Hawkins N C, Van Buskirk C, Grossniklaus U, Schüpbach T
Howard Hughes Medical Institute, Department of Molecular Biology, Princeton University, NJ 08544, USA.
Development. 1997 Dec;124(23):4801-10. doi: 10.1242/dev.124.23.4801.
Establishment of anterior-posterior and dorsal-ventral polarity within the Drosophila egg chamber requires signaling between the germline and the somatic cells of the ovary. The gene gurken (grk) encodes a TGFalpha-like protein that is localized within the developing oocyte and is thought to locally activate torpedo/Egfr (top/Egfr), the Drosophila homolog of the EGF receptor, which is expressed throughout the follicular epithelium surrounding the oocyte. grk-Egfr signaling is required early in oogenesis for specification of posterior follicle cell fate and later in oogenesis for dorsal follicle cell fate determination, thus establishing the axes of the egg shell and embryo. Previous studies have shown that these patterning processes are highly sensitive to changes in the levels and localization of grk mRNA. Here we show that post-transcriptional regulation of Grk protein levels is required for correct pattern formation. encore (enc), a gene that functions in the regulation of germline mitosis and maintenance of oocyte identity, is also required for the accumulation of Grk protein during oogenesis. We present evidence that enc regulates Grk post-transcriptionally to ensure adequate levels of signaling for establishment of the anterior-posterior and dorsal-ventral axes.
果蝇卵室前后轴和背腹轴极性的建立需要生殖系与卵巢体细胞之间的信号传导。gurken（grk）基因编码一种类TGFα蛋白，该蛋白定位于发育中的卵母细胞内，并被认为可局部激活torpedo/Egfr（top/Egfr），即果蝇中与表皮生长因子受体（EGF受体）同源的蛋白，其在围绕卵母细胞的整个卵泡上皮中表达。grk-Egfr信号传导在卵子发生早期对于确定后卵泡细胞命运是必需的，而在卵子发生后期对于确定背卵泡细胞命运是必需的，从而确立了卵壳和胚胎的轴。先前的研究表明，这些模式形成过程对grk mRNA水平和定位的变化高度敏感。在这里，我们表明Grk蛋白水平的转录后调控对于正确的模式形成是必需的。encore（enc）基因在生殖系有丝分裂调控和卵母细胞身份维持中发挥作用，在卵子发生过程中Grk蛋白的积累也需要该基因。我们提供的证据表明，enc在转录后调控Grk，以确保有足够水平的信号传导来建立前后轴和背腹轴。
