NMDA receptor-nitric oxide transmission mediates neuronal iron homeostasis via the GTPase Dexras1

Convergent and divergent transcriptional reprogramming of motor and sensory neurons underlying response to peripheral nerve injury

INTRODUCTION

Motor neurons differ from sensory neurons in aspects including origins and surrounding environment. Understanding the similarities and differences in molecular response to peripheral nerve injury (PNI) and regeneration between sensory and motor neurons is crucial for developing effective drug targets for CNS regeneration. However, genome-wide comparisons of molecular changes between sensory and motor neurons following PNI remains limited.

OBJECTIVES

This study aims to investigate genome-wide convergence and divergence of injury response between sensory and motor neurons to identify novel drug targets for neural repair.

METHODS

We analyzed two large-scale RNA-seq datasets of in situ captured sensory neurons (SNs) and motoneurons (MNs) upon PNI, retinal ganglion cells and spinal cord upon CNS injury. Additionally, we integrated these with other related single-cell level datasets. Bootstrap DESeq2 and WGCNA were used to detect and explore co-expression modules of differentially expressed genes (DEGs).

RESULTS

We found that SNs and MNs exhibited similar injury states, but with a delayed response in MNs. We identified a conserved regeneration-associated module (cRAM) with 274 shared DEGs. Of which, 47% of DEGs could be changed in injured neurons supported by single-cell resolution datasets. We also identified some less-studied candidates in cRAM, including genes associated with transcription, ubiquitination (Rnf122), and neuron-immune cells cross-talk. Further in vitro experiments confirmed a novel role of Rnf122 in axon growth. Analysis of the top 10% of DEGs with a large divergence suggested that both extrinsic (e.g., immune microenvironment) and intrinsic factors (e.g., development) contributed to expression divergence between SNs and MNs following injury.

CONCLUSIONS

This comprehensive analysis revealed convergent and divergent injury response genes in SNs and MNs, providing new insights into transcriptional reprogramming of sensory and motor neurons responding to axonal injury and subsequent regeneration. It also identified some novel regeneration-associated candidates that may facilitate the development of strategies for axon regeneration.

Proteomic Investigation of Neurotrophic trans-Banglene Reveals Potential Link to Iron Homeostasis

In an effort to gain insight into cellular systems impacted by neurotrophic trans-banglene (t-BG), global proteomic profiling and Western blot analyses were employed. Expression level changes in response to t-BG treatment were compared to those observed with nerve growth factor (NGF), a natural neurotrophic protein and functional analog to t-BG. Findings from these studies did not point to direct interception of NGF/TrkA signaling by t-BG. Instead, significant alterations in iron-binding and iron-regulating proteins were observed. While total iron levels showed no change across all treatments, intracellular iron measurements and mitochondrial iron measurements demonstrated lower ferrous (Fe2+) ion levels in t-BG treated cells but not in NGF treated cells. These results highlight a potential connection between iron regulation and neurotrophic activity, a relationship which has, to date, not been well studied. These results are also notable given that iron dysregulation occurs in most neurodegenerative disease settings, and that iron has been shown to facilitate protein aggregation and apoptotic mechanisms.

Ferroptosis in eye diseases: a systematic review

Ferroptosis is a type of iron-dependent cell death that differs from apoptosis, necroptosis, autophagy, and other forms of cell death. It is mainly characterized by the accumulation of intracellular lipid peroxides, redox imbalance, and reduced levels of glutathione and glutathione peroxidase 4. Studies have demonstrated that ferroptosis plays an important regulatory role in the occurrence and development of neurodegenerative diseases, stroke, traumatic brain injury, and ischemia-reperfusion injuries. Multiple mechanisms, such as iron metabolism, ferritinophagy, p53, and p62/Keap1/Nrf2, as well as the combination of FSP1/CoQ/NADPH and hepcidin/FPN-1 can alter the vulnerability to ferroptosis. Nevertheless, there has been limited research on the development and management of ferroptosis in the realm of eye disorders, with most studies focusing on retinal conditions such as age-related macular degeneration and retinitis pigmentosa. This review offers a thorough examination of the disruption of iron homeostasis in eye disorders, investigating the underlying mechanisms. We anticipate that the occurrence of ferroptotic cell death will not only establish a fresh field of study in eye diseases, but also present a promising therapeutic target for treating these diseases.

Biomimetic Nanomotors for Deep Ischemia Penetration and Ferroptosis Inhibition in Neuroprotective Therapy of Ischemic Stroke

Nerve injury represents the primary reason of mortality and disability in ischemic stroke, but effective drug delivery to the region of cerebral ischemia and hypoxia poses a significant challenge in neuroprotective treatment. To address these clinical challenges, a biomimetic nanomotor, Pt@LF is designed, to facilitate deep delivery of neuroprotective agents and inhibit ferroptosis in ischemic stroke. Pt@LF traverses the blood-brain barrier (BBB) and penetrates into deep cerebral ischemic-hypoxic areas due to the active targeting capacity of apo-lactoferrin (Apo-LF) and the self-propelling motion properties of nanomotors. Subsequently, Pt@LF loosens thrombus and alleviates the "no reflow" phenomenon via mechanical thrombolysis. Thanks to the various enzyme-like abilities and multi-target ferroptosis inhibition capability, Pt@LF ameliorates the inflammatory microenvironment and rescues dying neurons. In conclusion, Pt@LF demonstrates efficiently deep penetration and neuroprotective effects in vitro and vivo. And this study provides a promising therapeutic platform for the treatment of ischemic stroke.

S-Nitrosylation of Dexras1 Controls Post-Stroke Recovery via Regulation of Neuronal Excitability and Dendritic Remodeling

AIMS

Stroke is a major public health concern leading to high rates of death and disability worldwide, unfortunately with no effective treatment available for stroke recovery during the repair phase.

METHODS

Photothrombotic stroke was induced in mice. Adeno-associated viruses (AAV) were microinjected into the peri-infarct cortex immediately after photothrombotic stroke. Grid-walking task and cylinder task were used to assess motor function. Western blotting, Golgi staining, and electrophysiology recordings were performed to uncover the mechanisms.

RESULTS

The ternary complex of neuronal nitric oxide synthase (nNOS), carboxy-terminal PDZ ligand of nNOS (CAPON) and dexamethasone-induced ras protein 1 (Dexras1) is structurally beneficial for S-nitrosylation of Dexras1 (SNO-Dexras1). In our previous study, uncoupling nNOS-CAPON interaction by Tat-CAPON-12C promoted functional recovery after stroke. Here, we show that ischemia elevated the levels of nNOS-Dexras1 complex and SNO-Dexras1 in the peri-infarct cortex in the days 4-10 after stroke induction, and as excepted, Tat-CAPON-12C, a peptide disrupting nNOS-CAPON interaction, significantly reversed these changes. The above information implies that repressed SNO-Dexras1 may mediate functional-promoting effects of Tat-CAPON-12C and SNO-Dexras1 could be the vital molecular substrate for post-stroke functional recovery in the repair phage. Inhibiting the ischemia-induced SNO-Dexras1 by AAV vector-mediated knockdown of Dexras1 or over-expression of dominant negative Dexras1 (Dexras1-C11S) produced sustained recovery of motor function from stroke. In contrast, up-regulation of SNO-Dexras1 by over-expressing Dexras1 worsened stroke outcome. Using electrophysiology recordings, we also observed that silence of Dexras1 in the peri-infarct cortex increased the spike number and the miniature excitatory postsynaptic currents (mEPSCs) frequency, suggesting enhancement of neuronal excitability. In addition, silence of Dexras1 increased dendritic complexity in cultured neuron and more importantly enhanced dendritic spine density in the peri-infarct cortex, implying dendritic remodeling.

CONCLUSION

Thus, inhibition of SNO-Dexras1 positively regulates post-stroke functional recovery via enhanced neuronal excitability and dendritic remodeling. Our results identify that SNO-Dexras1 may serve as a novel target for promoting motor functional restoration from stroke in the delayed phase, shedding light on stroke treatment.

An update on the role of ferroptosis in ischemic stroke: from molecular pathways to Neuroprotection

INTRODUCTION

Ischemic stroke (IS), a major cause of mortality and disability worldwide, remains a significant healthcare challenge due to limited therapeutic options. Ferroptosis, a distinct iron-dependent form of regulated cell death characterized by lipid peroxidation and oxidative stress, has emerged as a crucial mechanism in IS pathophysiology. This review explores the role of ferroptosis in IS and its potential for driving innovative therapeutic strategies.

AREA COVERED

This review delves into the practical implications of ferroptosis in IS, focusing on molecular mechanisms like lipid peroxidation, iron accumulation, and their interplay with inflammation, reactive oxygen species (ROS), and the Nrf2-ARE antioxidant system. It highlights ferroptotic proteins, small-molecule inhibitors, and non-coding RNA modulators as emerging therapeutic targets to mitigate neuroinflammation and neuronal cell death. Studies from PubMed (1982-2024) were identified using MeSH terms such as 'Ferroptosis' and 'Ischemic Stroke,' and only rigorously screened articles were included.

