title: Role for endocytosis of a constitutively active GPCR (GPR185) in releasing vertebrate oocyte meiotic arrest.
abstract: Vertebrate oocytes are naturally arrested at prophase of meiosis I for sustained periods of time before resuming meiosis in a process called oocyte maturation that prepares the egg for fertilization. Members of the constitutively active GPR3/6/12 family of G-protein coupled receptors represent important mediators of meiotic arrest. In the frog oocyte the GPR3/12 homolog GPRx (renamed GPR185) has been shown to sustain meiotic arrest by increasing intracellular cAMP levels through GαSβγ. Here we show that GPRx is enriched at the cell membrane (~80%), recycles through an endosomal compartment at steady state, and loses its ability to signal once trapped intracellularly. Progesterone-mediated oocyte maturation is associated with significant internalization of both endogenous and overexpressed GPRx. Furthermore, a GPRx mutant that does not internalize in response to progesterone is significantly more efficient than wild-type GPRx at blocking oocyte maturation. Collectively our results argue that internalization of the constitutively active GPRx is important to release oocyte meiotic arrest.
authors.affiliation: Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar.
authors.forename: Nancy
authors.initials: N
authors.lastname: Nader
authors.affiliation: Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar.
authors.forename: Maya
authors.initials: M
authors.lastname: Dib
authors.affiliation: Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar.
authors.forename: Arwa
authors.initials: A
authors.lastname: Daalis
authors.affiliation: Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar.
authors.forename: Rashmi P
authors.initials: RP
authors.lastname: Kulkarni
authors.affiliation: Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City - Qatar Foundation, Doha, Qatar. Electronic address: Khm2002@qatar-med.cornell.edu.
authors.forename: Khaled
authors.initials: K
authors.lastname: Machaca
mesh_terms: D000818:Animals; D015153:Blotting, Western; D059447:Cell Cycle Checkpoints / Q000502:physiology*; D000242:Cyclic AMP / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004705:Endocytosis / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008540:Meiosis / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009865:Oocytes / Q000254:growth & development*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis / Q000254:growth & development*; D000097573:Red Fluorescent Protein
chemical_list: D000242:Cyclic AMP; D017931:DNA Primers; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D043562:Receptors, G-Protein-Coupled; D029867:Xenopus Proteins; D000097573:Red Fluorescent Protein; C528932:GPRx protein, Xenopus
keywords: Constitutive; G-protein coupled receptor; GPR185; GPRx; Internalization; Meiotic arrest; Oocyte maturation; Trafficking; Xenopus laevis; cAMP