Cu-Zn superoxide dismutase activates muscarinic acetylcholine M1 receptor pathway in neuroblastoma cells

Lipopolysaccharide-Preconditioned Dental Follicle Stem Cells Derived Small Extracellular Vesicles Treating Periodontitis via Reactive Oxygen Species/Mitogen-Activated Protein Kinase Signaling-Mediated Antioxidant Effect

Purpose

Lipopolysaccharide (LPS) pretreatment can enhance the therapeutic effect of dental follicle stem cells-derived small extracellular vesicles (DFC-sEV) for periodontitis, and this study aimed to investigate the underlying mechanisms and clinical application Of LPS-preconditioned DFC-sEV in periodontitis.

Methods

The protein spectrum of DFC-sEV before and after LPS pretreatment was determined by liquid chromatography-tandem mass spectrometry and bioinformatic analysis. Their effects on inflammatory periodontal ligament stem cells (PDLSCs) and macrophages were investigated for cell proliferation, migration, type 2 macrophage (M2) polarization, and intracellular reactive oxygen species (ROS) levels separately. In addition, the regulation of ROS/Jun amino-terminal kinases (JNK) and ROS/extracellular signal-related kinases (ERK) signaling by LPS-preconditioned DFC-sEV was also studied to reveal the antioxidant mechanism. In vivo, two kinds of DFC-sEV loaded with 0.2% hyaluronic acid (HA) gel were applied for canine periodontitis to evaluate the therapeutic potential.

Results

The proteomic analysis showed that thirty-eight proteins were differentially expressed in LPS-preconditioned DFC-sEV, and interestingly, the highly expressed proteins were mainly involved in antioxidant and enzyme-regulating activities. In addition to promoting PDLSCs and macrophage proliferation, LPS-preconditioned DFC-sEV inhibited intracellular ROS as an antioxidant. It reduced the RANKL/OPG ratio of PDLSCs by inhibiting ROS/JNK signaling under inflammatory conditions and promoted macrophages to polarize toward the M2 phenotype via ROS/ERK signaling. Furthermore, LPS-preconditioned DFC-sEV loaded with the HA injectable system could sustainably release sEV and enhance the therapeutic efficacy for periodontitis in canines.

Conclusion

LPS-preconditioned DFC-sEV could be effectively used as an auxiliary method for periodontitis treatment via antioxidant effects in a subgingival environment, and loading it with HA is feasible and effective for clinical applications.

The Impact of the Renin-Angiotensin-Aldosterone System on Inflammation, Coagulation, and Atherothrombotic Complications, and to Aggravated COVID-19

Atherosclerosis is considered a disease caused by a chronic inflammation, associated with endothelial dysfunction, and several mediators of inflammation are up-regulated in subjects with atherosclerotic disease. Healthy, intact endothelium exhibits an antithrombotic, protective surface between the vascular lumen and vascular smooth muscle cells in the vessel wall. Oxidative stress is an imbalance between anti- and prooxidants, with a subsequent increase of reactive oxygen species, leading to tissue damage. The renin-angiotensin-aldosterone system is of vital importance in the pathobiology of vascular disease. Convincing data indicate that angiotensin II accelerates hypertension and augments the production of reactive oxygen species. This leads to the generation of a proinflammatory phenotype in human endothelial and vascular smooth muscle cells by the up-regulation of adhesion molecules, chemokines and cytokines. In addition, angiotensin II also seems to increase thrombin generation, possibly via a direct impact on tissue factor. However, the mechanism of cross-talk between inflammation and haemostasis can also contribute to prothrombotic states in inflammatory environments. Thus, blocking of the renin-angiotensin-aldosterone system might be an approach to reduce both inflammatory and thrombotic complications in high-risk patients. During COVID-19, the renin-angiotensin-aldosterone system may be activated. The levels of angiotensin II could contribute to the ongoing inflammation, which might result in a cytokine storm, a complication that significantly impairs prognosis. At the outbreak of COVID-19 concerns were raised about the use of angiotensin converting enzyme inhibitors and angiotensin receptor blocker drugs in patients with COVID-19 and hypertension or other cardiovascular comorbidities. However, the present evidence is in favor of continuing to use of these drugs. Based on experimental evidence, blocking the renin-angiotensin-aldosterone system might even exert a potentially protective influence in the setting of COVID-19.