EXPERT OPINION

Despite preclinical evidence supporting the neuroprotective effects of ferroptosis inhibitors, clinical translation faces hurdles such as suboptimal pharmacokinetics and safety concerns. Advances in drug delivery systems, bioinformatics, and AI-driven drug discovery may optimize ferroptosis-targeting strategies, develop biomarkers, and improve therapeutic outcomes for IS patients.

Hippocampal excitation-inhibition balance underlies the 5-HT2C receptor in modulating depressive behaviours

The implication of 5-hydroxytryptamine 2C receptor (5-HT2CR) activity in depression is a topic of debate, and the underlying mechanisms remain largely unclear. Here, we elucidate how hippocampal excitation-inhibition (E/I) balance underlies the regulatory effects of 5-HT2CR in depression. Molecular biological analyses showed that chronic mild stress (CMS) reduced the expression of 5-HT2CR in hippocampus. We revealed that inhibition of 5-HT2CR induced depressive-like behaviours, reduced GABA release and shifted the E/I balance towards excitation in CA3 pyramidal neurons using behavioural analyses, microdialysis coupled with mass spectrometry and electrophysiological recordings. Moreover, 5-HT2CR modulated the neuronal nitric oxide synthase (nNOS)-carboxy-terminal PDZ ligand of nNOS (CAPON) interaction by influencing intracellular Ca2+ release, as determined by fibre photometry and coimmunoprecipitation. Notably, disruption of nNOS-CAPON with the specific small molecule compound ZLc-002 or AAV-CMV-CAPON-125C-GFP abolished 5-HT2CR inhibition-induced depressive-like behaviours, as well as the impairment in soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly-mediated GABA vesicle release and consequent E/I imbalance. Importantly, optogenetic inhibition of CA3 GABAergic neurons prevented the effects of AAV-CMV-CAPON-125C-GFP on depressive behaviours in the presence of a 5-HT2CR antagonist. Conclusively, our findings disclose the regulatory role of 5-HT2CR in depressive-like behaviours and highlight hippocampal nNOS-CAPON coupling-triggered E/I imbalance as a pivotal cellular event underpinning the behavioural consequences of 5-HT2CR inhibition.

Posttranslational modifications: an emerging functional layer of diet-host-microbe interactions

The microbiome plays a vital role in human health, with changes in its composition impacting various aspects of the body. Posttranslational modification (PTM) regulates protein activity by attaching chemical groups to amino acids in an enzymatic or non-enzymatic manner. PTMs offer fast and dynamic regulation of protein expression and can be influenced by specific dietary components that induce PTM events in gut microbiomes and their hosts. PTMs on microbiome proteins have been found to contribute to host-microbe interactions. For example, in Escherichia coli, S-sulfhydration of tryptophanase regulates uremic toxin production and chronic kidney disease in mice. On a broader microbial scale, the microbiomes of patients with inflammatory bowel disease exhibit distinct PTM patterns in their metaproteomes. Moreover, pathogens and commensals can alter host PTM profiles through protein secretion and diet-regulated metabolic shifts. The emerging field of metaPTMomics focuses on understanding PTM profiles in the microbiota, their association with lifestyle factors like diet, and their functional effects on host-microbe interactions.

Golgi protein ACBD3 downregulation sensitizes cells to ferroptosis

Ferroptosis, a form of cell death driven by iron-dependent lipid peroxidation, is emerging as a promising target in cancer therapy. It is regulated by a network of molecules and pathways that modulate lipid metabolism, iron homeostasis and redox balance, and related processes. However, there are still numerous regulatory molecules intricately involved in ferroptosis that remain to be identified. Here, we indicated that suppression of Golgi protein acyl-coenzyme A binding domain A containing 3 (ACBD3) increased the sensitivity of Henrieta Lacks and PANC1 cells to ferroptosis. ACBD3 knockdown increases labile iron levels by promoting ferritinophagy. This increase in free iron, coupled with reduced levels of glutathione peroxidase 4 due to ACBD3 knockdown, leads to the accumulation of reactive oxygen species and lipid peroxides. Moreover, ACBD3 knockdown also results in elevated levels of polyunsaturated fatty acid-containing glycerophospholipids through mechanisms that remain to be elucidated. Furthermore, inhibition of ferrtinophagy in ACBD3 downregulated cells by knocking down the nuclear receptor co-activator 4 or Bafilomycin A1 treatment impeded ferroptosis. Collectively, our findings highlight the pivotal role of ACBD3 in governing cellular resistance to ferroptosis and suggest that pharmacological manipulation of ACBD3 levels is a promising strategy for cancer therapy.

KA-mediated excitotoxicity induces neuronal ferroptosis through activation of ferritinophagy

OBJECTIVES

This study aims to elucidate the role of Fe2+ overload in kainic acid (KA)-induced excitotoxicity, investigate the involvement of ferritinophagy selective cargo receptor NCOA4 in the pathogenesis of excitotoxicity.

METHODS

Western blotting was used to detect the expression of FTH1, NCOA4, Lamp2, TfR, FPN, and DMT1 after KA stereotaxic injection into the unilateral striatum of mice. Colocalization of Fe2+ with lysosomes in KA-treated primary cortical neurons was observed by using confocal microscopy. Desferrioxamine (DFO) was added to chelate free iron, a CCK8 kit was used to measure cell viability, and the Fe2+ levels were detected by FerroOrange. BODIPY C11 was used to determine intracellular lipid reactive oxygen species (ROS) levels, and the mRNA levels of PTGS2, a biomarker of ferroptosis, were measured by fluorescent quantitative PCR. 3-Methyladenine (3-MA) was employed to inhibit KA-induced activation of autophagy, and changes in ferritinophagy-related protein expression and the indicated biomarkers of ferroptosis were detected. Endogenous NCOA4 was knocked down by lentivirus transfection, and cell viability and intracellular Fe2+ levels were observed after KA treatment.

RESULTS

Western blot results showed that the expression of NCOA4, DMT1, and Lamp2 was significantly upregulated, while FTH1 was downregulated, but there were no significant changes in TfR and FPN. The fluorescence results indicated that KA enhanced the colocalization of free Fe2+ with lysosomes in neurons. DFO intervention could effectively rescue cell damage, reduce intracellular lipid peroxidation, and decrease the increased transcript levels of PTGS2 caused by KA. Pretreatment with 3-MA effectively reversed KA-induced ferritinophagy and ferroptosis. Endogenous interference with NCOA4 significantly improved cell viability and reduced intracellular free Fe2+ levels in KA-treated cells.

CONCLUSION

KA-induced excitotoxicity activates ferritinophagy, and targeting ferritinophagy effectively inhibits downstream ferroptosis. Interference with NCOA4 effectively attenuates KA-induced neuronal damage. This study provides a potential therapeutic target for excitotoxicity related disease conditions.

Novel insight into the role of A-kinase anchoring proteins (AKAPs) in ischemic stroke and therapeutic potentials

Ischemic stroke, a devastating disease associated with high mortality and disability worldwide, has emerged as an urgent public health issue. A-kinase anchoring proteins (AKAPs) are a group of signal-organizing molecules that compartmentalize and anchor a wide range of receptors and effector proteins and have a major role in stabilizing mitochondrial function and promoting neurodevelopmental development in the central nervous system (CNS). Growing evidence suggests that dysregulation of AKAPs expression and activity is closely associated with oxidative stress, ion disorder, mitochondrial dysfunction, and blood-brain barrier (BBB) impairment in ischemic stroke. However, the underlying mechanisms remain inadequately understood. This review provides a comprehensive overview of the composition and structure of A-kinase anchoring protein (AKAP) family members, emphasizing their physiological functions in the CNS. We explored in depth the molecular and cellular mechanisms of AKAP complexes in the pathological progression and risk factors of ischemic stroke, including hypertension, hyperglycemia, lipid metabolism disorders, and atrial fibrillation. Herein, we highlight the potential of AKAP complexes as a pharmacological target against ischemic stroke in the hope of inspiring translational research and innovative clinical approaches.

Exploring Potential Mechanisms Accounting for Iron Accumulation in the Central Nervous System of Patients with Alzheimer's Disease

Elevated levels of iron occur in both cortical and subcortical regions of the CNS in patients with Alzheimer's disease. This accumulation is present early in the disease process as well as in more advanced stages. The factors potentially accounting for this increase are numerous, including: (1) Cells increase their uptake of iron and reduce their export of iron, as iron becomes sequestered (trapped within the lysosome, bound to amyloid β or tau, etc.); (2) metabolic disturbances, such as insulin resistance and mitochondrial dysfunction, disrupt cellular iron homeostasis; (3) inflammation, glutamate excitotoxicity, or other pathological disturbances (loss of neuronal interconnections, soluble amyloid β, etc.) trigger cells to acquire iron; and (4) following neurodegeneration, iron becomes trapped within microglia. Some of these mechanisms are also present in other neurological disorders and can also begin early in the disease course, indicating that iron accumulation is a relatively common event in neurological conditions. In response to pathogenic processes, the directed cellular efforts that contribute to iron buildup reflect the importance of correcting a functional iron deficiency to support essential biochemical processes. In other words, cells prioritize correcting an insufficiency of available iron while tolerating deposited iron. An analysis of the mechanisms accounting for iron accumulation in Alzheimer's disease, and in other relevant neurological conditions, is put forward.

