title: Xenopus Lefty requires proprotein cleavage but not N-linked glycosylation to inhibit nodal signaling.
abstract: The Nodal and Nodal-related morphogens are utilized for the specification of distinct cellular identity throughout development by activating discrete target genes in a concentration-dependant manner. Lefty is a principal extracellular antagonist involved in the spatiotemporal regulation of the Nodal morphogen gradient during mesendoderm induction. The Xenopus Lefty proprotein contains a single N-linked glycosylation motif in the mature domain and two potential cleavage sites that would be expected to produce long (Xlefty(L)) and short (Xlefty(S)) isoforms. Here we demonstrate that both isoforms were secreted from Xenopus oocytes, but that Xlefty(L) is the only isoform detected when embryonic tissue was analyzed. In mesoderm induction assays, Xlefty(L) is the functional blocker of Xnr signaling. When secreted from oocytes, vertebrate Lefty molecules were N-linked glycosylated. However, glycan addition was not required to inhibit Xnr signaling and did not influence its movement through the extracellular space. These findings demonstrate that Lefty molecules undergo post-translational modifications and that some of these modifications are required for the Nodal inhibitory function.
authors.affiliation: Vanderbilt University Program in Developmental Biology, Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: Joby J
authors.initials: JJ
authors.lastname: Westmoreland
authors.forename: Shuji
authors.initials: S
authors.lastname: Takahashi
authors.forename: Christopher V E
authors.initials: CV
authors.lastname: Wright
mesh_terms: D000818:Animals; D001665:Binding Sites; D004095:Dihydropyridines; D004625:Embryo, Nonmammalian; D004627:Embryonic Induction; D006031:Glycosylation; D055458:Left-Right Determination Factors; D008648:Mesoderm / Q000166:cytology; D009865:Oocytes; D020033:Protein Isoforms; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000502:physiology; D014981:Xenopus; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D004095:Dihydropyridines; D055458:Left-Right Determination Factors; D020033:Protein Isoforms; D016212:Transforming Growth Factor beta; D029867:Xenopus Proteins; C512833:nodal1 protein, Xenopus; C082341:F 0401