1
通讯作者：
Schaap, Pauline
中科院分区：
文献类型：
--
作者：
Kawabe, Yoshinori;Morio, Takahiro;Schaap, Pauline
后生动物胚胎发育由有限数量的信号模块控制，这些信号模块在连续的发育阶段重复使用。社会性阿米巴虫的发展也显示出对cAMP介导的信号的类似重复使用。在盘基网柄菌的模型中，作用于4个cAMP受体(cARs1-4)的分泌型cAMP协调细胞在聚集和子实体形成过程中的运动，并诱导聚集和产孢子基因在连续发育阶段的表达。为了确定cAMP在多种角色中的等级，我们研究了CAR的异质性和社会阿米巴系统发育过程中的功能。产生CARS 2-4的基因复制发生在进化的后期。许多物种只有一个cAR1直系同源基因，在Polysphondylids和Acytostelids中独立复制。两个CAR基因的破坏不会影响聚集性，但会导致子实体形态发生的完全崩溃。这些发育不良的结构含有无序的柄细胞，支持大量的包囊而不是孢子；cAMP在Ppal中触发了孢子基因的表达，但在CAR零突变体中没有，这解释了它的产孢量缺陷。囊化是单生阿米巴虫的生存策略，较低的类群，如Ppal，仍然可以包囊为单细胞。最近的发现表明，细胞内cAMP的积累足以触发包囊作用，而它是孢子形成的补充要求。综上所述，这些数据表明，社会阿米巴中的cAMP信号是从cAMP介导的单生阿米巴囊化进化而来的；聚集中的cAMP分泌促使饥饿的细胞形成孢子而不是包囊，并另外组织了子实体的形态发生。CAMP介导的聚合是最新的创新。
Metazoan embryogenesis is controlled by a limited number of signaling modules that are used repetitively at successive developmental stages. The development of social amoebas shows similar reiterated use of cAMP-mediated signaling. In the model Dictyostelium discoideum, secreted cAMP acting on 4 cAMP receptors (cARs1-4) coordinates cell movement during aggregation and fruiting body formation, and induces the expression of aggregation and sporulation genes at consecutive developmental stages. To identify hierarchy in the multiple roles of cAMP, we investigated cAR heterogeneity and function across the social amoeba phylogeny. The gene duplications that yielded cARs 2-4 occurred late in evolution. Many species have only a cAR1 ortholog that duplicated independently in the Polysphondylids and Acytostelids. Disruption of both cAR genes of Polysphondylium pallidum (Ppal) did not affect aggregation, but caused complete collapse of fruiting body morphogenesis. The stunted structures contained disorganized stalk cells, which supported a mass of cysts instead of spores; cAMP triggered spore gene expression in Ppal, but not in the cAR null mutant, explaining its sporulation defect. Encystation is the survival strategy of solitary amoebas, and lower taxa, like Ppal, can still encyst as single cells. Recent findings showed that intracellular cAMP accumulation suffices to trigger encystation, whereas it is a complementary requirement for sporulation. Combined, the data suggest that cAMP signaling in social amoebas evolved from cAMP-mediated encystation in solitary amoebas; cAMP secretion in aggregates prompted the starving cells to form spores and not cysts, and additionally organized fruiting body morphogenesis. cAMP-mediated aggregation was the most recent innovation.