Analysis of\nBrain Protein Stability Changes in a Mouse\nModel of Alzheimer’s Disease

The stability of proteins from rates of oxidation (SPROX),\nthermal\nproteome profiling (TPP), and limited proteolysis (LiP) techniques\nwere used to profile the stability of ∼2500 proteins in hippocampus\ntissue cell lysates from 2- and 8-months-old wild-type (C57BL/6J; <i>n</i> = 7) and transgenic (5XFAD; <i>n</i> = 7) mice\nwith five Alzheimer’s disease (AD)-linked mutations. Approximately\n200–500 protein hits with AD-related stability changes were\ndetected by each technique at each age point. The hit overlap from\ntechnique to technique was low, and all of the techniques generated\nprotein hits that were more numerous and largely different from those\nidentified in protein expression level analyses, which were also performed\nhere. The hit proteins identified by each technique were enriched\nin a number of the same pathways and biological processes, many with\nknown connections to AD. The protein stability hits included 25 high-value\nconformation biomarkers with AD-related stability changes detected\nusing at least 2 techniques at both age points. Also discovered were\nsubunit- and age-specific AD-related stability changes in the proteasome,\nwhich had reduced function at both age points. The different folding\nstability profiles of the proteasome at the two age points are consistent\nwith a different mechanism for proteasome dysfunction at the early\nand late stages of AD.