α-Synuclein Translocates to the Nucleus to Activate Retinoic Acid-Dependent Gene Transcription

α-Synuclein (α-Syn) is a protein implicated in the pathogenesis of Parkinson’s disease (PD). It is primarily cytosolic and reversibly interacts with cell membranes. α-Syn also occurs in the nucleus, however, the mechanisms involved in its nuclear localization are poorly understood. We analyzed alterations in gene expression following induced α-Syn expression in SH-SY5Y cells. Analysis for upstream regulators pointed at retinoic acid receptor (RAR) and additional nuclear receptors. We show that α-Syn binds RA and translocates to the nucleus to selectively enhance gene transcription. Nuclear translocation of α-Syn is regulated by calreticulin, in a leptomycin-B independent mechanism. Importantly, nuclear translocation of α-Syn following RA treatment enhances its toxicity in cultured neurons and the expression levels of PD-associated genes, among which are two familial PD-associated genes, ATPase cation transporting 13A2 (ATP13A2) and PTEN-induced kinase 1 (PINK1). The results link a physiological role for α-Syn in the regulation of RA-mediated gene transcription and its toxicity in the synucleinopathies.