Analysis of Brain Protein Stability Changes in a Mouse Model of Alzheimer’s Disease

The stability of proteins from rates of oxidation (SPROX),
thermal
proteome profiling (TPP), and limited proteolysis (LiP) techniques
were used to profile the stability of ∼2500 proteins in hippocampus
tissue cell lysates from 2- and 8-months-old wild-type (C57BL/6J; n = 7) and transgenic (5XFAD; n = 7) mice
with five Alzheimer’s disease (AD)-linked mutations. Approximately
200–500 protein hits with AD-related stability changes were
detected by each technique at each age point. The hit overlap from
technique to technique was low, and all of the techniques generated
protein hits that were more numerous and largely different from those
identified in protein expression level analyses, which were also performed
here. The hit proteins identified by each technique were enriched
in a number of the same pathways and biological processes, many with
known connections to AD. The protein stability hits included 25 high-value
conformation biomarkers with AD-related stability changes detected
using at least 2 techniques at both age points. Also discovered were
subunit- and age-specific AD-related stability changes in the proteasome,
which had reduced function at both age points. The different folding
stability profiles of the proteasome at the two age points are consistent
with a different mechanism for proteasome dysfunction at the early
and late stages of AD.