Apparent continuity between the messenger transport organizer and late RNA localization pathways during oogenesis in Xenopus.
The localization of RNAs at the vegetal cortex in Xenopus oocytes is a complex process, involving at least two different pathways. The early, or messenger transport organizer (METRO), pathway, localizes RNAs such as Xlsirts, Xcat2 and Xwnt11 during stages 1 and 2 of oogenesis, while the late pathway localizes RNAs such as Vg1 during stages 2-4. We demonstrate that the onset of Vg1 localization is characterized by its microtubule-independent binding to a subdomain of the endoplasmic reticulum (ER). The formation of this unique ER structure is intimately associated with the movement of the mitochondrial cloud toward the vegetal cortex. In addition, we demonstrate that the mitochondrial cloud contains a gamma-tubulin-positive structure that may function as a microtubule organizing center for establishing microtubule tracks for Vg1 localization. These data, support, although they do not prove, a model in which the development of the late pathway machinery relies upon the prior functioning of the early pathway.
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Department of Molecular Genetics, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
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D000818:Animals; D001692:Biological Transport / Q000235:genetics; D018385:Centrosome / Q000378:metabolism; D004627:Embryonic Induction / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000235:genetics; D006023:Glycoproteins / Q000235:genetics; D008870:Microtubules / Q000235:genetics; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D009866:Oogenesis / Q000235:genetics*; D012313:RNA / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D016212:Transforming Growth Factor beta; D014404:Tubulin / Q000235:genetics; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics
C513103:GDF1 protein, Xenopus; D006023:Glycoproteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D014404:Tubulin; D029867:Xenopus Proteins; D012313:RNA