Limited expression of Nrf2 in neurons across the central nervous system

Lipid metabolism, remodelling and intercellular transfer in the CNS

Lipid metabolism encompasses the catabolism and anabolism of lipids, and is fundamental for the maintenance of cellular homeostasis, particularly within the lipid-rich CNS. Increasing evidence further underscores the importance of lipid remodelling and transfer within and between glial cells and neurons as key orchestrators of CNS lipid homeostasis. In this Review, we summarize and discuss the complex landscape of processes involved in lipid metabolism, remodelling and intercellular transfer in the CNS. Highlighted are key pathways, including those mediating lipid (and lipid droplet) biogenesis and breakdown, lipid oxidation and phospholipid metabolism, as well as cell-cell lipid transfer mediated via lipoproteins, extracellular vesicles and tunnelling nanotubes. We further explore how the dysregulation of these pathways contributes to the onset and progression of neurodegenerative diseases, and examine the homeostatic and pathogenic impacts of environment, diet and lifestyle on CNS lipid metabolism.

Piceatannol-3'-O-β-D-glucopyranoside inhibits neuroexcitotoxicity and ferroptosis through NMDAR/NRF2/BACH1/ACSL4 pathway in acute ischemic stroke

BACKGROUND

Neuronal protection is a well-established method of acute ischemic stroke (AIS) treatment. The pharmacodynamic effect of Piceatannol-3'-O-β-D-glucopyranoside (Chinese name: Hartigan, QZZG) on AIS has been reported, but the molecular mechanism of this effect remains unknown.

PURPOSE

The purpose of this study is to elucidate the pharmacodynamic effects and mechanisms of QZZG in the treatment of AIS.

METHODS

A combined network pharmacology and metabolomics approach was used to predict the key targets and pathways of QZZG in the treatment of AIS and to elucidate the mechanism of QZZG through experimental validation.

RESULTS

In this study, QZZG improved histopathologic features and reduced infarct volume and neurologic deficit scores. Integrated network pharmacology and metabolomics revealed that QZZG may protect neurons by regulating glutamate and its receptors, and that glutamate is closely related to NMDAR1, NRF2, and Caspase-3. Pathway analysis results suggested that NMDAR-mediated Ca2+ inward flow is one of the critical pathways. In terms of neuroexcitotoxicity QZZG inhibited glutamate content, reduced Ca2+ inward flow, protected mitochondrial function, and reduced ROS, as well as being able to effectively inhibit the expression of NMDAR1, Caspase-3, Bax, and promote the expression of Bcl-2, NMDAR2A. In terms of ferroptosis QZZG promoted NRF2, HO-1, GPX4 and nuclear-NRF2, inhibited the expression of BACH1 and ACSL4, and suppressed Fe2+ accumulation and lipid peroxidation. Silencing of BACH1 resulted in elevated expression of NRF2 and decreased expression of ACSL4, which inhibited the sensitivity of neurons to ferroptosis. QZZG was able to further increase NRF2 expression under conditions of silencing BACH1. QZZG induced NRF2 and inhibited BACH1, ACSL4 was inhibited by ML385, and inhibition of NRF2 induced the expression of BACH1 and ACSL4, QZZG protects neurons in an NRF2-dependent manner.

CONCLUSION

In summary, QZZG inhibited neuroexcitotoxicity and ferroptosis by regulating the NMDAR/NRF2/BACH1/ACSL4 pathway. The study provided a relatively novel perspective on the mechanism of traditional Chinese medicine (TCM) treatment of the disease.

Multitarget Effects of Nrf2 Signalling in the Brain: Common and Specific Functions in Different Cell Types

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial regulator of cellular defence mechanisms, essential for maintaining the brain's health. Nrf2 supports mitochondrial function and protects against oxidative damage, which is vital for meeting the brain's substantial energy and antioxidant demands. Furthermore, Nrf2 modulates glial inflammatory responses, playing a pivotal role in preventing neuroinflammation. This review explores these multifaceted functions of Nrf2 within the central nervous system, focusing on its activity across various brain cell types, including neurons, astrocytes, microglia, and oligodendrocytes. Due to the brain's vulnerability to oxidative stress and metabolic challenges, Nrf2 is emerging as a key therapeutic target to enhance resilience against oxidative stress, inflammation, mitochondrial dysfunction, and demyelination, which are central to many neurodegenerative diseases.

