Developmental compartments and planar polarity in Drosophila
Developmental compartments and planar polarity in Drosophila
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DOI：
10.1016/s0960-9822(02)00974-0
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发表时间：
2002-07-23
期刊：
影响因子：
9.2
通讯作者：
Lawrence, PA
中科院分区：
文献类型：
--
作者：
Casal, J;Struhl, G;Lawrence, PA
背景：平面极性是指细胞在上皮平面内的不对称性；例如，细胞可能形成指向后方向的毛发，或者纤毛可能单向跳动。该属性意味着细胞具有有关其方向的信息；我们希望了解该信息的性质。昆虫的身体平面也是相关的，在外胚层和体细胞中胚层中，昆虫的身体平面由一系列交替的前后间隔组成，这些间隔是发育的基本单位，具有独立的细胞谱系，并受到独立的基因控制。结果：利用成年果蝇的腹部，我们提取了正常极性所需的基因，并将其移除或在细胞的小克隆中结构性表达，并观察了对极性的影响。到目前为止，所有这些对极性基因的研究都没有发现不同隔室之间的行为差异。我们在此报告三种基因，四关节基因、达克苏基因和脂肪基因，在前室和后室引起相反的影响。例如，在前室，异位表达四个关节的克隆颠倒了克隆前面细胞的极性，而在后室，它们反转到克隆后面。其他人已报道这三个基因在功能上是连锁的。结论：这一发现影响了细胞如何读取极性的模型。一类模型的核心是这样一个假设，即细胞的极性是由形态梯度的矢量决定的。在这里，我们提出的证据表明，腹部细胞的极性取决于至少两个蛋白质梯度(Fj和DS)，每个梯度都反映在间隔边界上。因此，这些渐变在两个隔间中具有相反的坡度。因为腹部细胞形成的所有极化结构都指向后面，我们推测每个间隔中的细胞被编程用相反的符号来解释这些蛋白质梯度，在一个间隔中向上指向梯度，在另一个间隔中向下指向梯度。
Background: Planar polarity refers to the asymmetry of a cell within the plane of the epithelium; for example, cells may form hairs that point in a posterior direction, or cilia may beat in one way. This property implies that cells have information about their orientation; we wish to understand the nature of this information. Relevant also is the body plan of insects, which, in the ectoderm and somatic mesoderm, consists of a chain of alternating anterior and posterior compartments - basic units of development with independent cell lineage and subject to independent genetic control.Results: Using the abdomen of adult Drosophila, we have taken genes required for normal polarity and either removed the gene or constitutively expressed it in small clones of cells and observed the effects on polarity. Hitherto, all such studies of polarity genes have not found any difference of behavior between the different compartments. We report here that the three genes, four-jointed, dachsous, and fat, cause opposite effects in anterior and posterior compartments. For example, in anterior compartments, clones ectopically expressing four-jointed reverse the polarity of cells in front of the clone, while, in posterior compartments, they reverse behind the clone. These three genes have been reported by others to be functionally linked.Conclusions: This discovery impacts on models of how cells read polarity. At the heart of one class of models is the hypothesis that cell polarity is determined by the vector of a morphogen gradient. Here, we present evidence that cell polarity in the abdomen depends on at least two protein gradients (Fj and Ds), each of which is reflected at compartment borders. Consequently, these gradients have opposing slopes in the two compartments. Because all polarized structures made by abdominal cells point posteriorly, we surmise that cells in each compartment are programmed to interpret these protein gradients with opposite signs, pointing up the gradient in one compartment and down the gradient in the other.