Activation of ULK1 to trigger FUNDC1-mediated mitophagy in heart failure: Effect of Ginsenoside Rg3 intervention.

Background: Although the development of therapies for heart failure (HF) continues apace, clinical outcomes are often far from ideal. Unc51-like-kinase 1 (ULK1)-mediated mitophagy prevents pathological cardiac remodeling and heart failure (HF). Molecularly ULK1-targeted agent to enhance mitophagy is scanty.

Hypothesis/purpose: This study aimed to investigate whether Ginsenoside Rg3 (Rg3) can activate ULK1 to trigger FUNDC1-mediated mitophagy for protecting heart failure.

Methods: Molecular docking and surface plasmon resonance were used to detect the ULK1 binding behavior of Rg3. Established HF model in rats and transcriptome sequencing were used to evaluate the therapeutic effect and regulatory mechanism of Rg3. Loss-of-function approaches in vivo and in vitro were performed to determine the role of ULK1 in Rg3-elicited myocardial protection against HF. FUNDC1 recombinant plasmid of site mutation was applied to elucidate more in-depth mechanisms.

Results: Structurally, a good binding mode was unveiled between ULK1 and Rg3. In vivo, Rg3 improved cardiac dysfunction, adverse remodeling, and mitochondrial damage in HF rats. Furthermore, Rg3 promoted Ulk1-triggered mitophagy both in vivo and in vitro, manifested by the impetus of downstream Fundc1-Lc3 interaction. Of note, the protective effects conferred by Rg3 against mitophagy defects, pathological remodeling, and cardiac dysfunction were compromised by Ulk1 gene silencing both in vivo and in vitro. Mechanistically, Rg3 activated mitophagy by inducing ULK1-mediated phosphorylation of FUNDC1 at the Ser17 site, not the Ser13 site.

Conclusion: Together these observations demonstrated that Rg3 acts as a ULK1 activator for the precise treatment of HF, which binds to ULK1 to activate FUNDC1-mediated mitophagy.