Sepsis-induced cardiomyopathy (SICM) is a severe complication of sepsis characterized by myocardial depression and high mortality, yet the underlying mechanisms remain incompletely understood. Here, we provide evidence supporting reverse electron transfer (RET) at mitochondrial complex I as a contributing pathogenic mechanism linking metabolic disturbances to myocardial injury in SICM. Using LPS-stimulated H9C2 cardiomyocytes and cecal ligation and puncture (CLP)-induced septic rats, we integrated metabolomic profiling, mitochondrial functional analyses, and pharmacological interventions to investigate the role of RET in sepsis-induced cardiac dysfunction. We found that sepsis establishes a permissive metabolic environment for RET, characterized by elevated mitochondrial membrane potential (ΔΨm), NADH/NAD[+] redox imbalance, and impaired downstream electron transport chain function. Enhanced RET is associated with excessive mitochondrial superoxide production, accompanied by oxidative stress, inflammation, and cardiomyocyte apoptosis. Notably, succinate accumulation provided the reducing equivalents necessary to fuel RET under these conditions. Pharmacological targeting of the RET pathway by inhibiting succinate dehydrogenase with dimethyl malonate (DMM) attenuated LPS-induced cellular injury and CLP-induced cardiac dysfunction, whereas supplementation with the succinate precursor dimethyl succinate (DMS) exacerbated these pathologies consistently with enhanced RET involvement. Collectively, our findings implicate RET at complex I as a significant contributing mechanism in SICM and highlight RET-targeted interventions as a promising therapeutic strategy for this devastating condition.

In this study, we investigated the role of intracellular heme metabolism in regulating artesunate (ATS)-induced cytotoxicity to overcome therapeutic resistance in refractory cervical cancer. CD44v-positive CaSki cells exhibited resistance to both cisplatin and the ferroptosis inducer erastin, associated with elevated antioxidant capacity and impaired iron mobilization. Although ATS cytotoxicity was enhanced by exogenous heme, stimulation of endogenous heme biosynthesis with 5-aminolevulinic acid (ALA) increased intracellular heme levels and lipid peroxidation but failed to significantly enhance cell death. Targeting canonical antioxidant pathways, including reduction of glutathione (GSH) availability and inhibition of nuclear factor erythroid 2-related factor 2 (NRF2) or glutathione peroxidase 4 (GPX4), produced variable but incomplete sensitization to ATS in CaSki cells. In contrast, simultaneous stimulation of heme biosynthesis with ALA and inhibition of heme degradation with zinc protoporphyrin IX markedly increased intracellular labile heme levels and produced the strongest sensitization to ATS among the treatment conditions examined in CaSki cells. These findings support a role for intracellular heme availability in modulating the heme-dependent bioactivation and cytotoxic efficacy of ATS and suggest that the extent of labile heme accumulation may influence ATS responsiveness in CaSki cells. Collectively, our results suggest that coordinated modulation of heme biosynthesis and degradation can enhance ATS cytotoxicity and may provide a strategy for sensitizing therapy-resistant cervical cancer cells to ATS.

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease, and tubulointerstitial fibrosis (TIF) represents its final pathological hallmark. Progestin and adipoQ receptor 3 (PAQR3) has been implicated in metabolism and inflammation, but its role in DKD remains largely unexplored. Here, we report that PAQR3 expression is markedly upregulated in the kidneys of STZ-induced diabetic mice and in high glucose-stimulated NRK-52E tubular epithelial cells, correlating with the onset of tubular epithelial-mesenchymal transition (EMT) and fibrosis. Functional studies demonstrated that PAQR3 overexpression via AAV delivery in db/db mice significantly exacerbated renal dysfunction, fibrotic lesions, and EMT, whereas PAQR3 knockdown in cultured tubular cells attenuated the EMT phenotype. Mechanistically, PAQR3 selectively increased NOX4 protein levels without affecting its mRNA expression, leading to enhanced ROS production and oxidative stress. Notably, PAQR3 suppressed STUB1-mediated NOX4 ubiquitination, thereby stabilizing NOX4 protein. Collectively, these findings suggest that PAQR3 modulates NOX4 protein stability by suppressing its ubiquitination and the PAQR3-STUB1-NOX4 axis may contribute to TIF progression in DKD.

