Physiological mitochondrial ROS regulate diapause by enhancing HSP60/Lon complex stability in Helicoverpa armigera

Diapause is a long-lived stage which has evolved into an important strategy for insects to circumvent extreme environments.In the pupal stage,Helicoverpa armigera can enter diapause,a state characterized by significantly decreased metabolic activity and enhanced stress resistance,to survive cold winters.Previous studies have shown that reactive oxygen species(ROS)can promote the diapause process by regulating a distinct insulin signaling pathway.However,the source of ROS in the diapause-destined pupal brains and mechanisms by which ROS regulate diapause are still unknown.In this study,we showed that diapause-destined pupal brains accumulated high levels of mitochondrial ROS(mtROS)and total ROS during the diapause process,suggesting that mitochondria are the main source of ROS in diapause-destined pupal brains.In addition,injection of 2-deoxy-D-glucose(DOG),a glucose metabolism inhibitor,could delay pupal development by elevating mtROS levels in the nondiapause-destined pupal brains.Furthermore,the injection of a metabolite mixture to increase metabolic activity could avert the diapause process in diapause-destined pupae by decreasing mtROS levels.We also found that ROS could activate HSP60 expression and promote the stability of the HSP60-Lon complex,increasing its ability to degrade mitochondrial transcription factor A(TFAM)and decreasing mitochondrial activity or biogenesis under oxidative stress.Thus,this study illustrated the beneficial function of ROS in diapause or lifespan extension by decreasing mitochondrial activity.

Mito-TEMPO Ameliorates Sodium Palmitate Induced Ferroptosis in MIN6 Cells through PINK1/Parkin-Mediated Mitophagy

Objective Mitochondrial reactive oxygen species(mtROS)could cause damage to pancreaticβ-cells,rendering them susceptible to oxidative damage.Hence,investigating the potential of the mitochondriatargeted antioxidant(Mito-TEMPO)to protect pancreaticβ-cells from ferroptosis by mitigating lipid peroxidation becomes crucial.Methods MIN6 cells were cultured in vitro with 100μmol/L sodium palmitate(SP)to simulate diabetes.FerroOrange was utilized for the detection of Fe2+fluorescence staining,BODIPY581/591C11 for lipid reactive oxygen species,and MitoSox-Red for mtROS.Alterations in mitophagy levels were assessed through the co-localization of lysosomal and mitochondrial fluorescence.Western blotting was employed to quantify protein levels of Acsl4,GPX4,FSP1,FE,PINK1,Parkin,TOMM20,P62,and LC3.Subsequently,interventions were implemented using Mito-TEMPO and Carbonyl cyanide 3-chlorophenylhydrazone(CCCP)to observe changes in ferroptosis and mitophagy within MIN6 cells.Results We found that SP induced a dose-dependent increase in Fe2+and lipid ROS in MIN6 cells while decreasing the expression levels of GPX4 and FSP1 proteins.Through bioinformatics analysis,it has been uncovered that mitophagy assumes a crucial role within the ferroptosis pathway associated with diabetes.Additionally,SP decreased the expression of mitophagy-related proteins PINK1 and Parkin,leading to mtROS overproduction.Conversely,Mito-TEMPO effectively eliminated mtROS while activating the mitophagy pathways involving PINK1 and Parkin,thereby reducing the occurrence of ferroptosis in MIN6 cells.CCCP also demonstrated efficacy in reducing ferroptosis in MIN6 cells.Conclusion In summary,Mito-TEMPO proved effective in attenuating mtROS production and initiating mitophagy pathways mediated by PINK1 and Parkin in MIN6 cells.Consequently,this decreased iron overload and lipid peroxidation,ultimately safeguarding the cells from ferroptosis.

PTEN和mTOR信号转导通路在实验性脊髓损伤中的表达

目的:研究mTOR和PTEN蛋白在实验性脊髓损伤中的表达及其在脊髓损伤发生、发展中的作用。方法:用免疫组织化学方法和RT-PCR法,检测脊髓组织内mTOR和PTEN的表达。结果:与正常组织相比,免疫组化法和RT-PCR两种方法结果均显示,脊髓损伤后mTOR表达明显下降,而PTEN的表达明显增加;两者呈负相关(r=-0.862,P<0.01)。结论:PI3K/PTEN/AKT/mTOR信号转导通路中重要的调节位点和节点PTEN在实验性脊髓损伤中的表达明显增高,而mTOR的表达明显降低。提示该信号转导通路在介导实验性脊髓损伤的发生、发展的过程中起重要作用。

Regulation of mitochondrial NAD pool via NAD^+ transporter 2 is essential for matrix NADH homeostasis and ROS production in Arabidopsis

Reactive oxygen species(ROS) play a crucial role in numerous biological processes in plants, including development, responses to environmental stimuli, and programmed cell death(PCD). Deficiency in MOSAIC DEATH 1(MOD1), a plastid-localized enoyl-ACP reductase essential for de novo fatty acid biosynthesis in Arabidopsis thaliana, leads to the increased malate export from chloroplasts to mitochondria, and the subsequent accumulation of mitochondria-generated ROS and PCD. In this study, we report the identification and characterization of a mod1 suppressor, som592. SOM592 encodes mitochondrion-localized NAD^+ transporter 2(NDT2). We show that the mitochondrial NAD pool is elevated in the mod1 mutant. The som592 mutation fully suppressed mitochondrial NADH hyper-accumulation, ROS production, and PCD in the mod1 mutant, indicating a causal relationship between mitochondrial NAD accumulation and ROS/PCD phenotypes. We also show that in wild-type plants, the mitochondrial NAD+uptake is involved in the regulation of ROS production in response to continuous photoperiod. Elevation of the alternative respiration pathway can suppress ROS accumulation and PCD in mod1, but leads to growth restriction. These findings uncover a regulatory mechanism for mitochondrial ROS production via NADH homeostasis in Arabidopsis thaliana that is likely important for growth regulation in response to altered photoperiod.