The role of PLC beta 1 in the control of oocyte meiosis during folliculogenesis.

The dynamics of the subcellular distribution of PLCbeta1 was investigated during meiosis competence acquisition and meiosis resumption in relation to oocyte diameter and to nonsurrounded-nucleolus or surrounded-nucleolus chromatin configurations. Oocytes collected after both in vivo and in vitro folliculogenesis were studied. In both conditions, at the beginning of the process, most oocytes exhibited a nuclear PLCbeta 1 associated with a nonsurrounded-nucleolus chromatin configuration. Then at the final stage of the process, the factors shifted mainly toward a cytoplasmic PLCbeta1 and a surrounded-nucleolus chromatin configuration, typical of a preovulatory fertilizable oocyte. Additionally, only germinal vesicle oocytes with a diameter > 75 microm, and exhibiting cytoplasmic PLC beta1 distribution and surrounded-nucleolus chromatin configuration, resumed meiosis. Our findings demonstrate a strong correlation between oocyte diameter, chromatin configuration, and PLCbeta1 localization. Thus, PLCbeta1 localization appears to be a key factor determining the progressive acquisition of meiotic competence and final resumption of meiosis.