... patterning. We show that changes in the distribution of the TGFα-like ligand Gurken (GRK), a crucial ligand for axis formation, underlies EGFR activation and DR formation in D. willistoni . Furthermore, we demonstrate that GRK from D. willistoni rescues a grk -null D. melanogaster fly and, remarkably...

... demonstrated that female mutants for jvl produce ventralized eggs owing to the defects in the localization and translation of gurken mRNA during mid-oogenesis. Mutations in jvl also affect oskar and bicoid mRNA localization. Analysis of cytoskeleton organization in the mutants reveal defects in both MT...

... in cells producing the TGFα-like ligand Gurken,but not in EGFR-expressing cells. Strikingly, we find that GSLs are not essential for Gurken trafficking and secretion. However, we characterize for the first time the extracellular Gurken gradient and show that GSLs affect its formation by controlling Gurken...

...Wei-Ling Chang; Willisa Liou; Hsiao-Chung Pen; He-Yen Chou; Yu-Wei Chang; Wei-How Li; Wei Chiang; Li-Mei Pai The asymmetric localization of gurken mRNA and post-translational sorting mechanisms are responsible for the polar distribution of Gurken protein in Drosophila . However, endocytosis of Egfr...

... the correct delivery of secretory pathway components, such as the TGFαhomolog Gurken, to the plasma membrane. Moreover, in the absence of Drab6, osk mRNA localization and the organization of microtubule plus-ends at the posterior of the oocyte were both severely affected. Our results point to a possible...

...Bhupendra V. Shravage; Gabriela Altmann; Martin Technau; Siegfried Roth The Drosophila eggshell is patterned by the combined action of the epidermal growth factor [EGF; Gurken (Grk)] and transforming growth factorβ [TGF-β; Decapentaplegic (Dpp)] signaling cascades. Although Grk signaling alone can...

.... virilis oocyte and D. melanogaster follicle cells showed the evolution of DA number was not attributable to germline Gurken (Grk) signaling, but to divergence in events downstream of Grk signaling affecting the rho enhancer activity in somatic follicle cells. We found that a transcription factor,Mirror...

..., and found that the gene is essential for viability. During oogenesis, ik2 is required in an NF-κB-independent process that is essential for the localization of oskar and gurken mRNAs; as a result, females that lack ik2 in the germline produce embryos that are both bicaudal and ventralized. The abnormal RNA...

...Lucía Cáceres; Laura A. Nilson The asymmetric localization of gurken mRNA and protein in the developing Drosophila oocyte defines both the anteroposterior and dorsoventral axes of the future embryo. Understanding the origin of these asymmetries requires knowledge of the source of gurken...

... similar to a vas null mutation. Accumulation of Gurken (Grk) protein is greatly reduced when Vas-eIF5B interaction is reduced, suggesting that this interaction is crucial for translational regulation of grk . In addition, we show that reduction in Vas-eIF5B interaction virtually abolishes germ cell...

... of gurken ( grk ) mRNA. We show that Sqd interacts with Hrb27C, an hnRNP previously implicated in splicing. Like sqd , hrb27C mutants lay eggs with dorsoventral defects and Hrb27C can directly bind to grk RNA. Our data demonstrate a novel role for Hrb27C in promoting grk localization. We also observe...

...Christian Ghiglione; Erika A. Bach; Yolande Paraiso; Kermit L. Carraway, III; Stéphane Noselli; Norbert Perrimon We have analyzed the mechanism of activation of the Epidermal growth factor receptor (Egfr) by the transforming growth factor (TGF) α-like molecule, Gurken (Grk). Grk is expressed...

... for the formation and initial differentiation of the egg chamber, while later in oogenesis it functions in the determination of the dorsoventral (DV) and anteroposterior axes of egg and embryo. In the studies reported here, we have examined the role of the orb gene in the gurken ( grk )- Drosophila epidermal growth...

...Donald Morisato Dorsal-ventral polarity of the Drosophila embryo is established by a nuclear gradient of Dorsal protein, generated by successive gurken-Egfr and spätzle-Toll signaling. Overexpression of extracellular Spätzle dramatically reshapes the Dorsal gradient: the normal single peak...

...Nina MacDougall; Yatish Lad; Gavin S. Wilkie; Helen Francis-Lang; William Sullivan; Ilan Davis ABSTRACT In Drosophila , the formation of the embryonic axes is initiated by Gurken, a transforming growth factor α signal from the oocyte to the posterior follicle cells, and an unknown polarising signal...

... of Gurken protein within the oocyte, leading to the production of ventralized eggs. Here we show that enc mutants also exhibit abnormalities in karyosome morphology, similar to other ventralizing mutants such as okra and spindle B . Unlike these mutants, however, the defects in Gurken accumulation...

...-ventral axis, as loss of dDP function prevents the localized expression of the EGFR ligand Gurken in the oocyte, which initiates dorsal-ventral polarity in the egg chamber. Thus we have uncovered new functions for E2F transcription factors during development, including an unexpected role in pattern...

.... The polarity defects of vasa mutants appear to be caused by a reduction in the amount of Gurken protein at stages of oogenesis critical for the establishment of polarity. Vasa is required for translation of gurken mRNA during early oogenesis and for achieving wild-type levels of gurken mRNA expression later...

...Amir Sapir; Ronen Schweitzer; Ben-Zion Shilo ABSTRACT 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...

... when one of these cells is selected to become the oocyte. Anterior-posterior polarity originates when the oocyte then comes to lie posterior to the nurse cells and signals through the Gurken/Egfr pathway to induce the adjacent follicle cells to adopt a posterior fate. This directs the movement...