Sen J, Goltz J S, Konsolaki M, Schüpbach T, Stein D
Department of Molecular Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Development. 2000 Dec;127(24):5541-50. doi: 10.1242/dev.127.24.5541.
Drosophila embryonic dorsal-ventral polarity originates in the ovarian follicle through the restriction of pipe gene expression to a ventral subpopulation of follicle cells. Pipe, a homolog of vertebrate glycosaminoglycan-modifying enzymes, directs the ventral activation of an extracellular serine proteolytic cascade which defines the ventral side of the embryo. When pipe is expressed uniformly in the follicle cell layer, a strong ventralization of the resulting embryos is observed. Here, we show that this ventralization is dependent on the other members of the dorsal group of genes controlling dorsal-ventral polarity, but not on the state of the Epidermal Growth Factor Receptor signal transduction pathway which defines egg chamber polarity. Pipe protein expressed in vertebrate tissue culture cells localizes to the endoplasmic reticulum. Strikingly, coexpression of the dorsal group gene windbeutel in those cells directs Pipe to the Golgi. Similarly, Pipe protein exhibits an altered subcellular localization in the follicle cells of females mutant for windbeutel. Thus, Windbeutel protein enables the correct subcellular distribution of Pipe to facilitate its pattern-forming activity.
果蝇胚胎的背腹极性起源于卵巢卵泡，通过将管道基因的表达限制在卵泡细胞的腹侧亚群中实现。管道是脊椎动物糖胺聚糖修饰酶的同源物，它指导细胞外丝氨酸蛋白酶级联反应在腹侧的激活，该反应定义了胚胎的腹侧。当管道在卵泡细胞层中均匀表达时，会观察到所得胚胎出现强烈的腹侧化。在这里，我们表明这种腹侧化依赖于控制背腹极性的背侧基因群的其他成员，但不依赖于定义卵室极性的表皮生长因子受体信号转导途径的状态。在脊椎动物组织培养细胞中表达的管道蛋白定位于内质网。引人注目的是，在这些细胞中共同表达背侧基因风袋会将管道导向高尔基体。同样，在风袋突变的雌性果蝇的卵泡细胞中，管道蛋白表现出改变的亚细胞定位。因此，风袋蛋白能够使管道进行正确的亚细胞分布，以促进其模式形成活性。
