Production of superoxide dismutase by Deinococcus radiophilus

Culturomics of Bacteria from Radon-Saturated Water of the World's Oldest Radium Mine

Balneotherapeutic water springs, such as those with thermal, saline, sulfur, or any other characteristics, have recently been the subject of phylogenetic studies with a closer focus on the description and/or isolation of phylogenetically novel or biotechnologically interesting microorganisms. Generally, however, most such microorganisms are rarely obtained in pure culture or are even, for now, unculturable under laboratory conditions. In this culture-dependent study of radioactive water springs of Jáchymov (Joachimstahl), Czech Republic, we investigated a combination of classical cultivation approaches with those imitating sampling source conditions. Using these environmentally relevant cultivation approaches, over 1,000 pure cultures were successfully isolated from 4 radioactive springs. Subsequent dereplication yielded 121 unique taxonomic units spanning 44 genera and 9 taxonomic classes, ~10% of which were identified as hitherto undescribed taxa. Genomes of the latter were sequenced and analyzed, with a special focus on endogenous defense systems to withstand oxidative stress and aid in radiotolerance. Due to their origin from radioactive waters, we determined the resistance of the isolates to oxidative stress. Most of the isolates were more resistant to menadione than the model strain Deinococcus radiodurans DSM 20539T. Moreover, isolates of the Deinococcacecae, Micrococcaceae, Bacillaceae, Moraxellaceae, and Pseudomonadaceae families even exhibited higher resistance in the presence of hydrogen peroxide. In summary, our culturomic analysis shows that subsurface water springs contain diverse bacterial populations, including as-yet-undescribed taxa and strains with promising biotechnological potential. Furthermore, this study suggests that environmentally relevant cultivation techniques increase the efficiency of cultivation, thus enhancing the chance of isolating hitherto uncultured microorganisms. IMPORTANCE The mine Svornost in Jáchymov (Joachimstahl), Czech Republic is a former silver-uranium mine and the world's first and for a long time only radium mine, nowadays the deepest mine devoted to the extraction of water which is saturated with radon and has therapeutic benefits given its chemical properties. This healing water, which is approximately 13 thousand years old, is used under medical supervision for the treatment of patients with neurological and rheumatic disorders. Our culturomic approach using low concentrations of growth substrates or the environmental matrix itself (i.e., water filtrate) in culturing media combined with prolonged cultivation time resulted in the isolation of a broad spectrum of microorganisms from 4 radioactive springs of Jáchymov which are phylogenetically novel and/or bear various adaptive or coping mechanisms to thrive under selective pressure and can thus provide a wide spectrum of capabilities potentially exploitable in diverse scientific, biotechnological, or medical disciplines.

Small-Molecule Mn Antioxidants in Caenorhabditis elegans and Deinococcus radiodurans Supplant MnSOD Enzymes during Aging and Irradiation

Denham Harman's oxidative damage theory identifies superoxide (O₂^•-) radicals as central agents of aging and radiation injury, with Mn²⁺-dependent superoxide dismutase (MnSOD) as the principal O₂^•--scavenger. However, in the radiation-resistant nematode Caenorhabditis elegans, the mitochondrial antioxidant enzyme MnSOD is dispensable for longevity, and in the model bacterium Deinococcus radiodurans, it is dispensable for radiation resistance. Many radiation-resistant organisms accumulate small-molecule Mn²⁺-antioxidant complexes well-known for their catalytic ability to scavenge O₂^•-, along with MnSOD, as exemplified by D. radiodurans. Here, we report experiments that relate the MnSOD and Mn-antioxidant content to aging and oxidative stress resistances and which indicate that C. elegans, like D. radiodurans, may rely on Mn-antioxidant complexes as the primary defense against reactive oxygen species (ROS). Wild-type and ΔMnSOD D. radiodurans and C. elegans were monitored for gamma radiation sensitivities over their life spans while gauging Mn²⁺-antioxidant content by electron paramagnetic resonance (EPR) spectroscopy, a powerful new approach to determining the in vivo Mn-antioxidant content of cells as they age. As with D. radiodurans, MnSOD is dispensable for radiation survivability in C. elegans, which hyperaccumulates Mn-antioxidants exceptionally protective of proteins. Unexpectedly, ΔMnSOD mutants of both the nematodes and bacteria exhibited increased gamma radiation survival compared to the wild-type. In contrast, the loss of MnSOD renders radiation-resistant bacteria sensitive to atmospheric oxygen during desiccation. Our results support the concept that the disparate responses to oxidative stress are explained by the accumulation of Mn-antioxidant complexes which protect, complement, and can even supplant MnSOD. IMPORTANCE The current theory of cellular defense against oxidative damage identifies antioxidant enzymes as primary defenders against ROS, with MnSOD being the preeminent superoxide (O₂^•-) scavenger. However, MnSOD is shown to be dispensable both for radiation resistance and longevity in model organisms, the bacterium Deinococcus radiodurans and the nematode Caenorhabditis elegans. Measured by electron paramagnetic resonance (EPR) spectroscopy, small-molecule Mn-antioxidant content was shown to decline in unison with age-related decreases in cell proliferation and radioresistance, which again are independent of MnSOD presence. Most notably, the Mn-antioxidant content of C. elegans drops precipitously in the last third of its life span, which links with reports that the steady-state level of oxidized proteins increases exponentially during the last third of the life span in animals. This leads us to propose that global responses to oxidative stress must be understood through an extended theory that includes small-molecule Mn-antioxidants as potent O₂^•--scavengers that complement, and can even supplant, MnSOD.