Rasd1 is involved in white matter injury through neuron-oligodendrocyte communication after subarachnoid hemorrhage

AIMS

Rasd1 has been reported to be correlated with neurotoxicity, metabolism, and rhythm, but its effect in case of subarachnoid hemorrhage (SAH) remained unclear. White matter injury (WMI) and ferroptosis participate in the early brain injury (EBI) after SAH. In this work, we have investigated whether Rasd1 can cause ferroptosis and contribute to SAH-induced WMI.

METHODS

Lentivirus for Rasd1 knockdown/overexpression was administrated by intracerebroventricular (i.c.v) injection at 7 days before SAH induction. SAH grade, brain water content, short- and long-term neurobehavior, Western blot, real-time PCR, ELISA, biochemical estimation, immunofluorescence, diffusion tensor imaging (DTI), and transmission electron microscopy (TEM) were systematically performed. Additionally, genipin, a selective uncoupling protein 2(UCP2) inhibitor, was used in primary neuron and oligodendrocyte co-cultures for further in vitro mechanistic studies.

RESULTS

Rasd1 knockdown has improved the neurobehavior, glia polarization, oxidative stress, neuroinflammation, ferroptosis, and demyelination. Conversely, Rasd1 overexpression aggravated these changes by elevating the levels of reactive oxygen species (ROS), inflammatory cytokines, MDA, free iron, and NCOA4, as well as contributing to the decrease of the levels of UCP2, GPX4, ferritin, and GSH mechanistically. According to the in vitro study, Rasd1 can induce oligodendrocyte ferroptosis through inhibiting UCP2, increasing reactive oxygen species (ROS), and activating NCOA4-mediated ferritinophagy.

CONCLUSIONS

It can be concluded that Rasd1 exerts a modulated role in oligodendrocytes ferroptosis in WMI following SAH.

Curbing Rhes Actions: Mechanism-based Molecular Target for Huntington's Disease and Tauopathies

A highly interconnected network of diverse brain regions is necessary for the precise execution of human behaviors, including cognitive, psychiatric, and motor functions. Unfortunately, degeneration of specific brain regions causes several neurodegenerative disorders, but the mechanisms that elicit selective neuronal vulnerability remain unclear. This knowledge gap greatly hinders the development of effective mechanism-based therapies, despite the desperate need for new treatments. Here, we emphasize the importance of the Rhes (Ras homolog-enriched in the striatum) protein as an emerging therapeutic target. Rhes, an atypical small GTPase with a SUMO (small ubiquitin-like modifier) E3-ligase activity, modulates biological processes such as dopaminergic transmission, alters gene expression, and acts as an inhibitor of motor stimuli in the brain striatum. Mutations in the Rhes gene have also been identified in selected patients with autism and schizophrenia. Moreover, Rhes SUMOylates pathogenic form of mutant huntingtin (mHTT) and tau, enhancing their solubility and cell toxicity in Huntington's disease and tauopathy models. Notably, Rhes uses membrane projections resembling tunneling nanotubes to transport mHTT between cells and Rhes deletion diminishes mHTT spread in the brain. Thus, we predict that effective strategies aimed at diminishing brain Rhes levels will prevent or minimize the abnormalities that occur in HD and tauopathies and potentially in other brain disorders. We review the emerging technologies that enable specific targeting of Rhes in the brain to develop effective disease-modifying therapeutics.

"NO" Time in Fear Response: Possible Implication of Nitric-Oxide-Related Mechanisms in PTSD

Post-traumatic stress disorder (PTSD) is a psychiatric condition characterized by persistent fear responses and altered neurotransmitter functioning due to traumatic experiences. Stress predominantly affects glutamate, a neurotransmitter crucial for synaptic plasticity and memory formation. Activation of the N-Methyl-D-Aspartate glutamate receptors (NMDAR) can trigger the formation of a complex comprising postsynaptic density protein-95 (PSD95), the neuronal nitric oxide synthase (nNOS), and its adaptor protein (NOS1AP). This complex is pivotal in activating nNOS and nitric oxide (NO) production, which, in turn, activates downstream pathways that modulate neuronal signaling, including synaptic plasticity/transmission, inflammation, and cell death. The involvement of nNOS and NOS1AP in the susceptibility of PTSD and its comorbidities has been widely shown. Therefore, understanding the interplay between stress, fear, and NO is essential for comprehending the maintenance and progression of PTSD, since NO is involved in fear acquisition and extinction processes. Moreover, NO induces post-translational modifications (PTMs), including S-nitrosylation and nitration, which alter protein function and structure for intracellular signaling. Although evidence suggests that NO influences synaptic plasticity and memory processing, the specific role of PTMs in the pathophysiology of PTSD remains unclear. This review highlights pathways modulated by NO that could be relevant to stress and PTSD.

Signalling pathways and cell death mechanisms in glaucoma: Insights into the molecular pathophysiology

Glaucoma is a complex multifactorial eye disease manifesting in retinal ganglion cell (RGC) death and optic nerve degeneration, ultimately causing irreversible vision loss. Research in recent years has significantly enhanced our understanding of RGC degenerative mechanisms in glaucoma. It is evident that high intraocular pressure (IOP) is not the only contributing factor to glaucoma pathogenesis. The equilibrium of pro-survival and pro-death signalling pathways in the retina strongly influences the function and survival of RGCs and optic nerve axons in glaucoma. Molecular evidence from human retinal tissue analysis and a range of experimental models of glaucoma have significantly contributed to unravelling these mechanisms. Accumulating evidence reveals a wide range of molecular signalling pathways that can operate -either alone or via intricate networks - to induce neurodegeneration. The roles of several molecules, including neurotrophins, interplay of intracellular kinases and phosphates, caveolae and adapter proteins, serine proteases and their inhibitors, nuclear receptors, amyloid beta and tau, and how their dysfunction affects retinal neurons are discussed in this review. We further underscore how anatomical alterations in various animal models exhibiting RGC degeneration and susceptibility to glaucoma-related neuronal damage have helped to characterise molecular mechanisms in glaucoma. In addition, we also present different regulated cell death pathways that play a critical role in RGC degeneration in glaucoma.

The Physiological Function of nNOS-Associated CAPON Proteins and the Roles of CAPON in Diseases

In this review, the structure, isoform, and physiological role of the carboxy-terminal PDZ ligand of neuronal nitric oxide synthase (CAPON) are summarized. There are three isoforms of CAPON in humans, including long CAPON protein (CAPON-L), short CAPON protein (CAPON-S), and CAPON-S' protein. CAPON-L includes three functional regions: a C-terminal PDZ-binding motif, carboxypeptidase (CPE)-binding region, and N-terminal phosphotyrosine (PTB) structural domain. Both CAPON-S and CAPON-S' only contain the C-terminal PDZ-binding motif. The C-terminal PDZ-binding motif of CAPON can bind with neuronal nitric oxide synthase (nNOS) and participates in regulating NO production and neuronal development. An overview is given on the relationship between CAPON and heart diseases, diabetes, psychiatric disorders, and tumors. This review will clarify future research directions on the signal pathways related to CAPON, which will be helpful for studying the regulatory mechanism of CAPON. CAPON may be used as a drug target, which will provide new ideas and solutions for treating human diseases.

Regulated Cell Death of Retinal Ganglion Cells in Glaucoma: Molecular Insights and Therapeutic Potentials

Glaucoma is a group of diseases characterized by the degeneration of retinal ganglion cells (RGCs) and progressive, irreversible vision loss. High intraocular pressure (IOP) heightens the likelihood of glaucoma and correlates with RGC loss. While the current glaucoma therapy prioritizes lower the IOP; however, RGC, and visual loss may persist even when the IOP is well-controlled. As such, discovering and creating IOP-independent neuroprotective strategies for safeguard RGCs is crucial for glaucoma management. Investigating and clarifying the mechanism behind RGC death to counteract its effects is a promising direction for glaucoma control. Empirical studies of glaucoma reveal the role of multiple regulated cell death (RCD) pathways in RGC death. This review delineates the RCD of RGCs following IOP elevation and optic nerve damage and discusses the substantial benefits of mitigating RCD in RGCs in preserving visual function.

