title: Concordance and interaction of guanine nucleotide dissociation inhibitor (RhoGDI) with RhoA in oogenesis and early development of the sea urchin.
abstract: Rho GTPases are Ras-related GTPases that regulate a variety of cellular processes. In the sea urchin Strongylocentrotus purpuratus, RhoA in the oocyte associates with the membrane of the cortical granules and directs their movement from the cytoplasm to the cell cortex during maturation to an egg. RhoA also plays an important role regulating the Na(+) -H(+) exchanger activity, which determines the internal pH of the cell during the first minutes of embryogenesis. We investigated how this activity may be regulated by a guanine-nucleotide dissociation inhibitor (RhoGDI). The sequence of this RhoA regulatory protein was identified in the genome on the basis of its similarity to other RhoGDI species, especially for key segments in the formation of the isoprenyl-binding pocket and in interactions with the Rho GTPase. We examined the expression and the subcellular localization of RhoGDI during oogenesis and in different developmental stages. We found that RhoGDI mRNA levels were high in eggs and during cleavage divisions until blastula, when it disappeared, only to reappear in gastrula stage. RhoGDI localization overlaps the presence of RhoA during oogenesis and in embryonic development, reinforcing the regulatory premise of the interaction. By use of recombinant protein interactions in vitro, we also find that these two proteins selectively interact. These results support the hypothesis of a functional relationship in vivo and now enable mechanistic insight for the cellular and organelle rearrangements that occur during oogenesis and embryonic development.
authors.affiliation: Department of Biology, Natural and Exact Sciences Division, Guanajuato Campus, University of Guanajuato, Box 187, Guanajuato, Gto. 36000, Mèxico.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Zazueta-Novoa
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Martínez-Cadena
authors.forename: Gary M
authors.initials: GM
authors.lastname: Wessel
authors.forename: Roberto
authors.initials: R
authors.lastname: Zazueta-Sandoval
authors.forename: Laura
authors.initials: L
authors.lastname: Castellano
authors.forename: Jesús
authors.initials: J
authors.lastname: García-Soto
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology*; D047108:Embryonic Development / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D009866:Oogenesis / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D047270:Strongylocentrotus purpuratus / Q000166:cytology / Q000196:embryology*; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020742:rhoA GTP-Binding Protein / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D020730:Guanine Nucleotide Dissociation Inhibitors; D012333:RNA, Messenger; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D020742:rhoA GTP-Binding Protein