Incardona J P, Lee J H, Robertson C P, Enga K, Kapur R P, Roelink H
Department of Biological Structure and Center for Developmental Biology, University of Washington, Seattle, WA 98195, USA.
Proc Natl Acad Sci U S A. 2000 Oct 24;97(22):12044-9. doi: 10.1073/pnas.220251997.
Patched (Ptc) is the ligand-binding component of the Hedgehog (Hh) receptor complex. In the Drosophila embryo, Ptc and Hh colocalize in vesicular punctate structures. However, receptor-mediated endocytosis of Hh proteins has not been demonstrated. By using chick neural plate explants, we show that Sonic hedgehog (Shh)-responsive neural precursor cells internalize recombinant and endogenous Shh and provide direct evidence for a gradient of endogenous Shh in the ventral neural tube. Shh internalization is blocked by a monoclonal antibody whose epitope overlaps the Ptc-binding site of Shh. These findings suggest that Shh internalization is mediated by Ptc-1 and may be linked to signaling. Concordantly, transfection of mammalian cell lines with a Ptc-1 cDNA confers the ability to internalize multiple forms of Shh, including transmembrane-anchored Shh, by a dynamin-dependent process.
patched（Ptc）是刺猬索尼克（Hh）受体复合物的配体结合成分。在果蝇胚胎中，Ptc和Hh共定位于囊泡状点状结构中。然而，尚未证实Hh蛋白的受体介导的内吞作用。通过使用鸡神经板外植体，我们发现对刺猬索尼克（Shh）有反应的神经前体细胞内化重组和内源性Shh，并为腹侧神经管中内源性Shh梯度提供了直接证据。Shh的内化被一种单克隆抗体阻断，该抗体的表位与Shh的Ptc结合位点重叠。这些发现表明，Shh的内化是由Ptc-1介导的，并且可能与信号传导有关。与此一致的是，用Ptc-1 cDNA转染哺乳动物细胞系赋予了通过依赖发动蛋白的过程内化多种形式的Shh（包括跨膜锚定的Shh）的能力。
