Neuroprotective Effects of CGP3466B on Apoptosis Are Modulated by Protein-L-isoaspartate (D-aspartate) O-methyltransferase/Mst1 Pathways after Traumatic Brain Injury in Rats

PCMT1 as a prognostic marker in breast cancer

INTRODUCTION

Triple-negative breast cancer (TNBC) is one of the most aggressive cancers in women, therefore it is necessary to determine novel prognostic markers to estimate survival and advancement the treatment of the disease. Recently, PCMT1, a protein mediating TNBC immune infiltration, has gained attention as a potential therapeutic target. The aim of the study was to demonstrate the relationship between PCMT1 protein overexpression as a prognostic indicator for patients with TNBC cancer and patient survival.

MATERIALS AND METHODS

The study included 64 samples collected from 64 TNBC patients. We used the ImageJ software with the IHC Profiler driver for image analysis. To improve the reliability of the results, we expanded the analysis by including The Cancer Genome Atlas cohort.

RESULTS

We observed strong PCMT1 immunoreactivity in breast cancer samples and PCMT1 expression in TNBC was significantly higher than in the control group. Patients with high PCMT1 expression had a significantly lower overall survival rate (60.62% vs. 90.35%, respectively) than patients with low PCMT1 expression. In our study and TCGA groups, PCMT1 expression did not correlate with lymph node involvement and distant metastases but correlated with tumor stage. The results obtained in a larger TCGA group are consistent with those in our research group. Overexpression of PCMT1 was a prognostic marker of shorter survival in patients with TNBC.

CONCLUSIONS

The overexpression of the PCMT1 protein in triple negative breast cancer significantly correlated with shorter overall survival. The confirmed association could be a potential prognostic biomarker for patients with TNBC.

Glucose-oxygen coupling can serve as a biomarker for neuroinflammation-related genetic variants

The single-nucleotide polymorphism rs3197999 in the macrophage-stimulating protein 1 gene is a missense variant. Studies have indicated that macrophage-stimulating protein 1 mediates neuronal loss and synaptic plasticity damage, and overexpression of the macrophage-stimulating protein 1 gene leads to the excessive activation of microglial cells, thereby resulting in an elevation of cerebral glucose metabolism. Traditional diagnostic models may be disrupted by neuroinflammation, making it difficult to predict the pathological status of patients solely based on single-modal images. We hypothesize that the macrophage-stimulating protein 1 rs3197999 single-nucleotide polymorphism may lead to imbalances in glucose and oxygen metabolism, thereby influencing cognitive resilience and the progression of Alzheimer's disease. In this study, we found that among 121 patients with mild cognitive impairment, carriers of the macrophage-stimulating protein 1 rs3197999 risk allele showed a significant reduction in the coupling of glucose and oxygen metabolism in the dorsolateral prefrontal cortex region. However, the rs3197999 variant did not induce significant differences in glucose metabolism and neuronal activity signals. Furthermore, the rs3197999 risk allele correlated with a higher rate of increase in clinical dementia score, mediated by the coupling of glucose and oxygen metabolism.

HIGHLIGHT

An update on the role of Hippo signaling pathway in ischemia-associated central nervous system diseases

The most frequent reason of morbidity and mortality in the world, cerebral ischemia sets off a chain of molecular and cellular pathologies that associated with some central nervous system (CNS) disorders mainly including ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy and other CNS diseases. In recent times, despite significant advancements in the treatment of the pathological processes underlying various neurological illnesses, effective therapeutic approaches that are specifically targeted to minimizing the damage of such diseases remain absent. Hippo signaling pathway, characterized by enzyme linked reactions between MSTI/2, LAST1/2, and YAP or TAZ proteins, controls cell division, survival, and differentiation, as well as being engaged in a variety of biological activities, such as the development and transformation of the nervous system. Recently, accumulating studies demonstrated that Hippo pathway takes part in the processes of ischemic stroke, AD, PD, etc., including but not limited to oxidative stress, inflammatory response, blood-brain barrier damage, mitochondrial disorders, and neural cells death. Thus, it's crucial to understand the molecular basis of the Hippo signaling pathway for determining potential new therapeutic targets against ischemia-associated CNS diseases. Here, we discuss latest advances in the deciphering of the Hippo signaling pathway and highlight the therapeutic potential of targeting the pathway in treating ischemia-associated CNS diseases.

