A new perspective on the role of CuZn superoxide dismutase (SOD1)

Abstract The CuZn superoxide dismutase (SOD1), a member of a group of isoenzymes involved in the scavenger of superoxide anions, is a dimeric carbohydrate free protein, mainly localized in the cytosol. The reactive oxygen species (ROS) are involved in many pathophysiological events correlated with mutagenesis, cancer, degenerative processes and aging. In the first part of this mini-review the well known role of SOD1 and ROS are briefly summarized. Following, a potential novel biological action that SOD1 could exert is described, based on the recent researches demonstrating the secretion of this enzyme in many cellular lines. Moreover, the role of impaired mutant SOD1 secretion, associated with cytoplasmic toxic inclusion, which occurs in familial amyotrophic lateral sclerosis (ALS), is summarized. In addition, a depolarization-dependent release of SOD1 in pituitary GH3 cells and in rat synaptosomes through a calcium and SNARE-dependent mechanism is reported

Effects of Propionyl-L-Carnitine on Ischemia–Reperfusion Injury in Hamster Cheek Pouch Microcirculation

Background and purpose Propionyl-l-carnitine (pLc) exerts protective effects in different experimental models of ischemia–reperfusion (I/R). The aim of the present study was to assess the effects of intravenously and topically applied pLc on microvascular permeability increase induced by I/R in the hamster cheek pouch preparation. Methods The hamster cheek pouch microcirculation was visualized by fluorescence microscopy. Microvascular permeability, leukocyte adhesion to venular walls, perfused capillary length, and capillary red blood cell velocity (VRBC) were evaluated by computer-assisted methods. E-selectin expression was assessed by in vitro analysis. Lipid peroxidation and reactive oxygen species (ROS) formation were determined by thiobarbituric acid-reactive substances (TBARS) and 2′-7′-dichlorofluorescein (DCF), respectively. Results In control animals, I/R caused a significant increase in permeability and in the leukocyte adhesion in venules. Capillary perfusion and VRBC decreased. TBARS levels and DCF fluorescence significantly increased compared with baseline. Intravenously infused pLc dose-dependently prevented leakage and leukocyte adhesion, preserved capillary perfusion, and induced vasodilation at the end of reperfusion, while ROS concentration decreased. Inhibition of nitric oxide synthase prior to pLc caused vasoconstriction and partially blunted the pLc-induced protective effects; inhibition of the endothelium-derived hyperpolarizing factor (EDHF) abolished pLc effects. Topical application of pLc on cheek pouch membrane produced the same effects as observed with intravenous administration. pLc decreased the E-selectin expression. Conclusions pLc prevents microvascular changes induced by I/R injury. The reduction of permeability increase could be mainly due to EDHF release induce vasodilatation together with NO. The reduction of E-selectin expression prevents leukocyte adhesion and permeability increase

Reactive oxygen species derived from NOX3 and NOX5 drive differentiation of human oligodendrocytes

Reactive oxygen species (ROS) are signaling molecules that mediate stress response, apoptosis, DNA damage, gene expression and differentiation. We report here that differentiation of oligodendrocytes (OLs), the myelin forming cells in the CNS, is driven by ROS. To dissect the OL differentiation pathway, we used the cell line MO3-13, which display the molecular and cellular features of OL precursors. These cells exposed 1–4 days to low levels of H2O2 or to the protein kinase C (PKC) activator, phorbol-12-Myristate-13-Acetate (PMA) increased the expression of specific OL differentiation markers: the specific nuclear factor Olig-2, and Myelin Basic Protein (MBP), which was processed and accumulated selectively in membranes. The induction of differentiation genes was associated with the activation of ERK1-2 and phosphorylation of the nuclear cAMP responsive element binding protein 1 (CREB). PKC mediates ROS-induced differentiation because PKC depletion or bis-indolyl-maleimide (BIM), a PKC inhibitor, reversed the induction of differentiation markers by H2O2. H2O2 and PMA increased the expression of membrane-bound NADPH oxidases, NOX3 and NOX5. Selective depletion of these proteins inhibited differentiation induced by PMA. Furthermore, NOX5 silencing down regulated NOX3 mRNA levels, suggesting that ROS produced by NOX5 up-regulate NOX3 expression. These data unravel an elaborate network of ROS-generating enzymes (NOX5 to NOX3) activated by PKC and necessary for differentiation of OLs. Furthermore, NOX3 and NOX5, as inducers of OL differentiation, represent novel targets for therapies of demyelinating diseases, including multiple sclerosis, associated with impairment of OL differentiation