Sphingomyelin synthase 2 (SMS2) is a key enzyme in sphingomyelin synthesis and is implicated in atherosclerosis (AS). Both endothelial dysfunction (ED) and ferroptosis contribute to AS, but their relationship with SMS2 remains unclear. To explore this, we inhibited SMS2 with Ly93 and then performed RNA sequencing to assess its relationship with ferroptosis, as well as the expression, cholesterol homeostasis, and alternative splicing of NFE2L1 in endothelial cells. We also validated the relationship between SMS2, ferroptosis, and NFE2L1 in ApoE[-/-] mice and clinical atherosclerotic plaque samples. Results showed that SMS2 inhibition by Ly93 reduced ferroptosis and ED. SMS2 inhibition also decreased cholesterol accumulation, enhanced skipping-exon (SE) alternative splicing of NFE2L1, and increased L-NFE2L1 levels; knockdown of L-NFE2L1 reversed these effects. In ApoE[-/-] mice, endothelial-specific SMS2 overexpression worsened ED and plaque formation while reducing NFE2L1/GPX4 expression. Conversely, the ferroptosis inhibitor Fer-1 attenuated both ED and plaque burden. In unstable human plaques, SMS2 was elevated, whereas NFE2L1, GPX4, and SLC7A11 were reduced. Collectively, these findings suggest that SMS2 inhibition promotes L-NFE2L1 expression, and this effect is mediated, at least in part, by the suppression of cholesterol accumulation-driven alternative splicing of the NFE2L1 splicing event, a process that ultimately reduces oxidative stress. This depress ED via ferroptosis and ultimately decrease AS, identifying SMS2 as a potential therapeutic target.

Proteasome inhibitors, particularly bortezomib (BTZ) which induces oxidative stress, remain the cornerstone of multiple myeloma (MM) therapy. However, resistance driven by metabolic reprogramming and redox adaptation limits their long-term efficacy. Here, we identify a cholesterol biosynthesis-dependent antioxidant mechanism that shields MM cells from BTZ-induced generation of reactive oxygen species (ROS). High cholesterol biosynthesis activity characterizes BTZ-nonresponsive plasma cells and correlates with poor prognosis. Genetic silencing of SREBF2, the master transcriptional regulator of cholesterol metabolism, sensitized MM cells to BTZ both in vitro and in vivo. Pharmacological inhibition of HMG-CoA reductase, the rate-limiting enzyme of cholesterol biosynthesis, with the clinically approved atorvastatin likewise enhanced the anti-myeloma activity of BTZ in vitro and in vivo. Mechanistically, the lipid raft protein FLOT1 promoted FOXO3 nuclear translocation and SREBF2 activation, thereby driving increased cholesterol biosynthesis and accumulation of the intermediate metabolite 7-dehydrocholesterol (7-DHC), a critical antioxidant that mitigated BTZ-induced cytotoxicity. Decreasing 7-DHC production by disrupting SREBF2 activation or treating with atorvastatin impaired the cellular ROS detoxification capacity and enhanced BTZ-induced cytotoxicity. Collectively, our findings identify that MM cells resist therapy-induced ROS by accumulating 7-DHC through activation of cholesterol biosynthesis, and provide preclinical evidence for repurposing statins to augment the efficacy of BTZ therapy.

