Regulation of intracellular pH by p90Rsk-dependent activation of an Na(+)/H(+) exchanger in starfish oocytes.

ABSTRACT: Starfish oocytes arrest at metaphase of the first meiotic division (MI arrest) in the ovary and resume meiosis after spawning into seawater. MI arrest is maintained by lower intracellular pH (pH(i)) and release from arrest by cellular alkalization. To elucidate pH(i) regulation in oocytes, we cloned the starfish (Asterina pectinifera) Na(+)/H(+) exchanger 3 (ApNHE3) expressed in the plasma membrane of oocytes. The cytoplasmic domain of ApNHE3 contains p90 ribosomal S6 kinase (p90Rsk) phosphorylation sites, and injection of a constitutively active p90Rsk and the upstream regulator Mos to immature oocytes, stimulated an increase in pH(i). This increase was blocked by 5-(N-ethyl-N-isopropyl)-amiloride, a NHE inhibitor, and SL0101, a specific Rsk inhibitor. The MAPK kinase (MEK) inhibitor U012

SUBMITTER: Harada K 

PROVIDER: S-EPMC2911288 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature