The SIRT3 activator ganoderic acid D regulates airway mucin MUC5AC expression via the NRF2/GPX4 pathway

PURPOSE

The expression of MUC5AC, a highly prevalent airway mucin, is regulated by stimulatory factors such as oxidative stress. Ganoderic acid D (GAD) activates mitochondrial deacetylase SIRT3. SIRT3 regulates mitochondrial function through deacetylation of mitochondrial proteins, thereby playing a significant role in alleviating oxidative stress-related diseases. Therefore, this study aimed to investigate the mechanisms and rationale underlying the regulation of MUC5AC expression by GAD.

METHODS

Human airway epithelial cells (NCI-H292) were exposed to pyocyanin (PCN) to establish an in vitro cell model of airway mucus hypersecretion. The expression of SIRT3, MUC5AC, and NRF2 pathway proteins in cells was assessed. Cellular mitochondrial morphology and oxidative stress markers were analyzed. C57BL/6 mice were induced with Pseudomonas aeruginosa (PA) to establish an in vivo mouse model of airway mucus hypersecretion. The expression of SIRT3 and MUC5AC in the airways was examined. In addition, the differential expression of target genes in the airway epithelial tissues of patients with chronic obstructive pulmonary disease (COPD) was analyzed using publicly available databases.

RESULTS

The results revealed a significant upregulation of MUC5AC expression and a significant downregulation of SIRT3 expression in relation to airway mucus hypersecretion. GAD inhibited the overexpression of MUC5AC in PCN-induced NCI-H292 cells and PA-induced mouse airways by upregulating SIRT3. GAD activated the NRF2/GPX4 pathway and inhibited PCN-induced oxidative stress and mitochondrial morphological changes in NCI-H292 cells. However, ML385 inhibited the regulatory effects of GAD on MUC5AC expression.

CONCLUSION

The SIRT3 activator GAD downregulated MUC5AC expression, potentially through activation of the NRF2/GPX4 pathway. Accordingly, GAD may be a potential treatment approach for airway mucus hypersecretions.

Effect of ganoderic acid D on colon cancer Warburg effect: Role of SIRT3/cyclophilin D

Ganoderic acid D (GAD) is a highly oxygenated tetracyclic triterpenoid. This study aims to assess the effects of GAD on the energy metabolism of colon cancer through the regulation of SIRT3 expression and whether this effect is related to acetylated cyclophilin D. The results demonstrated that GAD inhibits the energy reprogramming of colon cancer cells including glucose uptake, lactate production, pyruvate and acetyl-coenzyme production in colon cancer cells. Meanwhile, GAD upregulated the protein expression of SIRT3. Furthermore, the interruption of SIRT3 expression significantly reversed all the effects of SIRT3 on the energy reprogramming of colon cancer. In addition, GAD induced the deacetylated cyclophilin D (CypD) by SIRT3, whereas SIRT3-shRNA inhibited its combining effect on CypD. The energy reprogramming effects of GAD on colon cancer seem to be mediated by SIRT3 upregulation via acetylated CypD inhibition.