NADPH oxidases promote apoptosis by activating ZNRF1 ubiquitin ligase in neurons treated with an exogenously applied oxidant

Myricanol represses renal fibrosis by activating TFAM and ZNRF1 to inhibit tubular epithelial cells ferroptosis

BACKGROUND

Mitochondrial dysfunction induces ferroptosis in renal tubular epithelial cells (TECs). Studies have shown that myricanol maintains muscle cell function by enhancing mitochondrial energy metabolism.

HYPOTHESIS

Myricanol delays renal fibrosis by maintaining mitochondrial integrity and inhibiting ferroptosis in TECs.

METHODS

Mice kidney lacking mitochondrial transcription factor A (TFAM), blood specimens, or pathological sections of renal tissue from patients with renal failure were used to explore the relationship between mitochondrial and renal functions. Erastin induced-TECs ferroptosis was used to study the potential mechanism by which TFAM regulates renal fibrosis. Chronic kidney disease (CKD) mice were utilized to explore the anti-fibrotic effects of myricanol.

RESULTS

The number of mitochondria and TFAM expression were decreased in human blood samples and pathological sections. Renal TFAM-deficient mice exhibited abnormalities in renal function, including ferroptosis and fibrosis. Ferrostatin-1 significantly inhibited renal fibrosis by preventing TECs ferroptosis. Transcriptional sequencing results indicated that zinc and ring finger 1 (ZNRF1) were important downstream genes of TFAM that regulate ferroptosis. We demonstrated that TFAM deficiency and ferroptosis, which destroyed interaction between ZNRF1 and the iron transport-related protein lipocalin-2 (LCN2), but myricanol clould reverse this effect. Overexpression of ZNRF1 efficiently maintained mitochondrial integrity and inhibited renal fibrosis. Myricanol ameliorated transforming growth factor β1-induced mitochondrial impairment. We firstly confirmed that myricanol efficiently improved renal function and suppresses fibrosis in CKD mice.

CONCLUSIONS

Myricanol efficiently inhibit fibrosis through activating TFAM to stimulate the interaction between ZNRF1 and LCN2.

Mechanism of initiation and regulation of axonal degeneration with special reference to NMNATs and Sarm1

Axonal degeneration is observed in a variety of contexts in both the central and peripheral nervous systems. Pathological signaling to regulate the progression of axonal degeneration has long been studied using Wallerian degeneration, the prototypical axonal degradation observed after injury, as a representative model. Understanding metabolism of nicotinamide adenine dinucleotide (NAD+) and the functional regulation of Sarm1 has generated great progress in this field, but there are a number of remaining questions. Here, in this short review, we describe our current understanding of the axonal degeneration mechanism, with special reference to the biology related to wlds mice and Sarm1. Furthermore, variations of axonal degeneration initiation are discussed in order to address the remaining questions needed for mechanistic clarification.

Optogenetics in Alzheimer's Disease: Focus on Astrocytes

Alzheimer's disease (AD) is the most common form of dementia, resulting in disability and mortality. The global incidence of AD is consistently surging. Although numerous therapeutic agents with promising potential have been developed, none have successfully treated AD to date. Consequently, the pursuit of novel methodologies to address neurodegenerative processes in AD remains a paramount endeavor. A particularly promising avenue in this search is optogenetics, enabling the manipulation of neuronal activity. In recent years, research attention has pivoted from neurons to glial cells. This review aims to consider the potential of the optogenetic correction of astrocyte metabolism as a promising strategy for correcting AD-related disorders. The initial segment of the review centers on the role of astrocytes in the genesis of neurodegeneration. Astrocytes have been implicated in several pathological processes associated with AD, encompassing the clearance of β-amyloid, neuroinflammation, excitotoxicity, oxidative stress, and lipid metabolism (along with a critical role in apolipoprotein E function). The effect of astrocyte-neuronal interactions will also be scrutinized. Furthermore, the review delves into a number of studies indicating that changes in cellular calcium (Ca2+) signaling are one of the causes of neurodegeneration. The review's latter section presents insights into the application of various optogenetic tools to manipulate astrocytic function as a means to counteract neurodegenerative changes.