Novel Mechanisms of Perioperative Neurocognitive Disorders: Ferroptosis and Pyroptosis

Perioperative neurocognitive disorders (PNDs) are some of the most common postoperative complications among the elderly and susceptible individuals, which significantly worsens the clinical outcome of patients. However, the prevention and treatment strategies of PNDs are difficult to determine and implement since the pathogenesis of PNDs is not well understood. The development of living organisms is associated with active and organized cell death, which is essential for maintaining the homeostasis of life. Ferroptosis is a programmed cell death (different from apoptosis and necrosis) mainly caused by an imbalance in the generation and degradation of intracellular lipid peroxides due to iron overload. Pyroptosis is an inflammatory cell death characterized by the creation of membrane holes mediated by the gasdermin (GSDM) family, followed by cell lysis and the release of pro-inflammatory cytokines. Ferroptosis and pyroptosis are involved in the pathogenesis of various central nervous system (CNS) diseases. Furthermore, ferroptosis and pyroptosis are closely associated with the occurrence and development of PNDs. This review summarizes the main regulatory mechanisms of ferroptosis and pyroptosis and the latest related to PNDs. Based on the available evidence, potential intervention strategies that can alleviate PNDs by inhibiting ferroptosis and pyroptosis have also been provided.

Moxibustion ameliorates cerebral ischemia-reperfusion injury by regulating ferroptosis in rats

Moxibustion is an effective treatment for the clinical management of acute cerebral infarction. However, its exact mechanism of action is still not fully understood. This study aimed to investigate the protective effect of moxibustion on cerebral ischemia-reperfusion injury (CIRI) in rats. Middle cerebral artery occlusion/reperfusion (MCAO/R) was used to construct a CIRI rat model, all animals were randomly divided into four groups including sham operation group, MCAO/R group (MCAO/R), moxibustion therapy + MCAO/R (Moxi) and ferrostatin-1 + MCAO/R (Fer-1) group. In the Moxi group, moxibustion treatment was initiated 24 h after modeling, once a day for 30 mins each time for 7 days. Moreover, the Fer-1 group received intraperitoneal injections of Fer-1 12 h after modeling, once a day for a total of 7 days. The results showed that moxibustion could reduce nerve function damage and neuronal death. Additionally, moxibustion could reduce the production of lipid peroxides such as lipid peroxide, malondialchehyche and ACSL4 to regulate lipid metabolism, promote the production of glutathione and glutathione peroxidase 4 and reduce the expression of hepcidin by inhibiting the production of inflammatory factor interleukin-6, therefore, downregulating the expression of SLC40A1, reducing the iron level in the cerebral cortex, reducing the accumulation of reactive oxygen species and inhibiting ferroptosis. Based on our studies, it can be concluded that moxibustion has the ability to inhibit ferroptosis of nerve cells post CIRI and plays a protective role in the brain. This protective role can be attributed to the regulation of iron metabolism of nerve cells, reduction of iron deposition in the hippocampus and lowering the level of lipid peroxidation.

The Endolysosomal Transporter DMT1 is Required for Morphine Regulation of Neuronal Ferritin Heavy Chain

NeuroHIV and other neurologic disorders present with altered iron metabolism in central nervous system neurons. Many people with HIV also use opioids, which can worsen neuroHIV symptoms by further dysregulating neuronal iron metabolism. Our previous work demonstrated that the μ-opioid agonist morphine causes neuronal endolysosomes to release their iron stores, and neurons respond by upregulating ferritin heavy chain (FHC), an iron storage protein associated with cognitive impairment in neuroHIV. Here, we investigated if this process required divalent metal transporter 1 (DMT1), a well-known iron transporter expressed on endolysosomes. We first optimized conditions to detect DMT1 isoforms (DMT1 1B ± iron responsive element) using fluorescently labeled rat DMT1 constructs expressed in HEK-293 cells. We also expressed these constructs in primary rat cortical neurons to compare their expression and subcellular distribution with endogenous DMT1 isoforms. We found endogenous DMT1 isoforms in the cytoplasm that colocalized with lysosomal-associated protein 1 (LAMP1), a marker of endolysosomes. Next, we blocked endogenous DMT1 isoforms using ebselen, a potent pharmacological inhibitor of DMT1 iron transport. Ebselen pre-treatment blocked morphine's ability to upregulate FHC protein, suggesting this pathway requires DMT1 iron transport from endolysosomes. This was further validated using viral-mediated genetic silencing of DMT1±IRE in cortical neurons, which also blocked FHC upregulation in the presence of morphine. Overall, our work demonstrates that the μ-opioid agonist morphine utilizes the endolysosomal iron transporter DMT1 to modulate neuronal cellular iron metabolism, upregulate FHC protein, and contribute to cognitive decline in neuroHIV. Morphine requires DMT1 to upregulate neuronal FHC. Cortical neurons treated with morphine release their endolysosomal iron stores to the cytoplasm and upregulate FHC, an iron storage protein associated with dendritic spine deficits and cognitive impairment in neuroHIV. This pathway requires the endolysosomal iron transporter DMT1, as pharmacological and genetic inhibitors of the transporter completely block morphine's ability to upregulate FHC. Created with BioRender.com .

Brain Iron Metabolism, Redox Balance and Neurological Diseases

The incidence of neurological diseases, such as Parkinson's disease, Alzheimer's disease and stroke, is increasing. An increasing number of studies have correlated these diseases with brain iron overload and the resulting oxidative damage. Brain iron deficiency has also been closely linked to neurodevelopment. These neurological disorders seriously affect the physical and mental health of patients and bring heavy economic burdens to families and society. Therefore, it is important to maintain brain iron homeostasis and to understand the mechanism of brain iron disorders affecting reactive oxygen species (ROS) balance, resulting in neural damage, cell death and, ultimately, leading to the development of disease. Evidence has shown that many therapies targeting brain iron and ROS imbalances have good preventive and therapeutic effects on neurological diseases. This review highlights the molecular mechanisms, pathogenesis and treatment strategies of brain iron metabolism disorders in neurological diseases.

Research progress of iron metabolism in retinal diseases

Background

Retinal diseases can lead to severe visual impairment and even blindness, but current treatments are limited. For precise targeted therapy, the pathophysiological mechanisms of the diseases still need to be further explored. Iron serves an essential role in many biological activities and helps maintain the function and morphology of the retina. The vision problems caused by retinal diseases are affecting more and more people, the study of iron metabolism in retinal diseases possesses great potential for clinical application.

Main text

Iron maintains a dynamic balance in the retina but in excess is toxic to the retina. Iron overload can lead to various pathological changes in the retina through oxidative stress, inflammation, cell death, angiogenesis and other pathways. It is therefore involved in the progression of retinal diseases such as age-related macular degeneration, glaucoma, diabetic retinopathy, retinitis pigmentosa, and hereditary iron overload. In recent years, iron chelators have been shown to be effective in the treatment of retinal diseases, but the exact mechanism is not yet fully understood. This question prompted further investigation into the specific mechanisms by which iron metabolism is involved in retinal disease.

Conclusions

This review summarizes iron metabolism processes in the retina and mechanistic studies of iron metabolism in the progression of retinal disease. It also highlights the therapeutic potential of iron chelators in retinal diseases.

Perturbed iron biology in the prefrontal cortex of people with schizophrenia

Despite loss of grey matter volume and emergence of distinct cognitive deficits in young adults diagnosed with schizophrenia, current treatments for schizophrenia do not target disruptions in late maturational reshaping of the prefrontal cortex. Iron, the most abundant transition metal in the brain, is essential to brain development and function, but in excess, it can impair major neurotransmission systems and lead to lipid peroxidation, neuroinflammation and accelerated aging. However, analysis of cortical iron biology in schizophrenia has not been reported in modern literature. Using a combination of inductively coupled plasma-mass spectrometry and western blots, we quantified iron and its major-storage protein, ferritin, in post-mortem prefrontal cortex specimens obtained from three independent, well-characterised brain tissue resources. Compared to matched controls (n = 85), among schizophrenia cases (n = 86) we found elevated tissue iron, unlikely to be confounded by demographic and lifestyle variables, by duration, dose and type of antipsychotic medications used or by copper and zinc levels. We further observed a loss of physiologic age-dependent iron accumulation among people with schizophrenia, in that the iron level among cases was already high in young adulthood. Ferritin, which stores iron in a redox-inactive form, was paradoxically decreased in individuals with the disorder. Such iron-ferritin uncoupling could alter free, chemically reactive, tissue iron in key reasoning and planning areas of the young-adult schizophrenia cortex. Using a prediction model based on iron and ferritin, our data provide a pathophysiologic link between perturbed cortical iron biology and schizophrenia and indicate that achievement of optimal cortical iron homeostasis could offer a new therapeutic target.

