Contrasting effects of NADPH oxidases on the fungal hyphae growth and immune responses in Pleurotus ostreatus.

Pleurotus ostreatus is one of the most consumed mushroom species, as it serves as a high-quality food, favors a rich secondary metabolism, and has remarkable adaptability to the environment and predators. In this study, we investigated the function of two key reactive oxygen species producing enzyme NADPH oxidase (PoNoxA and PoNoxB) in P. ostreatus hyphae growth, metabolite production, signaling pathway activation, and immune responses to different stresses. Characterization of the Nox mutants showed that PoNoxB played an important role in the hyphal formation of the multicellular structure, while PoNoxA regulated apical dominance. The ability of P. ostreatus to tolerate a series of abiotic stress conditions (e.g., osmotic, oxidative, membrane, and cell-wall stresses) and mechanical damage repair was enhanced with PoNoxA over-expression. PoNoxB had a greater responsibility in regulating the polysaccharide composition of the cell wall and methyl jasmonate and gibberellin GA1 biosynthesis, and improved mushroom resistance against Tyrophagus putrescentiae. Moreover, mutants were involved in the jasmonate and GA signaling pathway, and toxic protein defense metabolite production. Our findings shed light on how the oyster mushroom senses stress signals and responds to adverse environments by the complex regulators of Noxs.

The Drug-Drug Interaction Between Erlotinib and OSI-930 is Mediated Through Aldehyde Oxidase Inhibition.

The propensity for aldehyde oxidase (AO) substrates to be implicated in drug-drug interactions (DDI) is not well-understood due to the dearth of potent inhibitors that elicit in vivo inhibition of AO. While there is only one reported instance of DDI that has been ascribed to the inhibition of AO to-date, the supporting evidence for this clinical interaction is rather tenuous and its veracity has been called into question. Our group recently reported that the epidermal growth factor receptor inhibitor erlotinib engendered potent time-dependent inhibition of AO with inactivation kinetic constants in the same order of magnitude as its free circulating plasma concentrations. At the same time, it was previously reported that the concomitant administration of erlotinib with the investigational drug OSI-930 culminated in a ~2-fold increase in its systemic exposure. Although the basis underpinning this interaction remains unclear, the structure of OSI-930 contains a quinoline motif which is amenable to oxidation at the electrophilic carbon adjacent to the nitrogen atom by molybdenum-containing hydroxylases like AO. In this study, we conducted metabolite identification which revealed that OSI-930 undergoes AO metabolism to a mono-oxygenated 2-oxo metabolite and assessed its formation kinetics in human liver cytosol. Additionally, reaction phenotyping in human hepatocytes revealed that AO contributes nearly ~50% to the overall metabolism of OSI-930. Finally, modelling the interaction between erlotinib and OSI-930 using a mechanistic static model projected an ~1.85-fold increase in the systemic exposure of OSI-930 - which accurately recapitulated clinical observations. Significance Statement In this study, we delineate an AO metabolic pathway in the investigational drug OSI-930 for the first time and confirmed that it represented a major route of metabolism through reaction phenotyping in human hepatocytes. Our study provided compelling mechanistic and modelling evidence for the first instance of an AO-mediated clinical DDI stemming from the in vivo inhibition of the AO-mediated quinoline 2-oxidation pathway in OSI-930 by erlotinib.

Spatio-temporal expression of polyphenol oxidase unveils the dynamics of L-DOPA accumulation in faba bean (Vicia faba L.).

