Testing hypotheses for the functions of APC family proteins using null and truncation alleles in Drosophila
Testing hypotheses for the functions of APC family proteins using null and truncation alleles in Drosophila
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DOI：
10.1242/dev.02398
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发表时间：
2006-06-15
期刊：
影响因子：
4.6
通讯作者：
Peifer, Mark
中科院分区：
文献类型：
--
作者：
McCartney, Brooke M.;Price, Meredith H.;Peifer, Mark
结肠腺瘤性息肉病（APC）在结肠癌中发生突变。在正常发育过程中，APC蛋白是Wnt信号传导的重要负调控因子，具有细胞骨架功能。已经提出了APC蛋白的许多功能，但这些功能通常依赖于显性负性或部分功能丧失的方法。因此，尽管对APC有浓厚的兴趣，但关于其全部细胞功能以及基因突变如何影响这些功能的重要问题仍然存在。我们分离出6个新的果蝇APC 2等位基因。两个类似于人类肿瘤中发现的截短等位基因，一个是蛋白质无效。我们产生了APC 2和APC 1无效的卵巢和胚胎，并评估了APC功能完全丧失的后果，使我们能够测试先前的几个假设。令人惊讶的是，尽管APC 1和APC 2的完全丧失导致Wingless信号传导的强烈激活，但它并没有实质上改变细胞活力、基于钙粘蛋白的粘附、纺锤体形态、分裂平面的取向或选择，如从先前的研究预测的。我们还测试了肿瘤中发现的截短APC蛋白是显性阴性的假设。两种突变蛋白对细胞骨架调节具有显性作用，影响合胞体胚胎中Wnt独立的核保留。然而，它们对Wnt信号传导没有显性负效应。
Adenomatous polyposis coli (APC) is mutated in colon cancers. During normal development, APC proteins are essential negative regulators of Wnt signaling and have cytoskeletal functions. Many functions have been proposed for APC proteins, but these have often rested on dominant-negative or partial loss-of-function approaches. Thus, despite intense interest in APC, significant questions remain about its full range of cellular functions and about how mutations in the gene affect these. We isolated six new alleles of Drosophila APC2. Two resemble the truncation alleles found in human tumors and one is a protein null. We generated ovaries and embryos null for both APC2 and APC1, and assessed the consequences of total loss of APC function, allowing us to test several previous hypotheses. Surprisingly, although complete loss of APC1 and APC2 resulted in strong activation of Wingless signaling, it did not substantially alter cell viability, cadherin-based adhesion, spindle morphology, orientation or selection of division plane, as predicted from previous studies. We also tested the hypothesis that truncated APC proteins found in tumors are dominant negative. Two mutant proteins have dominant effects on cytoskeletal regulation, affecting Wnt-independent nuclear retention in syncytial embryos. However, they do not have dominant-negative effects on Wnt signaling.