Role for endocytosis of a constitutively active GPCR (GPR185) in releasing vertebrate oocyte meiotic arrest

摘要

VertebrateoocytesarenaturallyarrestedatprophaseofmeiosisIforsustainedperiodsoftimebeforeresumingmeiosisinaprocesscalledoocytematurationthatpreparestheeggforfertilization.MembersoftheconstitutivelyactiveGPR3/6/12familyofG-proteincoupledreceptorsrepresentimportantmediatorsofmeioticarrest.InthefrogoocytetheGPR3/12homologGPRx(renamedGPR185)hasbeenshowntosustainmeioticarrestbyincreasingintracellularcAMPlevelsthroughGemα/emsubS/subemβγ/em.HereweshowthatGPRxisenrichedatthecellmembrane(~80%),recyclesthroughanendosomalcompartmentatsteadystate,andlosesitsabilitytosignaloncetrappedintracellularly.Progesterone-mediatedoocytematurationisassociatedwithsignificantinternalizationofbothendogenousandoverexpressedGPRx.Furthermore,aGPRxmutantthatdoesnotinternalizeinresponsetoprogesteroneissignificantlymoreefficientthanwild-typeGPRxatblockingoocytematuration.CollectivelyourresultsarguethatinternalizationoftheconstitutivelyactiveGPRxisimportanttoreleaseoocytemeioticarrest./p/div