The Drosophila AP axis is polarised by the cadherin-mediated positioning of the oocyte.
The Drosophila AP axis is polarised by the cadherin-mediated positioning of the oocyte.
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发表时间：
1998-09
期刊：
影响因子：
4.6
通讯作者：
A. González-Reyes;D. Johnston
中科院分区：
文献类型：
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作者：
A. González-Reyes;D. Johnston
果蝇的前后轴起源于早期卵子发生过程中的两个对称破坏步骤。首先，选择 16 个生殖细胞囊肿内的两个原卵母细胞之一作为卵母细胞。然后，该细胞位于囊肿的其他生殖系细胞的后面，从而定义了轴的极性。在这里，我们展示了卵母细胞分两步到达囊肿的后部。 (1) 当囊肿进入生殖细胞的 2b 区域时，囊肿会变平，将两个原卵母细胞置于囊肿的中心，在那里它们与后卵泡细胞接触。 (2) 当囊肿进入区域 3 时，一个细胞被选择成为卵母细胞并突出到后卵泡细胞层。在这种生殖细胞重排过程中，同源钙粘蛋白粘附复合物的成分、DE-钙粘蛋白、犰狳和 α-连环蛋白沿着卵母细胞和后卵泡细胞之间的边界积累。此外，卵母细胞的定位需要这两种细胞类型之间的钙粘蛋白依赖性粘附，因为当从种系或后卵泡细胞中去除DE-钙粘蛋白时，卵母细胞经常会错位。我们得出的结论是，卵母细胞到达生殖系囊肿的后部，因为在囊肿移动到区域 3 时发生的生殖细胞重排过程中，卵母细胞与后卵泡细胞的粘附力比其邻居更强。因此，果蝇前后轴因生殖细胞和中胚层卵泡细胞之间不寻常的钙粘蛋白介导的粘附而变得极化。
The anterior-posterior axis of Drosophila originates from two symmetry-breaking steps during early oogenesis. First, one of the two pro-oocytes within the cyst of 16 germline cells is selected to become the oocyte. This cell then comes to lie posterior to the other germline cells of the cyst, thereby defining the polarity of the axis. Here we show that the oocyte reaches the posterior of the cyst in two steps. (1) The cyst flattens as it enters region 2b of the germarium to place the two pro-oocytes in the centre of the cyst, where they contact the posterior follicle cells. (2) One cell is selected to become the oocyte and protrudes into the posterior follicle cell layer when the cyst rounds up on entering region 3. During this germ cell rearrangement, the components of the homophilic cadherin adhesion complex, DE-cadherin, Armadillo and alpha-catenin, accumulate along the border between the oocyte and the posterior follicle cells. Furthermore, the positioning of the oocyte requires cadherin-dependent adhesion between these two cell types, since the oocyte is frequently misplaced when DE-cadherin is removed from either the germline or the posterior follicle cells. We conclude that the oocyte reaches the posterior of the germline cyst because it adheres more strongly to the posterior follicle cells than its neighbours during the germ cell rearrangement that occurs as the cyst moves into region 3. The Drosophila anterior-posterior axis therefore becomes polarised by an unusual cadherin-mediated adhesion between a germ cell and mesodermal follicle cells.