Faba bean (Vicia faba L.) is a winter season grain legume and a rich source of the anti-parkinson drug, L-3,4-dihydroxyphenylalanine (L-DOPA). The biosynthesis of L-DOPA in plants is not uniform and remains largely unexplored. While the hydroxylase activities of Tyrosine Hydroxylase (TH), the Cytochrome P450 (CYP450) class of enzymes, and Polyphenol Oxidases (PPOs) on tyrosine substrate have been reported in plants, only the roles of PPOs in L-DOPA biosynthesis have been recently established in velvet bean (Mucuna pruriens). To understand the differential accumulation of L-DOPA in different tissues of faba bean, profiling of L-Tyrosine, L-DOPA, Tyramine, and Dopamine in different tissues was performed. Differential accumulation of L-DOPA depended on tissue type and maturity. Furthermore, dopamine biosynthesis through L-DOPA from L-Tyr was confirmed in faba bean. The expression analysis of PPOs in leaf and flower tissues revealed the selective induction of only four (HePPO-2, HePPO-7, HePPO-8b, and HePPO-10) out of ten genes encoding different PPOs mined from the faba bean genome. Higher accumulation of L-DOPA in young leaves and flower buds than in mature leaves and flowers was accompanied by significantly higher expression of HePPO-10 and HePPO-7, respectively. The role of various transcription factors contributing to such metabolite dynamics was also predicted. Further exploration of this mechanism using a multi-omics approach can provide meaningful insight and pave the way for enhancing L-DOPA content in crops. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-024-01449-2.

Indanone: a promising scaffold for new drug discovery against neurodegenerative disorders.

Indanone is a versatile scaffold that has a number of pharmacological properties. The successful development and ensuing approval of indanone-derived donepezil as a drug of choice for Alzheimer's disease attracted significant scientific interest in this moiety. Indanones could act as small molecule chemical probes as they have strong affinity towards several critical enzymes associated with the pathophysiology of various neurological disorders. Inhibition of these enzymes elevates the levels of neuroprotective brain chemicals such as norepinephrine, serotonin and dopamine. Further, indanone derivatives are capable of modulating the activities of both monoamine oxidases (MAO-A and -B) and acetylcholinesterase (AChE), and thus could be useful in various neurodegenerative diseases. This review article presents a panoramic view of the research carried out on the indanone nucleus in the development of potential neuroprotective agents.

Diapocynin treatment induces functional and structural improvements in an advanced disease state in the mdx5Cv mice.

Duchenne muscular dystrophy (DMD) is the most common muscular disorder affecting children. It affects nearly 1 male birth over 5000. Oxidative stress is a pervasive feature in the pathogenesis of DMD. Recent work shows that the main generators of ROS are NADPH oxidases (NOX), suggesting that they are an early and promising target in DMD. In addition, skeletal muscles of mdx mice, a murine model of DMD, overexpress NOXes. We investigated the impact of diapocynin, a dimer of the NOX inhibitor apocynin, on the chronic disease phase of mdx5Cv mice. Treatment of these mice with diapocynin from 7 to 10 months of age resulted in decreased hypertrophy of several muscles, prevented force loss induced by tetanic and eccentric contractions, improved muscle and respiratory functions, decreased fibrosis of the diaphragm and positively regulated the expression of disease modifiers. These encouraging results ensure the potential role of diapocynin in future treatment strategies.

Towards cost-effective drug discovery: Reusable immobilized enzymes for neurological disease research.

Enzyme handling and utilization bears many challenges such as their limited stability, intolerance of organic solvents, high cost, or inability to reuse. Most of these limitations can be overcome by enzyme immobilization on the surface of solid support. In this work, the recombinant form of human cholinesterases and monoamine oxidases as important drug targets for neurological diseases were immobilized on the surface of magnetic non-porous microparticles by a non-covalent bond utilizing the interaction between a His-tag terminus on the recombinant enzymes and cobalt (Co2+) ions immobilized on the magnetic microparticles. This type of binding led to targeted enzyme orientation, which completely preserved the catalytic activity and allowed high reproducibility of immobilization. In comparison with free enzymes, the immobilized enzymes showed exceptional stability in time and the possibility of repeated use. Relevant Km, Vmax, and IC50 values using known inhibitors were obtained using particular immobilized enzymes. Such immobilized enzymes on magnetic particles could serve as an excellent tool for a sustainable approach in the early stage of drug discovery.

Structure-based design of multitargeting ChEs-MAO B inhibitors based on phenyl ring bioisosteres: AChE/BChE selectivity switch and drug-like characterization.