Superoxide Dismutase 1 in Health and Disease: How a Frontline Antioxidant Becomes Neurotoxic

Cu/Zn superoxide dismutase (SOD1) is a frontline antioxidant enzyme catalysing superoxide breakdown and is important for most forms of eukaryotic life. The evolution of aerobic respiration by mitochondria increased cellular production of superoxide, resulting in an increased reliance upon SOD1. Consistent with the importance of SOD1 for cellular health, many human diseases of the central nervous system involve perturbations in SOD1 biology. But far from providing a simple demonstration of how disease arises from SOD1 loss-of-function, attempts to elucidate pathways by which atypical SOD1 biology leads to neurodegeneration have revealed unexpectedly complex molecular characteristics delineating healthy, functional SOD1 protein from that which likely contributes to central nervous system disease. This review summarises current understanding of SOD1 biology from SOD1 genetics through to protein function and stability.

Superoxide Dismutase Administration: A Review of Proposed Human Uses

Superoxide dismutases (SODs) are metalloenzymes that play a major role in antioxidant defense against oxidative stress in the body. SOD supplementation may therefore trigger the endogenous antioxidant machinery for the neutralization of free-radical excess and be used in a variety of pathological settings. This paper aimed to provide an extensive review of the possible uses of SODs in a range of pathological settings, as well as describe the current pitfalls and the delivery strategies that are in development to solve bioavailability issues. We carried out a PubMed query, using the keywords "SOD", "SOD mimetics", "SOD supplementation", which included papers published in the English language, between 2012 and 2020, on the potential therapeutic applications of SODs, including detoxification strategies. As highlighted in this paper, it can be argued that the generic antioxidant effects of SODs are beneficial under all tested conditions, from ocular and cardiovascular diseases to neurodegenerative disorders and metabolic diseases, including diabetes and its complications and obesity. However, it must be underlined that clinical evidence for its efficacy is limited and consequently, this efficacy is currently far from being demonstrated.

5-Hydroxytryptamine Modulates Maturation and Mitochondria Function of Human Oligodendrocyte Progenitor M03-13 Cells

Inside the adult CNS, oligodendrocyte progenitor cells (OPC_S) are able to proliferate, migrate and differentiate into mature oligodendrocytes (OLs) which are responsible for the production of myelin sheet and energy supply for neurons. Moreover, in demyelinating diseases, OPCs are recruited to the lesion areas where they undergo differentiation and myelin synthesis. Serotonin (5-hydroxytryptamine, 5-HT) is involved in OLs’ development and myelination, but so far the molecular mechanisms involved or the effects of 5-HT on mitochondria function have not yet been well documented. Our data show that 5-HT inhibits migration and proliferation committing cells toward differentiation in an immortalized human oligodendrocyte precursor cell line, M03-13. Migration blockage is mediated by reactive oxygen species (ROS) generation since antioxidants, such as Vit C and Cu-Zn superoxide dismutase, prevent the inhibitory effects of 5-HT on cell migration. 5-HT inhibits OPC migration and proliferation and increases OL phenotypic markers myelin basic protein (MBP) and Olig-2 via protein kinase C (PKC) activation since the inhibitor of PKC, bis-indolyl-maleimide (BIM), counteracts 5-HT effects. NOX inhibitors as well, reverse the effects of 5-HT, indicating that 5-HT influences the maturation process of OPCs by NOX-dependent ROS production. Finally, 5-HT increases mitochondria function and antioxidant activity. The identification of the molecular mechanisms underlying the effects of 5-HT on maturation and energy metabolism of OPCs could pave the way for the development of new treatments for autoimmune demyelinating diseases such as Multiple Sclerosis where oligodendrocytes are the primary target of immune attack.

