Phospholipase D2 Regulates Microtubule Acetylation by Modulating Gsk3β-Tau Signaling in Mouse Oocytes During Meiotic Maturation

Abstract

Phospholipase D2 (PLD2) modulates cytoskeletal dynamics and membrane trafficking processes by converting phosphatidylcholine (PC) into phosphatidic acid (PA) and choline within somatic cells. Nonetheless, the role in oocyte meiosis remains largely unknown. Here, we demonstrate that PLD2 is selectively targeted to the meiotic spindle in mouse oocytes. The knockdown of PLD2 via the specific morpholino oligonucleotides (MOs) or its inhibition with VU 0364739 led to a marked increase in α-tubulin acetylation and induced a meiotic arrest at metaphase I (MI), accompanied by misaligned chromosomes. These defects were effectively rescued by the ectopic expression of Pld2 complementary RNA (cRNA). Furthermore, our findings implicate the Pld2 MO-induced alterations in the AKT-GSK3-Tau signaling cascade in oocytes. The overexpression of a gain-of-function GSK3β mutant (GSK3β^S9A) and a Tau-phosphorylation-enhancing mutant (Tau^P301L) substantially reversed the increased microtubule acetylation and the reduced rate of the first polar body extrusion (PBE) in oocytes lacking PLD2 activity. Additionally, the co-immunoprecipitation revealed a direct physical interaction between PLD2, GSK3β, and Tau in mouse oocytes. Together, PLD2 finely regulates α-tubulin acetylation through the modulation of the AKT-GSK3β-Tau signaling axis, thereby preserving an optimal microtubule dynamic equilibrium and ensuring the fidelity of the spindle apparatus function during oocyte meiosis.