Which factor regulates organ size and regeneration in planaria?
Regenerative scaling requires coordination of growth and patterning to match body size. Notum-Wnt antagonistic balance achieves this: posterior muscle cells secrete Wnt ligands promoting proliferation of underlying neoblast progeny and posterior tail expansion, while anterior midline muscle secretes Notum deactivating Wnt locally limiting growth and allowing head differentiation. Negative feedback adjusts Wnt range ensuring proportional head-tail domains regardless of fragment size. Hedgehog modulates wnt expression but not size sensing, JAK-STAT influences stem cell maintenance and differenti
Ref: Nature, Position control genes: Notum-Wnt balance regulates scaling and organ size in planarian regeneration.
