Calcineurin (CN) is a protein phosphatase and widely distributed in eukaryotes, with an extremely high level of expression in mammalian brain. Alpha-synuclein (alpha-syn) is a small soluble protein expressed primarily at presynaptic terminals in the central nervous system. In our present study, we explored the interactions between CN and alpha-syn in vitro. Based on the data from microscale thermophoresis, GST pull down assays, and co-immunoprecipitation, we found that CN binds alpha-syn. Furthermore, this interaction is mediated by calciumicalmodulin (Ca2+/CaM) signaling. Additionally, thapsigargin (TG) triggered an increase in CN activity and alpha-syn aggregation in HEK293 cells stably transfected with alpha-syn. Our previous study in vivo suggest that overexpression of alpha-syn in transgenic mice significantly promoted CN activity and subsequent nuclear translocation of nuclear factor of activated T-cells (NFAT) in the midbrain dopaminergic (mDA) neurons. These in vivo and in vitro studies have been complementary with each other, representing the changes in the CN-dependent pathway affected by overexpression of alpha-syn. (C) 2018 Elsevier Inc. All rights reserved.