PLC-IP3 signaling promotes sensory hair cell formation in zebrafish neuromast.

Sensorineural hearing loss primarily results from irreversible damage to sensory hair cells (HCs), and regenerative strategies remain limited by inefficient HC formation and incomplete functional maturation of newly generated cells. Here, using pharmacological perturbation, single-cell transcriptomics sequencing, and genetic analysis in zebrafish neuromasts, we identify phosphoinositide-specific phospholipase C (PLC) signaling as an intracellular regulator of HC development and maturation. Activation of PLC signaling increases the number of HCs and FM4-64 labeling, whereas inhibition reduces HC number and impairs sensory-driven behavior. Single-cell trajectory and RNA velocity analyses reveal that PLC signaling does not alter lineage topology, but promotes progression along the HC differentiation trajectory. Among PLC isoforms, plcd4a is selectively enriched in HCs and is necessary to promote HC formation and maturation. Mechanistically, pathway perturbation experiments suggest that PLC-IP3 signaling functionally interacts with Notch and Wnt pathways during HC differentiation. Together, these findings support a model in which PLC signaling promotes HC differentiation and maturation-associated progression, providing insight into mechanisms that may promote HC regeneration.