A Rho GTPase controls the rate of protein synthesis in the sea urchin egg.
Fertilization of the sea urchin egg triggers a Ca(2+)-dependent cortical granule exocytosis and cytoskeletal reorganization, both of which are accompanied by an accelerated protein synthesis. The signaling mechanisms leading to these events are not completely understood. The possible role of Rho GTPases in sea urchin egg activation was studied using the Clostridium botulinum C3 exotoxin, which specifically ADP-ribosylates Rho proteins and inactivates them. We observed that incubation of eggs with C3 resulted in in situ ADP-ribosylation of Rho. Following fertilization, C3-treated eggs were capable of performing cortical granule exocytosis but not the first cytokinesis. C3 caused in both unfertilized eggs and early embryos alterations in the state of actin polymerization and inhibition of the spindle formation. Moreover, C3 diminished markedly the rate of protein synthesis. These findings suggested that Rho is involved in regulating the acceleration of protein synthesis that accompanies the egg activation by sperm.
Manzo
Salvador
S
Instituto de Investigación en Biología Experimental, Facultad de Química, Universidad de Guanajuato, Gto. CP, Mexico.
Martínez-Cadena
Guadalupe
G
López-Godínez
Juana
J
Pedraza-Reyes
Mario
M
García-Soto
Jesús
J
D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D005089:Exocytosis; D005306:Fertilization; D008856:Microscopy, Fluorescence; D014176:Protein Biosynthesis; D012617:Sea Urchins; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors; D020741:rho GTP-Binding Proteins / Q000502:physiology*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D001905:Botulinum Toxins; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; C096324:botulinum toxin type C; D002118:Calcium