Conserved cholesterol-related activities of Dispatched drive Sonic hedgehog shedding from the cell membrane
The Sonic hedgehog (Shh) pathway controls embryonic development and tissue homeostasis after birth. Long-lasting questions about this pathway are how dual-lipidated, firmly plasma membrane-associated Shh ligand is released from producing cells to signal to distant target cells, and how the resistance-nodulation-division transporter Dispatched (Disp) regulates this process. Here we show that Disp inactivation in Shh expressing cells specifically impairs proteolytic Shh release from its lipidated terminal peptides, a process called ectodomain shedding. Shh shedding from Disp-deficient cells was restored by pharmacological membrane cholesterol extraction and by overexpressed transgenic Disp or structurally related Patched (Ptc, a putative cholesterol transporter). These data suggest that Disp regulates physiological Shh function via controlled cell surface shedding and that molecular mechanisms shared by Disp and Ptc exercise such sheddase control.