Superoxide Dismutase-1 intracellular content in T lymphocytes associates with increased Regulatory T Cell level in Multiple Sclerosis subjects undergoing immune-modulating treatment.

Reactive oxygen species (ROS) participate in the T-cell activation processes. ROS-dependent regulatory networks are usually mediated by peroxides, which are more stable and able to freely migrate inside cells. Superoxide dismutase (SOD)-1 represents the major physiological intracellular source of peroxides. We found that antigen-dependent activation represents a triggering element for SOD-1 production and secretion by human T lymphocytes. A deranged T-cell proinflammatory response characterizes the pathogenesis of multiple sclerosis (MS). We previously observed a decreased SOD-1 intracellular content in leukocytes of MS individuals at diagnosis, with increasing amounts of such enzyme after interferon (IFN)-b 1b treatment. Here, we analyzed in depth SOD-1 intracellular content in T cells in a cohort of MS individuals undergoing immune-modulating treatment. Higher amounts of the enzyme were associated with increased availability of regulatory T cells (Treg) preferentially expressing Foxp3-exon 2 (Foxp3-E2), as described for effective Treg. In vitro administration of recombinant human SOD-1 to activated T cells, significantly increased their IL-17 production, while SOD-1 molecules lacking dismutase activity were unable to interfere with cytokine production by activated T cells in vitro. Furthermore, hydrogen peroxide addition was observed to mimic, in vitro, the SOD-1 effect on IL-17 production. These data add SOD-1 to the molecules involved in the molecular pathways contributing to re-shaping the T-cell cytokine profile and Treg differentiation

T cell activation induces CuZn Superoxide Dismutase (SOD)-1) intracellular re-localization, production and secretion

Reactive Oxygen Species (ROS) behave as second messengers in signal transduction for a series of receptor/ligand interactions. A major regulatory role is played by hydrogen peroxide (H2O2), more stable and able to freely diffuse through cell membranes. CuZn Superoxide dismutase (SOD)-1 is a cytosolic enzyme involved in scavenging oxygen radicals to H2O2 and molecular oxygen, thus representing a major cytosolic source of peroxides. Previous studies suggested that superoxide anion and H2O2 generation are involved in T Cell Receptor (TCR)-dependent signaling. Here, we describe that antigen-dependent activation of human T lymphocytes significantly increased extracellular SOD-1 levels in lymphocyte cultures. This effect was accompanied by the synthesis of SOD-1-specific mRNA and by the induction of microvesicle SOD-1 secretion. It is of note that SOD-1 increased its concentration specifically in T cell population, while no significant changes were observed in the “non T” cell counterpart. Moreover, confocal microscopy showed that antigen-dependent activation was able to modify SOD-1 intracellular localization in T cells. Indeed, was observed a clear SOD-1 recruitment by TCR clusters. The ROS scavenger N-acetylcysteine (NAC) inhibited this phenomenon. Further studies are needed to define whether SOD-1-dependent superoxide/peroxide balance is relevant for regulation of T cell activation, as well as in the functional cross talk between immune effectors

The Effects of Angiotensin II or Angiotensin 1-7 on Rat Pial Microcirculation during Hypoperfusion and Reperfusion Injury: Role of Redox Stress