Modulation of Ferroptosis by microRNAs in Human Cancer

Ferroptosis is a cell death pathway triggered by an imbalance between the production of oxidants and antioxidants, which plays an emerging role in tumorigenesis. It is mainly regulated at three different levels including iron metabolism, the antioxidant response, and lipid metabolism. Epigenetic dysregulation is a "hallmark" of human cancer, with nearly half of all human cancers harboring mutations in epigenetic regulators such as microRNA. While being the crucial player in controlling gene expression at the mRNA level, microRNAs have recently been shown to modulate cancer growth and development via the ferroptosis pathway. In this scenario, some miRNAs have a function in upregulating, while others play a role in inhibiting ferroptosis activity. The investigation of validated targets using the miRBase, miRTarBase, and miRecords platforms identified 13 genes that appeared enriched for iron metabolism, lipid peroxidation, and antioxidant defense; all are recognized contributors of tumoral suppression or progression phenotypes. This review summarizes and discuss the mechanism by which ferroptosis is initiated through an imbalance in the three pathways, the potential function of microRNAs in the control of this process, and a description of the treatments that have been shown to have an impact on the ferroptosis in cancer along with potential novel effects.

Disrupting the nNOS/NOS1AP interaction in the medial prefrontal cortex impairs social recognition and spatial working memory in mice

The neuronal isoform of nitric oxide synthase (nNOS) and its interacting protein NOS1AP have been linked to several mental disorders including schizophrenia and depression. An increase in the interaction between nNOS and NOS1AP in the frontal cortex has been suggested to contribute to the emergence of these disorders. Here we aimed to uncover whether disruption of their interactions in the frontal cortex leads to mental disorder endophenotypes. Targeting the medial prefrontal cortex (mPFC), we stereotaxically injected wild-type C57BL/6J mice with recombinant adeno-associated virus (rAAV) expressing either full-length NOS1AP, the nNOS binding region of NOS1AP (i.e. NOS1AP_396-503), or the nNOS amino-terminus (i.e. nNOS_1-133), which was shown to disrupt the interaction of endogenous nNOS with PSD-95. We tested these mice in a comprehensive behavioural battery, assessing different endophenotypes related to mental disorders. We found no differences in anxiety-related and exploratory behaviours. Likewise, social interaction was comparable in all groups. However, social recognition was impaired in NOS1AP and NOS1AP_396-503 mice. These mice, as well as mice overexpressing nNOS_1-133 also displayed impaired spatial working memory (SWM) capacity, while spatial reference memory (SRM) remained intact. Finally, mice overexpressing NOS1AP and nNOS_1-133, but not NOS1AP_396-503, failed to habituate to the startling pulses in an acoustic startle response (ASR) paradigm, though we found no difference in overall startle intensity or prepulse inhibition (PPI) of the ASR. Our findings indicate a distinct role of NOS1AP/nNOS/PSD-95 interactions in the mPFC to contribute to specific endophenotypic changes observed in different mental disorders.

Synaptic Activity Regulates Mitochondrial Iron Metabolism to Enhance Neuronal Bioenergetics

Synaptic activity is the main energy-consuming process in the central nervous system. We are beginning to understand how energy is supplied and used during synaptic activity by neurons. However, the long-term metabolic adaptations associated with a previous episode of synaptic activity are not well understood. Herein, we show that an episode of synaptic activity increases mitochondrial bioenergetics beyond the duration of the synaptic activity by transcriptionally inducing the expression of iron metabolism genes with the consequent enhancement of cellular and mitochondrial iron uptake. Iron is a necessary component of the electron transport chain complexes, and its chelation or knockdown of mitochondrial iron transporter Mfrn1 blocks the activity-mediated bioenergetics boost. We found that Mfrn1 expression is regulated by the well-known regulator of synaptic plasticity CREB, suggesting the coordinated expression of synaptic plasticity programs with those required to meet the associated increase in energetic demands.

Role of amyloid beta (25-35) neurotoxicity in the ferroptosis and necroptosis as modalities of regulated cell death in Alzheimer's disease

Neuronal cell death as a prominent pathological feature contributes to cognitive decline and memory loss in Alzheimer's disease. We investigated the role of two forms of cell death pathways, ferroptosis and necroptosis, and their interactions following entorhinal cortex (EC) amyloidopathy. The Aβ_25-35 was bilaterally injected into the rat's EC, and Morris Water Maze was applied to determine spatial performance one week after Aβ injection. For evaluation of ferroptosis and necroptosis involvement in Aβ induced pathology, ferroptosis inhibitor, Ferrostatin (Fer-1), and necroptosis inhibitor, Necrostatin (Nec-1), were injected into the EC during training days of behavioral test. Our behavioral and histological assessment showed spatial learning and memory impairment, along with neuropathology changes such as cell survival and intracellular Aβ deposits in response to EC amyloidopathy, which were ameliorated by treatment with Fer-1 or Nec-1. The expression of ferroptosis key factors GPX4 and SLC7A11 were decreased and the level of TfR was increased following Aβ toxicity. Also, Necroptosis pathway related factors RIP1, RIP3, and MLKL were modulated by Aβ neurotoxicity. However, application of Fer-1 or Nec-1 could inhibit the hippocampal ferroptosis and necroptosis pathways due to EC amyloidopathy. Our data also demonstrated that Aβ-induced necroptosis suppressed by Fer-1, although Nec-1 had no effect on ferroptosis, indicating that ferroptosis pathway is upstream of necroptosis process in the Aβ neurotoxicity. Moreover, Aβ induced hippocampal mGLUR5 overexpression and reduced level of STIM1/2 recovered by Fer-1 or Nec-1. According to our findings ferroptosis and necroptosis pathways are involved in Aβ neurotoxicity through modulation of mGLUR5 and STIM1/2 signaling.

The initiator of neuroexcitotoxicity and ferroptosis in ischemic stroke: Glutamate accumulation

Glutamate plays an important role in excitotoxicity and ferroptosis. Excitotoxicity occurs through over-stimulation of glutamate receptors, specifically NMDAR, while in the non-receptor-mediated pathway, high glutamate concentrations reduce cystine uptake by inhibiting the System Xc-, leading to intracellular glutathione depletion and resulting in ROS accumulation, which contributes to increased lipid peroxidation, mitochondrial damage, and ultimately ferroptosis. Oxidative stress appears to crosstalk between excitotoxicity and ferroptosis, and it is essential to maintain glutamate homeostasis and inhibit oxidative stress responses in vivo. As researchers work to develop natural compounds to further investigate the complex mechanisms and regulatory functions of ferroptosis and excitotoxicity, new avenues will be available for the effective treatment of ischaemic stroke. Therefore, this paper provides a review of the molecular mechanisms and treatment of glutamate-mediated excitotoxicity and ferroptosis.

Hydrogen-Rich Saline Attenuates Chronic Allodynia after Bone Fractures via Reducing Spinal CXCL1/CXCR2-Mediated Iron Accumulation in Mice

PURPOSE

Neuroinflammation often initiates iron overload in the pathogenesis of neurological disorders. Chemokine-driven neuroinflammation is required for central sensitization and chronic allodynia following fractures, but specific molecular modulations are elusive. This present study explored whether hydrogen-rich saline, as one potent anti-inflammatory pharmaceutical, could alleviate fracture-caused allodynia by suppressing chemokine CXCL1 expression and iron overload.

METHODS

A mouse model of tibial fracture with intramedullary pinning was employed for establishing chronic allodynia. Three applications of hydrogen-rich saline (1, 5 or 10 mL/kg) were administrated intraperitoneally on a daily basis from days 4 to 6 following fractures. Spinal CXCL1 and its receptor CXCR2 levels, transferrin receptor 1 (TfR1) expression and iron concentration were examined. Recombinant CXCL1, a selective CXCR2 antagonist and an iron chelator were used for verification of mechanisms.

RESULTS

Repetitive injections of hydrogen-rich saline (5 and 10 mL/kg but not 1 mL/kg) prevent fracture-caused mechanical allodynia and cold allodynia in a dose-dependent manner. Single exposure to hydrogen-rich saline (10 mL/kg) on day 14 after orthopedic surgeries controls the established persistent fracture allodynia. Furthermore, hydrogen-rich saline therapy reduces spinal CXCL1/CXCR2 over-expression and TfR1-mediated iron accumulation in fracture mice. Spinal CXCR2 antagonism impairs allodynia and iron overload following fracture surgery. Intrathecal delivery of recombinant CXCL1 induces acute allodynia and spinal iron overload, which is reversed by hydrogen-rich saline. Moreover, iron chelation alleviates exogenous CXCL1-induced acute pain behaviors.

CONCLUSIONS

These findings identify that hydrogen-rich saline confers protection against fracture-caused chronic allodynia via spinal down-modulation of CXCL1-dependent TfR1-mediated iron accumulation in mice.

Genetic Analysis of RASD1 as a Candidate Gene for Schizophrenia

Background

RASD1 encodes Dexamethasone-induced Ras-related protein 1 (Dexras1), a protein with a critical role in signal transduction in neurons. There is a strong suspicion that dysfunction of Dexras1 might contribute to the pathogenesis of neuropsychiatric diseases. Related to its functions in intracellular signaling pathways, Dexras1 has a potential role in the etiology of schizophrenia because of its close interaction with NOS1, NOS1AP, and NMDAR, which have previously been associated with schizophrenia.

