Ca super(2+) sub(cyt) negatively regulates the initiation of oocyte maturation

Ca super(2+) is a ubiquitous intracellular messenger that is important for cell cycle progression. Genetic and biochemical evidence support a role for Ca super(2+) in mitosis. In contrast, there has been a long-standing debate as to whether Ca super(2+) signals are required for oocyte meiosis. Here,...

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Bibliographic Details
Published in:The Journal of cell biology 2004-04, Vol.165 (1), p.63-75
Main Authors: Sun, L, Machaca, K
Format: Article
Language:English
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Xenopus
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Summary:Ca super(2+) is a ubiquitous intracellular messenger that is important for cell cycle progression. Genetic and biochemical evidence support a role for Ca super(2+) in mitosis. In contrast, there has been a long-standing debate as to whether Ca super(2+) signals are required for oocyte meiosis. Here, we show that cytoplasmic Ca super(2+) (Ca super(2+) sub(cyt)) plays a dual role during Xenopus oocyte maturation. Ca super(2+) signals are dispensable for meiosis entry (germinal vesicle breakdown and chromosome condensation), but are required for the completion of meiosis I. Interestingly, in the absence of Ca super(2+) sub(cyt) signals oocytes enter meiosis more rapidly due to faster activation of the MAPK-maturation promoting factor (MPF) kinase cascade. This Ca super(2+)-dependent negative regulation of the cell cycle machinery (MAPK-MPF cascade) is due to Ca super(2+) sub(cyt) acting downstream of protein kinase A but upstream of Mos (a MAPK kinase kinase). Therefore, high Ca super(2+) sub(cyt) delays meiosis entry by negatively regulating the initiation of the MAPK-MPF cascade. These results show that Ca super(2+) modulates both the cell cycle machinery and nuclear maturation during meiosis.
ISSN:0021-9525
DOI:10.1083/jcb.200309138