Rho, Rho-kinase, and the actin cytoskeleton regulate the Na super(+)-H super(+) exchanger in sea urchin eggs

At fertilization, the sea urchin egg undergoes an internal pH (pH sub(i)) increase mediated by a Na super(+)-H super(+) exchanger. We used antibodies against the mammalian antiporters NHE1 and NHE3 to characterize this exchanger. In unfertilized eggs, only anti-NHE3 cross-reacted specifically with a...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2007-01, Vol.352 (1), p.264-269
Main Authors: Rangel-Mata, F, Mendez-Marquez, R, Martinez-Cadena, G, Lopez-Godinez, J, Nishigaki, T, Darszon, A, Garcia-Soto, J
Format: Article
Language:English
Subjects:
Echinoidea
Marine
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Summary:At fertilization, the sea urchin egg undergoes an internal pH (pH sub(i)) increase mediated by a Na super(+)-H super(+) exchanger. We used antibodies against the mammalian antiporters NHE1 and NHE3 to characterize this exchanger. In unfertilized eggs, only anti-NHE3 cross-reacted specifically with a protein of 81-kDa, which localized to the plasma membrane and cortical granules. Cytochalasin D, C3 exotoxin (blocker of RhoGTPase function), and Y-27632 (inhibitor of Rho-kinase) prevented the pH sub(i) change in fertilized eggs. These inhibitors blocked the first cleavage division of the embryo, but not the cortical granule exocytosis. Thus, the sea urchin egg has an epithelial NHE3-like Na super(+)-H super(+) exchanger which can be responsible for the pH sub(i) change at fertilization. Determinants of this pH sub(i) change can be: (i) the increase of exchangers in the plasma membrane (via cortical granule exocytosis) and (ii) Rho, Rho-kinase, and optimal organization of the actin cytoskeleton as regulators, among others, of the intrinsic activity of the exchanger.
ISSN:0006-291X
DOI:10.1016/j.bbrc.2006.11.015