Sapir A, Schweitzer R, Shilo B Z
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.
Development. 1998 Jan;125(2):191-200. doi: 10.1242/dev.125.2.191.
Previous work has demonstrated a role for the Drosophila EGF receptor (Torpedo/DER) and its ligand, Gurken, in the determination of anterioposterior and dorsoventral axes of the follicle cells and oocyte. The roles of DER in establishing the polarity of the follicle cells were examined further, by following the expression of DER-target genes. One class of genes (e.g. kekon) is induced by the DER pathway at all stages. Broad expression of kekon at the stage in which the follicle cells migrate posteriorly over the oocyte, demonstrates the capacity of the pathway to pattern all follicle cells except the ventral-most rows. This may provide the spatial coordinates for the ventral-most follicle cell fates. A second group of target genes (e.g. rhomboid (rho)) is induced only at later stages of oogenesis, and may require additional inputs by signals emanating from the anterior, stretch follicle cells. The function of Rho was analyzed by ectopic expression in the stretch follicle cells, and shown to induce a non-autonomous dorsalizing activity that is independent of Gurken. Rho thus appears to be involved in processing a DER ligand in the follicle cells, to pattern the egg chamber and allow persistent activation of the DER pathway during formation of the dorsal appendages.
先前的研究表明，果蝇表皮生长因子受体（鱼雷/果蝇表皮生长因子受体）及其配体 Gurken 在决定卵泡细胞和卵母细胞的前后轴和背腹轴方面发挥作用。通过追踪果蝇表皮生长因子受体靶基因的表达，进一步研究了果蝇表皮生长因子受体在建立卵泡细胞极性中的作用。一类基因（如 kekon）在所有阶段都由果蝇表皮生长因子受体信号通路诱导表达。在卵泡细胞向后迁移至卵母细胞上方的阶段，kekon 广泛表达，这表明该信号通路能够调控除最腹侧排之外的所有卵泡细胞，这可能为最腹侧卵泡细胞的命运提供空间坐标。另一组靶基因（如菱形基因（rho））仅在卵子发生的后期被诱导表达，可能需要来自前部伸展卵泡细胞发出的信号提供额外输入。通过在伸展卵泡细胞中异位表达来分析 Rho 的功能，结果表明它能诱导一种不依赖 Gurken 的非自主背化活性。因此，Rho 似乎参与了卵泡细胞中果蝇表皮生长因子受体配体的加工过程，从而对卵室进行模式化，并在背侧附属物形成过程中使果蝇表皮生长因子受体信号通路持续激活。