Neuroprotective Effects of Licochalcone D in Oxidative-Stress-Induced Primitive Neural Stem Cells from Parkinson's Disease Patient-Derived iPSCs

Parkinson's disease (PD) is one of the most common neurodegenerative diseases caused by the loss of dopaminergic neurons in the substantia nigra pars compacta. Although the etiology of PD is still unclear, the death of dopaminergic neurons during PD progression was revealed to be associated with abnormal aggregation of α-synuclein, elevation of oxidative stress, dysfunction of mitochondrial functions, and increased neuroinflammation. In this study, the effects of Licochalcone D (LCD) on MG132-induced neurotoxicity in primitive neural stem cells (pNSCs) derived from reprogrammed iPSCs were investigated. A cell viability assay showed that LCD had anti-apoptotic properties in MG132-induced oxidative-stressed pNSCs. It was confirmed that apoptosis was reduced in pNSCs treated with LCD through 7-AAD/Annexin Ⅴ staining and cleaved caspase3. These effects of LCD were mediated through an interaction with JunD and through the EGFR/AKT and JNK signaling pathways. These findings suggest that LCD could be a potential antioxidant reagent for preventing disease-related pathological phenotypes of PD.

Selective phosphorylation of serine 345 on p47-phox serves as a priming signal of ROS-mediated axonal degeneration

Oxidative stress is a well-known inducer of two major neurodegenerative pathways, neuronal cell death and neurite degeneration. We previously reported that reactive oxygen species (ROS) generated by NADPH oxidases induces EGFR-dependent phosphorylation and activation of ZNRF1 ubiquitin ligase in neurons, which promotes neuronal cell death and neurite degeneration. While these findings provide a potential therapeutic avenue for neurodegeneration, a deeper understanding of the molecular mechanisms of this pathway have emerged as key points of interest. Here, we show that a NADPH oxidase subunit p47-phox/neutrophil cytosolic factor 1 regulates ZNRF1 activity. Using an in vitro neurite degeneration model, we demonstrate that transection-induced phosphorylation of p47-phox at the 345th serine residue by p38 MAPK serves as an initiating signal to activate ZNRF1. The phosphorylated p47 (pS345) or a phospho-mimetic mutant p47-phox binds directly to ZNRF1 whereas a phosphorylation-resistant mutant p47-phox cannot bind to ZNRF1 and its overexpression in neurites significantly suppresses ZNRF1 activation, AKT ubiquitination, and degeneration after transection, suggesting that pS345 might enhance the EGFR-mediated phosphorylation-dependent activation of ZNRF1. These results suggest that pS345 might represent an important checkpoint to initiate the ZNRF1-mediated neurite degeneration. Our findings provide novel insights into the mechanism of ROS-mediated neurodegeneration.

Repurposed anti-cancer epidermal growth factor receptor inhibitors: mechanisms of neuroprotective effects in Alzheimer's disease

Numerous molecular mechanisms are being examined in an attempt to discover disease-modifying drugs to slow down the underlying neurodegeneration in Alzheimer’s disease. Recent studies have shown the beneficial effects of epidermal growth factor receptor inhibitors on the enhancement of behavioral and pathological sequelae in Alzheimer’s disease. Despite the promising effects of epidermal growth factor receptor inhibitors in Alzheimer’s disease, there is no irrefutable neuroprotective evidence in well-established animal models using epidermal growth factor receptor inhibitors due to many un-explored downstream signaling pathways. This caused controversy about the potential involvement of epidermal growth factor receptor inhibitors in any prospective clinical trial. In this review, the mystery beyond the under-investigation of epidermal growth factor receptor in Alzheimer’s disease will be discussed. Furthermore, their molecular mechanisms in neurodegeneration will be explained. Also, we will shed light on SARS-COVID-19 induced neurological manifestations mediated by epidermal growth factor modulation. Finally, we will discuss future perspectives and under-examined epidermal growth factor receptor downstream signaling pathways that warrant more exploration. We conclude that epidermal growth factor receptor inhibitors are novel effective therapeutic approaches that require further research in attempts to be repositioned in the delay of Alzheimer’s disease progression.

Pharmacological Inhibition of Brain EGFR Activation By a BBB-penetrating Inhibitor, AZD3759, Attenuates α-synuclein Pathology in a Mouse Model of α-Synuclein Propagation

Aggregation and deposition of α-synuclein (α-syn) in Lewy bodies within dopamine neurons of substantia nigra (SN) is the pathological hallmark of Parkinson's disease (PD). These toxic α-syn aggregates are believed to propagate from neuron-to-neuron and spread the α-syn pathology throughout the brain beyond dopamine neurons in a prion-like manner. Targeting propagation of such α-syn aggregates is of high interest but requires identifying pathways involving in this process. Evidence from previous Alzheimer's disease reports suggests that EGFR may be involved in the prion-like propagation and seeding of amyloid-β. We show here that EGFR regulates the uptake of exogenous α-syn-PFFs and the levels of endogenous α-syn in cell cultures and a mouse model of α-syn propagation, respectively. Thus, we tested the therapeutic potentials of AZD3759, a highly selective BBB-penetrating EGFR inhibitor, in a preclinical mouse model of α-syn propagation. AZD3759 decreases activated EGFR levels in the brain and reduces phosphorylated α-synuclein (pSyn) pathology in brain sections, including striatum and SN. As AZD3759 is already in the clinic, this paper's results suggest a possible repositioning of AZD3759 as a disease-modifying approach for PD.

