Cancer-associated Notch receptor variants lead to O-fucosylation defects that can deregulate Notch signaling

ABSTRACT: NOTCH1 is a transmembrane receptor that initiates the Notch signaling pathway involved in embryonic development and maintenance of adult tissue homeostasis. The extracellular part of NOTCH1 is composed largely of EGF-like domains (EGFs) many of which can be O-fucosylated by protein O-fucosyltransferase 1 (POFUT1). O-fucosylation of NOTCH1 is necessary for its function. The Notch pathway is deregulated in many cancers, and alteration of POFUT1 has been reported in some cancers. Using the Biomuta and COSMIC databases, we selected 9 NOTCH1 variants that could cause a change in O-fucosylation of key EGFs. Cell-based N1 signaling assays, Notch ligand-binding assays and cell surface N1 analysis were used to determine the effect of each mutation on Notch activation. Then mass spectral glycoproteomic site mapping was used to identify alterations in the O-fucosylation of EGFs containing the selected mutation. One of the variants had few effects, two lead to a gain of function (GOF) and six to a loss of function (LOF). Most GOF and LOF could be associated with a change in O-fucosylation. Finally, by comparing our results with known NOTCH1 alterations in cancers from which our mutations originated, we were able to establish a correlation between our results and the known GOF or LOF of NOTCH1 in these cancers. This study shows that point mutations in NOTCH1 can lead to alterations in O-fucosylation that deregulate the Notch pathway and be associated with cancer processes.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: FLORIAN PENNARUBIA  

LAB HEAD: Robert S Haltiwanger

PROVIDER: PXD036345 | Pride | 2022-10-21

REPOSITORIES: Pride