Error-prone meiotic division and subfertility in mice with oocyte-conditional knockdown of pericentrin

Claudia Baumann, Xiaotian Wang, Luhan Yang, Maria M. Viveiros

Mouse oocytes lack canonical centrosomes and instead contain unique acentriolar microtubule-organizing centers (aMTOCs). To test the function of these distinct aMTOCs in meiotic spindle formation -Pericentrin (Pcnt), an essential centrosome/MTOC protein, was knocked down exclusively in oocytes using transgenic RNAi. Here we provide evidence that disruption of aMTOC function in oocytes promotes spindle instability and severe meiotic errors that lead to pronounced female subfertility. Pcnt-depleted oocytes from transgenic (Tg) mice are ovulated at metaphase-II, but show significant chromosome misalignment, aneuploidy and premature sister chromatid separation. These defects were associated with loss of key Pcnt-interacting proteins (γ-Tubulin, Nedd1 and Cep215) from meiotic spindle poles, altered spindle structure, and chromosome-microtubule attachment errors. Live cell imaging revealed disruptions in the dynamics of spindle assembly and organization together with chromosome attachment and congression defects. Notably, spindle formation was dependent on Ran-GTPase activity in Pcnt-deficient oocytes. Our findings establish that meiotic division is highly error-prone in the absence of Pcnt and disrupted aMTOCs, similar to defects reported in human oocytes. Moreover, these data underscore crucial differences between MTOC-dependent and independent meiotic spindle assembly.