Matoba, H. | bioRxiv Science

bioRxiv2026

Oxidized phosphatidylinositol impairs lysosomal membrane repair to promote ferroptosis

Ferroptosis is a regulated form of cell death driven by iron-dependent and unrestrained lipid peroxidation, which generates phospholipid hydroperoxides that cause membrane rupture. Oxidized phospholipid species, including oxidized arachidonic acid-containing phosphatidylethanolamines (PE), are abundant during ferroptosis. However, previous studies have examined only a limited number of lipid species, and it remains unclear which oxidized phospholipids consistently arise across distinct cell types and ferroptosis-inducing conditions. Here, we comprehensively profiled oxidized phospholipids generated during ferroptosis across multiple cell lines and animal models. We identified PE 18:0_20:4;O3 and phosphatidylinositol (PI) 18:0_20:4;O3 as oxidized phospholipid species that are consistently detectable across all tested ferroptosis-inducing conditions. Furthermore, oxidized phosphatidylinositol impairs the phosphoinositide-initiated membrane tethering and lipid transport (PITT) pathway, a key mechanism for lysosomal membrane repair. These results indicate that the oxidized phospholipids identified here may serve as markers of ferroptosis while also acting as bioactive mediators that compromise lysosomal membrane homeostasis and repair.

cell biology↗

bioRxiv2026

Glutathione acts as an exometabolite that rescues functionally distinct genetic mutations in fission yeast

Microorganisms in nature form communities through diverse interactions, such as mutualism and competition, to adapt to their ecological environments. These interactions seem to be mediated by extracellular metabolites (exometabolites), yet the chemical and biological diversity underlying these processes remains largely unexplored. In this study, we examined the chemical basis of cell-cell communication in the fission yeast Schizosaccharomyces pombe by a genome-wide screen employing 3,420 viable gene deletion mutants. We identified 37 strains that exhibited growth defects in monoculture on a minimal medium but exhibited growth recovery in the vicinity of wild-type colonies (co-culture), suggesting that exometabolites secreted by wild-type cells compensated for the gene deletion. Both lipophilic and water-soluble fractions obtained by solvent partitioning of the wild-type culture supernatant promoted growth recovery. Among the 11 mutants rescued by the water-soluble fraction, six were cysteine auxotrophs, prompting analyses of thiol-containing metabolites by liquid chromatography-mass spectrometry (LC-MS), revealing the presence of glutathione (GSH) in the culture supernatant. GSH restored growth in most strains as a nutrient source. In contrast, GSH rescued cell morphology defects in the hob3{Delta} mutant, lacking the Bin/Amphiphysin/Rvs (BAR) adaptor protein Hob3, through a mechanism independent of nutrition. This research advances understanding of exometabolite-mediated interactions in S. pombe by highlighting the role of GSH as one of the communication molecules that influence cellular processes and shape microbial communities. Author summaryMicroorganisms secrete a wide range of metabolites that control microbial community behavior. These extracellular metabolites (exometabolites) include not only well-studied signaling molecules but also diverse primary and secondary metabolites, suggesting complex interactions among microbes. However, the molecular basis of these interactions remains poorly understood, partly due to challenges in detecting them experimentally. In this study, we surveyed exometabolites involved in cell-cell interactions in the model eukaryotic microorganism Schizosaccharomyces pombe. S. pombe secretes a wide variety of metabolites, including previously reported nitrogen signaling factors (NSFs) and glutathione identified in this work. By analyzing gene deletion mutants that depend on GSH for growth, we provide new insights into how microbes regulate collective behavior by sharing exometabolites.

microbiology↗

bioRxiv2023

Nitrogen signaling factor triggers a respiration-like gene expression program

Microbes have evolved intricate communication systems that enable individual cells of a population to send and receive signals in response to changes in their immediate environment. In the fission yeast Schizosaccharomyces pombe, the oxylipin Nitrogen Signaling Factor (NSF) is part of such communication system, which functions to regulate the usage of different nitrogen sources. Yet, the pathways and mechanisms by which NSF acts are poorly understood. Here, we show that NSF physically interacts with the mitochondrial sulfide:quinone oxidoreductase Hmt2 and that it prompts a change from a fermentation- to a respiration-like gene expression program independently of the carbon source. Our results suggest that NSF activity is not restricted to nitrogen metabolism alone and that it could function as a rheostat to prepare a population of S. pombe cells for an imminent shortage of their preferred nutrients.

microbiology↗