A structure-based drug design approach was focused on incorporating phenyl ring heterocyclic bioisosteres into coumarin derivative 1, previously reported as potent dual AChE-MAO B inhibitor, with the aim of improving drug-like features. Structure-activity relationships highlighted that bioisosteric rings were tolerated by hMAO B enzymatic cleft more than hAChE. Interestingly, linker homologation at the basic nitrogen enabled selectivity to switch from hAChE to hBChE. In the present work, we identified thiophene-based isosteres 7 and 15 as dual AChE-MAO B (IC50 = 261 and 15 nM, respectively) and BChE-MAO B (IC50 = 375 and 20 nM, respectively) inhibitors, respectively. Both 7 and 15 were moderately water-soluble and membrane-permeant agents by passive diffusion (PAMPA-HDM). Moreover, they were able to counteract oxidative damage induced by both H2O2 and 6-OHDA in SH-SY5Y cells and predicted to penetrate into CNS in a cell-based model mimicking blood-brain barrier. Molecular dynamics (MD) simulations shed light on key differences in AChE and BChE recognition processes promoted by the basic chain homologation from 7 to 15.

Chemical composition analysis and transcriptomics reveal the R2R3-MYB genes and phenol oxidases regulating the melanin formation in black radish.

Melanins are dark-brown to black-colored biomacromolecules which have been thoroughly studied in animals and microorganisms. However, the biochemical and molecular basis of plant melanins are poorly understood. We first characterized melanin from the black radish (Raphanus sativus var. niger) 'HLB' through spectroscopic techniques. p-Coumaric acid was identified as the main precursor of radish melanin. Moreover, a joint analysis of transcriptome and coexpression network was performed for the two radish accessions with black and white cortexes, 'HLB' and '55'. A set of R2R3-type RsMYBs and enzyme-coding genes exhibited a coexpression pattern, and were strongly correlated with melanin formation in radish. Transient overexpression of two phenol oxidases RsLAC7 (laccase 7) or RsPOD22-1 (peroxidase 22-1) resulted in a deeper brown color around the infiltration sites and a significant increase in the total phenol content. Furthermore, co-injection of the transcriptional activator RsMYB48/RsMYB97 with RsLAC7 and/or RsPOD22-1, markedly increased the yield of black extracts. Spectroscopic analyses revealed that these extracts are similar to the melanin found in 'HLB'. Our findings advance the understanding of structural information and the transcriptional regulatory mechanism underlying melanin formation in radish.

NADPH Oxidases in Neurodegenerative Disorders: Mechanisms and Therapeutic Opportunities.

Significance: The nicotinamide adenine dinucleotide phosphate oxidase (NOX) enzyme family, located in the central nervous system, is recognized as a source of reactive oxygen species (ROS) in the brain. Despite its importance in cellular processes, excessive ROS generation leads to cell death and is involved in the pathogenesis of neurodegenerative disorders. Recent advances: NOX enzymes contribute to the development of neurodegenerative diseases, such as Parkinson's disease (PD), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and stroke, highlighting their potential as targets for future therapeutic development. This review will discuss NOX's contribution and therapeutic targeting potential in neurodegenerative diseases, focusing on PD, AD, ALS, and stroke. Critical issues: Homeostatic and physiological levels of ROS are crucial for regulating several processes, such as development, memory, neuronal signaling, and vascular homeostasis. However, NOX-mediated excessive ROS generation is deeply involved in the damage of DNA, proteins, and lipids, leading to cell death in the pathogenesis of a wide range of diseases, namely neurodegenerative diseases. Future directions: It is essential to understand the role of NOX homologs in neurodegenerative disorders and the pathological mechanisms undergoing neurodegeneration mediated by increased levels of ROS. This further knowledge will allow the development of new specific NOX inhibitors and their application for neurodegenerative disease therapeutics.

Design and discovery of anthranilamide derivatives as a potential treatment for neurodegenerative disorders via targeting cholinesterases and monoamine oxidases.