Metabolism Regulation and Redox State: Insight into the Role of Superoxide Dismutase 1

Energy metabolism and redox state are strictly linked; energy metabolism is a source of reactive oxygen species (ROS) that, in turn, regulate the flux of metabolic pathways. Moreover, to assure redox homeostasis, metabolic pathways and antioxidant systems are often coordinately regulated. Several findings show that superoxide dismutase 1 (SOD1) enzyme has effects that go beyond its superoxide dismutase activity and that its functions are not limited to the intracellular compartment. Indeed, SOD1 is secreted through unconventional secretory pathways, carries out paracrine functions and circulates in the blood bound to lipoproteins. Striking experimental evidence links SOD1 to the redox regulation of metabolism. Important clues are provided by the systemic effects on energy metabolism observed in mutant SOD1-mediated amyotrophic lateral sclerosis (ALS). The purpose of this review is to analyze in detail the involvement of SOD1 in redox regulation of metabolism, nutrient sensing, cholesterol metabolism and regulation of mitochondrial respiration. The scientific literature on the relationship between ALS, mutated SOD1 and metabolism will also be explored, in order to highlight the metabolic functions of SOD1 whose biological role still presents numerous unexplored aspects that deserve further investigation.

Effect of beta- and alpha-glucans on immune modulating factors expression in enterocyte-like Caco-2 and goblet-like LS 174T cells

Glucans are complex polysaccharides consisting of repeated units of d-glucose linked by glycosidic bonds. The nutritional contribution in α-glucans is mainly given by starch and glycogen while in β-glucans by mushrooms, yeasts and whole grains, such as barley and spelt well represented in the Mediterranean Diet. Numerous and extensive studies performed on glucans highlighted their marked anti-tumor, antioxidant and immunomodulatory activity. It has recently been shown that rather than merely being a passive barrier, the intestinal epithelium is an essential modulator of immunity. Indeed, epithelial absorptive enterocytes and mucin secreting goblet cells can produce specific immune modulating factors, driving innate immunity to pathogens as well as preventing autoimmunity. Despite the clear evidence of the effects of glucans on immune system cells, there are only limited data about their effects on immune activity of mucosal intestinal cells strictly related to intestinal barrier integrity. The aim of the study was to evaluate the effects of α and β glucans, alone or in combination with other substances with antioxidant properties, on reactive oxygen species (ROS) levels, on the expression of ROS-generating enzyme DUOX-2 and of the immune modulating factors Tumor Necrosis Factor (TNF-α), Interleukin 1 β (IL-1β) and cyclooxygenase-2 (COX-2) in two intestinal epithelial cells, the enterocyte-like Caco-2 cells and goblet cell-like LS174T. In our research, the experiments were carried out incubating the cells with glucans for 18 h in culture medium containing 0.2% FBS and measuring ROS levels fluorimetrically as dihydrodichlorofluoresce diacetate (DCF-DA) fluorescence, protein levels of DUOX-2 by Western blotting and mRNA levels of, TNF-α, IL-1β and COX-2 by qRT-PCR. α and β glucans decreased ROS levels in Caco-2 and LS 174T cells. The expression levels of COX-2, TNF-α, and IL-1β were also reduced by α- and β-glucans. Additive effects on the expression of these immune modulating factors were exerted by vitamin C. In Caco-2 cells, the dual oxidase DUOX-2 expression is positively modulated by ROS. Accordingly, in Caco-2 or LS174T cells treated with α and β-glucans alone or in combination with Vitamin C, the decrease of ROS levels was associated with a reduced expression of DUOX-2. The treatment of cells with the NADPH oxidase (NOX) inhibitor apocynin decrease ROS, DUOX-2, COX-2, TNF-α and IL-1β levels indicating that NOX dependent ROS regulate the expression of immune modulating factors of intestinal cells. However, the combination of vitamin C, α and β-glucans with apocynin did not exert an additive effect on COX-2, TNF-α and IL-1β levels when compared with α-, β-glucans and Vitamin C alone. The present study showing a modulatory effect of α and β-glucans on ROS and on the expression of immune modulating factors in intestinal epithelial cells suggests that the assumption of food containing high levels of these substances or dietary supplementation can contribute to normal immunomodulatory function of intestinal barrier.

