The role of synphilin-1 in synaptic function and protein degradation

The name synphilin-1 comes from its identification as an alpha-synuclein-interacting protein (SNCAIP) in yeast two-hybrid screens. Since alpha-synuclein (PARK1) was the first gene identified as causing inherited forms of Parkinson's disease (PD), synphilin-1 was quickly implicated in neurodegeneration in PD. Recently, the first genetic evidence for the direct contribution of synphilin-1 in the pathogenesis of PD has been defined with the identification of an R621C mutation as a susceptibility factor for PD in two German patients. Extensive in vitro studies have determined the physiological functions of synphilin-1, identified novel synphilin-1-interacting proteins, and linked synphilin-1 to ubiquitin-mediated protein degradation. The present article provides an overview of the current concepts of the role of synphilin-1 in synaptic function and protein degradation and in the molecular mechanisms leading to neurodegeneration in PD.