[Study on the role of calcium signal during mature resumption of isolated mouse germinal vesicles in a cell free system].
A cell-free system including HeLa cell lysate of synchronized metaphase or G2-phase and isolated germinal vesicles (GV) from mouse oocytes was used to study the role of calcium and its downstream mediator during mature resumption. The isolated GVs could resume meiotic maturation in the lysate prepared from M phase HeLa cell, which marked by chromatin condensation. And this process was not affected by calcium chelating agent. But calcium in lysate from G2 phase cells was critical to meiotic maturation. Only in mid-G2 phase cell lysate (released from nocodazole for about 20-23h) chromatin condensation could be induced by calcium. Calcium had no effect on the cell lysate prepared from earlier (18-20h) and later (24h) G2 phase cells. Further studies showed that down stream mediator CaM and CaMKII might also involove in this process. Inhibition the function of CaM and CaMKII could block GVBD and first polar body extrusion of DOs cultured in vitro. The target of calcium signal might be MPF because MPF was existed from mid-G2 phase to metaphase and the tyrosine phosphorylation level of Cdc2 subunit was significantly dephosphorylated in M phase. Our results further confirmed that the resumption of meiosis maturation was promoted in a calcium/CaM depended pathway.
Dai
Gu
G
Life Sciences Academy of Nanjing Normal University, Nanjng 210097.
Bi
Chun Ming
CM
Wu
Yao Chun
YC
Zhao
Dong Hong
DH
Chen
Yan
Y
Zhang
Xi Ran
XR
Li
Chao Jun
CJ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002474:Cell-Free System / Q000378:metabolism; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008540:Meiosis / Q000502:physiology; D000090204:Mesothelin; D051379:Mice; D009865:Oocytes / Q000378:metabolism / Q000502:physiology
D002147:Calmodulin; C000715528:Msln protein, mouse; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D000090204:Mesothelin; D002118:Calcium