Dual Role of Reactive Oxygen Species in Muscle Function: Can Antioxidant Dietary Supplements Counteract Age-Related Sarcopenia?

Sarcopenia is characterized by the progressive loss of skeletal muscle mass and strength. In older people, malnutrition and physical inactivity are often associated with sarcopenia, and, therefore, dietary interventions and exercise must be considered to prevent, delay, or treat it. Among the pathophysiological mechanisms leading to sarcopenia, a key role is played by an increase in reactive oxygen and nitrogen species (ROS/RNS) levels and a decrease in enzymatic antioxidant protection leading to oxidative stress. Many studies have evaluated, in addition to the effects of exercise, the effects of antioxidant dietary supplements in limiting age-related muscle mass and performance, but the data which have been reported are conflicting. In skeletal muscle, ROS/RNS have a dual function: at low levels they increase muscle force and adaptation to exercise, while at high levels they lead to a decline of muscle performance. Controversial results obtained with antioxidant supplementation in older persons could in part reflect the lack of univocal effects of ROS on muscle mass and function. The purpose of this review is to examine the molecular mechanisms underlying the dual effects of ROS in skeletal muscle function and the analysis of literature data on dietary antioxidant supplementation associated with exercise in normal and sarcopenic subjects.

Carcinogenesis and Reactive Oxygen Species Signaling: Interaction of the NADPH Oxidase NOX1-5 and Superoxide Dismutase 1-3 Signal Transduction Pathways

SIGNIFICANCE

Reduction/oxidation (redox) balance could be defined as an even distribution of reduction and oxidation complementary processes and their reaction end products. There is a consensus that aberrant levels of reactive oxygen species (ROS), commonly observed in cancer, stimulate primary cell immortalization and progression of carcinogenesis. However, the mechanism how different ROS regulate redox balance is not completely understood. Recent Advances: In the current review, we have summarized the main signaling cascades inducing NADPH oxidase NOX1-5 and superoxide dismutase (SOD) 1-3 expression and their connection to cell proliferation, immortalization, transformation, and CD34+ cell differentiation in thyroid, colon, lung, breast, and hematological cancers.

CRITICAL ISSUES

Interestingly, many of the signaling pathways activating redox enzymes or mediating the effect of ROS are common, such as pathways initiated from G protein-coupled receptors and tyrosine kinase receptors involving protein kinase A, phospholipase C, calcium, and small GTPase signaling molecules.

FUTURE DIRECTIONS

The clarification of interaction of signal transduction pathways could explain how cells regulate redox balance and may even provide means to inhibit the accumulation of harmful levels of ROS in human pathologies.

Effect of Mutated Cu, Zn Superoxide Dismutase (SOD1G93A) on Modulation of Transductional Pathway Mediated by M1 Muscarinic Receptor in SK-N-BE and NSC-34 Cells

The constitutive secretion of antioxidant Cu-Zn Superoxide dismutase (SOD1) has been widely demonstrated in many cellular lines. In addition, we showed that as well as the basal SOD1 secretion, this enzyme is also exported through depolarization of excitable cells by high extracellular K concentration. Recent data showed that SOD1 was able to activate muscarinic M1 receptor producing the activation, via phospholipase C, of ERK1-2 and AKT pathways. It is also known that about 20% of familial amyotrophic lateral sclerosis (fALS) is due to mutations in the gene coding for SOD1. The aim of the present research is to evaluate whether, analogously to wild type SOD1 (SOD1^wt), the mutated form of SOD1^G93A is able to activate ERK1-2 and AKT through muscarinic M1 receptor in SK-N-BE as well as in motoneuron like NSC-34. Our results demonstrated that in NSC-34 and SK-N-BE cells mutated SOD1^G93A carried out a more evident activation of ERK1-2 and AKT and a stronger increase of intracellular calcium levels compared to SOD1^WT; we also demonstrated that these effects are mediated by the M1 receptor as shown using pirenzepine, a specific M1 inhibitor and the calcium chelator BAPTA. Of note, M1 receptor pathway activation by SOD1G93A, but not by SOD1WT, is associated with both an increase of reactive oxygen species and a cytotoxic effect.

