Small Peptide Inhibitor of JNK3 Protects Dopaminergic Neurons from MPTP Induced Injury via Inhibiting the ASK1-JNK3 Signaling Pathway

INTRODUCTION AND AIMS The ASK1-JNK3 signaling pathway plays a pivotal role in the pathogenesis of Parkinson's disease (PD). The specific binding of β-arrestin2 to JNK3 is essential for activation of the ASK1-JNK3 cascade, representing a potential therapeutic target for preventing dopaminergic neuronal death in PD. The aim of this study was to identify a novel strategy for the prevention of dopaminergic neuronal death in PD. METHODS Based on the specific binding of β-arrestin2 to JNK3, a 21-amino-acid fusion peptide, termed JNK3-N-Tat, was synthesized. We evaluated the ability of this peptide to inhibit the binding of β-arrestin2 to its target domain in JNK3 in vitro and in vivo. RESULTS The JNK3-N-Tat peptide inhibited activation of the ASK1-JNK3 cascade by disrupting the interaction between β-arrestin2 and JNK3. JNK3-N-Tat exerted beneficial effects through pathways downstream of JNK3 and improved mitochondrial function, resulting in attenuated MPP+/MPTP-induced damage. JNK3-N-Tat protected mesencephalic dopaminergic neurons against MPTP-induced toxicity. CONCLUSIONS JNK3-N-Tat, a JNK3-inhibitory peptide, protects dopaminergic neurons against MPP+/MPTP-induced injury by inhibiting the ASK1-JNK3 signaling pathway.