Genome-Wide Screening in Human Embryonic Stem Cells Highlights the Hippo Signaling Pathway as Granting Synthetic Viability in ATM Deficiency

ATM depletion is associated with the multisystemic neurodegenerative syndrome ataxia-telangiectasia (A-T). The exact linkage between neurodegeneration and ATM deficiency has not been established yet, and no treatment is currently available. In this study, we aimed to identify synthetic viable genes in ATM deficiency to highlight potential targets for the treatment of neurodegeneration in A-T. We inhibited ATM kinase activity using the background of a genome-wide haploid pluripotent CRISPR/Cas9 loss-of-function library and examined which mutations confer a growth advantage on ATM-deficient cells specifically. Pathway enrichment analysis of the results revealed the Hippo signaling pathway as a major negative regulator of cellular growth upon ATM inhibition. Indeed, genetic perturbation of the Hippo pathway genes SAV1 and NF2, as well as chemical inhibition of this pathway, specifically promoted the growth of ATM-knockout cells. This effect was demonstrated in both human embryonic stem cells and neural progenitor cells. Therefore, we suggest the Hippo pathway as a candidate target for the treatment of the devastating cerebellar atrophy associated with A-T. In addition to the Hippo pathway, our work points out additional genes, such as the apoptotic regulator BAG6, as synthetic viable with ATM-deficiency. These genes may help to develop drugs for the treatment of A-T patients as well as to define biomarkers for resistance to ATM inhibition-based chemotherapies and to gain new insights into the ATM genetic network.

Therapeutic potential of blocking GAPDH nitrosylation with CGP3466b in experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a neuroinflammatory disease of the central nervous system (CNS). Although classically considered a demyelinating disease, neuroaxonal injury occurs in both the acute and chronic phases and represents a pathologic substrate of disability not targeted by current therapies. Nitric oxide (NO) generated by CNS macrophages and microglia contributes to neuroaxonal injury in all phases of MS, but candidate therapies that prevent NO-mediated injury have not been identified. Here, we demonstrate that the multifunctional protein glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is robustly nitrosylated in the CNS in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. GAPDH nitrosylation is blocked in vivo with daily administration of CGP3466b, a CNS-penetrant compound with an established safety profile in humans. Consistent with the known role of nitrosylated GAPDH (SNO-GAPDH) in neuronal cell death, blockade of SNO-GAPDH with CGP3466b attenuates neurologic disability and reduces axonal injury in EAE independent of effects on the immune system. Our findings suggest that SNO-GAPDH contributes to neuroaxonal injury during neuroinflammation and identify CGP3466b as a candidate neuroprotective therapy in MS.

S-Glutathionylation and S-Nitrosylation in Mitochondria: Focus on Homeostasis and Neurodegenerative Diseases

Redox post-translational modifications are derived from fluctuations in the redox potential and modulate protein function, localization, activity and structure. Amongst the oxidative reversible modifications, the S-glutathionylation of proteins was the first to be characterized as a post-translational modification, which primarily protects proteins from irreversible oxidation. However, a growing body of evidence suggests that S-glutathionylation plays a key role in core cell processes, particularly in mitochondria, which are the main source of reactive oxygen species. S-nitrosylation, another post-translational modification, was identified >150 years ago, but it was re-introduced as a prototype cell-signaling mechanism only recently, one that tightly regulates core processes within the cell’s sub-compartments, especially in mitochondria. S-glutathionylation and S-nitrosylation are modulated by fluctuations in reactive oxygen and nitrogen species and, in turn, orchestrate mitochondrial bioenergetics machinery, morphology, nutrients metabolism and apoptosis. In many neurodegenerative disorders, mitochondria dysfunction and oxidative/nitrosative stresses trigger or exacerbate their pathologies. Despite the substantial amount of research for most of these disorders, there are no successful treatments, while antioxidant supplementation failed in the majority of clinical trials. Herein, we discuss how S-glutathionylation and S-nitrosylation interfere in mitochondrial homeostasis and how the deregulation of these modifications is associated with Alzheimer’s, Parkinson’s, amyotrophic lateral sclerosis and Friedreich’s ataxia.

