PIP5K1A-PIP2-RhoA Signaling Orchestrates Membrane Remodeling during Early Porcine Embryo Development

Dynamic plasma membrane remodeling is fundamental for cleavage, signal transduction, and cytoskeletal organization during mammalian embryogenesis. Although oocyte activation triggers membrane remodeling and elevates phosphatidylinositol (4,5)-bisphosphate (PIP2), the underlying regulatory mechanisms remain elusive. Here, we identify phosphatidylinositol-4-phosphate 5-kinase type I alpha (PIP5K1A), an enzyme responsible for generating PIP2, as a key regulator of membrane remodeling in porcine embryos. Maternal depletion of PIP5K1A impaired oocyte activation, disrupted actin organization and vesicle trafficking, and blocked early development. Conversely, excessive expression of PIP5K1A caused accumulation of PIP2-enriched vesicles that trapped filamentous actin and reduced membrane contractility, resulting in cleavage failure. Structure-function analysis revealed that residue Q169 mediates PIP5K1A interaction with RhoA, the PIPB motif anchors it to the plasma membrane, and the activation loop drives catalytic activity and is required for proper RhoA membrane localization and is associated with endocytic abnormalities when mutated. PIP5K1A also sustains phospholipase C-inositol trisphosphate-Ca²⁺ signaling, coordinating vesicle fusion and cytoskeletal remodeling. During cytokinesis, PIP5K1A-enriched membrane clusters serve as hubs for RhoA recruitment. These findings suggest PIP5K1A as a central organizer of lipid signaling, actin dynamics, and membrane contractility to drive successful early embryonic development in mammals.