Regulation of Rap1 activity is required for differential adhesion, cell-type patterning and morphogenesis in Dictyostelium
Regulation of Rap1 activity is required for differential adhesion, cell-type patterning and morphogenesis in Dictyostelium
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DOI：
10.1242/jcs.036822
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发表时间：
2009-02-01
影响因子：
4
通讯作者：
Thompson, Christopher R. L.
中科院分区：
文献类型：
--
作者：
Parkinson, Katie;Bolourani, Parvin;Thompson, Christopher R. L.
调节细胞粘附和运动在生长、发育和组织稳态中具有重要作用。因此，已经做出了很大的努力来鉴定控制这些过程的基因。一个候选者是Rap 1，因为它涉及细胞培养中粘附和运动的调节。为了进一步研究Rap 1在多细胞发育过程中的作用，我们在网骨藻中产生了一个潜在的Rap 1 GTAPB激活蛋白（RapGAPB）的突变体。与野生型细胞相比，rapGAPB（-）细胞具有增加的活性Rap 1水平，表明RapGAPB调节Rap 1活性。此外，rapGAPB（-）细胞表现出其他已知突变体的标志性表型，具有过度激活的Rap 1，包括增加的底物粘附和异常的F-肌动蛋白分布。然而，与这些其他突变体不同，rapGAPB（-）细胞没有表现出受损的运动性或趋化性，表明RapGAPB可能只调节Rap 1的特定作用。重要的是，我们还发现RapGAPB在多细胞发育过程中调节Rap 1活性，并且是正常形态发生所必需的。首先，聚集的rapGAPB（-）细胞流由于细胞-细胞粘附减少而破裂。第二，rapGAPB（-）细胞在前茎细胞模式中表现出细胞自主缺陷。使用细胞类型特异性标记，我们证明了RapGAPB是不同细胞类型的正确分选行为所必需的。最后，我们表明，RapGAPB的失活影响prestalk和prepore细胞粘附。因此，我们提出RapGAPB调节细胞分选的可能机制是通过差异粘附。
Regulated cell adhesion and motility have important roles during growth, development and tissue homeostasis. Consequently, great efforts have been made to identify genes that control these processes. One candidate is Rap1, as it has been implicated in the regulation of adhesion and motility in cell culture. To further study the role of Rap1 during multicellular development, we generated a mutant in a potential Rap1 GTPase activating protein (RapGAPB) in Dictyostelium. rapGAPB(-) cells have increased levels of active Rap1 compared with wild-type cells, indicating that RapGAPB regulates Rap1 activity. Furthermore, rapGAPB(-) cells exhibit hallmark phenotypes of other known mutants with hyperactivated Rap1, including increased substrate adhesion and abnormal F-actin distribution. However, unlike these other mutants, rapGAPB(-) cells do not exhibit impaired motility or chemotaxis, indicating that RapGAPB might only regulate specific roles of Rap1. Importantly, we also found that RapGAPB regulates Rap1 activity during multicellular development and is required for normal morphogenesis. First, streams of aggregating rapGAPB(-) cells break up as a result of decreased cell-cell adhesion. Second, rapGAPB(-) cells exhibit cell-autonomous defects in prestalk cell patterning. Using cell-type-specific markers, we demonstrate that RapGAPB is required for the correct sorting behaviour of different cell types. Finally, we show that inactivation of RapGAPB affects prestalk and prespore cell adhesion. We therefore propose that a possible mechanism for RapGAPB-regulated cell sorting is through differential adhesion.