Bellaïche Yohanns, Beaudoin-Massiani Olivia, Stuttem Isabella, Schweisguth François
Ecole Normale Supérieure, UMR 8542, 46, rue d'Ulm, 75230 Paris, Cedex 05, France.
Development. 2004 Jan;131(2):469-78. doi: 10.1242/dev.00928.
Cell fate diversity is generated in part by the unequal segregation of cell-fate determinants during asymmetric cell division. In the Drosophila bristle lineage, the sensory organ precursor (pI) cell is polarized along the anteroposterior (AP) axis by Frizzled (Fz) receptor signaling. We show here that Fz localizes at the posterior apical cortex of the pI cell prior to mitosis, whereas Strabismus (Stbm) and Prickle (Pk), which are also required for AP polarization of the pI cell, co-localize at the anterior apical cortex. Thus, asymmetric localization of Fz, Stbm and Pk define two opposite cortical domains prior to mitosis of the pI cell. At mitosis, Stbm forms an anterior crescent that overlaps with the distribution of Partner of Inscuteable (Pins) and Discs-large (Dlg), two components of the anterior Dlg-Pins-Galphai complex that regulates the localization of cell-fate determinants. At prophase, Stbm promotes the anterior localization of Pins. By contrast, Dishevelled (Dsh) acts antagonistically to Stbm by excluding Pins from the posterior cortex. We propose that the Stbm-dependent recruitment of Pins at the anterior cortex of the pI cell is a novel read-out of planar cell polarity.
细胞命运多样性部分是由不对称细胞分裂过程中细胞命运决定因子的不均等分离产生的。在果蝇刚毛谱系中，感觉器官前体细胞（pI）通过卷曲蛋白（Fz）受体信号沿前后（AP）轴极化。我们在此表明，Fz在有丝分裂前定位于pI细胞的后顶端皮质，而pI细胞AP极化所需的斜视蛋白（Stbm）和刺蛋白（Pk）在前顶端皮质共定位。因此，Fz、Stbm和Pk的不对称定位在pI细胞有丝分裂前定义了两个相对的皮质结构域。在有丝分裂时，Stbm形成一个前新月形，与前Dlg-Pins-Galphai复合体的两个成分——无柄伴侣蛋白（Pins）和盘状大蛋白（Dlg）的分布重叠，该复合体调节细胞命运决定因子的定位。在前期，Stbm促进Pins的前定位。相比之下，散乱蛋白（Dsh）通过将Pins排除在后皮质而与Stbm起拮抗作用。我们提出，pI细胞前皮质中Stbm依赖的Pins募集是平面细胞极性的一种新表现形式。