Neurodegenerative diseases with progressive cellular loss of the central nervous system and elusive disease etiology provide a continuous impetus to explore drug discovery programmes aiming at identifying robust and effective inhibitors of cholinesterase and monoamine oxidase enzymes. We herein present a concise library of anthranilamide derivatives involving a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction to install the diverse structural diversity required for the desired biological action. Using Ellman's method, cholinesterase inhibitory activity was performed against AChE and BuChE enzymes. In vitro assay results demonstrated that anthranilamides are potent inhibitors with remarkable potency. Compound 6k emerged as the lead candidate and dual inhibitor of both enzymes with IC50 values of 0.12 ± 0.01 and 0.49 ± 0.02 µM against AChE and BuChE, respectively. Several other compounds were found as highly potent and selective inhibitors. Anthranilamide derivatives were also tested against monoamine oxidase (A and B) enzymes using fluorometric method. In vitro data revealed compound 6h as the most potent inhibitor against MAO-A, showing an IC50 value of 0.44 ± 0.02 µM, whereas, compound 6k emerged as the top inhibitor of MAO-B with an IC50 value of 0.06 ± 0.01 µM. All the lead inhibitors were analyzed for the identification of their mechanism of action using Michaelis-Menten kinetics experiments. Compound 6k and 6h depicted a competitive mode of action against AChE and MAO-A, whereas, a non-competitive and mixed-type of inhibition was observed against BuChE and MAO-B by compounds 6k. Molecular docking analysis revealed remarkable binding affinities of the potent inhibitors with specific residues inside the active site of receptors. Furthermore, molecular dynamics simulations were performed to explore the ability of potent compounds to form energetically stable complexes with the target protein. Finally, in silico ADME calculations also demonstrated that the potent compounds exhibit promising pharmacokinetic profile, satisfying the essential criteria for drug-likeness. Altogether, the findings reported in the current work clearly suggest that the identified anthranilamide derivatives have the potential to serve as effective drug candidates for future investigations.

Secondary Structure in Enzyme-Inspired Polymer Catalysts Impacts Water Oxidation Efficiency.

Protein structure plays an essential role on their stability, functionality, and catalytic activity. In this work, the interplay between the ß-sheet structure and its catalytic implications to the design of enzyme-inspired materials is investigated. Here, inspiration is drawn from the active sites and ß-sheet rich structure of the highly efficient multicopper oxidase (MCO) to engineer a bio-inspired electrocatalyst for water oxidation utilizing the abundant metal, copper. Copper ions are coordinated to poly-histidine (polyCuHis), as they are in MCO active sites. The resultant polyCuHis material effectively promotes water oxidation with low overpotentials (0.15 V) in alkaline systems. This activity is due to the 3D structure of the poly-histidine backbone. By increasing the prevalence of ß-sheet structure and decreasing the random coil nature of the polyCuHis secondary structures, this study is able to modulates the electrocatalytic activity of this material is modulated, shifting it toward water oxidation. These results highlight the crucial role of the local environment at catalytic sites for efficient, energy-relevant transformations. Moreover, this work highlights the importance of conformational structure in the design of scaffolds for high-performance electrocatalysts.

Effects of Lignin-Diverted Reductant with Polyphenol Oxidases on Cellulose Degradation by Wild and Mutant Types of Lytic Polysaccharide Monooxygenase.

