title: Accumulation of the Drosophila Torso-like protein at the blastoderm plasma membrane suggests that it translocates from the eggshell.
abstract: The eggshell serves as a depository for proteins that play an important role in early embryonic development. In particular, the Drosophila eggshell is responsible for transferring asymmetries from the egg chamber to specify the regions at both ends of the embryo through the uneven activation of the Torso (Tor) receptor in its membrane. This process relies on the restricted expression of the gene torso-like (tsl) in subpopulations of follicle cells during oogenesis and its protein accumulation at both poles of the eggshell, but it is not known how this signal is transmitted to the embryo. Here, we show that Tsl accumulates at the embryonic plasma membrane, even in the absence of the Tor receptor. However, during oogenesis, we detected Tsl accumulation only at the eggshell. These results suggest that there is a two-step mechanism to transfer the asymmetric positional cues from the egg chamber into the early embryo: initial anchoring of Tsl at the eggshell as it is secreted, followed by its later translocation to the egg plasma membrane, where it enables Tor receptor activation. Translocation of anchored determinants from the eggshell might then regulate the spatial and temporal control of early embryonic developmental processes.
authors.affiliation: Institut de Biologia Molecular de Barcelona (CSIC), Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Catalonia, Spain.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Mineo
authors.affiliation: Institut de Biologia Molecular de Barcelona (CSIC), Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Catalonia, Spain mfebmc@ibmb.csic.es jcrbmc@ibmb.csic.es.
authors.forename: Marc
authors.initials: M
authors.lastname: Furriols
authors.affiliation: Institut de Biologia Molecular de Barcelona (CSIC), Institute for Research in Biomedicine (IRB Barcelona), 08028 Barcelona, Catalonia, Spain mfebmc@ibmb.csic.es jcrbmc@ibmb.csic.es.
authors.forename: Jordi
authors.initials: J
authors.lastname: Casanova
mesh_terms: D000818:Animals; D001756:Blastoderm / Q000196:embryology / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology* / Q000378:metabolism*; D004528:Egg Shell / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005260:Female; D008954:Models, Biological; D006080:Ovarian Follicle / Q000378:metabolism; D021381:Protein Transport
chemical_list: D029721:Drosophila Proteins; C085211:tsl protein, Drosophila
keywords: Drosophila; MACPF domain; Plasma membrane; Torso; Torso-like; Vitelline membrane