a novel signaling pathway mediated by the nuclear targeting of c-terminal fragments of mammalian patched 1一种新的信号通路介导的核目标c端片段的哺乳动物修补1.pdfVIP

A Novel Signaling Pathway Mediated by the Nuclear Targeting of C-Terminal Fragments of Mammalian Patched 1 1,2 2 2 2 2 Hiroki Kagawa , Yuka Shino , Daigo Kobayashi , Syunsuke Demizu , Masumi Shimada , Hiroyoshi 1 2 Ariga , Hiroyuki Kawahara * 1 Department of Molecular Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan, 2 Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan Abstract Background: Patched 1 (Ptc1) is a polytopic receptor protein that is essential for growth and differentiation. Its extracellular domains accept its ligand, Sonic Hedgehog, while the function of its C-terminal intracellular domain is largely obscure. Principal Findings: In this study, we stably expressed human Ptc1 protein in HeLa cells and found that it is subjected to proteolytic cleavage at the C-terminus, resulting in the generation of soluble C-terminal fragments. These fragments accumulated in the nucleus, while the N-terminal region of Ptc1 remained in the cytoplasmic membrane fractions. Using an anti-Ptc1 C-terminal domain antibody, we provide conclusive evidence that C-terminal fragments of endogenous Ptc1 accumulate in the nucleus of C3H10T1/2 cells. Similar nuclear accumulation of endogenous C-terminal fragments was observed not only in C3H10T1/2 cells but also in mouse embryonic primary cells. Importantly, the C-terminal fragments of Ptc1 modulate transcriptional activity of Gli1. Conclusions: Although Ptc1 protein was originally thought to be restricted to cell membrane fractions, our findings suggest that its C-terminal fragments can function as an alternative signal transducer that is direct