Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10766938 | Biochemical and Biophysical Research Communications | 2007 | 6 Pages |
Abstract
Sperm must undergo the acrosome reaction (AR) in order to fertilize the egg. In sea urchins, this reaction is triggered by the egg jelly (EJ) which, upon binding to its sperm receptor, induces increases in the ion permeability of the plasma membrane and changes in protein phosphorylation. Here, we demonstrated that the sperm expresses ROCK (â¼135Â kDa), which is a serine/threonine protein kinase. ROCK localized, as RhoGTPase (Rho), in the acrosomal region, midpiece and flagellum. H-1152, a ROCK antagonist, inhibited the two cellular processes defining the AR: the acrosomal exocytosis and the actin polymerization. The ionophores nigericin and A23187 reversed the AR inhibition induced by H-1152, suggesting that ROCK functions at the level of the EJ-induced ion fluxes. Accordingly, H-1152 blocked 70% the intracellular alkalinization induced by EJ. These results indicate that EJ activates a Na+-H+ exchanger (NHE) in the sperm through a Rho/ROCK-dependent signaling pathway that culminates in the AR.
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Authors
Citlali Urióstegui de la Sancha, Guadalupe MartÃnez-Cadena, Juana López-GodÃnez, Laura E. Castellano, Takuya Nishisaki, Alberto Darszon, Jesús GarcÃa-Soto,