Conclusions: The results indicate that the a-mannosidase activity present in the CSF is of lysosomal type and of brain origin. Furthermore, the in- termediate form of a-mannosidase from plasma does not cross the blood- brain-barrier. Thus CSF a-mannosidase activity might mirror the brain pathological changes linked to neurodegenerative disorders such as PD. P 6.058. SYNAPSIN III ALTERATIONS IN PARKINSON'S DISEASE Arianna Bellucci 1 , Michela Zaltieri 1 , Francesca Longhena 1 , Gaia Faustini 1 , Jessica Grigoletto 1 , Gaia Favero 2 , Stefania Castrezzati 2 , Rita Rezzani 2 , Marina Pizzi 1 , Fabio Benfenati 3 , Maria Grazia Spillantini 4 , Cristina Missale 1 , PierFranco Spano 5 . 1 Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy; 2 Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy; 3 Department of Neuroscience and Brain Technologies, Italian Institute of Technology, Genoa, Italy; 4 Department of Clinical Neuroscience, University of Cambridge, Cambridge, United Kingdom; 5 IRCCS San Camillo Hospital for Neurorehabilitation (NHS-Italy), Venice, Italy Objectives: The main neuropathological hallmarks of Parkinson's disease (PD) are loss of nigro-striatal dopamine neurons and intraneuronal Lewy Bodies (LB), proteinaceous inclusions mainly composed by a-synuclein. Recently, we found that a-synuclein interacts and cooperates with a spe- cific member of the synapsin phosphoprotein family: synapsin III, in the regulation of dopaminergic neuron function. The aim of this study was to investigate whether synapsin III alterations may be related to a-synuclein pathology in PD. We thus investigated the occurrence of alterations of synapsin III expression and distribution in “the brain of patients affected by PD and DLB (Human brain samples were kindly provided by the UK Parkinson's disease Brain Bank). Methods: We used molecular biology and immunohistochemical tech- niques as well as the “in situ” proximity ligation assay (PLA) to investigate the expression levels and the distribution of synapsin III in the PD brain. Results: By immunohistochemistry, we showed a marked accumulation of synapsin III in the caudate/putamen of patients affected by PD when compared to age matched controls. In addition, many LB-like structures in the substantia nigra of PD patients were found to be immunoreactive for synapsin III, that by confocal fluorescence microscopy resulted to be accumulated in the core of LB. By co-immunoprecipitation and “in situ” PLA we found that synapsin III directly interacted with a-synuclein and that these two proteins were co-redistributed in mice and human brains. Finally, western blot analysis showed significant alterations of synapsin III levels that correlated with alteration of a-synuclein in the caudate/puta- men and substantia nigra of PD patients. Conclusions: Altogether, our data support a critical involvement of syn- apsin III in PD pathophysiology P 6.059. UNDERSTANDING THE DIFFERENTIAL REGULATION OF GBA AND GBAP1 EXPRESSION Valeria Rimoldi 1 , Giulia Rovaris 2 , Letizia Straniero 2 , Gianni Pezzoli 3 , Stefano Goldwurm 3 , Giulia Sold a 1 , Rosanna Asselta 1 , Stefano Duga 1 . 1 Humanitas University, Humanitas Clinical and Research Center, Rozzano, Milano, Italy; 2 Universit a degli Studi di Milano, Humanitas Clinical and Research Center, Rozzano, Milano, Italy; 3 Parkinson Institute, Istituti Clinici di Perfezionamento, Milano, Italy Objectives: GBA downregulation was demonstrated to have a crucial role in Parkinson's Disease. We previously showed that there is a miRNA-mediated regulatory circuit linking GBA and its pseudogene (GBAP1) expression and that they are coexpressed in most tissues with a GBA/GBAP1 ratio ranging from 2 to 200. Furthermore, we demonstrated that GBAP1 levels are downregulated by the NMD pathway. GBA and GBAP1 share a similar genomic structure characterized by a proximal (P1) and a distal (P2) promoter but there are no data on the differential regulation at the transcriptional