Ferroptosis is a form of necrotic cell death caused by iron-dependent peroxidation of polyunsaturated phospholipids on cell membranes and is actively suppressed by the cellular antioxidant systems. ...We report here that oxidoreductases, including NADPH-cytochrome P450 reductase (POR) and NADH-cytochrome b5 reductase (CYB5R1), transfer electrons from NAD(P)H to oxygen to generate hydrogen peroxide, which subsequently reacts with iron to generate reactive hydroxyl radicals for the peroxidation of the polyunsaturated fatty acid (PUFA) chains of membrane phospholipids, thereby disrupting membrane integrity during ferroptosis. Genetic knockout of POR and CYB5R1 decreases cellular hydrogen peroxide generation, preventing lipid peroxidation and ferroptosis. Moreover, POR knockdown in mouse liver prevents ConA-induced liver damage. Ferroptosis, therefore, is a result of incidental electron transfer carried out by POR/CYB5R1 oxidoreductase and thus needs to be constitutively countered by the antioxidant systems.
Display omitted
•The oxidoreductases POR and CYB5R1 are required for ferroptosis•POR and CYB5R1 produce H2O2 to initiate iron-dependent Fenton reaction•POR and CYB5R1 induce lipid peroxidation and membrane rupture in liposomes•Knockdown of POR in vivo protects ConA-induced ferroptotic liver damage
Yan et al. found that, during ferroptosis, the oxidoreductases POR and CYB5R1 transfer electrons from NAD(P)H to oxygen to generate H2O2, which reacts with iron to produce hydroxyl radials for peroxidation of PUFA-containing membrane phospholipids to cause membrane damage and necrotic cell death.
Abstract
The promotion of apoptosis in tumor cells is a popular strategy for developing anti-cancer drugs. Here, we demonstrate that the plant indole alkaloid natural product nauclefine induces ...apoptosis of diverse cancer cells via a PDE3A-SLFN12 dependent death pathway. Nauclefine binds PDE3A but does not inhibit the PDE3A’s phosphodiesterase activity, thus representing a previously unknown type of PDE3A modulator that can initiate apoptosis without affecting PDE3A’s canonical function. We demonstrate that PDE3A’s H840, Q975, Q1001, and F1004 residues—as well as I105 in SLFN12—are essential for nauclefine-induced PDE3A-SLFN12 interaction and cell death. Extending these molecular insights, we show in vivo that nauclefine inhibits tumor xenograft growth, doing so in a PDE3A- and SLFN12-dependent manner. Thus, beyond demonstrating potent cytotoxic effects of an alkaloid natural product, our study illustrates a potentially side-effect-reducing strategy for targeting PDE3A for anti-cancer therapeutics without affecting its phosphodiesterase activity.
Display omitted
•A MOFs-based intelligent nanoplatform with pH-triggered release of protocatechuic acid was constructed.•The released rate of protocatechuic acid was adaptive to the degree of disc ...degeneration.•The MOFs nanoplatform effectively delayed the degeneration process in rat disc degeneration model.
Lower back pain is a significant contributor to disability and incapacity in adults. Up to 40 % of lower back pain is considered to be caused primarily by disc degeneration. The pH value in the intervertebral disc (IVD) usually decreases with the progression of degeneration, which can act as an initiator to trigger the release of drugs precisely for inhibiting the intervertebral disc degeneration (IDD). Herein, we fabricated a pH-responsive metal organic framework (MOF) to load anti-inflammatory protocatechuic acid (PCA), followed by the encapsulation of hyaluronic acid (HA), the final product was abbreviated as MOF@PH. The results showed that the acidic microenvironment could trigger drug release from MOF@PH featured by an increasing release proportion with pH decreasing. The cell assessment indicated that MOF@PH could suppress the inflammatory response of the nucleus pulposus significantly, downregulate the expression of related inflammatory markers (IL-6, ROS, NLRP-3 etc.) and promote the expression of nucleus pulposus specific markers. The administration of MOF@PH in rat disc degeneration model was proven able to effectively delay the degeneration process. The pH-sensitive MOF@PH may offer an effective strategy to precisely treat the IDD with desired therapeutic effects.
