The nexus between redox state and intermediary metabolism

Selenium-Doped Nanoheterojunctions for Highly Efficient Cancer Radiosensitization

Exploring efficient and low-toxicity radiosensitizers to break through the bottleneck of radiation tolerance, immunosuppression and poor prognosis remains one of the critical developmental challenges in radiotherapy. Nanoheterojunctions, due to their unique physicochemical properties, have demonstrated excellent radiosensitization effects in radiation energy deposition and in lifting tumor radiotherapy inhibition. Herein, they doped selenium (Se) into prussian blue (PB) to construct a nano-heterojunction (Se@PB), which could promote the increase of Fe2+/Fe3+ ratio and conversion of Se to a high valence state with Se introduction. The Fe2+-Se-Fe3+ electron transfer chain accelerates the rate of electron transfer on the surface of the nanoparticles, which in turn endows it with efficient X-ray energy transfer and electron transport capability, and enhances radiotherapy physical sensitivity. Furthermore, Se@PB induces glutathione (GSH) depletion and Fe2+ accumulation through pro-Fenton reaction, thereby disturbs the redox balance in tumor cells and enhances biochemical sensitivity of radiotherapy. As an excellent radiosensitizer, Se@PB effectively enhances X-ray induced mitochondrial dysfunction and DNA damage, thereby promotes cell apoptosis and synergistic cervical cancer radiotherapy. This study elucidates the radiosensitization mechanism of Se-doped nanoheterojunction from the perspective of the electron transfer chain and biochemistry reaction, which provides an efficient and low-toxic strategy in radiotherapy.

Cellular and molecular effects of fipronil in lipid metabolism of HepG2 and its possible connection to non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a global public health problem that affects more than a quarter of the population. The development of this disease is correlated with metabolic dysfunctions that lead to lipid accumulation in the liver. Pesticides are one of etiologies that support NAFLD establishment. Therefore, the effects of the insecticide fipronil on the lipid metabolism of the human hepatic cell line, HepG2, was investigated, considering its widespread use in field crops and even to control domestic pests. To address the goals of the study, biochemical, cellular, and molecular analyses of different concentrations of fipronil in cell cultures were investigated, after 24 h of incubation. Relevant metabolites such as triglycerides, glucose levels, β-oxidation processes, and gene expression of relevant elements correlated with lipid and metabolism of xenobiotics were investigated. The results suggested that at 20 μM, the pesticide increased the accumulation of triglycerides and neutral lipids by reducing fatty acid oxidation and increasing de novo lipogenesis. In addition, changes were observed in genes that control oxidative stress and the xenobiotic metabolism. Together, the results suggest that the metabolic changes caused by the insecticide fipronil may be deleterious if persistent, favoring the establishment of hepatic steatosis.

A big picture of the mitochondria-mediated signals: From mitochondria to organism

Mitochondria, well-known for years as the powerhouse and biosynthetic center of the cell, are dynamic signaling organelles beyond their energy production and biosynthesis functions. The metabolic functions of mitochondria, playing an important role in various biological events both in physiological and stress conditions, transform them into important cellular stress sensors. Mitochondria constantly communicate with the rest of the cell and even from other cells to the organism, transmitting stress signals including oxidative and reductive stress or adaptive signals such as mitohormesis. Mitochondrial signal transduction has a vital function in regulating integrity of human genome, organelles, cells, and ultimately organism.

Reactive oxygen species- and nitric oxide-dependent regulation of ion and metal homeostasis in plants

Deterioration and impoverishment of soil, caused by environmental pollution and climate change, result in reduced crop productivity. To adapt to hostile soils, plants have developed a complex network of factors involved in stress sensing, signal transduction, and adaptive responses. The chemical properties of reactive oxygen species (ROS) and reactive nitrogen species (RNS) allow them to participate in integrating the perception of external signals by fine-tuning protein redox regulation and signal transduction, triggering specific gene expression. Here, we update and summarize progress in understanding the mechanistic basis of ROS and RNS production at the subcellular level in plants and their role in the regulation of ion channels/transporters at both transcriptional and post-translational levels. We have also carried out an in silico analysis of different redox-dependent modifications of ion channels/transporters and identified cysteine and tyrosine targets of nitric oxide in metal transporters. Further, we summarize possible ROS- and RNS-dependent sensors involved in metal stress sensing, such as kinases and phosphatases, as well as some ROS/RNS-regulated transcription factors that could be involved in metal homeostasis. Understanding ROS- and RNS-dependent signaling events is crucial to designing new strategies to fortify crops and improve plant tolerance of nutritional imbalance and metal toxicity.