Role of Proprotein Convertase Subtilisin/Kexin Type 9 in the Pathogenesis of Graves' Orbitopathy in Orbital Fibroblasts

BACKGROUND

The proprotein convertase subtilisin/kexin type 9 (PCSK9) has been implicated in the pathogenesis of inflammatory diseases. We sought to investigate the role of PCSK9 in the pathogenesis of Graves' orbitopathy (GO) and whether it may be a legitimate target for treatment.

METHODS

The PCSK9 was compared between GO (n=11) and normal subjects (n=7) in orbital tissue explants using quantitative real-time PCR, and in cultured interleukin-1β (IL-1β)-treated fibroblasts using western blot. Western blot was used to identify the effects of PCSK9 inhibition on IL-1β-induced pro-inflammatory cytokines production and signaling molecules expression as well as levels of adipogenic markers and oxidative stress-related proteins. Adipogenic differentiation was identified using Oil Red O staining. The plasma PCSK9 concentrations were compared between patients with GO (n=44) and healthy subjects (n=26) by ELISA.

RESULTS

The PCSK9 transcript level was higher in GO tissues. The depletion of PCSK9 blunted IL-1β-induced expression of intercellular adhesion molecule 1 (ICAM-1), IL-6, IL-8, and cyclooxygenase-2 (COX-2) in GO and non-GO fibroblasts. The levels of activated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and phosphorylated forms of Akt and p38 were diminished when PCSK9 was suppressed in GO fibroblasts. Decreases in lipid droplets and attenuated levels of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein β (C/EBPβ), and leptin as well as hypoxia-inducible factor 1α (HIF-1α), manganese superoxide dismutase (MnSOD), thioredoxin (Trx), and heme oxygenase-1 (HO-1) were noted when PCSK9 was suppressed during adipocyte differentiation. The plasma PCSK9 level was significantly higher in GO patients and correlated with level of thyrotropin binding inhibitory immunoglobulin (TBII) and the clinical activity score (CAS).

CONCLUSIONS

PCSK9 plays a significant role in GO. The PCSK9 inhibition attenuated the pro-inflammatory cytokines production, oxidative stress, and fibroblast differentiation into adipocytes. PCSK9 may serve as a therapeutic target and biomarker for GO.

Saikosaponin-D attenuates heat stress-induced oxidative damage in LLC-PK1 cells by increasing the expression of anti-oxidant enzymes and HSP72