[Mechanism of axonal degeneration: from molecular signaling to the development of therapeutic applications]

Neurons communicate with other cells via long processes, i.e., axons and dendrites, functionally and morphologically specialized tree-like structures. Formation and maintenance of such processes play a crucial role in neuronal functions. Axons are particularly important for construction of neuronal network, and, together with synapses at the end of them, play a central role in transmission of information. Axonal degeneration, a phenomenon that once formed axons lose structural integrity, is most typically observed as "Wallerian degeneration", in which injured axonal segment (distal to the site of injury) degenerates. Different forms of axonal degeneration are also observed in a variety of contexts, including pathogenesis and progression of different neurodegenerative disorders, as well as neuronal network formation during development. Thus, understanding of regulatory mechanism of axonal degeneration is important in many aspects, such as for clarification of neuronal morphogenesis mechanism, and for development of neuroprotective therapy against neurological disorders. Here, I discuss recent progress in the research field of axonal degeneration mechanism.

Inhibition of Brain Epidermal Growth Factor Receptor Activation: A Novel Target in Neurodegenerative Diseases and Brain Injuries

Several reports have been published recently demonstrating a beneficial effect of epidermal growth factor receptor (EGFR) inhibitors in improving pathologic and behavioral conditions in neurodegenerative diseases (NDDs) such as Alzheimer's disease and Amyotrophic Lateral Sclerosis (ALS) as well as the brain and spinal cord injuries (SCI). Despite successful therapeutic effects of EGFR inhibition in these pathologic conditions, there is still no report of proof-of-concept studies in well-characterized animal models using recently developed blood-brain barrier (BBB)-penetrating EGFR inhibitors, which is due to previous conflicting reports concerning the level of EGFR or activated EGFR in normal and pathologic conditions that caused target engagement to be a concern in any future EGFR inhibition therapy. In this review, the level of EGFR expression and activation in the developing central nervous system (CNS) compared with the adult CNS will be explained as well as how neuronal injury or pathologic conditions, especially inflammation and amyloid fibrils, induce reactive astrocytes leading to an increase in the expression and activation of EGFR and, finally, neurodegeneration. Furthermore, in this review, we will discuss two main molecular mechanisms that can be proposed as the neuroprotective effects of EGFR inhibition in these pathologic conditions. We will also review the recent advances in the development of BBB-penetrating EGFR inhibitors in cancer therapy, which may eventually be repositioned for NDDs and SCI therapy in the future. SIGNIFICANCE STATEMENT: Based on the lessons from the applications of EGFR inhibitors in oncology, it is concluded that EGFR inhibitors can be beneficial in treatment of neurodegenerative diseases and spinal cord injuries. They carry their therapeutic potentials through induction of autophagy and attenuation of reactive astrocytes.

SIRT3, PP2A and TTP protein stability in the presence of TNF-α on vincristine-induced apoptosis of leukaemia cells

The contribution of vincristine (VCR)-induced microtubule destabilization to evoke apoptosis in cancer cells remains to be resolved. Thus, we investigated the cytotoxic mechanism of VCR on U937 and HL-60 human leukaemia cell lines. We discovered that VCR treatment resulted in the up-regulation of TNF-α expression and activation of the death receptor pathway, which evoked apoptosis of U937 cells. Moreover, VCR induced microtubule destabilization and mitotic arrest. VCR treatment down-regulated SIRT3, and such down-regulation caused mitochondrial ROS to initiate phosphorylation of p38 MAPK. p38 MAPK suppressed MID1-modulated degradation of the protein phosphatase 2A (PP2A) catalytic subunit. The SIRT3-ROS-p38 MAPK-PP2A axis inhibited tristetraprolin (TTP)-controlled TNF-α mRNA degradation, consequently, up-regulating TNF-α expression. Restoration of SIRT3 and TTP expression, or inhibition of the ROS-p38 MAPK axis increased the survival of VCR-treated cells and repressed TNF-α up-regulation. In contrast to suppression of the ROS-p38 MAPK axis, overexpression of SIRT3 modestly inhibited the effect of VCR on microtubule destabilization and mitotic arrest in U937 cells. Apoptosis of HL-60 cells, similarly, went through the same pathway. Collectively, our data indicate that the SIRT3-ROS-p38 MAPK-PP2A-TTP axis modulates TNF-α expression, which triggers apoptosis of VCR-treated U937 and HL-60 cells. We also demonstrate that the apoptotic signalling is not affected by VCR-elicited microtubule destabilization.