Our recent study showed that two oxidoreductases - NADPH-cytochrome P450 reductase (POR) and NADH-cytochrome b5 reductase (CYB5R1) - transfer electrons to oxygen to generate hydrogen peroxide (H
2
O
...2
). H
2
O
2
then reacts with ferrous iron, generating hydroxyl radicals that cause peroxidation of polyunsaturated-fatty-acid chains of membrane phospholipids, resulting in plasma membrane rupture and ferroptosis.
The study aimed to investigate the effect and mechanism of eugenol treatment on fresh-peeled Chinese water chestnuts (CWCs). The results found that eugenol treatment maintained the appearance of ...fresh-peeled CWCs, accompanied by higher L* value, total solids and O
2
contents, as well as lower browning degree, weight loss rate, CO
2
content, a* and b* values. In addition, eugenol treatment significantly reduced the activities of peroxidase, phenylalanine ammonia-lyase, and polyphenol oxidase, as well as the total content of soluble quinone in fresh-peeled CWCs. Meanwhile, fresh-peeled CWCs treated with eugenol showed markedly lower content of total flavonoids, which may be related to yellowing. Furthermore, eugenol treatment suppressed the rates of O
2
·
-
and OH·
-
production as well as the contents of H
2
O
2
and malondialdehyde in fresh-peeled CWCs. During the storage, eugenol treatment not only increased the activities of catalase, superoxide dismutase, ascorbate peroxidase and glutathione reductase as well as the DPPH free radical scavenging rate, but also increased the total phenolics, ascorbic acid and glutathione contents. In summary, eugenol treatment delayed the surface discoloration of fresh-peeled CWCs by improving the antioxidant capacity, inhibiting the phenolic compound metabolism and scavenging ROS, thus effectively maintaining the quality of fresh-peeled CWCs while extending their shelf life.
Lotus (
Gaertn) is a wetland vegetable famous for its nutritional and medicinal value. Phenolic compounds are secondary metabolites that play important roles in the browning of fresh-cut fruits and ...vegetables, and chemical constituents are extracted from lotus for medicine due to their high antioxidant activity. Studies have explored in depth the changes in phenolic compounds during browning, while little is known about their synthesis during the formation of lotus rhizome. In this study, transcriptomic analyses of six samples were performed during lotus rhizome formation using a high-throughput tag sequencing technique. About 23 million high-quality reads were generated, and 92.14% of the data was mapped to the reference genome. The samples were divided into two stages, and we identified 23,475 genes in total, 689 of which were involved in the biosynthesis of secondary metabolites. A complex genetic crosstalk-regulated network involved in the biosynthesis of phenolic compounds was found during the development of lotus rhizome, and 25 genes in the phenylpropanoid biosynthesis pathway, 18 genes in the pentose phosphate pathway, and 30 genes in the flavonoid biosynthesis pathway were highly expressed. The expression patterns of key enzymes assigned to the synthesis of phenolic compounds were analyzed. Moreover, several differentially expressed genes required for phenolic compound biosynthesis detected by comparative transcriptomic analysis were verified through qRT-PCR. This work lays a foundation for future studies on the molecular mechanisms of phenolic compound biosynthesis during rhizome formation.
The nutritional value of duck meat is well acknowledged due to its low cholesterol and high protein content. Nevertheless, the impacts of deep-frying and baking on its quality characteristics are not ...extensively documented in literature.
The objective of this study is to examine the effects of deep-frying, pre-boilingdeep-frying, baking, and pre-boiling-baking on the quality attributes, water distribution, microstructure, and flavor characteristics of duck jerky.
The findings revealed that the deep-frying group had better quality attributes than the baking, pre-boiling-deep-frying, and pre-boiling-baking groups. The deepfried duck jerky had a higher a* value (4.25) and a lower b* value (5.87), with a more appropriate texture profile, and had the highest comprehensive impression score (5.84). Moreover, the drying rate was faster, and the intensity of the free water and oil signal was significantly elevated in the deep-frying group. The microstructure results indicated that the muscle fibers in the deep-frying group were closely packed, whereas those in the baking group were relatively loose. Furthermore, the GC-IMS test revealed that the deep-fried duck jerky had a wider range of volatile flavor compounds, including 11 unique compounds that were only found in this particular product.
Lipid peroxidation of polyunsaturated fatty acid (PUFA) phospholipids induces necrotic cell death through compromised cell membrane integrity during ferroptosis. We established assays to investigate ...oxidoreductase-mediated oxidative rupture, specifically via NADPH-cytochrome P450 reductase (POR) and NADH-cytochrome b5 reductase (CYB5R1), of PUFA phospholipids in artificially generated protein-free liposomes. Liposome breakage was detected via Tb3+ liposome release and electron microscopy liposome morphology imaging. This protocol was also applied to other oxidoreductases with analogous functions and investigation of ferroptotic membrane damage in cell-free systems.
