Multilayered N‑Glycoproteome Profiling Reveals Highly Heterogeneous and Dysregulated Protein N‑Glycosylation Related to Alzheimer’s Disease

Protein N-glycosylation is ubiquitous in the brain and
is closely
related to cognition and memory. Alzheimer’s disease (AD) is
a multifactorial disorder that lacks a clear pathogenesis and treatment.
Aberrant N-glycosylation has been suggested to be involved in AD pathology.
However, the systematic variations in protein N-glycosylation and
their roles in AD have not been thoroughly investigated due to technical
challenges. Here, we applied multilayered N-glycoproteomics to quantify
the global protein expression levels, N-glycosylation sites, N-glycans,
and site-specific N-glycopeptides in AD (APP/PS1 transgenic) and wild-type
mouse brains. The N-glycoproteomic landscape exhibited highly complex
site-specific heterogeneity in AD mouse brains. The generally dysregulated
N-glycosylation in AD, which involved proteins such as glutamate receptors
as well as fucosylated and oligomannose glycans, were explored by
quantitative analyses. Furthermore, functional studies revealed the
crucial effects of N-glycosylation on proteins and neurons. Our work
provides a systematic multilayered N-glycoproteomic strategy for AD
and can be applied to diverse biological systems.