The enzyme L-isoaspartyl (D-aspartyl) methyltransferase promotes migration and invasion in human U-87 MG and U-251 MG glioblastoma cell lines

The protein L-isoaspartyl (D-aspartyl) methyltransferase (PIMT) recognizes abnormal L-isoaspartyl and D-aspartyl residues in proteins. Among examined tissues, PIMT shows the highest level in the brain. The U-87 MG cell line is a commonly used cellular model to study the most frequent brain tumor, glioblastoma. Previously, we reported that PIMT amount increased when U-87 MG cells were detached from the extracellular matrix. Recently, we also showed that PIMT possessed pro-angiogenic properties. Together, these PIMT features led us to postulate that PIMT could play a critical role in glioblastoma growth. Here, we investigate PIMT role in U-87 MG cell viability, adhesion, migration, invasion, and colony formation and in the reorganization of the actin and tubulin cytoskeleton. PIMT inhibition by siRNA significantly reduced in vitro cell migration and invasion in various assays, including wound-healing assay, Boyden chambers coated with gelatin and Matrigel invasion assay. Conversely, in stably transfected U-87 MG cells overexpressing wild-type PIMT, cell migration, invasive capacity and colony formation significantly increased. However, in stably transfected cells with the gene encoding for mutated PIMT(D83V), despite of its overexpression, migration and invasion remained similar to those observed in control cells. In all these conditions, cell viability was unaffected. Importantly, overexpressed wild-type PIMT and mutated PIMT(D83V) have opposite effects on the organization of microtubules and actin cytoskeleton and thus on morphology of U-87 cells. These data highlighted the importance of PIMT level and its catalytic activity in migration and invasion of U-87 glioma cells and its possible contribution in cancer invasion during glioma growth.

Hippo signaling: bridging the gap between cancer and neurodegenerative disorders

During development, regulation of organ size requires a balance between cell proliferation, growth and cell death. Dysregulation of these fundamental processes can cause a variety of diseases. Excessive cell proliferation results in cancer whereas excessive cell death results in neurodegenerative disorders. Many signaling pathways known-to-date have a role in growth regulation. Among them, evolutionarily conserved Hippo signaling pathway is unique as it controls both cell proliferation and cell death by a variety of mechanisms during organ sculpture and development. Neurodegeneration, a complex process of progressive death of neuronal population, results in fatal disorders with no available cure to date. During normal development, cell death is required for sculpting of an organ. However, aberrant cell death in neuronal cell population can result in neurodegenerative disorders. Hippo pathway has gathered major attention for its role in growth regulation and cancer, however, other functions like its role in neurodegeneration are also emerging rapidly. This review highlights the role of Hippo signaling in cell death and neurodegenerative diseases and provide the information on the chemical inhibitors employed to block Hippo pathway. Understanding Hippo mediated cell death mechanisms will aid in development of reliable and effective therapeutic strategies in future.

Redox Post-translational Modifications of Protein Thiols in Brain Aging and Neurodegenerative Conditions-Focus on S-Nitrosation

Reactive oxygen species and reactive nitrogen species (RONS) are by-products of aerobic metabolism. RONS trigger a signaling cascade that can be transduced through oxidation-reduction (redox)-based post-translational modifications (redox PTMs) of protein thiols. This redox signaling is essential for normal cellular physiology and coordinately regulates the function of redox-sensitive proteins. It plays a particularly important role in the brain, which is a major producer of RONS. Aberrant redox PTMs of protein thiols can impair protein function and are associated with several diseases. This mini review article aims to evaluate the role of redox PTMs of protein thiols, in particular S-nitrosation, in brain aging, and in neurodegenerative diseases. It also discusses the potential of using redox-based therapeutic approaches for neurodegenerative conditions.