Heat stress stimulates the production of reactive oxygen species (ROS), which cause oxidative damage in the kidney. This study clarifies the mechanism by which saikosaponin-d (SSd), which is extracted from the roots of Bupleurum falcatum L, protects heat-stressed pig kidney proximal tubular (LLC-PK1) cells against oxidative damage. SSd alone is not cytotoxic at concentrations of 1 or 3 μg/mL as demonstrated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. To assess the effects of SSd on heat stress-induced cellular damage, LLC-PK1 cells were pretreated with various concentrations of SSd, heat stressed at 42°C for 1 h, and then returned to 37°C for 9 h. DNA ladder and MTT assays demonstrated that SSd helped to prevent heat stress-induced cellular damage when compared to untreated cells. Additionally, pretreatment with SSd increased the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) but decreased the concentration of malondialdehyde (MDA) in a dose-dependent manner when compared to controls. Furthermore, real-time PCR and Western blot analysis demonstrated that SSd significantly increased the expression of copper and zinc superoxide dismutase (SOD-1), CAT, GPx-1 and heat shock protein 72 (HSP72) at both the mRNA and protein levels. In conclusion, these results are the first to demonstrate that SSd ameliorates heat stress-induced oxidative damage by modulating the activity of anti-oxidant enzymes and HSP72 in LLC-PK1 cells.

Superoxide dismutases from larvae of the camel tick Hyalomma dromedarii

Three superoxide dismutases (EC 1.15.1.1) (TLSOD1, TLSOD2 and TLSOD3) were purified from larvae of the camel tick Hyalomma dromedarii by ammonium sulfate precipitation, ion exchange and gel filtration columns. SDS-PAGE revealed that the subunit molecular masses of the SODs are 40±2 kDa, 67±1.5 kDa and 45±2.6 kDa for TLSOD1, TLSOD2 and TLSOD3, respectively. TLSOD1 and TLSOD2 are monomeric proteins, while TLSOD3 isoenzyme exhibits dimeric structure with native molecular mass of 90 kDa. The pI values are estimated at pH 8.0, pH 7.2 and pH 6.6 for the three SODs which displayed pH optima at 7.6, 8.0 and 7.8, respectively. CuCl(2) and ZnCl(2) increase the activity of TLSOD2 and TLSOD3, while MnCl(2) increases the activity of TLSOD1. KCN inhibits the activity of TLSOD2 and TLSOD3, while a remarkable resistance of TLSOD1 isoenzyme was detected. TLSOD1 is suggested to be a manganese containing isoenzyme while TLSOD2 and TLSOD3 are suggested to be copper/zinc-containing isoenzymes. These results indicate the presence of three different forms of SODs in the larval stage of camel tick. This finding will contribute to our understanding of the physiology of these ectoparasites and the development of non-traditional methods to control them.

Chronic intermittent hypobaric hypoxia protects the heart against ischemia/reperfusion injury through upregulation of antioxidant enzymes in adult guinea pigs

AIM

To investigate the protection and the anti-oxidative mechanism afforded by chronic intermittent hypobaric hypoxia (CIHH) against ischemia/reperfusion (I/R) injury in guinea pig hearts.

METHODS

Adult male guinea pigs were exposed to CIHH by mimicking a 5000 m high altitude (p(B)=404 mmHg, p(O2)=84 mmHg) in a hypobaric chamber for 6 h/day for 28 days. Langendorff-perfused isolated guinea pig hearts were used to measure variables of left ventricular function during baseline perfusion, ischemia and the reperfusion period. The activity and protein expression of antioxidant enzymes in the left myocardium were evaluated using biochemical methods and Western blotting, respectively. Intracellular reactive oxygen species (ROS) were assessed using ROS-sensitive fluorescence.

RESULTS

After 30 min of global no-flow ischemia followed by 60 min of reperfusion, myocardial function had better recovery rates in CIHH guinea pig hearts than in control hearts. The activity and protein expression of superoxide dismutase (SOD) and catalase (CAT) were significantly increased in the myocardium of CIHH guinea pigs. Pretreatment of control hearts with an antioxidant mixture containing SOD and CAT exerted cardioprotective effects similar to CIHH. The irreversible CAT inhibitor aminotriazole (ATZ) abolished the cardioprotection of CIHH. Cardiac contractile dysfunction and oxidative stress induced by exogenous hydrogen peroxide (H(2)O(2)) were attenuated by CIHH and CAT.

CONCLUSIONS

These data suggest that CIHH protects the heart against I/R injury through upregulation of antioxidant enzymes in guinea pig.Acta Pharmacologica Sinica (2009) 30: 947-955; doi: 10.1038/aps.2009.57; published online 22 June 2009.

