Unraveling Small Molecule-Mediated Sirtuin 3 Activation at a Distinct Binding Site for Cardioprotective Therapies.

Sirtuin 3 (SIRT3), a pivotal mitochondrial deacetylase, plays a critical role in restoring mitochondrial function, particularly through the activation of autophagy. Despite its promise as a cardioprotective target, developing SIRT3 activators and their therapeutic applications remains challenging. Here, we report the identification of SKLB-11A, a SIRT3 activator with submicromolar affinity and high efficacy. Structural and mutagenesis analyses revealed a unique allosteric site for SKLB-11A in SIRT3, where a conformational change in Leu298 drives its potent activation. Subsequent studies demonstrated that SKLB-11A drives autophagy/mitophagy signaling pathways, effectively preventing mitochondrial dysfunction, and improving cardiac dysfunction in both doxorubicin (Dox)-induced cardiotoxicity and myocardial ischemia/reperfusion (I/R) models. Collectively, our data highlight the potential of pharmacological SIRT3 activation as an effective therapeutic strategy for cardioprotection. SKLB-11A, as a first-in-class SIRT3 allosteric activator with a distinct binding mode, not only offers a valuable tool for exploring the physiological and pathological roles of SIRT3 deacetylation but also holds promise for the development of targeted cardioprotective therapies.