Injury to dopaminergic neurons development via the Lmx1a/Wnt1 autoregulatory loop induced by simazine

Simazine is a kind of persistent organic pollutant that is detected in both ground and water and has several routes of exposure. Here, we explored the mechanisms underlying simazine-related effects on dopaminergic neurons via development-related factors using mouse embryos and embryonic mesencephalic hybrid cell line (MN9D cells). We treated pregnant mice with 50 μg/kg bw, 200 μg/kg bw simazine from the 0.5 day to the 10.5 day of embryonic phase and MN9D cells with 600 μM simazine for 24 h to research the mechanism of dopaminergic neurons acute respond to simazine through preliminary experiments. Protein expressions of LIM homeobox transcription factor 1-alpha (Lmx1a) and LIM homeobox transcription factor 1-beta (Lmx1b) displayed a dose- and time-dependent increase after the exposure to simazine. In the 200 μg/kg bw of embryos and the 24h-600 μM of MN9D cells, protein levels of dopaminergic developmental factors were significantly upregulated, and dopaminergic function was significantly damaged for the abnormal expression of Dyt5b. We demonstrated simazine induced the injury to dopaminergic neurons via the Lmx1a/wingless-related integration site 1 (Wnt1) and Lmx1b pathways. In the transfection experiments, we knocked down Lmx1a and Lmx1b of cells to verify the potential target of simazine-induced injury to dopaminergic neurons, respectively. We detected the protein and mRNA levels of development-related genes of dopaminergic neurons and intracellular dopamine levels in different treatment groups. Based on our experiments' results, we demonstrated an acute response to 24 h-600 μM simazine treatment, the simazine-induced injury to dopaminergic neuronal which leads to abnormal dopamine levels and dopaminergic impairment is via the activation of the Lmx1a/Wnt1 autoregulatory loop. Lmx1a is a promising target in the search for the mechanisms underlying simazine-induced dopaminergic injury.

Neural stem cell conditioned medium alleviates Aβ25-35 damage to SH-SY5Y cells through the PCMT1/MST1 pathway

Alzheimer's disease (AD) is a progressive, neurodegenerative disease. Accumulating evidence suggests that protein isoaspartate methyltransferase 1 (PCMT1) is highly expressed in brain tissue (substantia nigra, blue plaque, paraventricular nucleus). In this study, we investigated the effect of neural stem cell conditioned medium alleviates Aβ25-35 damage to SH-SY5Y cells by PCMT1/MST1 pathway. Results demonstrated that Aβ25-35 significantly decreased the cell viability in time and dose dependent manner. However, Neural stem cell-complete medium (NSC-CPM) or NSC-CDM had inhibitory effect on toxicity when fibrillation of Aβ25-35 occurred in their presence and NSC-CDM had a better inhibitor result. An increase of the PCMT1 expression levels was found in Aβ25-35 + NSC-CDM group. sh-PCMT1 significantly reduced the PCMT1, the cell viability and inhibited the protective effect; induced apoptosis and increased the expression of p-MST1. Overexpression of PCMT1 group reversed the effect of Aβ25-35 inhibited the cell viability and Aβ25-35 induced the apoptosis. In conclusion, NSC-CDM corrects the damage of Aβ25-35 to cells by increasing PCMT1, reducing MST phosphorylation.

The role of medical gas in stroke: an updated review

Medical gas is a large class of bioactive gases used in clinical medicine and basic scientific research. At present, the role of medical gas in neuroprotection has received growing attention. Stroke is a leading cause of death and disability in adults worldwide, but current treatment is still very limited. The common pathological changes of these two types of stroke may include excitotoxicity, free radical release, inflammation, cell death, mitochondrial disorder, and blood-brain barrier disruption. In this review, we will discuss the pathological mechanisms of stroke and the role of two medical gases (hydrogen and hydrogen sulfide) in stroke, which may potentially provide a new insight into the treatment of stroke.

The emerging role of Hippo signaling in neurodegeneration

Neurodegeneration refers to the complex process of progressive degeneration or neuronal apoptosis leading to a set of incurable and debilitating conditions. Physiologically, apoptosis is important in proper growth and development. However, aberrant and unrestricted apoptosis can lead to a variety of degenerative conditions including neurodegenerative diseases. Although dysregulated apoptosis has been implicated in various neurodegenerative disorders, the triggers and molecular mechanisms underlying such untimely and faulty apoptosis are still unknown. Hippo signaling pathway is one such apoptosis-regulating mechanism that has remained evolutionarily conserved from Drosophila to mammals. This pathway has gained a lot of attention for its tumor-suppressing task, but recent studies have emphasized the soaring role of this pathway in inflaming neurodegeneration. In addition, strategies promoting inactivation of this pathway have aided in the rescue of neurons from anomalous apoptosis. So, a thorough understanding of the relationship between the Hippo pathway and neurodegeneration may serve as a guide for the development of therapy for various degenerative diseases. The current review focuses on the mechanism of the Hippo signaling pathway, its upstream and downstream regulatory molecules, and its role in the genesis of numerous neurodegenerative diseases. The recent efforts employing the Hippo pathway components as targets for checking neurodegeneration have also been highlighted.