Mitophagy and mitochondrial quality-control pathways are impaired in Alzheimer's disease (AD), but the relevance of peripheral mitophagy markers and their regulation during sustained amyloid-β (Aβ) stress remain unclear. We investigated whether serum optineurin, a mitophagy receptor, is altered in mild cognitive impairment (MCI) and AD, and explored mitophagy dynamics in an in vitro model of Aβ1-42-induced mitochondrial stress. To achieve this aim, serum optineurin was measured in 458 older individuals, including controls and patients with AD, mild cognitive impairment (MCI), and mixed Alzheimer's disease/vascular dementia (MIXED). Complementary in vitro experiments were performed in SH-SY5Y neuroblastoma cells exposed to Aβ1-42 over time, to evaluate mitochondrial function, oxidative stress, lipid peroxidation, lactate release, Parkin/optineurin recruitment, mitophagy, mitochondrial quality-control markers, apoptosis, and cell viability. Serum optineurin was markedly lower in MCI and AD groups than in controls (p < 0.001 for both) and was also reduced in MIXED (p < 0.001). Serum 4-HNE was increased in MCI and AD, consistent with systemic oxidative stress. In vitro, Aβ1-42 induced an early increase in mitophagy and optineurin expression, followed by a later decline associated with impaired mitochondrial quality-control markers, apoptotic activation, and reduced cell viability. In conclusion, optineurin emerges as a candidate peripheral biomarker associated with AD and MCI. In vitro, Aβ1-42 exposure was associated with an early increase in mitophagy-related responses followed by progressive mitochondrial dysfunction, oxidative stress, apoptotic activation, and reduced cell viability. These findings support the relevance of optineurin within mitochondrial quality-control pathways under AD-related stress.

Although light broadly affects animal physiology, it remains unclear whether specific wavelengths directly reshape basal glucose and lipid metabolism in developing non-visual photoreceptive animals, and what specific molecular pathways mediate these effects. Here, using Caenorhabditis elegans (C. elegans), a model lacking visual organs but retaining conserved metabolic pathways, we systematically evaluated metabolic phenotypes following early-life (L1 to young adult) exposure to red, green, blue, and white light spectra. We identified that blue light (450-460 nm) most strongly drove triglyceride accumulation and free glucose elevation, with the L4-to-young adult transition being the most susceptible developmental window. Mechanistically, blue light induced oxidative stress and mitochondrial dysfunction; antioxidants limited glucose and lipid abnormalities and reshaped physiology, establishing a functional role for ROS. Integrated multi-omics revealed that elevated ROS upregulated the DEG/ENaC family channel acd-1 and promoted the accumulation of an oxidized lipid metabolite feature putatively annotated as 12(13)Ep-9-KODE (EKODE), which was functionally evaluated as a candidate downstream oxidized lipid mediator associated with ACD-1-dependent metabolic remodeling. Moreover, chemically induced oxidative stress similarly upregulated both acd-1 mRNA expression and the abundance of this EKODE-annotated oxidized-lipid feature. Notably, in mammalian cells, overexpression of the human homolog ASIC4 or exogenous EKODE supplementation recapitulated key metabolic features, including lipid-droplet accumulation, triglyceride elevation, and coordinated bioenergetic remodeling. Together, our findings support a ROS-dependent ACD-1-associated oxidized lipid regulatory module in C. elegans and reveal how early-life blue light and oxidative challenges influence metabolic homeostasis.

Recently, pesticide residues have become a serious environmental hazard due to the widespread employment of pesticides in agricultural production. With the continuous accumulation of pesticide in vivo, liver injury caused by pesticide metabolism has become a rapidly developing disease. Although pesticide-mediated liver injury (PMLI) has attracted extensive attention, its diagnosis and treatment still face serious challenges. Previous studies have indicated that PMLI is closely related to oxidative stress caused by pesticides, in which the abnormal level of hydrogen peroxide (H2O2) is a critical biomarker. Consequently, monitoring the H2O2 level is essential for the early diagnosis and efficacy assessment in PMLI. Based on the advantages of near-infrared fluorescence imaging technology, this study designed and synthesized a novel fluorescence probe (DOA-1) to real-time image H2O2 in PMLI. DOA-1 exhibited excellent imaging capacity toward exogenous and endogenous H2O2 in living cells and zebrafish models, with high sensitivity and selectivity. At the same time, DOA-1 was successfully applied to image H2O2 in pesticide-induced cells, zebrafish and mouse models, thereby confirming that oxidative stress was the main factor causing liver injury by pesticides. Furthermore, DOA-1 facilitated the efficacy assessment of flavonoid compounds, identifying that puerarin could effectively alleviate oxidative stress caused by pesticides. Molecular mechanism studies revealed that puerarin could ameliorate lipid peroxidation and fibrosis in PMLI by regulating Keap1-Nrf2 signaling pathway. Overall, this study provides a novel tool for diagnosing and assessing the impact of oxidative stress caused by pesticide residues on liver function.