For complete details on the use and execution of this protocol, please refer to Yan et al. (2020).
Display omitted
•Protocol for POR/CYB5R1-mediated liposome rupture•Two methods for accessing liposome membrane damage•Tips on how to use POR/CYB5R1 for oxidative membrane damage
Lipid peroxidation of polyunsaturated fatty acid (PUFA) phospholipids induces necrotic cell death through compromised cell membrane integrity during ferroptosis. We established assays to investigate oxidoreductase-mediated oxidative rupture, specifically via NADPH-cytochrome P450 reductase (POR) and NADH-cytochrome b5 reductase (CYB5R1), of PUFA phospholipids in artificially generated protein-free liposomes. Liposome breakage was detected via Tb3+ liposome release and electron microscopy liposome morphology imaging. This protocol was also applied to other oxidoreductases with analogous functions and investigation of ferroptotic membrane damage in cell-free systems.
Browning limits the commercial value of fresh-cut lotus root slices. Melatonin has been reported to play crucial plant roles in growth and development. However, the mechanisms in repressing the ...browning of fresh-cut lotuses are still unclear. In this study, fresh-cut lotus root slices were treated with melatonin, the physical signs of browning were tested, and then the selected samples (0 d, 6 d, 12 d) were used in multiomics analysis. Fresh-cut lotus root slices with a thickness of 4 mm were soaked in a 40 mmol/L melatonin solution for 10 min; then, the slices were packed in pallets and packages and stored at 10 ± 1 °C. The results show that the 40 mmol/L melatonin selected for repressing the browning of lotus roots significantly delayed the decrease in water, total soluble solid content, and Vitamin C, decreased the growth of microorganisms, enhanced total phenolic content, improved total antioxidant capacity, and decreased ·OH, H
O
, and O
· contents. Moreover, this treatment enhanced phenylalanine ammonialyase, polyphenol oxidase, superoxide dismutase, and catalase activities and reduced peroxidase activities and soluble quinones. NnSOD (104590242), NnCAT (104609297), and some NnPOD genes showed a similar transcript accumulation pattern with enzyme activity. It can be seen from these results that exogenous melatonin accelerated an enhancement in the antioxidant system and AsA-GSH cycle system by regulating ROS-metabolism-related genes, thereby improving the capacity to withstand browning and the quality of lotus root slices. The microbiome also showed that melatonin suppressed the fertility of spoilage organisms, such as Pseudomonas, Tolumonas, Acinetobacter, Stenotrophomonas, and Proteobacteria. Metabonomics data uncovered that the metabolites of flavonoid biosynthesis, phenylpropanoid biosynthesis, tyrosine metabolism, and phenylalanine metabolism were involved in the process.
Apoptosis, the first regulated form of cell death discovered in mammalian cells, is executed by caspase-3/7, which are dormant in living cells but become activated by upstream caspase-8 or caspase-9 ...in responding to extracellular cytokines or intracellular stress signals, respectively. The same cell death-inducing cytokines also cause necroptosis when caspase-8 is inhibited, resulting in the activation of receptor-interacting protein kinase 3 (RIPK3), which phosphorylates pseudokinase MLKL to trigger its oligomerization and membrane-disrupting activity. Caspase-1/4/5/11, known as inflammatory caspases, instead induce pyroptosis by cleaving gasdermin D, whose caspase-cleaved N terminus forms pores on the plasma membrane. The membrane protein NINJ1 amplifies the extent of membrane rupture initiated by gasdermin D. Additionally, disturbance of peroxidation of polyunsaturated fatty acid tails of membrane phospholipids triggers ferroptosis, an iron-dependent and caspases-independent necrotic death. This review will discuss how these regulated cell death pathways act individually and interconnectively in particular cell types to carry out specific physiological and pathological functions.
Apoptosis, necroptosis, pyroptosis, and ferroptosis are four forms of regulated cell death in mammalian cells that are controlled by distinctive biochemical pathways and have important physiological functions in development and immunity and pathological contributions to many human diseases including cancer, autoimmune diseases, and organ degenerative diseases.
PDF