Oxygen matters: Unraveling the role of oxygen in the neuronal response to cisplatin

BACKGROUND AND AIMS

Cell culture is a fundamental experimental tool for understanding cell physiology. However, translating these findings to in vivo settings has proven challenging. Replicating donor tissue conditions, including oxygen levels, is crucial for achieving meaningful results. Nevertheless, oxygen culture conditions are often overlooked, particularly in the context of chemotherapy-induced neurotoxicity.

METHODS

In this study, we investigated the role of oxygen levels in primary neuronal cultures by comparing neuronal performance under cisplatin exposure (1 μg/mL) in supraphysiological normoxia (representing atmospheric conditions in a standard incubator; 18.5% O2) and physioxia (representing physiologic oxygen conditions in nervous tissue; 5% O2). Experiments were also conducted to assess survival, neurite development, senescence marker expression, and proinflammatory cytokine secretion.

RESULTS

Under control conditions, both oxygen concentration conditions exhibited similar behaviors. However, after cisplatin administration, sensory neurons cultured under supraphysiological normoxic conditions show higher mortality, exhibit an evolutionarily proinflammatory cytokine profile over time, and activate apoptotic-regulated neuron death markers. In contrast, under physiological conditions, neurons treated with cisplatin exhibited senescence marker expression and an attenuated inflammatory secretome.

INTERPRETATION

These results underscore the critical role of oxygen in neuronal culture, particularly in studying compounds where neuronal damage is mechanistically linked to oxidative stress. Even at identical doses of evaluated neurotoxic drugs, distinct cellular phenotypic fates can emerge, impacting translatability to the in vivo setting.

Suppression of ferroptosis by vitamin A or radical-trapping antioxidants is essential for neuronal development

The development of functional neurons is a complex orchestration of multiple signaling pathways controlling cell proliferation and differentiation. Because the balance of antioxidants is important for neuronal survival and development, we hypothesized that ferroptosis must be suppressed to gain neurons. We find that removal of antioxidants diminishes neuronal development and laminar organization of cortical organoids, which is fully restored when ferroptosis is inhibited by ferrostatin-1 or when neuronal differentiation occurs in the presence of vitamin A. Furthermore, iron-overload-induced developmental growth defects in C. elegans are ameliorated by vitamin E and A. We determine that all-trans retinoic acid activates the Retinoic Acid Receptor, which orchestrates the expression of anti-ferroptotic genes. In contrast, retinal and retinol show radical-trapping antioxidant activity. Together, our study reveals an unexpected function of vitamin A in coordinating the expression of essential cellular gatekeepers of ferroptosis, and demonstrates that suppression of ferroptosis by radical-trapping antioxidants or by vitamin A is required to obtain mature neurons and proper laminar organization in cortical organoids.

Dynamics in Redox-Active Molecules Following Ischemic Preconditioning in the Brain

It is well known that the brain is quite vulnerable to oxidative stress, initiating neuronal loss after ischemia-reperfusion (IR) injury. A potent protective mechanism is ischemic preconditioning (IPC), where proteins are among the primary targets. This study explores redox-active proteins' role in preserving energy supply. Adult rats were divided into the control, IR, and IPC groups. Protein profiling was conducted to identify modified proteins and then verified through activity assays, immunoblot, and immunohistochemical analyses. IPC protected cortex mitochondria, as evidenced by a 2.26-fold increase in superoxide dismutase (SOD) activity. Additionally, stable core subunits of respiratory chain complexes ensured sufficient energy production, supported by a 16.6% increase in ATP synthase activity. In hippocampal cells, IPC led to the downregulation of energy-related dehydrogenases, while a significantly higher level of peroxiredoxin 6 (PRX6) was observed. Notably, IPC significantly enhanced glutathione reductase activity to provide sufficient glutathione to maintain PRX6 function. Astrocytes may mobilize PRX6 to protect neurons during initial ischemic events, by decreased PRX6 positivity in astrocytes, accompanied by an increase in neurons following both IR injury and IPC. Maintained redox signaling via astrocyte-neuron communication triggers IPC's protective state. The partnership among PRX6, SOD, and glutathione reductase appears essential in safeguarding and stabilizing the hippocampus.