level. Hence, we want to study the P1 and P2 promoters of both genes. Methods: We cloned 1kb of the 4 promoters in a luciferase vector and produced serial 5'-deletion constructs of each promoter. These plasmids were transfected in different cell lines. Results: We demonstrated that:  P2 promoters are stronger than P1s, for both GBA and GBAP1;  in HeLa cells, as expected, GBAP1 promoters are weaker than GBA ones, while in SH-SY5Y cells, the pseudogene P2 promoter has the highest activity;  the TFEB binding sites seem to be the most important regulatory ele- ments for P1 promoters. Conclusions: The transcriptional activity of both GBAP1 promoters, as assessed by luciferase assays, was unexpectedly higher compared to the mRNA levels detected in vivo. Besides differences in epigenetic regulation not faithfully modeled in our system, NMD is likely to be the major determinant of the relative expression of GBA/GBAP1 transcripts. P 6.061. STRUCTURAL ANALYSIS OF ALPHA-SYNUCLEIN OLIGOMERS VIA ANTIBODY FINGERPRINTING Lina Nilsson 1 , Tohidul Islam 2 , Irina Iakovleva 2 , Kristoffer Br€ annstr€ om 2 , Anders Olofsson 2 . 1 Department of Chemistry, Umeå, Sweden; 2 Department of Medical Biochemistry and Biophysics, Umeå, Sweden Objectives: Despite the increasingly accepted role for alpha-synuclein (asyn) oligomers as a toxic specie in Parkinson's disease (PD) structural information about them remains scarce due to their transient nature and their size. Using a library of peptide antibodies, spanning the sequence of asyn, we can uncover regions in the oligomers that differ in exposure when comparing with the monomer. Methods: With the help of an oligomeric-specific antibody we are able to capture oligomers from complex samples and using the library of peptide antibodies we will examine different types of oligomers; oligomers derived from CSF from patients with PD and from healthy individuals, dopamine and drug-induced oligomers. Results: By comparing the pattern of exposure we can acquire a finger- print for each type of oligomer and reveal structural differences between them. We can today show that oligomers formed with a ring-fused 2- pyridone compound, FN075, significantly differs in structure compared to the monomer. Conclusions: Understanding the structure of the oligomeric species is vital for development of effective therapeutics against this toxic specie. P 6.062. DEREGULATION OF MIRNAS 103A, 30B AND 29A IN PERIPHERAL BLOOD OF L-DOPA TREATED PARKINSON'S PATIENTS Alice Serafin 1 , Luisa Foco 1 , Stefano Zanigni 1,2 , Hagen Blankenburg 1 , Anne Picard 1 , Alessandra Zanon 1 , Giulia Giannini 1 , Irene Pichler 1 , Maurizio F. Facheris 1 , Pietro Cortelli 3,4 , Peter P. Pramstaller 1, 2, 5 , Andrew A. Hicks 1 , Francisco S. Domingues 1 , Christine Schwienbacher 1 . 1 Center for Biomedicine, European Academy Bozen/Bolzano (EURAC) (Affiliated Institute of the University of Lubeck, Lubeck, Germany), Bolzano, Italy; 2 Department of Neurology, General Central Hospital, Bolzano, Italy; 3 IRCCS Institute of Neurological Sciences of Bologna, Bologna, Italy; 4 Department of Biomedical and NeuroMotor Sciences (DiBiNeM), Alma Mater Studiorum, University of Bologna, Bologna, Italy; 5 Department of Neurology, University of Lübeck, Lübeck, Germany Objectives: The aim of the study is to identify deregulated blood miRNAs as potential diagnostic biomarkers for Parkinson's disease and assess their biological relevance. Methods: We analyzed candidate miRNAs from PBMCs of 36 L-dopa- treated, 10 drug-naïve PD patients and not affected controls (matched by age and sex). Expression data were generated by RT-qPCR and analyzed using a two-tailed paired t-test. To predict miRNA targets, we combined several miRNA resources to generate an overall score for the candidate genes using weighted rank aggregation. Results: We observed a significant overexpression of miRNAs 103a-3p, Abstracts / Parkinsonism and Related Disorders 22 (2016) e149ee192 e189