Protein Components of Lewy Bodies (LBs) Identified from Synthetic Proteasome Inhibitor (PSI)-induced Inclusions in PC12 Cells by MS Analysis / 中国生物化学与分子生物学报

Proteomic analysis is an effective way to identify protein constituent in Lewy bedy-like inclusions (or aggresome) in vitro. Exposure to synthetic proteasome inhibitor (PSI, 10 μmol/L) for 48 hours was used to induce the formation of cytoplasmic proteineous inclusions (termed as PSi-induced inclusions) in PC12 cells.The proteomic approaches of biochemical fractionation, two-dimensional electrophoresis (2-D) and identification via peptide mass fingerprints (PMF) were deployed, and 20 protein components of LBs were identified,i ncluding 2 proteins involved in the production of synaptic neurotransmitter, 6 subunits of the 26 S proteasome,2 cytoskeleton proteins, 2 subunits of mitochondrial complexes, 1 anti-oxidant protein, and 7 chaperone proteins and (or) chaperone-like proteins. The results suggested that these LB protein components might had been recruited in PSI-induced inclusions formed in PC12 cells under the condition of proteasome inhibition.

Eukaryotic Translation Factors Resided in PSI-induced Inclusions in PC12 / 中国生物化学与分子生物学报

Lewy body (LB), an eosinophilic inclusion localized in the neuronal perikaryon, consists of a wide range of proteins, including the consistent organization and the selective composition. Treatment of PC12 cells with synthetic proteasome inhibitor (PSI) at 10 μmol/L for 48 hours induced the formation of inclusions, which were detected by eosin staining and immunostaining for α-synuclein. To investigate the potential new components of PSI-induced inclusions in vitro, pure intact inclusions were successfully obtained by fractionation and subjected to two-dimensional electrophoresis (2-DE) then analyzed with unequivocal matrixassisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Eukaryotic translation initiation factor 3 subunit 5 (eIF-3ε), eukaryotic elongation factor 2 (eEF-2) and mitochondrial elongation factor Tu (EF-Tumt) were identified. The results suggest that 3 eukaryotic translation factors recruited in PSI-induced inclusions may influence formation of the intermediate organelles following the inhibition of proteasomes.