title: Epidermal growth factor receptor signaling-dependent calcium elevation in cumulus cells is required for NPR2 inhibition and meiotic resumption in mouse oocytes.
abstract: In preovulatory ovarian follicles, the oocyte is maintained in meiotic prophase arrest by natriuretic peptide precursor C (NPPC) and its receptor natriuretic peptide receptor 2 (NPR2). LH treatment results in the decrease of NPR2 guanylyl cyclase activity that promotes resumption of meiosis. We investigated the regulatory mechanism of LH-activated epidermal growth factor (EGF) receptor signaling on NPR2 function. Cumulus cell-oocyte complex is cultured in the medium with 30 nM NPPC to prevent oocyte spontaneous maturation. In this system, EGF could stimulate oocyte meiotic resumption after 4 hours of incubation. Further study showed that EGF elevated intracellular calcium concentrations of cumulus cells and decreased cGMP levels in cumulus cells and oocytes, and calcium-elevating reagents ionomycin and sphingosine-1-phosphate mimicked the effects of EGF on oocyte maturation and cGMP levels. EGF-mediated cGMP levels and meiotic resumption could be reversed by EGF receptor inhibitor AG1478 and the calcium chelator bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester. EGF also decreased the expression of Npr2 mRNA in cumulus cells, which may not be involved in meiotic resumption, because the block of NPR2 protein de novo synthesis by cycloheximide had no effect on NPPC and EGF-mediated oocyte maturation. However, EGF had no effect on oocyte maturation when meiotic arrest was maintained in the present of cGMP analog 8-bromoadenosine-cGMP. These results suggest that EGF receptor signaling induces meiotic resumption by elevating calcium concentrations of cumulus cells to decrease NPR2 guanylyl cyclase activity.
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Science, China Agricultural University, 100193 Beijing, People's Republic of China.
authors.forename: Yakun
authors.initials: Y
authors.lastname: Wang
authors.forename: Nana
authors.initials: N
authors.lastname: Kong
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Xiaoqiong
authors.initials: X
authors.lastname: Hao
authors.forename: Kaiwen
authors.initials: K
authors.lastname: Wei
authors.forename: Xi
authors.initials: X
authors.lastname: Xiang
authors.forename: Guoliang
authors.initials: G
authors.lastname: Xia
authors.forename: Meijia
authors.initials: M
authors.lastname: Zhang
mesh_terms: D000818:Animals; D021461:Animals, Outbred Strains; D061207:Calcium Ionophores / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D054885:Cumulus Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D007986:Luteinizing Hormone / Q000378:metabolism; D008246:Lysophospholipids / Q000378:metabolism; D051379:Mice; D020098:Natriuretic Peptide, C-Type / Q000378:metabolism; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D009866:Oogenesis / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011498:Protein Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017461:Receptors, Atrial Natriuretic Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D046509:Tissue Culture Techniques; D000099242:Atrial Natriuretic Factor Receptor B
chemical_list: D061207:Calcium Ionophores; D002614:Chelating Agents; D006152:Cyclic GMP; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D007986:Luteinizing Hormone; D008246:Lysophospholipids; D020098:Natriuretic Peptide, C-Type; D047428:Protein Kinase Inhibitors; D011498:Protein Precursors; D012333:RNA, Messenger; D017461:Receptors, Atrial Natriuretic Factor; D013110:Sphingosine; D000099242:Atrial Natriuretic Factor Receptor B; C553310:natriuretic peptide precursor type C, mouse; C060506:sphingosine 1-phosphate; C541485:EGFR protein, mouse