Senescence is a driver of aging and a barrier to tumor progression, but its persistent accumulation drives inflammation and relapse. Thus, the success of chemotherapy could be jeopardized when senescence emerges in the tumor microenvironment. Here we identified the senolytic properties of a pore-forming toxin, sticholysin I (StnI). StnI and our engineered improved form, StnIG, selectively hampers viability of chemotherapy-induced senescent cancer cells, as well as senescent primary cells. We show that its selectivity is mediated by specific binding and lipid ratios associated with senescence, including compromised membrane bilayer asymmetry. Mechanistically, StnIG triggers sodium and calcium influx and an enduring potassium efflux in senescent cells. Calcium triggers the opening of calcium-activated potassium channels, leading to cell death by apoptosis and pyroptosis. Finally we show that StnIG synergizes with senescence-inducing chemotherapy to drive remission of solid tumors in mice. Our findings define StnI and StnIG as senotoxins with translational potential for cancer therapy.
Brain health is closely linked to bone homeostasis. Skeletal aging is characterized by inadequate bone formation and marrow adiposity, but whether the brain contributes to this imbalance remains unknown. This study shows that aged brain neurons, mainly those in the hippocampus and cerebral cortex, produce excess WD repeat and FYVE domain containing 1 (WDFY1) protein and transfer it to the bone via extracellular vesicles (EVs), leading to bone-fat imbalance and osteoporosis. Increasing brain Wdfy1 expression causes premature skeletal aging. Conversely, suppressing Wdfy1 in the whole brain, hippocampus or neurons, genetically deleting neuronal Wdfy1, and selectively inhibiting neuronal EV release all improve bone health. Mechanistically, WDFY1 binds to the retromer complex to promote the endosome-to-Golgi recycling of cathepsin D and peroxiredoxin 2, thus inhibiting osteogenesis and augmenting adipogenesis. This study identifies the role of aged brain neuronal EVs as an important messenger in triggering bone-fat imbalance by transferring WDFY1 to bone.
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