Quercetin Increases MUC2 and MUC5AC Gene Expression and Secretion in Intestinal Goblet Cell-Like LS174T via PLC/PKCα/ERK1-2 Pathway

The main dietary flavonoid quercetin, is known to preserve the integrity of gastrointestinal barrier and to have anti-inflammatory, anti-cancer, anti-fibrotic, and other beneficial properties. Many of the biological effects of quercetin appear to be associated to the modulation of cell signaling pathways, rather than to its antioxidant activity. In spite of the large number of data available on the molecular and cellular mechanisms by which quercetin exerts its biological effects, including protection of intestinal barrier function, there is a lack of data about the role of this substance on the expression and/or the secretion of mucins released by intestinal goblet cells. Here we investigated the effects of quercetin on the secretion and the gene expression of the main intestinal gel-forming mucins, MUC2 and MUC5AC, and the signaling mechanisms underlined, in human intestinal goblet cell-like LS174T. We found that quercetin increases intracellular Ca²⁺ levels and induces MUC2 and MUC5AC secretion in a Ca²⁺-dependent manner. Quercetin also induces mRNA levels of both secretory mucins. Quercetin stimulation of LS174T cells increases phosphorylation levels of extracellular signal regulated kinase (ERK)1-2 and protein kinase C (PKC) α and the induction of MUC2 and MUC5AC secretion and mRNA relies on phospholipase C (PLC), PKC, and ERK1-2 signaling pathways since the PLC inhibitor U73122, the PKC inhibitor bisindolylmaleimide (BIM) and the ERK1-2 pathway inhibitor PD98059, all revert the stimulatory effects of quercetin. We also demonstrated that the induction of mucin gene expression by quercetin is not limited to goblet cells. Indeed, quercetin induces mRNA levels of MUC2 and MUC5AC via PKCα/ERK1-2 pathway also in the human intestinal epithelial Caco-2 cells. These data highlight a novel mechanism thereby quercetin, regulating the secretory function of intestinal goblet cells and mucin levels in enterocytes may exert its protective effects on intestinal mucosal barrier.

Curcumin inhibits superoxide dismutase-induced epithelial-to-mesenchymal transition via the PI3K/Akt/NF-κB pathway in pancreatic cancer cells

Curcumin is a natural polyphenol compound derived from turmeric. It possesses multiple pharmacological properties, including antioxidant, anti-inflammatory and anti-tumor progression properties. Our recent study demonstrated that superoxide dismutase (SOD)-dependent production of hydrogen peroxide (H2O2) promoted the invasive and migratory activity of pancreatic cancer cells. However, whether curcumin suppresses SOD-induced cancer progression and the related mechanisms remains unclear. Since epithelial‑to-mesenchymal transition (EMT) plays a key role in tumor metastasis, the aim of the present study was to examine whether curcumin intervenes with SOD-induced EMT in pancreatic cancer and the underlying mechanism. The human pancreatic cancer cells BxPC-3 and Panc-1 were exposed to SOD in the presence or absence of curcumin, catalase (CAT, a scavenger of H2O2), or LY 294002 [a phosphoinositide-3 kinase (PI3K) inhibitor]. Intracellular reactive oxygen species (ROS) and H2O2 were evaluated by 2,7-dichlorodihydrofluorecein diacetate and H2O2 assay, respectively. The activation of p-Akt and p-nuclear factor (NF)-κB were examined by western blotting. The migratory and invasive abilities of pancreatic cancer cells were tested by the wound healing and Transwell invasion assays. The expression of E-cadherin, N-cadherin and vimentin (EMT-related genes) were measured by reverse transcription-quantitative polymerase chain reaction and western blotting at the mRNA and protein levels, respectively. The findings of the present study demonstrated that curcumin decreased SOD-induced production of ROS and H2O2 in BxPC-3 and Panc-1 cells. Curcumin was able to suppress SOD-induced invasion and migration, and it also regulated the expression of the above‑mentioned EMT-related genes and cell morphology. SOD-induced cell invasion was also inhibited by catalase and LY 294002. Furthermore, the levels of p-Akt and p-NF-κB caused by SOD could be offset by treatment with curcumin and LY 294002. To summarize, these results demonstrated that curcumin was able to prevent SOD-driven H2O2-induced pancreatic cancer metastasis by blocking the PI3K/Akt/NF-κB signaling pathway. The use of curcumin to inhibit the H2O2/Akt/NF-κB axis may be a promising therapeutic approach to the treatment of patients with pancreatic cancer.

