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Inhibition of Notch signalling using fucose analogs
Author(s) -
Hao Huilin,
Liu Zilei,
Wu Peng,
Haltiwanger Robert
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.04800
Subject(s) - notch signaling pathway , notch proteins , fucosylation , cyclin dependent kinase 8 , microbiology and biotechnology , fucose , chemistry , egf like domain , cell fate determination , cell , biology , signal transduction , biochemistry , protein domain , transcription factor , gene , glycoprotein
Notch is an evolutionarily conserved cell surface receptor for short range cell‐cell communication and has critical roles in many cell‐fate related events. Dysfunction of Notch signalling is associated with many congenital disorders and a wide range of human malignancies, making Notch an important target for drug development. However, the initial efforts to inhibit Notch activity with γ‐secretase inhibitors (GSIs) for cancer treatment have failed because of severe gastrointestinal toxicity. Novel Notch‐targeting strategies are urgently needed. Notch is unique for its heavily O ‐glycosylation on the extracellular domain (ECD), especially the O ‐fucosylation mediated by POFUT1 (Protein O ‐Fucosyltransferase 1). O ‐fucosylation is required for proper Notch function, such as protein stability, trafficking and interaction with ligands. We hypothesize that disrupting Notch O ‐fucosylation can be a potential approach for Notch inhibition. We have demonstrated that L‐fucose analogs with modifications on carbon 6 are potent Notch inhibitors, especially 6‐alkynyl and 6‐alkenyl fucose. The analogs are used by POFUT1 and incorporated to Notch EGF repeats with high efficiency, inhibiting Notch signalling at sub‐micromolar concentrations. Interestly, these analogs showed ligand‐specific activity, inhibiting Delta but not Jagged‐mediated Notch signalling. These analogs can be a powerful tool for Notch study being the first small molecule, ligand‐specific Notch inhibitors. Notch controls the early differentiation of T cells in thymus. Blocking Notch signalling with the analogs completely inhibit T cell differentiation with Delta ligands in an in vitro OP9 cell culture system. We have preliminary results showing the analogs also showed inhibitory effects in vivo using fetal thymus organ culture (FTOC). The 6‐alkynyl fucose analog can also act as a probe for EGF repeat O ‐fucosylation, and help to discover novel POFUT1 substrates. Additional fucose analogs are being synthesized and evaluated to find more effective inhibitors or analogs with distinct activities (e.g. Notch activation, Jagged‐specific or ligand‐nonspecific inhibition).