Centriole Biogenesis Constrains Whole Body Regeneration in Planarians

Whole-body regeneration in planarians represents the ultimate challenge in restoring a complete organism from a fragment, requiring coordinated mass proliferation, global repatterning, de novo organogenesis, and tissue remodeling. This review synthesizes evidence from recent functional studies to argue that centriole biogenesis acts as a fundamental constraint on every phase of this complex process. Disruption of centriole duplication or function leads to a hierarchical failure: early blockage of neoblast proliferation results in fragment lethality, while partial impairment yields specific defects in brain regeneration, eye formation, and axial patterning. These phenotypes stem from the centriole's multifunctional role as the orchestrator of mitotic fidelity, asymmetric cell divisions, primary cilia-based signaling, and cytoskeletal organization. A comparative analysis reveals that while centriole dependency is a conserved theme in regeneration, planarians present a uniquely stringent model due to their absolute reliance on a stem cell-driven morphogenetic program. The findings imply that "centriolar health" is a critical determinant of regenerative potential and suggest that evolutionary trade-offs involving centrosome regulation may underlie the loss of regenerative capacity in complex animals. For regenerative medicine, this underscores the necessity of ensuring centriole integrity in stem cell-based strategies.