Effect of N-Acetylcysteine on Antioxidant Defense, Oxidative Modification, and Salivary Gland Function in a Rat Model of Insulin Resistance

Oxidative stress plays a crucial role in the salivary gland dysfunction in insulin resistance (IR). It is not surprising that new substances are constantly being sought that will protect against the harmful effects of IR in the oral cavity environment. The purpose of this study was to evaluate the effect of N-acetylcysteine (NAC) on oxidative stress and secretory function of salivary glands in a rat model of insulin resistance. Rats were divided into 4 groups: C-normal diet, C + NAC-normal diet + NAC, HFD-high-fat diet, and HFD + NAC. We have demonstrated that NAC elevated enzymatic (superoxide dismutase, catalase, and peroxidase) and nonenzymatic antioxidants (reduced glutathione (GSH) and total antioxidant capacity (TAS)) in the parotid glands of HFD + NAC rats, while in the submandibular glands increased only GSH and TAS levels. NAC protects against oxidative damage only in the parotid glands and increased stimulated salivary secretion; however, it does not increase the protein secretion in the both salivary glands. Summarizing, NAC supplementation prevents the decrease of stimulated saliva secretion, seen in the HFD rats affected. NAC improves the antioxidative capacity of the both glands and protects against oxidative damage to the parotid glands of IR rats.

Oxidative Stress in Neurodegenerative Diseases: From Molecular Mechanisms to Clinical Applications

Increasing numbers of individuals, particularly the elderly, suffer from neurodegenerative disorders. These diseases are normally characterized by progressive loss of neuron cells and compromised motor or cognitive function. Previous studies have proposed that the overproduction of reactive oxygen species (ROS) may have complex roles in promoting the disease development. Research has shown that neuron cells are particularly vulnerable to oxidative damage due to their high polyunsaturated fatty acid content in membranes, high oxygen consumption, and weak antioxidant defense. However, the exact molecular pathogenesis of neurodegeneration related to the disturbance of redox balance remains unclear. Novel antioxidants have shown great potential in mediating disease phenotypes and could be an area of interest for further research. In this review, we provide an updated discussion on the roles of ROS in the pathological mechanisms of Alzheimer's disease, Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, and spinocerebellar ataxia, as well as a highlight on the antioxidant-based therapies for alleviating disease severity.

New perspectives on amyotrophic lateral sclerosis: the role of glial cells at the neuromuscular junction

Amyotrophic lateral sclerosis (ALS) is a disease leading to the death of motor neurons (MNs). It is also recognized as a non-cell autonomous disease where glial cells in the CNS are involved in its pathogenesis and progression. However, although denervation of neuromuscular junctions (NMJs) represents an early and major event in ALS, the importance of glial cells at this synapse receives little attention. An interesting possibility is that altered relationships between glial cells and MNs in the spinal cord in ALS may also take place at the NMJ. Perisynaptic Schwann cells (PSCs), which are glial cells at the NMJ, show great morphological and functional adaptability to ensure NMJ stability, maintenance and repair. More specifically, PSCs change their properties according to the state of innervation. Hence, abnormal changes or lack of changes can have detrimental effects on NMJs in ALS. This review will provide an overview of known and hypothesized interactions between MN nerve terminals and PSCs at NMJs during development, aging and ALS-induced denervation. These neuron-PSC interactions may be crucial to the understanding of how degenerative changes begin and progress at NMJs in ALS, and represent a novel therapeutic target.