Tannic acid-induced apoptosis and -enhanced sensitivity to arsenic trioxide in human leukemia HL-60 cells

Tannic acid (TA), a glucoside of gallic acid polymer, has been shown to possess anti-bacterial, anti-enzymatic, anti-tumor and astringent properties. However, the anti-cancer activity of TA in leukemia is still obscure. In this study, we showed TA-induced apoptotic death in acute myeloid leukemia (AML) HL-60 cells via dose- and time-dependent manner as well as increase of sub-G1 fraction, chromosome condensation, and DNA fragmentation. Further analysis demonstrated the involvement of activation of caspase cascade, cleavage of poly (ADP-ribose) polymerase (PARP), disruption of mitochondrial membrane potential, and release of Cytochrome C, in TA-induced apoptosis. These effects were probably associated with the increase of intracellular superoxide in mitochondrial signaling pathway which attributed to the down-regulation of superoxide dismutase (SOD). Notably, a low dose of TA is sufficient to aggravate arsenic trioxide (As(2)O(3))-induced cytotoxicity in HL-60 cells. Altogether, this study suggested the effects of TA to induce apoptosis in HL-60 and therapeutic potential in AML by being an adjunct to As(2)O(3).

Transforming growth factor-beta : biology and clinical relevance

Transforming growth factor-beta is a pleiotropic growth factor that has enthralled many investigators for approximately two decades. In addition to many reports that have clarified the basic mechanism of transforming growth factor-beta signal transduction, numerous laboratories have published on the clinical implication/application of transforming growth factor-beta . To name a few, dysregulation of transforming growth factor-beta signaling plays a role in carcinogenesis, autoimmunity, angiogenesis, and wound healing. In this report, we will review these clinical implications of transforming growth factor-beta .

Expression of Cu/Zn SOD Protein Is Suppressed in hsp 70.1 Knockout Mice

Heat shock proteins (HSPs) are known to protect cells from oxidative stress and other types of injuries. We previously reported the neuroprotective effect of HSP70 following cerebral ischemia and reperfusion using hsp 70.1 knockout (KO) mice. However, the precise role of HSP70 in neuroprotection has not been established yet. The purpose of this study was to investigate the relationship between HSP70 and antioxidant enzymes using hsp 70.1 KO mice. The activities of both SOD-1 and SOD-2 were significantly decreased in hsp 70.1 KO mice than in the wild type (WT) littermates. SOD-1 protein level in the hsp 70.1 KO mice was lower than that of WT. We speculate that HSP70 might be involved in regulation of expression of SOD-1 at the level of transcription or by post-transcriptional modification.

Purification and some properties of superoxide dismutase from Deinococcus radiophilus, the UV-resistant bacterium

The superoxide dismutase (SOD, EC 1.15.1.1) of Deinococcus radiophilus, a bacterium extraordinarily resistant to UV, ionizing radiations, and oxidative stress, was purified 1,920-fold with a 58% recovery yield from the cell-free extract of stationary cells by steps of ammonium sulfate fractionation and Superdex G-75 gel-filtration chromatography. A specific activity of the purified enzyme preparation was ca. 31,300 U mg(-1) protein. D. radiophilus SOD is Mn/FeSOD, judging by metal analysis and its insensitivity to cyanide and a partial sensitivity to H2O2. The molecular weights of the purified enzyme estimated by gel chromatography and polyacrylamide gel electrophoresis are 51.5+/-1 and 47.1+/-5 kDa, respectively. The SOD seems to be a homodimeric protein with a molecular mass of 26 +/- 0.5 kDa per monomer. The purified native SOD showed very acidic pI of ca. 3.8. The enzyme was stable at pH 5.0-11.0, but quite unstable below pH 5.0. SOD was thermostable up to 40 degrees C, but a linear reduction in activity above 50 degrees C. Inhibition of the purified SOD activity by beta-naphthoquinone-4-sulfonic acid, rho-diazobenzene sulfonic acid, and iodine suggests that lysine, histidine, and tyrosine residues are important for the enzyme activity. The N-terminal peptide sequence of D. radiophilus Mn/FeSOD (MAFELPQLPYAYDALEPHIDA(> D) is strikingly similar to those of D. radiodurans MnSOD and Aerobacter aerogenes FeSOD.