Ca2+ homeostasis regulates Xenopus oocyte maturation.
In contrast to the well-defined role of Ca2+ signals during mitosis, the contribution of Ca2+ signaling to meiosis progression is controversial, despite several decades of investigating the role of Ca2+ and its effectors in vertebrate oocyte maturation. We have previously shown that during Xenopus oocyte maturation, Ca2+ signals are dispensable for entry into meiosis and for germinal vesicle breakdown. However, normal Ca2+ homeostasis is essential for completion of meiosis I and extrusion of the first polar body. In this study, we test the contribution of several downstream effectors in mediating the Ca2+ effects during oocyte maturation. We show that calmodulin and calcium-calmodulin-dependent protein kinase II (CAMK2) are not critical downstream Ca2+ effectors during meiotic maturation. In contrast, accumulation of Aurora kinase A (AURKA) protein is disrupted in cells deprived of Ca2+ signals. Since AURKA is required for bipolar spindle formation, failure to accumulate AURKA may contribute to the defective spindle phenotype following Ca2+ deprivation. These findings argue that Ca2+ homeostasis is important in establishing the oocyte's competence to undergo maturation in preparation for fertilization and embryonic development.
Sun
Lu
L
Department of Physiology & Biophysics, and the Arkansas Cancer Research Center, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA.
Hodeify
Rawad
R
Haun
Shirley
S
Charlesworth
Amanda
A
MacNicol
Angus M
AM
Ponnappan
Subramaniam
S
Ponnappan
Usha
U
Prigent
Claude
C
Machaca
Khaled
K
D000818:Animals; D064127:Aurora Kinases; D002118:Calcium / Q000502:physiology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000502:physiology; D002147:Calmodulin / Q000502:physiology; D005260:Female; D006706:Homeostasis / Q000502:physiology*; D008540:Meiosis / Q000502:physiology; D009865:Oocytes / Q000254:growth & development*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D015398:Signal Transduction; D014981:Xenopus
D002147:Calmodulin; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D046988:Proteasome Endopeptidase Complex; D002118:Calcium