Establishing a multi-enzyme synergistic lignocellulosic biodegradation system using lytic polysaccharide monooxygenase (LPMO) and polyphenol oxidases is vital for efficiently utilizing plant biomass waste, ultimately benefiting the carbon cycle and promoting environmental protection. Single-residue mutations of LPMO can improve the efficiency of lignocellulosic biomass degradation. However, the activity of mutant-type LPMO in relation to lignin-diverted reducing agents has not been sufficiently explored. In this study, laccase and tyrosinase were initially investigated and their optimal conditions and impressive thermal stability were revealed, indicating their potential synergistic abilities with LPMO in lignocellulose biodegradation. When utilizing gallic acid as a reducing agent, the activities of LPMOs were increased by over 10%, which was particularly evident in mutant-type LPMOs after the addition of polyphenol oxidases. In particular, the combination of tyrosinase with either 4-hydroxy-3-methoxyphenylacetone or p-coumaric acid was shown to enhance the efficacy of LPMOs. Furthermore, the highest activity levels of wild-type LPMOs were observed with the addition of laccase and 3-methylcatechol. The similarities between wild and mutant LPMOs regarding their activities in lignin-diverted phenolic compounds and reducing agents are almost identical, suggesting that the single-residue mutation of LPMO does not have a detrimental effect on its performance. Above all, this study indicates that understanding the performance of both wild and mutant types of LPMOs in the presence of polyphenol oxidases and various reducing agents constitutes a key link in the industrialization of the multi-enzyme degradation of lignocellulose.

Superoxide signalling and antioxidant processing in the plant nucleus.

The superoxide anion radical (O2•-) is a one-electron reduction product of molecular oxygen. Compared to other forms of reactive oxygen species (ROS), superoxide has limited reactivity. Nevertheless, superoxide reacts with nitic oxide, ascorbate and the iron moieties of [Fe-S] cluster-containing proteins. Superoxide has largely been neglected as a signalling molecule in the plant literature in favour of the most stable ROS form, hydrogen peroxide. However, superoxide can accumulate in plant cells, particularly in meristems, where superoxide dismutase activity and ascorbate accumulation are limited (or absent), or when superoxide is generated within the lipid environment of membranes. Moreover, oxidation of the nucleus in response to environmental stresses is a widespread phenomenon. Superoxide is generated in many intracellular including mitochondria, chloroplasts and on the apoplastic/cell wall face of the plasma membrane. However, nuclear superoxide production and functions remain poorly documented in plants. Accumulating evidence suggests that the nuclear pools of antioxidants such as glutathione are discrete and separate from the cytosolic pools, allowing compartment-specific signalling in the nucleus. We consider the potential mechanisms of superoxide generation and targets in the nucleus, together with the importance of antioxidant processing in regulating superoxide signalling.

Novel 6-hydroxybenzothiazol-2-carboxamides as potent and selective monoamine oxidase B inhibitors endowed with neuroprotective activity.

In neurodegenerative diseases, using a single molecule that can exert multiple effects to modify the disease may have superior activity over the classical "one molecule-one target" approach. Herein, we describe the discovery of 6-hydroxybenzothiazol-2-carboxamides as highly potent and selective MAO-B inhibitors. Variation of the amide substituent led to several potent compounds having diverse side chains with cyclohexylamide 40 displaying the highest potency towards MAO-B (IC50 = 11 nM). To discover new compounds with extended efficacy against neurotoxic mechanisms in neurodegenerative diseases, MAO-B inhibitors were screened against PHF6, R3 tau, cellular tau and α-synuclein (α-syn) aggregation. We identified the phenethylamide 30 as a multipotent inhibitor of MAO-B (IC50 = 41 nM) and α-syn and tau aggregation. It showed no cytotoxic effects on SH-SY5Y neuroblastoma cells, while also providing neuroprotection against toxicities induced by α-syn and tau. The evaluation of key physicochemical and in vitro-ADME properties revealed a great potential as drug-like small molecules with multitarget neuroprotective activity.

Cyanide Insensitive Oxidase Confers Hydrogen Sulfide and Nitric Oxide Tolerance to Pseudomonas aeruginosa Aerobic Respiration.

