Characterization of functional protein complexes from Alzheimer's disease and healthy brain by mass spectrometry-based proteome analysis.

Alzheimer's disease (AD) is a complex neurodegenerative disorder with impaired protein activities. Proteins in the form of complexes have a ubiquitous role in diverse range of cellular functions. The key challenge is to identify novel disease associated protein complexes and their potential role in the progression of AD pathology. Protein complexes were obtained from AD brain prefrontal cortex and age matched controls by Blue Native-Polyacrylamide Gel Electrophoresis. A proteomic analysis was performed using second dimension SDS-PAGE followed by nano LC-MS/MS. Differentially expressed proteins were mapped to existing biological networks by Ingenuity Pathway Analysis (IPA). A total of 13 protein complexes with their interacting proteins were resolved on SDS-PAGE. We identified 34 protein spots and found significant abundance difference between the two experimental samples. IPA analysis revealed degeneration of neurons and cell death as a major consequence of protein dysregulation. Furthermore, focused network analysis suggested an integrated regulation of the identified proteins through APP and MAPT dependent mechanisms. The interacting differentially expressed proteins in AD were found to be part of concomitant signaling cascades terminating in neuronal cell death. The identified protein networks and pathways warrant further research to study their actual contribution to AD pathology.