Differential Effects of UCH-L1 Inhibition on a-Syn Figure 4. Immunohistochemical analysis of a-syn expression in the hippocampus of control and LDN-treated non tg and a-syn tg mice. Representative hippocampal vibratome sections from control and LDN-treated non tg and a-syn tg mice that were immunolabeled with the anti-a-syn antibody, that recognizes both human and mouse forms of this protein (A). Magnified insets corresponding to boxed areas in the CA1 (B) and CA3 (C) regions from (A) are shown. Mean fluorescence intensity in hippocampal sections from LDN-treated non tg and a-syn tg mice (D). * Indicates a significant difference between non tg mice that were treated with or without LDN P,0.05. ** Indicates significant difference between untreated non tg and a-syn tg mice P,0.05. # Indicates significant difference between a-syn tg mice that were treated with or without LDN P,0.05. Mean values 6 SEM are shown. N = 6 mice per group, 3 sections per mouse. UCH-L1 activity in hippocampal homogenates from non tg and a-syn tg mice treated with or without LDN (E). * Indicates a significant difference between non tg mice that were treated with or without LDN P,0.05. # Indicates a significant difference between a-syn tg mice that were treated with or without LDN P,0.01. N = 6 mice per group. Mean values 6 SEM are shown. AU = arbitrary unit. doi:10.1371/journal.pone.0034713.g004 levels were reduced by 18% in hippocampal lysates of LDN- treated a-syn tg mice (Figure 7A, C, a-syn tg, control, 1.060.08; LDN-treated, 0.8260.07). These results support the notion that LDN treatment was active and effective in the mice. There were no detectable differences in mono-ubiquitin levels between non tg and a-syn tg hippocampal lysates (Figure 7A, C). We then analyzed a-syn expression levels with antibodies that recognize both human and murine a-syn (Figure 7A, B) or only human a-syn (Syn211) (Figure 7A, D); the latter would only detect a-syn expression in a-syn tg mice. We found that blocking UCH-L1 activity had differential effects on a-syn expression in non tg vs. a- syn tg mice. In non tg mice, suppression of UCH-L1 activity led to PLoS ONE | www.plosone.org 7 April 2012 | Volume 7 | Issue 4 | e34713