The Cu, Zn Superoxide Dismutase: Not Only a Dismutase Enzyme

The Cu,Zn superoxide dismutase (SOD1) is an ubiquitary cytosolic dimeric carbohydrate free molecule, belonging to a family of isoenzymes involved in the scavenger of superoxide anions. This effect certainly represents the main and well known function ascribed to this enzyme. Here we highlight new aspects of SOD1 physiology that point out some inedited effects of this enzyme in addition to the canonic role of oxygen radical enzymatic dismutation. In the last two decades our research group produced many data obtained in in vitro studies performed in many cellular lines, mainly neuroblastoma SK-N-BE cells, indicating that this enzyme is secreted either constitutively or after depolarization induced by high extracellular K⁺ concentration. In addition, we gave many experimental evidences showing that SOD1 is able to stimulate, through muscarinic M1 receptor, pathways involving ERK1/2, and AKT activation. These effects are accompanied with an intracellular calcium increase. In the last part of this review we describe researches that link deficient extracellular secretion of mutant SOD1^G93A to its intracellular accumulation and toxicity in NSC-34 cells. Alternatively, SOD1^G93A toxicity has been attributed to a decrease of K_m for H₂O₂ with consequent OH radical formation. Interestingly, this last inedited effect of SOD1^G93A could represent a gain of function that could be involved in the pathogenesis of familial Amyotrophic Lateral Sclerosis (fALS).

SOD1 protein aggregates stimulate macropinocytosis in neurons to facilitate their propagation

BACKGROUND

Amyotrophic Lateral Sclerosis is characterized by a focal onset of symptoms followed by a progressive spread of pathology that has been likened to transmission of infectious prions. Cell-to-cell transmission of SOD1 protein aggregates is dependent on fluid-phase endocytosis pathways, although the precise molecular mechanisms remain to be elucidated.

RESULTS

We demonstrate in this paper that SOD1 aggregates interact with the cell surface triggering activation of Rac1 and subsequent membrane ruffling permitting aggregate uptake via stimulated macropinocytosis. In addition, other protein aggregates, including those associated with neurodegenerative diseases (TDP-43, Httex146Q, α-synuclein) also trigger membrane ruffling to gain entry into the cell. Aggregates are able to rupture unstructured macropinosomes to enter the cytosol allowing propagation of aggregation to proceed.

CONCLUSION

Thus, we conclude that in addition to basic proteostasis mechanisms, pathways involved in the activation of macropinocytosis are key determinants in the spread of pathology in these misfolding diseases.

The IFN-β 1b effect on Cu Zn superoxide dismutase (SOD1) in peripheral mononuclear blood cells of relapsing-remitting multiple sclerosis patients and in neuroblastoma SK-N-BE cells

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease leading to axonal injury. Even if the etiology of MS is still unknown the disease begins with inflammation involving autoreactive T lymphocytes activation in genetically susceptible subjects. Interferon beta-1b (IFN β 1b) is one of the most used drug in the MS therapy. The results obtained in this study show that the concentration of SOD1 in CSF of relapsing-remitting MS (RR-MS) patients, evaluated by enzyme-linked immunosorbent assay (ELISA), is decreased compared to pathological controls. Moreover, the Western blotting analysis demonstrated that SOD1 in human peripheral blood mononuclear cells (PBMC) in healthy controls was significantly higher compared to MS subjects before starting DMT therapy. In addition IFN β 1b therapy causes an increase of intracellular SOD1 protein as well as mRNA levels in PBMC. Moreover, the treatment of neuroblastoma SK-N-BE cells with IFN β 1b increased SOD1 protein and mRNA levels; these data also suggest that neuroprotective effect of this physiological molecule is, at least in part, carried out through its effect on SOD1. This study demonstrate that DMT therapy is able to increase SOD1 expression in PBMC of RR-MS patients. Therefore, the effectiveness of DMT therapy can be ascribed, at least in part, to an increased levels of this antioxidant enzyme as further confirmed by in vitro studies in SK-N-BE cells.

