Selective Covalent Inhibiting JNK3 by Small Molecules for Parkinson's Diseases.

c‐Jun N‐terminal kinases (JNKs) including JNK1/2/3 are key members of mitogen‐activated protein kinase family. Wherein JNK3 is specifically expressed in brain and emerges as therapeutic target, especially for neurodegenerative diseases. However, developing JNK3 selective inhibitors as chemical probes to investigate its therapeutic potential in diseases remains challenging. Here, we adopted the covalent strategy for identifying JNK3‐selective covalent inhibitor <bold>JC16I</bold>, with high inhibitory activity against JNK3. Despite targeting a conserved cysteine in the vicinity of ATP pocket in JNK family, <bold>JC16I</bold> exerted a greater than 160‐fold selectivity for JNK3 over JNK1/2. Importantly, even at low concentration, <bold>JC16I</bold> showed enhanced and long‐lasting inhibition against cellular JNK3. In addition, its alkyne‐containing probe <bold>JC‐P1</bold> could label JNK3 in SH‐SY5Y cell lysate and living cells, with good proteome‐wide selectivity. <bold>JC16I</bold> selectively suppressed the abnormal activation of JNK3 signaling and sufficiently exhibited neuroprotective effect in Parkinson's diseases (PD) models. Overall, our findings highlight the potential of developing isoform‐selective and cell‐active JNK3 inhibitors by covalent drug design strategy targeting a conserved cysteine. This work not only provides a valuable chemical probe for JNK3‐targeted investigations <italic>in vitro</italic> and <italic>in vivo</italic> but also opens new avenues for the treatment of PD. [ABSTRACT FROM AUTHOR]