Heterozygous Loss of KRIT1 in Mice Affects Metabolic Functions of the Liver, Promoting Hepatic Oxidative and Glycative Stress

KRIT1 loss-of-function mutations underlie the pathogenesis of Cerebral Cavernous Malformation (CCM), a major vascular disease affecting the central nervous system (CNS). However, KRIT1 is also expressed outside the CNS and modulates key regulators of metabolic and oxy-inflammatory pathways, including the master transcription factor FoxO1, suggesting a widespread functional significance. Herein, we show that the KRIT1/FoxO1 axis is implicated in liver metabolic functions and antioxidative/antiglycative defenses. Indeed, by performing comparative studies in KRIT1 heterozygous (KRIT1^+/−) and wild-type mice, we found that KRIT1 haploinsufficiency resulted in FoxO1 expression/activity downregulation in the liver, and affected hepatic FoxO1-dependent signaling pathways, which are markers of major metabolic processes, including gluconeogenesis, glycolysis, mitochondrial respiration, and glycogen synthesis. Moreover, it caused sustained activation of the master antioxidant transcription factor Nrf2, hepatic accumulation of advanced glycation end-products (AGEs), and abnormal expression/activity of AGE receptors and detoxifying systems. Furthermore, it was associated with an impairment of food intake, systemic glucose disposal, and plasma levels of insulin. Specific molecular alterations detected in the liver of KRIT1^+/− mice were also confirmed in KRIT1 knockout cells. Overall, our findings demonstrated, for the first time, that KRIT1 haploinsufficiency affects glucose homeostasis and liver metabolic and antioxidative/antiglycative functions, thus inspiring future basic and translational studies.

Anticancer and Anti-Inflammatory Mechanisms of NOSH-Aspirin and Its Biological Effects

NOSH-Aspirin, which is generated from NO, H2S, and aspirin, affects a variety of essential pathophysiological processes, including anti-inflammatory, analgesic, antipyretic, antiplatelet, and anticancer properties. Although many people acknowledge the biological significance of NOSH-Aspirin and its therapeutic effects, the mechanism of action of NOSH-Aspirin and its regulation of tissue levels remains obscure. This is in part due to its chemical and physical features, which make processing and analysis difficult. This review focuses on the biological effects of NOSH-Aspirin and provides a comprehensive analysis to elucidate the mechanism underlying its disease-protective benefits.

Oxidative stress and regeneration

Regeneration is the process of replacing/restoring a damaged cell/tissue/organ to its full function and is limited respecting complexity of specific organ structures and the level of differentiation of the cells. Unlike physiological cell turnover, this tissue replacement form is activated upon pathological stimuli such as injury and/or disease that usually involves inflammatory response. To which extent will tissue repair itself depends on many factors and involves different mechanisms. Oxidative stress is one of them, either acute, as in case of traumatic brin injury or chronic, as in case of neurodegeneration, oxidative stress within brain involves lipid peroxidation, which generates reactive aldehydes, such as 4-hydroxynonenal (4-HNE). While 4-HNE is certainly neurotoxic and causes disruption of the blood brain barrier in case of severe injuries, it is also physiologically produced by glial cells, especially astrocytes, but its physiological roles within CNS are not understood. Because 4-HNE can regulate the response of the other cells in the body to stress, enhance their antioxidant capacities, proliferation and differentiation, we could assume that it may also have some beneficial role for neuroregeneration. Therefore, future studies on the relevance of 4-HNE for the interaction between neuronal cells, notably stem cells and reactive astrocytes might reveal novel options to better monitor and treat consequences or brain injuries, neurodegeneration and regeneration.