論 文 題 目 Identification of domains for efficient Notch signaling activity in immobilized Notch ligand proteins.
固 相 化 Notch リ ガ ン ド タ ン パ ク 質 を 用 い た Notch シ グ ナ ル 活 性 化 ド メ イ ン に 関 す る 研 究
氏 名 LIU LEDI
論 文 要 約
Notch signaling is a critical pathway regulating cell fates during development and plays essential roles in many fundamental processes in metazoa. Notch signaling is a cell-cell communication system, and the Notch receptor is activated by the Notch ligand on a neighboring cell. Four Notch proteins (Notch1 - Notch4), three Delta-like (Dll1, 3, and 4) ligands, and two Jagged-family (Jagged1, and 2) ligands have been identified in mammals. Upon ligand binding to the Notch receptor, liberate the Notch intracellular domain (NICD), and it forms a complex with the DNA-binding protein then modulates the transcription of downstream target genes.
The DOS motif is conserved among Dll1, Jagged1, and Jagged2, but Dll3 and Dll4 do not have a DOS motif. Meanwhile, previous studies suggested that the N-terminal EGF3 region of Dll1 and Dll4 plays essential roles in Notch activation [3][4], but less is known about other ligands.
Here we immobilized Notch ligand proteins to beads and measured the time-course of Notch activity after the addition of Notch ligand-coated beads. We found that Dll4- and Jagged1-coated beads induced different activities of Notch signaling in a variety of cells that express fringe proteins and Notch receptors. Sufficient
Notch activity requires EGF repeat 1-3 of both Dll4 and Jagged1. Reconstruction of the DOS motif in Dll4 also increased its signal sending activity. Furthermore, active immobilized Dll4 ligand proteins on beads can induce a T cell fate from the fetal liver in vitro. We further used immobilized Dll4 binding to soluble form of Notch1Fc proteins as a convenient approach for screening chemical compounds that alter Notch signaling. These data suggest that immobilized Notch ligand proteins could be useful for analyzing Notch signaling activity both in vivo and in vitro.