Hydrogen sulfide (H2S) and nitric oxide (NO) are long-known inhibitors of terminal oxidases in the respiratory chain. Yet, they exert pivotal signaling roles in physiological processes, and in several bacterial pathogens have been reported to confer resistance against oxidative stress, host immune responses, and antibiotics. Pseudomonas aeruginosa, an opportunistic pathogen causing life-threatening infections that are difficult to eradicate, has a highly branched respiratory chain including four terminal oxidases of the haem-copper type (aa3, cbb3-1, cbb3-2, and bo3) and one oxidase of the bd-type (cyanide-insensitive oxidase, CIO). As Escherichia coli bd-type oxidases have been shown to be H2S-insensitive and to readily recover their activity from NO inhibition, here we tested the effect of H2S and NO on CIO by performing oxygraphic measurements on membrane preparations from P. aeruginosa PAO1 and isogenic mutants depleted of CIO only or all other terminal oxidases except CIO. We show that O2 consumption by CIO is unaltered even in the presence of high levels of H2S, and that CIO expression is enhanced and supports bacterial growth under such stressful conditions. In addition, we report that CIO is reversibly inhibited by NO, while activity recovery after NO exhaustion is full and fast, suggesting a protective role of CIO under NO stress conditions. As P. aeruginosa is exposed to H2S and NO during infection, the tolerance of CIO towards these stressors agrees with the proposed role of CIO in P. aeruginosa virulence.

Gene Expression and Prognostic Value of NADPH Oxidase Enzymes in Breast Cancer.

NADPH oxidase enzymes (NOX) are involved in all stages of carcinogenesis, but their expression levels and prognostic value in breast cancer (BC) remain unclear. Thus, we aimed to assess the expression and prognostic value of NOX enzymes in BC samples using online databases. For this, mRNA expression from 290 normal breast tissue samples and 1904 BC samples obtained from studies on cBioPortal, Kaplan-Meier Plotter, and The Human Protein Atlas were analyzed. We found higher levels of NOX2, NOX4, and Dual oxidase 1 (DUOX1) in normal breast tissue. NOX1, NOX2, and NOX4 exhibited higher expression in BC, except for the basal subtype, where NOX4 expression was lower. DUOX1 mRNA levels were lower in all BC subtypes. NOX2, NOX4, and NOX5 mRNA levels increased with tumor progression stages, while NOX1 and DUOX1 expression decreased in more advanced stages. Moreover, patients with low expression of NOX1, NOX4, and DUOX1 had lower survival rates than those with high expression of these enzymes. In conclusion, our data suggest an overexpression of NOX enzymes in breast cancer, with certain isoforms showing a positive correlation with tumor progression.

Particulate matter stimulates the NADPH oxidase system via AhR-mediated epigenetic modifications.

Stimulation of human keratinocytes with particulate matter 2.5 (PM2.5) elicits complex signaling events, including a rise in the generation of reactive oxygen species (ROS). However, the mechanisms underlying PM2.5-induced ROS production remain unknown. Here, we show that PM2.5-induced ROS production in human keratinocytes is mediated via the NADPH oxidase (NOXs) system and the Ca2+ signaling pathway. PM2.5 treatment increased the expression of NOX1, NOX4, and a calcium-sensitive NOX, dual oxidase 1 (DUOX1), in human epidermal keratinocyte cell line. PM2.5 bound to aryl hydrocarbon receptor (AhR), and this complex bound to promoter regions of NOX1 and DUOX1, suggesting that AhR acted as a transcription factor of NOX1 and DUOX1. PM2.5 increased the transcription of DUOX1 via epigenetic modification. Moreover, a link between DNA demethylase and histone methyltransferase with the promoter regions of DUOX1 led to an elevation in the expression of DUOX1 mRNA. Interestingly, PM2.5 increased NOX4 expression and promoted the interaction of NOX4 and Ca2+ channels within the cytoplasmic membrane or endoplasmic reticulum, leading to Ca2+ release. The increase in intracellular Ca2+ concentration activated DUOX1, responsible for ROS production. Our findings provide evidence for a PM2.5-mediated ROS-generating system network, in which increased NOX1, NOX4, and DUOX1 expression serves as a ROS signal through AhR and Ca2+ activation.

Curcumin Modulates NOX Gene Expression and ROS Production via P-Smad3C in TGF-ß-Activated Hepatic Stellate Cells.