Aims

To investigate the association of RASD1 variants with schizophrenia in a selected cohort from Turkey.

Study Design

A case-control study.

Methods

We performed targeted sequencing for the two exons, single intron, and untranslated regions of RASD1 gene in 200 individuals with schizophrenia and 100 healthy controls of Turkish origin.

Results

Two rare variants, RASD1 (NM_016084.5): c.722A>T and c*31G>A were identified in individuals with schizophrenia but not in any controls. The c.722A>T was found in a single individual with schizophrenia and is a missense heterozygous variant in the second exon of RASD1, which is extremely rare in GnomAD. The other variant, c*31G>A, which was found in another individual from this schizophrenia cohort, has not been reported previously. Seven previously identified common single nucleotide polymorphisms were also detected; however, they were not significantly associated with schizophrenia in this study cohort.

Conclusion

Our findings suggest that rare variants of RASD1 might be contributing to the etiopathogenesis of schizophrenia. Further studies are needed to elucidate the underlying mechanism of this association.

Neuroprotective Effects of Transferrin in Experimental Glaucoma Models

Iron is essential for retinal metabolism, but an excess of ferrous iron causes oxidative stress. In glaucomatous eyes, retinal ganglion cell (RGC) death has been associated with dysregulation of iron homeostasis. Transferrin (TF) is an endogenous iron transporter that controls ocular iron levels. Intraocular administration of TF is neuroprotective in various models of retinal degeneration, preventing iron overload and reducing iron-induced oxidative stress. Herein, we assessed the protective effects of TF on RGC survival, using ex vivo rat retinal explants exposed to iron, NMDA-induced excitotoxicity, or CoCl₂-induced hypoxia, and an in vivo rat model of ocular hypertension (OHT). TF significantly preserved RGCs against FeSO₄-induced toxicity, NMDA-induced excitotoxicity, and CoCl₂-induced hypoxia. TF protected RGCs from apoptosis, ferroptosis, and necrosis. In OHT rats, TF reduced RGC loss by about 70% compared to vehicle-treated animals and preserved about 47% of the axons. Finally, increased iron staining was shown in the retina of a glaucoma patient's eye as compared to non-glaucomatous eyes. These results indicate that TF can interfere with different cell-death mechanisms involved in glaucoma pathogenesis and demonstrate the ability of TF to protect RGCs exposed to elevated IOP. Altogether, these results suggest that TF is a promising treatment against glaucoma neuropathy.

Multiple types of programmed necrosis such as necroptosis, pyroptosis, oxytosis/ferroptosis, and parthanatos contribute simultaneously to retinal damage after ischemia-reperfusion

Ischemia-reperfusion (IR) injury is implicated in a large array of pathological conditions in the retina. Increasing experimental evidence suggests that programmed necrosis makes a significant contribution to inflammation and retinal damage triggered by IR. Since there are many types of programmed necrosis, it is important to identify those involved in retinal IR to determine the correct treatment. To this end, we used a mouse model of retinal IR and a variety of approaches including RNA-seq data analysis. Our RNA-seq data revealed the rapid development of ischemic pathology in the retina during the first 24 h after reperfusion. We found that at least four types of programmed necrosis including necroptosis, pyroptosis, oxytosis/ferroptosis, and parthanatos are simultaneously involved in retinal IR. Our data suggest that the high activity of the TNF pathway at the early stage of retinal IR leads to early activation of necroptosis while significant activity of other types of programmed necrosis appears later. Our results indicate that TNF, glutamate, and ferrous iron generated by Steap3 may be key players concurrently triggering at least necroptosis, oxytosis/ferroptosis, and parthanatos in ischemic retinal ganglion cells (RGCs). Thus, multiple signaling cascades involved in programmed necrosis should be synchronously targeted for therapeutic purposes to treat retinal IR.

The effect of narcotics on ferroptosis-related molecular mechanisms and signalling pathways

Ferroptosis is a novel programmed cell death form characterized by iron-mediated reactive oxygen species-induced lipid peroxidation and subsequent cell damage that is distinct from apoptosis, necroptosis, pyroptosis, and autophagy. Most studies on ferroptosis are based on its function and mechanism, but there have been relatively few studies on the effects of drugs, especially anaesthetics, on ferroptosis. Therefore, we summarized the recent literature on the effects of anaesthetics on ferroptosis to understand the underlying mechanism. In particular, we focused on the targets of various anaesthetics in different mechanisms of ferroptosis and the effects of ferroptosis induction or inhibition by narcotics on various diseases. The aims of this review are to provide a relatively reasonable drug regimen for clinicians, to explore potential ferroptosis protection drugs and targets, to reduce perioperative complications and to improve the postoperative performance of patients, especially those who are critically ill.

The mechanism of ferroptosis regulating oxidative stress in ischemic stroke and the regulation mechanism of natural pharmacological active components

Cerebrovascular diseases, such as ischemic stroke, pose serious medical challenges worldwide due to their high morbidity and mortality and limitations in clinical treatment strategies. Studies have shown that reactive oxygen species (ROS)-mediated inflammation, excitotoxicity, and programmed cell death of each neurovascular unit during post-stroke hypoxia and reperfusion play an important role in the pathological cascade. Ferroptosis, a programmed cell death characterized by iron-regulated accumulation of lipid peroxidation, is caused by abnormal metabolism of lipids, glutathione (GSH), and iron, and can accelerate acute central nervous system injury. Recent studies have gradually uncovered the pathological process of ferroptosis in the neurovascular unit of acute stroke. Some drugs such as iron chelators, ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1) can protect nerves after neurovascular unit injury in acute stroke by inhibiting ferroptosis. In addition, combined with our previous studies on ferroptosis mediated by natural compounds in ischemic stroke, this review summarized the progress in the regulation mechanism of natural chemical components and herbal chemical components on ferroptosis in recent years, in order to provide reference information for future research on ferroptosis and lead compounds for the development of ferroptosis inhibitors.

Potential application of traditional Chinese medicine in cerebral ischemia—Focusing on ferroptosis

Traditional Chinese medicine (TCM) has attracted a great deal of attention in the treatment of cerebral ischemia is credited with the remarkable neuroprotective effects. However, the imperfect functional mechanism of TCM is a major obstacle to their application. Many studies have been conducted to illustrate the pathophysiology of post-ischemic cerebral ischemia by elucidating the neuronal cell death pathway. Meanwhile, a new type of cell death, ferroptosis, is gradually being recognized in various diseases and is becoming a new pathway of therapeutic intervention strategy to solve many health problems. Especially since ferroptosis has been found to be closely involved into the pathogenesis of cerebral ischemia, it has been considered as a key target in the treatment of cerebral ischemia. Therefore, this paper reviews the latest research findings about the treatment of cerebral ischemia with TCM focused on ferroptosis as a target. Also, in order to explores the possibility of a new approach to treat cerebral ischemia with TCM, we discusses the correlation between ferroptosis and other cell death pathways such as apoptosis and autophagy, which would provide references for the following researches.

Ferroptosis is involved in regulating perioperative neurocognitive disorders: emerging perspectives

Since the twenty-first century, the development of technological advances in anesthesia and surgery has brought benefits to human health. However, the adverse neurological effects of perioperative-related factors (e.g., surgical trauma, anesthesia, etc.) as stressors cannot be ignored as well. The nervous system appears to be more "fragile" and vulnerable to damage in developing and aging individuals. Ferroptosis is a novel form of programmed cell death proposed in 2012. In recent years, the regulation of ferroptosis to treat cancer, immune system disorders, and neurodegenerative diseases have seen an unprecedented surge of interest. The association of ferroptosis with perioperative neurocognitive disorders has also received much attention. Cognitive impairment can not only affect the individual's quality of life, but also impose a burden on the family and society. Therefore, the search for effective preventive and therapeutic methods to alleviate cognitive impairment caused by perioperative-related factors is a challenge that needs to be urgently addressed. In our review, we first briefly describe the connection between iron accumulation in neurons and impairment of brain function during development and aging. It is followed by a review of the pathways of ferroptosis, mainly including iron metabolism, amino acid metabolism, and lipid metabolism pathway. Furthermore, we analyze the connection between ferroptosis and perioperative-related factors. The surgery itself, general anesthetic drugs, and many other relevant factors in the perioperative period may affect neuronal iron homeostasis. Finally, we summarize the experimental evidence for ameliorating developmental and degenerative neurotoxicity by modulating ferroptosis. The suppression of ferroptosis seems to provide the possibility to prevent and improve perioperative neurocognitive impairment.

