Loss of KEAP1 Causes an Accumulation of Nondegradative Organelles.
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ABSTRACT:
SUBMITTER: Uribe-Carretero E
PROVIDER: S-EPMC9311848 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Iron overload in the brain, defined as excess stores of iron, is known to be related to neurological disorder. Among neurodegeneration with brain iron accumulation, we reported a specific point mutation, 977-1G>A in WDR45, showing iron accumulation in the brain, and autophagy defects in the fibroblasts. In this study, we investigated whether fibroblasts with mutated WDR45 accumulated iron, and other effects on cellular organelles. We first identified the main location of iron accumulation in the mutant fibroblasts and then investigated the effects of this accumulation on other organelles, including lipid droplets, mitochondria, and lysosomes. Ultrastructure analysis using transmission electron microscopy (TEM) and confocal microscopy showed structural changes in the organelles. Increased numbers of lipid droplets, fragmented mitochondria, and increased lysosomal vesicles with functional disorder due to WDR45 deficiency were observed. The majority of iron accumulation occurred in the lysosomal vesicles, according to correlative light and electron microscopy (CLEM). These changes were related to defects in autophagy and defective protein and organelle turnover. Gene expression profiling analysis also showed significant changes in lipid metabolism, mitochondrial function, and autophagy-related genes. Those data suggested that functional and structural changes caused impaired lipid metabolism, mitochondrial disorder, and unbalanced autophagy fluxes, due to iron overload.
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Project description:Background and purposeTargeted therapy and immunotherapy have led to dramatic change in the treatment of lung cancer, however, the overall 5-year survival rate of lung cancer patients is still suboptimal. It is important to exploit new potential of molecularly targeted therapies. High-frequency somatic mutations in KEAP1/NRF2 (27.9%) have been identified in lung squamous cell carcinoma. In this research, we explored the role of KEAP1 somatic mutations in the development of LSCC and whether a nuclear factor erythroid 2-related factor 2(NRF2) inhibitor be potential to target lung cancer carrying KEAP1/NRF2 mutations.MethodsLung cancer cell lines A549 and H460 with loss-of-function mutations in KEAP1 stably transfected with wild-type (WT) KEAP1 or somatic mutations in KEAP1 were used to investigate the functions of somatic mutations in KEAP1. Flow cytometry, plate clone formation experiments, and scratch tests were used to examine reactive oxygen species, proliferation, and migration of these cell lines.ResultsThe expression of NRF2 and its target genes increased, and tumor cell proliferation, migration, and tumor growth were accelerated in A549 and H460 cells stably transfected with KEAP1 mutants compared to control cells with a loss-of-function KEAP1 mutation and stably transfected with WT KEAP1 in both in vitro and in vivo studies. The proliferation of A549 cell line trasfected with the R320Q KEAP1 mutant was inhibited more apparent than that of the A549 cell line trasfected with WT KEAP1 after treatment with NRF2 inhibitor ML385.ConclusionSomatic mutations of KEAP1 identified from patients with LSCC likely promote tumorigenesis mediated by activation of the KEAP1/NRF2 antioxidant stress response pathway. NRF2 inhibition with ML385 could inhibit the proliferation of tumor cells with KEAP1 mutation. Video abstract.
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