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Echinobase
ECB-ART-47452
J Cell Biol 2019 Nov 04;21811:3612-3629. doi: 10.1083/jcb.201812133.
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SGK regulates pH increase and cyclin B-Cdk1 activation to resume meiosis in starfish ovarian oocytes.

Hosoda E , Hiraoka D , Hirohashi N , Omi S , Kishimoto T , Chiba K .


Abstract
Tight regulation of intracellular pH (pHi) is essential for biological processes. Fully grown oocytes, having a large nucleus called the germinal vesicle, arrest at meiotic prophase I. Upon hormonal stimulus, oocytes resume meiosis to become fertilizable. At this time, the pHi increases via Na+/H+ exchanger activity, although the regulation and function of this change remain obscure. Here, we show that in starfish oocytes, serum- and glucocorticoid-regulated kinase (SGK) is activated via PI3K/TORC2/PDK1 signaling after hormonal stimulus and that SGK is required for this pHi increase and cyclin B-Cdk1 activation. When we clamped the pHi at 6.7, corresponding to the pHi of unstimulated ovarian oocytes, hormonal stimulation induced cyclin B-Cdk1 activation; thereafter, oocytes failed in actin-dependent chromosome transport and spindle assembly after germinal vesicle breakdown. Thus, this SGK-dependent pHi increase is likely a prerequisite for these events in ovarian oocytes. We propose a model that SGK drives meiotic resumption via concomitant regulation of the pHi and cell cycle machinery.

PubMed ID: 31537709
PMC ID: PMC6829648
Article link: J Cell Biol


Species referenced: Echinodermata
Genes referenced: cdk1 LOC100893907 LOC105438433 LOC105442554 LOC115919910 LOC115925415 LOC574811 LOC576121 LOC576586 LOC582192 LOC586734 LOC588766 LOC590297 LOC594261 pole tubgcp2
Antibodies: ccnb2 Ab2


Article Images: [+] show captions
References [+] :
Baltz, Intracellular pH regulation in the early embryo. 1993, Pubmed, Echinobase