Mucin-type glycosylation as a regulatory factor of amyloid precursor protein processing.

Mucin-type O-glycosylation is found not only in mucus proteins, but also in a number of cell membrane and secretory proteins. Several recent studies demonstrate that site-specific O-GalNAc glycosylation plays an important role in regulating protein functions by modulating proteolytic processing. Proteolysis of the amyloid precursor protein (APP) is physiologically important, since cleavages at β and γ positions generate amyloid β (Aβ), a major component in the brain of patients with Alzheimer's disease. Akasaka-Manya et al. (Excess APP O-glycosylation by GalNAc-T6 decreases Aβ production. J Biochem 2017;161:99-111) showed a specific glycosylation at a site proximal to the β-secretase cleavage site and decreased productions of Aβ1-40 and Aβ1-42 in HEK293T cells transfected with a particular mucin-type glycan initiation enzyme, GalNAc-T6, indicating a novel pharmaceutical strategy to inhibit the production of Aβ through the upregulation of mucin-type O-glycosylation.