Investigating impacts of mycothiazole and its synthetic derivative on mitochondrial function and aging in C. elegans

Small molecule inhibitors of mitochondrial electron transport chain (ETC) hold significant promise in the field of mitochondrial research and aging biology. In this study, we studied two molecules: mycothiazole (MTZ) - isolated from the marine sponge P. mycofijiensis and its semisynthetic acetylated derivative 8-O-acetylmycothiazole (8-OAc) as efficient alternatives for their high efficiency to inhibit ETC complex I function. Similar to rotenone, a widely used complex I inhibitor, these two compounds showed anticancer activity and strikingly demonstrate a lack of toxicity to non-cancer cells, a highly beneficial feature in the development of anti-cancer therapeutics. Furthermore, experiments with these small molecules in vivo utilizing C.elegans demonstrate their additional utilization to aging studies. We observed that both molecules have the ability to induce a mitochondria-specific unfolded protein response (UPRMT) pathway, which extends lifespan of worms when applied in their adult stage. Interestingly, we also found that these two molecules employ different pathways to extend lifespan in worms, where MTZ utilize the transcription factors, ATFS-1 and HSF-1, which are involved in the UPRMT and heat shock response (HSR) pathways, respectively. In opposition,8-OAc only required HSF-1 and not ATFS-1. This observation elucidates an important insight into the functional roles of various protein subunits of ETC complexes and their regulatory mechanisms associated with aging.