Low Dose DMSO Treatment Induces Oligomerization and Accelerates Aggregation of α-Synuclein

Abstract Dimethyl sulfoxide (DMSO) is a highly utilized small molecule that serves many purposes in scientific research. DMSO offers unique polar, aprotic and amphiphilic features, which makes it an ideal solvent for a wide variety of both polar and nonpolar molecules. Furthermore, DMSO is often used as a cryoprotectant in cell-based research. However, recent reports suggest that DMSO, even at low concentration, might interfere with important cellular processes, and cause macromolecular changes to proteins where a shift from α-helical to β-sheet structure can be observed. To investigate how DMSO might influence current research, we assessed biochemical and cellular impacts of DMSO treatment on the structure of the aggregation-prone protein α-synuclein, which plays a central role in the etiology of Parkinson’s disease, and other brain-related disorders, collectively termed the synucleinopathies. Here, we found that addition of DMSO increased the particle-size of α-synuclein, and accelerated the formation of seeding-potent fibrils in a dose-dependent manner. Moreover, as evident through aggregation specific antibody recognition and a bimolecular fluorescence complementation assay, cells exposed to DMSO experienced increased aggregation of α-synuclein. However, no observable α-synuclein abnormalities nor neuronal survival was affected by oral DMSO-treatment in either C57BL/6- or α-synuclein transgenic F28 mice. In summary, we demonstrate that low concentrations of DMSO makes 𝛼-synuclein susceptible to undergo aggregation both in vitro and in cells. This may affect experimental outcomes when studying α-synuclein in the presence of DMSO, and should call for careful consideration when such experiments are planned.