Differential expression of α‐synuclein isoforms in dementia with Lewy bodies

Abstract
Dementia with Lewy bodies (DLB) is characterized by the widespread presence of Lewy bodies (LBs) in the brain. α‐Synuclein, the main component of LBs, is expressed as two main isoforms (112 and 140), but little is known about their differential expression in the brain. We compared α‐synuclein 112 and α‐synuclein 140 expression levels in the prefrontal cortices of six DLB patients, eight Alzheimer disease (AD) patients, and six control subjects. Relative α‐synuclein 112 and α‐synuclein 140 expression levels were determined by real‐time polymerase chain reaction with competimer technology using a LightCycler System. Whereas total α‐synuclein levels were just marginally elevated in DLB in comparison with the other groups, α‐synuclein 112 was seen to be markedly increased in DLB compared with AD cases and controls. In contrast, α‐synuclein 140 levels were significantly diminished in both neurodegenerative disorders in comparison with controls. These results show differential overexpression of α‐synuclein 112 in DLB, a finding that could be of importance in DLB pathogenesis.