Neuronal Death Mechanisms and Therapeutic Strategy in Ischemic Stroke

Ischemic stroke caused by intracranial vascular occlusion has become increasingly prevalent with considerable mortality and disability, which gravely burdens the global economy. Current relatively effective clinical treatments are limited to intravenous alteplase and thrombectomy. Even so, patients still benefit little due to the short therapeutic window and the risk of ischemia/reperfusion injury. It is therefore urgent to figure out the neuronal death mechanisms following ischemic stroke in order to develop new neuroprotective strategies. Regarding the pathogenesis, multiple pathological events trigger the activation of cell death pathways. Particular attention should be devoted to excitotoxicity, oxidative stress, and inflammatory responses. Thus, in this article, we first review the principal mechanisms underlying neuronal death mediated by these significant events, such as intrinsic and extrinsic apoptosis, ferroptosis, parthanatos, pyroptosis, necroptosis, and autophagic cell death. Then, we further discuss the possibility of interventions targeting these pathological events and summarize the present pharmacological achievements.

Ferroptosis in cancer therapy: a novel approach to reversing drug resistance

Ferroptosis is an intracellular iron-dependent form of cell death that is distinct from apoptosis, necrosis, and autophagy. Extensive studies suggest that ferroptosis plays a pivotal role in tumor suppression, thus providing new opportunities for cancer therapy. The development of resistance to cancer therapy remains a major challenge. A number of preclinical and clinical studies have focused on overcoming drug resistance. Intriguingly, ferroptosis has been correlated with cancer therapy resistance, and inducing ferroptosis has been demonstrated to reverse drug resistance. Herein, we provide a detailed description of the mechanisms of ferroptosis and the therapeutic role of regulating ferroptosis in reversing the resistance of cancer to common therapies, such as chemotherapy, targeted therapy and immunotherapy. We discuss the prospect and challenge of regulating ferroptosis as a therapeutic strategy for reversing cancer therapy resistance and expect that our review could provide some references for further studies.

A gold revision of the Golgi Dynamics (GOLD) domain structure and associated cell functionalities

The classical secretory pathway is the key membrane-based delivery system in eukaryotic cells. Several families of proteins involved in the secretory pathway, with functionalities going from cargo sorting receptors to the maintenance and dynamics of secretory organelles, share soluble globular domains predicted to mediate protein-protein interactions. One of them is "Golgi Dynamics" (GOLD) domain, named after its strong association with the Golgi apparatus. There are many GOLD-containing protein families, such as the Transmembrane emp24 domain-containing proteins (TMED/p24 family), animal SEC14-like proteins, Human Golgi resident protein ACBD3, a splice variant of TICAM2 called TRAM with GOLD domain and FYCO1. Here, we critically review the state-of-the-art knowledge of the structures and functions of the main representatives of GOLD-containing proteins in vertebrates. We provide the first unified description of the GOLD domain structure across different families since the first high-resolution structure was determined. With a brand-new update on the definition of the GOLD domain, we also discuss how its tertiary structure fits the β-sandwich-like fold map and give exciting new directions for forthcoming studies.

Mechanistic Insights Expatiating the Redox-Active-Metal-Mediated Neuronal Degeneration in Parkinson's Disease

Parkinson’s disease (PD) is a complicated and incapacitating neurodegenerative malady that emanates following the dopaminergic (DArgic) nerve cell deprivation in the substantia nigra pars compacta (SN-PC). The etiopathogenesis of PD is still abstruse. Howbeit, PD is hypothesized to be precipitated by an amalgamation of genetic mutations and exposure to environmental toxins. The aggregation of α-synucelin within the Lewy bodies (LBs), escalated oxidative stress (OS), autophagy-lysosome system impairment, ubiquitin-proteasome system (UPS) impairment, mitochondrial abnormality, programmed cell death, and neuroinflammation are regarded as imperative events that actively participate in PD pathogenesis. The central nervous system (CNS) relies heavily on redox-active metals, particularly iron (Fe) and copper (Cu), in order to modulate pivotal operations, for instance, myelin generation, synthesis of neurotransmitters, synaptic signaling, and conveyance of oxygen (O₂). The duo, namely, Fe and Cu, following their inordinate exposure, are viable of permeating across the blood–brain barrier (BBB) and moving inside the brain, thereby culminating in the escalated OS (through a reactive oxygen species (ROS)-reliant pathway), α-synuclein aggregation within the LBs, and lipid peroxidation, which consequently results in the destruction of DArgic nerve cells and facilitates PD emanation. This review delineates the metabolism of Fe and Cu in the CNS, their role and disrupted balance in PD. An in-depth investigation was carried out by utilizing the existing publications obtained from prestigious medical databases employing particular keywords mentioned in the current paper. Moreover, we also focus on decoding the role of metal complexes and chelators in PD treatment. Conclusively, metal chelators hold the aptitude to elicit the scavenging of mobile/fluctuating metal ions, which in turn culminates in the suppression of ROS generation, and thereby prelude the evolution of PD.

Thymosin β4 Is an Endogenous Iron Chelator and Molecular Switcher of Ferroptosis

Thymosin β4 (Tβ4) was extracted forty years agofrom calf thymus. Since then, it has been identified as a G-actin binding protein involved in blood clotting, tissue regeneration, angiogenesis, and anti-inflammatory processes. Tβ4 has also been implicated in tumor metastasis and neurodegeneration. However, the precise roles and mechanism(s) of action of Tβ4 in these processes remain largely unknown, with the binding of the G-actin protein being insufficient to explain these multi-actions. Here we identify for the first time the important role of Tβ4 mechanism in ferroptosis, an iron-dependent form of cell death, which leads to neurodegeneration and somehow protects cancer cells against cell death. Specifically, we demonstrate four iron2+ and iron3+ binding regions along the peptide and show that the presence of Tβ4 in cell growing medium inhibits erastin and glutamate-induced ferroptosis in the macrophage cell line. Moreover, Tβ4 increases the expression of oxidative stress-related genes, namely BAX, hem oxygenase-1, heat shock protein 70 and thioredoxin reductase 1, which are downregulated during ferroptosis. We state the hypothesis that Tβ4 is an endogenous iron chelator and take part in iron homeostasis in the ferroptosis process. We discuss the literature data of parallel involvement of Tβ4 and ferroptosis in different human pathologies, mainly cancer and neurodegeneration. Our findings confronted with literature data show that controlled Tβ4 release could command on/off switching of ferroptosis and may provide novel therapeutic opportunities in cancer and tissue degeneration pathologies.

Seizure-mediated iron accumulation and dysregulated iron metabolism after status epilepticus and in temporal lobe epilepsy

Neuronal dysfunction due to iron accumulation in conjunction with reactive oxygen species (ROS) could represent an important, yet underappreciated, component of the epileptogenic process. However, to date, alterations in iron metabolism in the epileptogenic brain have not been addressed in detail. Iron-related neuropathology and antioxidant metabolic processes were investigated in resected brain tissue from patients with temporal lobe epilepsy and hippocampal sclerosis (TLE-HS), post-mortem brain tissue from patients who died after status epilepticus (SE) as well as brain tissue from the electrically induced SE rat model of TLE. Magnetic susceptibility of the presumed seizure-onset zone from three patients with focal epilepsy was compared during and after seizure activity. Finally, the cellular effects of iron overload were studied in vitro using an acute mouse hippocampal slice preparation and cultured human fetal astrocytes. While iron-accumulating neurons had a pyknotic morphology, astrocytes appeared to acquire iron-sequestrating capacity as indicated by prominent ferritin expression and iron retention in the hippocampus of patients with SE or TLE. Interictal to postictal comparison revealed increased magnetic susceptibility in the seizure-onset zone of epilepsy patients. Post-SE rats had consistently higher hippocampal iron levels during the acute and chronic phase (when spontaneous recurrent seizures are evident). In vitro, in acute slices that were exposed to iron, neurons readily took up iron, which was exacerbated by induced epileptiform activity. Human astrocyte cultures challenged with iron and ROS increased their antioxidant and iron-binding capacity, but simultaneously developed a pro-inflammatory phenotype upon chronic exposure. These data suggest that seizure-mediated, chronic neuronal iron uptake might play a role in neuronal dysfunction/loss in TLE-HS. On the other hand, astrocytes sequester iron, specifically in chronic epilepsy. This function might transform astrocytes into a highly resistant, pro-inflammatory phenotype potentially contributing to pro-epileptogenic inflammatory processes.

Neurophysiologic implications of neuronal nitric oxide synthase

The molecular and chemical properties of neuronal nitric oxide synthase (nNOS) have made it a key mediator in many physiological functions and signaling transduction. The NOS monomer is inactive, but the dimer form is active. There are three forms of NOS, which are neuronal (nNOS), inducible (iNOS), and endothelial (eNOS) nitric oxide synthase. nNOS regulates nitric oxide (NO) synthesis which is the mechanism used mostly by neurons to produce NO. nNOS expression and activation is regulated by some important signaling proteins, such as cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), calmodulin (CaM), heat shock protein 90 (HSP90)/HSP70. nNOS-derived NO has been implicated in modulating many physiological functions, such as synaptic plasticity, learning, memory, neurogenesis, etc. In this review, we have summarized recent studies that have characterized structural features, subcellular localization, and factors that regulate nNOS function. Finally, we have discussed the role of nNOS in the developing brain under a wide range of physiological conditions, especially long-term potentiation and depression.

