The deposition of alpha-synuclein as intracellular aggregates is a hallmark lesion of a subset of neurodegenerative disorders termed synucleinopathies, including Parkinsons disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy and Hallervorden-Spatz disease. Two rare mutations in the alpha-synuclein gene (A53T, A30P) have been identified in pedigrees of familial PD. Recently, we have identified a specific phosphorylation of Ser129 in insoluble alpha-synuclein deposited in synucleinopathy brains (Nature Cell Biol 4:160-164, 2002). Overexpression of human alpha-synuclein in neurons of transgenic animals, including mouse and Drosophila, has been shown to cause formation of cytoplasmic inclusions similar to Lewy bodies, as well as some defects in neuronal function or neuronal death, although the mechanism whereby alpha-synuclein aggregates and deteriorate neuronal functions and survival remains unclear. To understand the molecular pathogenesis of synucleinopathies, we have generated transgenic C. elegans overexpressing human alpha-synuclein in neurons. We expressed both normal and familial PD mutant forms of human alpha-synuclein in neurons of C. elegans using
unc-51 promoter for panneuronal expression. These transgenic animals expressed high levels of human alpha-synuclein in neurons. Neuronal cell bodies as well as neurites were extensively labeled by an anti-human alpha-synuclein antibody LB509, and phosphorylation of alpha-synuclein at Ser129 was detected in a restricted areas, predominantly in the nerve ring. Western blot analysis of lysates of transgenic animals showed ~15 kDa alpha-synuclein in the cytosolic fraction, that presumably corresponds to holoprotien of human alpha-synuclein. To study the effects of accumulation of wild-type or familial PD-linked mutant alpha-synuclein on the function of a specific subset of neurons, we generated transgenic worms that selectively overexpress human alpha-synuclein in touch neurons using a
mec-7 promotor, and confirmed the protein expression in these neurons by immunohistochemistry. We are currently conducting touch assays to examine the functional effects of alpha-synuclein accumulation in these neurons. Our goal is to generate a C. elegans model of synucleinopathies by overexpressing alpha-synuclein, that recapitulates features of synucleinopathies, i.e. formation of alpha-synuclein inclusions and neuronal death. Such models should contribute to the understanding of the molecular mechanism of, as well as to the development of therapeutic strategies to, intractable human synucleinopathies.