In hypoxic cells, dysfunctional mitochondria are selectively removed by a specialized autophagic process called mitophagy. The ER–mitochondrial contact site (MAM) is essential for fission of mitochondria prior to engulfment, and the outer mitochondrial membrane protein FUNDC1 interacts with LC3 to recruit autophagosomes, but the mechanisms integrating these processes are poorly understood. Here, we describe a new pathway mediating mitochondrial fission and subsequent mitophagy under hypoxic conditions. FUNDC1 accumulates at the MAM by associating with the ER membrane protein calnexin. As mitophagy proceeds, FUNDC1/calnexin association attenuates and the exposed cytosolic loop of FUNDC1 interacts with DRP1 instead. DRP1 is thereby recruited to the MAM, and mitochondrial fission then occurs. Knockdown of FUNDC1, DRP1, or calnexin prevents fission and mitophagy under hypoxic conditions. Thus, FUNDC1 integrates mitochondrial fission and mitophagy at the interface of the MAM by working in concert with DRP1 and calnexin under hypoxic conditions in mammalian cells. 相似文献
Sclerotinia stem rot (SSR), caused by the oxalate-secreting necrotrophic fungal pathogen Sclerotinia sclerotiorum, is one of the devastating diseases that causes significant yield loss in soybean (Glycine max). Until now, effective control of the pathogen is greatly limited by a lack of strong resistance in available commercial soybean cultivars. In this study, transgenic soybean plants overexpressing an oxalic acid (OA)-degrading oxalate oxidase gene OXO from wheat were generated and evaluated for their resistance to S. sclerotiorum. Integration and expression of the transgene were confirmed by Southern and western blot analyses. As compared with non-transformed (NT) control plants, the transgenic lines with increased oxalate oxidase activity displayed significantly reduced lesion sizes, i.e., by 58.71–82.73% reduction of lesion length in a detached stem assay (T3 and T4 generations) and 76.67–82.0% reduction of lesion area in a detached leaf assay (T4 generation). The transgenic plants also showed increased tolerance to the externally applied OA (60 mM) relative to the NT controls. Consecutive resistance evaluation further confirmed an enhanced and stable resistance to S. sclerotiorum in the T3 and T4 transgenic lines. Similarly, decreased OA content and increased hydrogen peroxide (H2O2) levels were also observed in the transgenic leaves after S. sclerotiorum inoculation. Quantitative real-time polymerase chain reaction analysis revealed that the expression level of OXO reached a peak at 1 h and 4 h after inoculation with S. sclerotiorum. In parallel, a significant up-regulation of the hypersensitive response-related genes GmNPR1-1, GmNPR1-2, GmSGT1, and GmRAR occurred, eventually induced by increased release of H2O2 at the infection sites. Interestingly, other defense-related genes such as salicylic acid-dependent genes (GmPR1, GmPR2, GmPR3, GmPR5, GmPR12 and GmPAL), and ethylene/jasmonic acid-dependent genes (GmAOS, GmPPO) also exhibited higher expression levels in the transgenic plants than in the NT controls. Our results demonstrated that overexpression of OXO enhances SSR resistance by degrading OA secreted by S. sclerotiorum and increasing H2O2 levels, and eliciting defense responses mediated by multiple signaling pathways.
The International Journal of Life Cycle Assessment - Low carbon footprint agriculture has received increasing attention in the effect of reducing greenhouse gas emissions and mitigating climate... 相似文献