Expression of Rasd1 in mouse endocrine pituitary cells and its response to dexamethasone

Dexamethasone-induced Ras-related protein 1 (Rasd1) is a member of the Ras superfamily of monomeric G proteins that have a regulatory function in signal transduction. Rasd1, also known as Dexras1 or AGS1, is rapidly induced by dexamethasone (Dex). While prior data indicates that Rasd1 is highly expressed in the pituitary and that the gene may function in regulation of corticotroph activity, its exact cellular localization in this tissue has not been delineated. Nor has it been determined which endocrine pituitary cell type(s) are responsive to Dex-induced expression of Rasd1. We hypothesized that Rasd1 is primarily localized in corticotrophs and furthermore, that its expression in these cells would be upregulated in response to exogenous Dex administration. Rasd1 expression in each pituitary cell type both under basal conditions and 1-hour post Dex treatment were examined in adult male mice. While a proportion of all endocrine pituitary cell types expressed Rasd1, a majority of corticotrophs and thyrotrophs expressed Rasd1 under basal condition. In vehicle treated animals, approximately 50-60% of corticotrophs and thyrotrophs cells expressed Rasd1 while the gene was detected in only 15-30% of lactotrophs, somatotrophs, and gonadotrophs. In Dex treated animals, Rasd1 expression was significantly increased in corticotrophs, somatotrophs, lactotrophs, and gonadotrophs but not thyrotrophs. In Dex treated animals, Rasd1 was detected in 80-95% of gonadotrophs and corticotrophs. In contrast, Dex treatment increased Rasd1 expression to a lesser extent (55-60%) in somatotrophs and lactotrophs. Corticotrophs of the pars intermedia, which lack glucocorticoid receptors, failed to display increased Rasd1 expression in Dex treated animals. Rasd1 is highly expressed in corticotrophs under basal conditions and is further increased after Dex treatment, further supporting its role in glucocorticoid negative feedback. In addition, the presence and Dex-induced expression of Rasd1 in endocrine pituitary cell types, other than corticotrophs, may implicate Rasd1 in novel pituitary functions.

Hippocampal overexpression of NOS1AP promotes endophenotypes related to mental disorders

BACKGROUND

Nitric oxide synthase 1 adaptor protein (NOS1AP; previously named CAPON) is linked to the glutamatergic postsynaptic density through interaction with neuronal nitric oxide synthase (nNOS). NOS1AP and its interaction with nNOS have been associated with several mental disorders. Despite the high levels of NOS1AP expression in the hippocampus and the relevance of this brain region in glutamatergic signalling as well as mental disorders, a potential role of hippocampal NOS1AP in the pathophysiology of these disorders has not been investigated yet.

METHODS

To uncover the function of NOS1AP in hippocampus, we made use of recombinant adeno-associated viruses to overexpress murine full-length NOS1AP or the NOS1AP carboxyterminus in the hippocampus of mice. We investigated these mice for changes in gene expression, neuronal morphology, and relevant behavioural phenotypes.

FINDINGS

We found that hippocampal overexpression of NOS1AP markedly increased the interaction of nNOS with PSD-95, reduced dendritic spine density, and changed dendritic spine morphology at CA1 synapses. At the behavioural level, we observed an impairment in social memory and decreased spatial working memory capacity.

INTERPRETATION

Our data provide a mechanistic explanation for a highly selective and specific contribution of hippocampal NOS1AP and its interaction with the glutamatergic postsynaptic density to cross-disorder pathophysiology. Our findings allude to therapeutic relevance due to the druggability of this molecule.

FUNDING

This study was funded in part by the DFG, the BMBF, the Academy of Finland, the NIH, the Japanese Society of Clinical Neuropsychopharmacology, the Ministry of Education of the Russian Federation, and the European Community.

Effects of Iron and Zinc on Mitochondria: Potential Mechanisms of Glaucomatous Injury

Glaucoma is the most substantial cause of irreversible blinding, which is accompanied by progressive retinal ganglion cell damage. Retinal ganglion cells are energy-intensive neurons that connect the brain and retina, and depend on mitochondrial homeostasis to transduce visual information through the brain. As cofactors that regulate many metabolic signals, iron and zinc have attracted increasing attention in studies on neurons and neurodegenerative diseases. Here, we summarize the research connecting iron, zinc, neuronal mitochondria, and glaucomatous injury, with the aim of updating and expanding the current view of how retinal ganglion cells degenerate in glaucoma, which can reveal novel potential targets for neuroprotection.

Research Progress of Ferroptosis: A Bibliometrics and Visual Analysis Study

Background

Ferroptosis is a type of cell death with major topic of debate under current research and plays an important role in disease regulation.

Objective

In this study, the literature management software Bibexcel and knowledge graph tool VOSviewer were used to summarize and analyze the international research trends and hotspots about ferroptosis in recent years, which highlight the disease mechanism, diagnosis, and treatment related to ferroptosis. Material/Methods. The core collection database of Web of Science was used for retrieving ferroptosis research literature. The information such as the amount of text, the country, the period, the institution, the fund, and the keywords was extracted by the bibliometric tool Bibexcel. The cooccurrence and clustering function of VOSviewer were used to analyze the high-frequency keywords and the cooperative network of the author, institution, and country.

Results

The research of ferroptosis started late and was formally proposed in 2012. It has developed rapidly and presented an “exponential” growth trend. China, the United States, Germany, Japan, and France are the main national forces of ferroptosis research development. The United States and China have a relatively high degree of support and attention to ferroptosis. Exploring oxidative stress, inducers/inhibitors, synergistic antitumor effect, relationships with other cell death types, GSH/GPX4 and iron metabolism imbalance related mechanisms of ferroptosis, and ferroptosis in the nervous system disease, ischemia-reperfusion injury, tumor, inflammation, and age-related diseases are the hot research directions.

Conclusion

Ferroptosis has been a research hotspot in the field of biomedicine in recent years and has attracted the attention of scholars all over the world. The occurrence mechanism of ferroptosis and its application in neurological diseases, ischemia and reperfusion injury, tumors, inflammation, and aging are the hot directions of current research. In the future, ferroptosis can be appropriately considered for strengthening new approaches, new diseases, new inductors, new inhibitors, clinical transformation, and traditional medicine research.

Impacts of Iron Metabolism Dysregulation on Alzheimer's Disease

BACKGROUND

Iron plays an important role in maintaining cell survival, with normal iron trafficking known to be regulated by the ceruloplasmin-transferrin (Cp-Tf) antioxidant system. Disruption to this system is thought to be detrimental to normal brain function.

OBJECTIVE

To determine whether an imbalance of iron and the proteins involved in its metabolism (ceruloplasmin and transferrin) are linked to Alzheimer's disease (AD) and to the expression of amyloid-beta (Aβ) peptide 1-42 (Aβ1-42), which is a major species of Aβ, and the most toxic.

METHODS

We evaluated the concentrations of iron, calcium, magnesium, and Aβ1-42 in the cerebrospinal fluid (CSF) of patients with AD and cognitively normal controls. Correlations between the components of the Cp-Tf antioxidant system in plasma were studied to determine the role of peripheral blood in the onset and/or development of AD. We used commercial ELISA immunoassays to measure Aβ1-42, immunoturbidimetry to quantify ceruloplasmin and transferrin, and colorimetry to quantify iron, calcium, and magnesium.

RESULTS

We found that the AD group had lower CSF concentrations of Aβ1-42 (p < 0.001) and calcium (p < 0.001), but a higher CSF concentration of iron (p < 0.001). Significantly lower plasma concentrations of ceruloplasmin (p = 0.003), transferrin (mean, p < 0.001), and iron (p < 0.001) were observed in the AD group than in cognitively normal adults. Moreover, we found a strong interdependence between most of these components.

CONCLUSION

Iron dyshomeostasis has a crucial role in the onset of AD and/or its development. Correcting metal misdistribution is an appealing therapeutic strategy for AD.

Nitric oxide and sex differences in dendritic branching and arborization

Nitric oxide (NO) is an important signaling molecule with many functions in the nervous system. Derived from the enzymatic conversion of arginine by several nitric oxide synthases (NOS), NO plays significant roles in neuronal developmental events such as the establishment of dendritic branching or arbors. A brief summary of the discovery, molecular biology, and chemistry of NO, and a description of important NO-mediated signal transduction pathways with emphasis on the role for NO in the development of dendritic branching during neurodevelopment are presented. Important sex differences in neuronal nitric oxide synthase expression during neuronal development are considered. Finally, a survey of endogenous and exogenous substances that disrupt dendritic patterning is presented with particular emphasis on how these molecules may drive NO-mediated sex differences in dendritic branching.