Angiotensin II (Ang II) is a peptide hormone that regulates vascular tone and blood pressure. Angiotensin-converting enzyme generates Ang II from angiotensin I, whereas angiotensin-converting enzyme 2 (ACE2) cleaves Ang II to angiotensin 1-7. We previously showed that the arginine residue at the second position (Arg2) of Ang II is critical for its interaction with ACE2 as a substrate. The present study examined the mechanistic role of Arg2 in Ang II recognition by ACE2 and the functional consequences of its modification. Cleavage of Arg2 from Ang II, or replacement of Arg2 with other amino acids, eliminated Ang II's ability to compete with the fluorogenic substrate in the ACE2 activity assay. The Arg2-to-Glu substitution also affected the interactions of angiotensin I and angiotensin III with ACE2, confirming Arg2 as a critical determinant of substrate recognition by the enzyme. Since oxidation of Arg and Pro residues generates glutamic semialdehyde, which can be further oxidized to Glu, we previously proposed that reactive oxygen species promote oxidant-mediated amino acid conversion among Arg, Pro, and Glu residues. Thus, Arg2 of Ang II could undergo oxidant-mediated amino acid residue conversion to either Glu or Pro. Mass spectrometry confirmed the presence of both circulating Ang II (Arg2Glu) and Ang II (Arg2Pro) in rats. Global gene expression analyses further revealed that Arg2Glu- and Arg2Pro-converted Ang II peptides elicit cellular signaling responses distinct from those induced by wild-type Ang II, suggesting that oxidant-mediated modifications of Arg2 generate naturally occurring angiotensin peptides with unique biological functions.

Aging disrupts the coupling between redox homeostasis and energy metabolism in brown adipose tissue (BAT), but the molecular nodes linking BAT redox-metabolic deterioration to systemic metabolic dysfunction remain unclear. Using aging mouse BAT time-course transcriptomics, we prioritized Acss1, encoding mitochondrial acetyl-CoA synthetase 1 (ACSS1), as a progressively age-decreased mitochondrial metabolic candidate. Acss1 expression correlated positively with BAT metabolic programs and negatively with oxidative stress and senescence-associated programs. Age-series single-nucleus transcriptomics further localized Acss1 mainly to adipocytes and classified BAT adipocyte nuclei into Acss1-high and Acss1-low transcriptional states. Acss1-high adipocytes retained thermogenic, oxidative phosphorylation and fatty acid oxidation programs, whereas Acss1-low adipocytes were enriched for stress- and senescence-related programs, with this divergence increasing with age. To test Acss1 function, we locally injected 18-month-old mouse BAT with an adeno-associated virus expressing Acss1 under the adipocyte-specific adiponectin (Adipoq) promoter. BAT-local Acss1 restoration attenuated redox imbalance, restored thermogenic programs and reduced senescence-associated injury. This local intervention also improved glucose and lipid metabolism, energy substrate utilization, motor performance and plasma antioxidant capacity, and was associated with improved histological and stress-related features in distal metabolic tissues. Matched BAT transcriptomic and plasma metabolomic profiling showed that Acss1 restoration shifted BAT redox-metabolic programs and was associated with spermidine-related circulating metabolic remodeling. In human BAT, ACSS1 expression correlated positively with oxidative phosphorylation and negatively with reactive oxygen species metabolic processes. These findings support brown adipocyte Acss1 as a regulator of redox-metabolic homeostasis in aged BAT, whose restoration is associated with improved local BAT state, improved systemic metabolic phenotypes and spermidine-related circulating metabolic remodeling.