Renin-angiotensin systems produce angiotensin II (Ang II) and angiotensin 1-7 (Ang 1-7), which are able to induce opposite effects on circulation. This study in vivo assessed the effects induced by Ang II or Ang 1-7 on rat pial microcirculation during hypoperfusion-reperfusion, clarifying the mechanisms causing the imbalance between Ang II and Ang 1-7. The fluorescence microscopy was used to quantify the microvascular parameters. Hypoperfusion and reperfusion caused vasoconstriction, disruption of blood-brain barrier, reduction of capillary perfusion and an increase in reactive oxygen species production. Rats treated with Ang II showed exacerbated microvascular damage with stronger vasoconstriction compared to hypoperfused rats, a further increase in leakage, higher decrease in capillary perfusion and marker oxidative stress. Candesartan cilexetil (specific Ang II type 1 receptor (AT1R) antagonist) administration prior to Ang II prevented the effects induced by Ang II, blunting the hypoperfusion-reperfusion injury. Ang 1-7 or ACE2 activator administration, preserved the pial microcirculation from hypoperfusion-reperfusion damage. These effects of Ang 1-7 were blunted by a Mas (Mas oncogene-encoded protein) receptor antagonist, while Ang II type 2 receptor antagonists did not affect Ang 1-7-induced changes. In conclusion, Ang II and Ang 1-7 triggered different mechanisms through AT1R or MAS receptors able to affect cerebral microvascular injury

Modulazione della CuZn superossido dismutasi (SOD1) nella risposta a citochine pro-infiammatorie in cellule normali e patologiche isolate da pazienti affetti da emoglobinuria parossistica notturna e da mielodisplasie.

L'Emoglobinuria Parossistica Notturna (EPN) rappresenta un disordine emopoietico caratterizzato dall'espansione di un precursore staminale con una mutazione del gene PIG-A che codifica per la struttura glicosil-fosfatidil-inositilica (GPI). Come conseguenza tutte le proteine che si ancorano alla membrana cellulare utilizzando tale struttura GPI non sono espresse dai cloni derivati dalla staminale mutata. Il precursore mutato dà origine ad una progenie GPI-difettiva, dando ragione del fenotipo misto GPI+ e GPI- che caratterizza il sangue di pazienti EPN. Le cellule GPI-difettive non dimostrano vantaggi di crescita e la loro espansione si associa ad una condizione di insufficienza midollare. Si può quindi ipotizzare che fattori estrinseci,verosimilmente immuno-mediati, coinvolti nella patogenesi dell'insufficienza midollare possano contribuire all'espansione del clone GPI-difettivo. I processi di selezione che si verificano durante la maturazione dei precursori emopoietici nel microambiente midollare si associano a massivi eventi apoptotici con un incremento dei livelli locali di specie reattive dell'ossigeno (ROS). L'enzima antiossidante Cu, Zn Superossido Dismutasi (SOD1) esercita un ruolo chiave nella risposta cellulare allo stress ossidativo dismutando il radicale superossido in perossido d'idrogeno e H2O. Nostri precedenti studi hanno dimostrato che la SOD1: a) è secreta da molte linee cellulari e svolge verosimilmente un ruolo paracrino e neuromodulatorio b) interagisce con la membrana di cellule di neuroblastoma umano attivando pathways dipendenti da fosfolipasi C (PLC) e Protein Chinasi C (PKC), incrementando i livelli di calcio citosolico c) Sembra giocare un ruolo anti-ossidante di tipo paracrino negli organi linfoidi primari quali il timo. Molte citochine sono state descritte regolare l'espressione della forma tetramerica di SOD (SOD3), ma finora le informazioni sul ruolo esercitato da SOD1 in risposta allo stress ossidativo indotto da reazioni immunitarie sono molto carenti. Scopo del nostro progetto è studiare la modulazione di SOD1 in linee cellulari linfoblastoidi umane GPI-difettive ottenute da pazienti EPN in risposta a lipopolisaccaridi batterici (LPS) nonché a citochine pro-infiammatorie. Un ulteriore scopo della nostra ricerca riguarderà i meccanismi trasduzionali coinvolti nella modulazione di SOD1 ad opera di stimoli pro-infiammatori. Infine ci proponiamo di studiare il ruolo esercitato da SOD1 nel mediare la resistenza a stress ossidativo nei precursori GPI-difettivi rispetto alla controparte normale