Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Waldeyerstrasse 15, D-48149 Münster, Germany.
Center for Molecular Biology of Inflammation, Institute for Medical Biochemistry, University of Münster, Von Esmarch Strasse 56, D-48149 Münster, Germany.
J Cell Sci. 2022 Mar 1;135(5). doi: 10.1242/jcs.258672. Epub 2021 Aug 19.
The Sonic hedgehog (Shh) pathway controls embryonic development and tissue homeostasis after birth. Long-standing questions about this pathway include how the 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 1 (Disp, also known as Disp1) regulates this process. Here, we show that inactivation of Disp in Shh-expressing human cells impairs proteolytic Shh release from its lipidated terminal peptides, a process called ectodomain shedding. We also show that cholesterol export from Disp-deficient cells is reduced, that these cells contain increased cholesterol amounts in the plasma membrane, and that Shh shedding from Disp-deficient cells is restored by pharmacological membrane cholesterol extraction and by overexpression of transgenic Disp or the structurally related protein Patched 1 (Ptc, also known as Ptch1; a putative cholesterol transporter). These data suggest that Disp can regulate Shh function via controlled cell surface shedding and that membrane cholesterol-related molecular mechanisms shared by Disp and Ptc exercise such sheddase control.
Sonic hedgehog (Shh) 信号通路在胚胎发育和出生后的组织稳态中起调控作用。长期以来，人们一直对该信号通路存在疑问，包括双重脂化的、牢固结合于质膜的 Shh 配体如何从产生细胞中释放出来，以向远处的靶细胞发出信号，以及 Resistance-Nodulation-Division (RND) 转运蛋白 Dispatched 1 (Disp，也称为 Disp1) 如何调控这一过程。本研究表明，在表达 Shh 的人细胞中失活 Disp 会损害其脂化末端肽的蛋白水解 Shh 释放，这一过程称为外显肽脱落。本研究还表明，Disp 缺陷细胞中的胆固醇外排减少，质膜中的胆固醇含量增加，用药理学方法提取细胞膜胆固醇，或过表达转基因 Disp 或结构相关蛋白 Patched 1 (Ptc，也称为 Ptch1；一种假定的胆固醇转运蛋白)，可以恢复 Disp 缺陷细胞中的 Shh 脱落。这些数据表明，Disp 可以通过控制细胞表面脱落来调节 Shh 的功能，并且 Disp 和 Ptc 之间存在共享的膜胆固醇相关分子机制，从而发挥这种脱落酶的调控作用。
