Upregulation of alphaB-crystallin expression in the substantia nigra of patients with Parkinson's disease.

Parkinson's disease (PD) is one of the most devastating neurodegenerative disorders. The underlying mechanisms of the characteristic neurodegeneration in the substantia nigra (SN) are still not fully understood. To better understand the molecular events occurring in the SN of PD brain, we used the culture-derived isotope tag-based quantitative proteomics to compare the protein expression profiles in the nigral tissue of PD patients and control subjects. We identified a total of 11 differentially expressed proteins, including alphaB-crystallin (Cryab). Both the levels and pattern of Cryab expression in the SN were validated. It was revealed that Cryab was markedly upregulated in the SN of PD brain. Cryab expression was also upregulated in reactive astrocytes and microglia in a neurotoxin-induced mouse PD model. Moreover, we showed increased expression of Cryab in cytoplasmic inclusions in a subset of glial cells in Parkinsonian brain. Thus, we identified Cryab that is highly expressed in the SN of PD brain and may be involved in the glial pathology during dopaminergic neuron degeneration in PD.