NOX signaling in molecular cardiovascular mechanisms involved in the blood pressure homeostasis

Blood pressure homeostasis is maintained by several mechanisms regulating cardiac output, vascular resistances, and blood volume. At cellular levels, reactive oxygen species (ROS) signaling is involved in multiple molecular mechanisms controlling blood pressure. Among ROS producing systems, NADPH oxidases (NOXs), expressed in different cells of the cardiovascular system, are the most important enzymes clearly linked to the development of hypertension. NOXs exert a central role in cardiac mechanosensing, endothelium-dependent relaxation, and Angiotensin-II (Ang-II) redox signaling regulating vascular tone. The central role of NOXs in redox-dependent cardiovascular cell functions renders these enzymes a promising pharmacological target for the treatment of cardiovascular diseases, including hypertension. The aim of the present review is to focus on the physiological role of the cardiovascular NOX-generating ROS in the molecular and cellular mechanisms affecting blood pressure.

Early and persistent abnormal decoding by glial cells at the neuromuscular junction in an ALS model

Amyotrophic lateral sclerosis (ALS) is a late-onset neuromuscular disease characterized by progressive loss of motor neurons (MNs) preceded by neuromuscular junction (NMJ) denervation. Despite the importance of NMJ denervation in ALS, the mechanisms involved remain unexplored and ill defined. The contribution of glial cells in the disease has been highlighted, including axonal Schwann cell activation that precedes the decline of motor function and the onset of hindlimb paralysis. Because NMJ denervation occurs early in the process and that perisynaptic Schwann cells (PSCs), glial cells at the NMJ, regulate morphological stability, integrity, and repair of the NMJ, one could predict that PSC functions would be altered even before denervation, contributing to NMJ malfunctions. We tested this possibility using a slowly progressive model of ALS (SOD1(G37R) mice). We observed a normal NMJ organization at a presymptomatic stage of ALS (120 d), but PSC detection of endogenous synaptic activity revealed by intracellular Ca(2+) changes was enhanced compared with their wild-type littermates. This inappropriate PSC decoding ability was associated with an increased level of neurotransmitter release and dependent on intrinsic glial properties related to enhanced muscarinic receptor activation. The alteration of PSC muscarinic receptor functions also persists during the preonset stage of the disease and became dependent on MN vulnerability with age. Together, these results suggest that PSC properties are altered in the disease process in a manner that would be detrimental for NMJ repair. The impairments of PSC functions may contribute to NMJ dysfunction and ALS pathogenesis.

An emerging role for misfolded wild-type SOD1 in sporadic ALS pathogenesis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that targets motor neurons, leading to paralysis and death within a few years of disease onset. While several genes have been linked to the inheritable, or familial, form of ALS, much less is known about the cause(s) of sporadic ALS, which accounts for ~90% of ALS cases. Due to the clinical similarities between familial and sporadic ALS, it is plausible that both forms of the disease converge on a common pathway and, therefore, involve common factors. Recent evidence suggests the Cu,Zn-superoxide dismutase (SOD1) protein to be one such factor that is common to both sporadic and familial ALS. In 1993, mutations were uncovered in SOD1 that represent the first known genetic cause of familial ALS. While the exact mechanism of mutant-SOD1 toxicity is still not known today, most evidence points to a gain of toxic function that stems, at least in part, from the propensity of this protein to misfold. In the wild-type SOD1 protein, non-genetic perturbations such as metal depletion, disruption of the quaternary structure, and oxidation, can also induce SOD1 to misfold. In fact, these aforementioned post-translational modifications cause wild-type SOD1 to adopt a “toxic conformation” that is similar to familial ALS-linked SOD1 variants. These observations, together with the detection of misfolded wild-type SOD1 within human post-mortem sporadic ALS samples, have been used to support the controversial hypothesis that misfolded forms of wild-type SOD1 contribute to sporadic ALS pathogenesis. In this review, we present data from the literature that both support and contradict this hypothesis. We also discuss SOD1 as a potential therapeutic target for both familial and sporadic ALS.