Induction of Neuronal PI3Kγ Contributes to Endoplasmic Reticulum Stress and Long-Term Functional Impairment in a Murine Model of Traumatic Brain Injury

Phosphoinositide 3-kinase γ (PI3Kγ) expressed in immune cells is linked to neuroinflammation in several neurological diseases. However, the expression and role of PI3Kγ in preclinical traumatic brain injury (TBI) have not been investigated. In WT mice, we found that TBI induced rapid and extensive expression of PI3Kγ in neurons within the perilesional cortex and the ipsilateral hippocampal subfields (CA1, CA3), which peaked between 1 and 3 days and declined significantly 7 days after TBI. Intriguingly, the induction of neuronal PI3Kγ in these subregions of the brain spatiotemporally coincided with both the TBI-induced activation of the neuronal ER stress pathway (p-eIF2α, ATF4, and CHOP) and neuronal cell death (marked by TUNEL-positive neurons) 3 days after TBI. Further, we show that the absence of PI3Kγ in knockout mice profoundly reduced the TBI-induced activation of the ER stress pathway and neuronal cell death. White matter disruption is a better predictor of long-term clinical outcomes than focal lesion size. We show that PI3Kγ deficiency not only reduced brain tissue loss but also alleviated white matter injury (determined by axonal injury and demyelination) up to 28 days after TBI. Importantly, PI3Kγ-knockout mice exhibited greater functional recovery including forepaw use, sensorimotor balance and coordination, and spatial learning and memory up to 28 days after TBI. These results unveil a previously unappreciated role for neuronal PI3Kγ in the regulation of ER stress associated with neuronal cell death, white matter damage, and long-term functional impairment after TBI.

AH6809 decreases production of inflammatory mediators by PGE2 - EP2 - cAMP signaling pathway in an experimentally induced pure cerebral concussion in rats

Increasing evidence suggests that PGE₂ metabolic pathway is involved in pathological changes of the secondary brain injury after traumatic brain injury. However, the underlying mechanisms, in particular, the correlation between various key enzymes and the brain injury, has remained to be fully explored. More specifically, it remains to be ascertained whether AH6809 (an EP2 receptor antagonist) would interfere with the downstream of the PGE₂, regulate the inflammatory mediators and improve neuronal damage in the hippocampus by PGE₂ - EP2 - cAMP signaling pathway. The expression and pathological changes of cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), microsomal prostaglandin-E synthase-1 (mPGES-1), E-prostanoid receptor 2 (EP2), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and inducible nitricoxide synthase (iNOS) in the CA1 area of hippocampus were evaluated by immunohistochemistry, Western blot and RT-PCR after pure cerebral concussion (PCC) induced by a metal pendulum closed brain injury in rats followed by AH6809 treatment. The morphology and number of neurons in CA1 region were analyzed by cresyl violet staining. The concentration of prostaglandin E₂ (PGE₂) and cyclic adenosine monophosphate (cAMP) was assayed by ELISA. Many neurons in hippocampal CA1 area appeared to undergo necrosis and the number of neurons was concomitantly reduced after PCC injury. With the passage of time, the protein and mRNA expression of various key enzymes including COX-1, COX-2 and mPGES-1, EP2 receptor, and inflammatory mediators including TNF-α, IL-1β and iNOS was increased; meanwhile, the concentration of PGE₂ and cAMP was enhanced. After PCC injury given AH6809 intervention, injury of neurons in hippocampal CA1 area was attenuated. The protein and mRNA expression of COX-1, COX-2, mPGES-1, EP2, TNF-α, IL-1β and iNOS was decreased, this was coupled with reduction of PGE₂ and cAMP. The results suggest that PGE₂ metabolic pathway is involved in secondary pathological changes of PCC. AH6809 improves the recovery of injured neurons in the hippocampal CA1 area and downregulates the inflammatory mediators by PGE₂ - EP2 - cAMP signaling pathway.