The homotypic fusion and protein sorting (HOPS) complex is a conserved, multi-subunit tethering complex in eukaryotic cells. In yeast and mammalian cells, the HOPS subunit vacuolar protein sorting-associated protein 41 (VPS41) is recruited to late endosomes after Ras-related protein 7 (Rab7) activation and is essential for vacuole fusion. However, whether VPS41 plays conserved roles in plants is not clear. Here, we demonstrate that in the model plant Arabidopsis (Arabidopsis thaliana), VPS41 localizes to distinct condensates in root cells in addition to its reported localization at the tonoplast. The formation of condensates does not rely on the known upstream regulators but depends on VPS41 self-interaction and is essential for vegetative growth regulation. Genetic evidence indicates that VPS41 is required for both homotypic vacuole fusion and cargo sorting from the adaptor protein complex 3, Rab5, and Golgi-independent pathways but is dispensable for the Rab7 cargo inositol transporter 1. We also show that VPS41 has HOPS-independent functions in vacuolar transport. Taken together, our findings indicate that Arabidopsis VPS41 is a unique subunit of the HOPS complex that carries out plant-specific roles in both vacuolar transport and developmental regulation.
Summary The homotypic fusion and vacuole protein sorting (HOPS) complex mediates membrane trafficking involved in endocytosis, autophagy, lysosome biogenesis, and phagocytosis. Defects in HOPS subunits are associated with various forms of cancer, but their potential as drug targets has rarely been examined. Here, we identified vacuolar protein sorting-associated protein 41 homolog (VPS41), a subunit of the HOPS complex, as a target of methyl 2,4-dihydroxy-3-(3-methyl-2-butenyl)-6-phenethylbenzoate (DMBP), a natural small molecule with preferable anticancer activity. DMBP induced methuosis and inhibited autophagic flux in cancer cells by inhibiting the function of VPS41, leading to the restrained fusion of late endosomes and autophagosomes with lysosomes. Moreover, DMBP effectively inhibited metastasis in a mouse metastatic melanoma model. Collectively, the current work revealed that targeting VPS41 would provide a valuable method of inhibiting cancer proliferation through methuosis.
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