Background: Liver fibrosis, associated with hepatic stellate cells (HSCs), occurs when a healthy liver sustains damage, thereby impairing its function. NADPH oxidases (NOXs), specifically isoforms 1, 2, and 4, play a role in reactive oxygen species (ROS) production during hepatic injuries, resulting in fibrosis. Curcumin has shown strong potential in mitigating liver fibrosis. Our research aimed to investigate the effects of curcumin on lowering NOX and ROS levels. This compound was also studied for its effects on NOXs, ROS concentrations through the inhibition of Smad3 phosphorylation in transforming growth factor beta (TGF-ß)-activated human HSCs. Methods: MTT assay investigated the cytotoxic effects of curcumin on HSCs. The cells were activated by exposure to TGF-ß (2 ng/mL) for 24 hours. After activating, the cells were treated with curcumin at 25-150 µM concentrations. After administering curcumin to the cells, we employed RT-PCR and Western blot techniques to evaluate the related gene and protein expression levels. This evaluation was primarily focused on the mRNA expression levels of NOX1, NOX2, NOX4 and phosphorylated Smad3C. Results: The mRNA expression level of aforesaid NOXs as well as α-smooth muscle actin (α-SMA), collagen1-α, and ROS levels were significantly reduced following 100 µM curcumin treatment. Furthermore, curcumin significantly decreased the p-Smad3C protein level in TGF-ß-activated cells, with fold changes of 3 and 2 observed at 75 and 100 µM, respectively. Conclusion: Curcumin decreased the levels of ROS and NOX, as well as the expression of α-SMA and collagen1-α. The primary mechanism for this reduction could be linked to the level of p-Smad3C. Hence, curcumin could serve as an effective therapeutic agent for liver fibrosis.

Under explored roles of microbial ligninolytic enzymes in aerobic polychlorinated biphenyl transformation.

Polychlorinated biphenyls (PCBs) are persistent organic pollutants in the environment that are responsible for many adverse health effects. Bioremediation appears to be a healthy and cost-effective alternative for remediating PCB-contaminated environments. While some microbial species have been observed to be capable of transforming PCBs, only two different microbial pathways (rdh and bph pathways) have been described to be involved in PCB transformations. Ligninolytic enzymes have been observed or are under suspicion in some microbial PCB transformations. However, the role of these promising PCB-transforming enzymes, which are produced by fungi and some aerobic bacteria, is still unclear. The present review describes their role by identifying microbial PCB-transforming species and their reported ligninolytic enzymes whether proven or suspected to be involved in PCB transformations. There are several lines of evidence that ligninolytic enzymes are responsible for PCB transformations such as (1) the ability of purified laccases from Myceliophthora thermophila, Pycnoporus cinnabarinus, Trametes versicolor, Cladosporium sp, and Coprinus cumatus to transform hydroxy-PCBs; (2) the increased production of laccases and peroxidases by many fungi in the presence of PCBs; and (3) the enhanced PCB transformation by Pseudomonas stutzeri and Sinorhizobium meliloti NM after the addition of ligninolytic enzyme enhancers. However, if the involvement of ligninolytic enzymes in PCB transformation is clearly demonstrated in some fungal species, it does not seem to be implicated in all microbial species suggesting other still unknown metabolic pathways involved in PCB transformation and different from the bph and rdh pathways. Therefore, PCB transformation may involve several metabolic pathways, some involving ligninolytic enzymes, bph or rdh genes, and some still unknown, depending on the microbial species. In addition, current knowledge does not fully clarify the role of ligninolytic enzymes in PCB oxidation and dechlorination. Therefore, further studies focusing on purified ligninolytic enzymes are needed to clearly elucidate their role in PCB transformation.

Nicotinamide adenine dinucleotide phosphate oxidase 2 deletion attenuates polyhexamethylene guanidine-induced lung injury in mice.

Inhalation of polyhexamethylene guanidine phosphate (PHMG) can cause pulmonary fibrosis. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox) are enzymes that produce reactive oxygen species, which may be involved in tissue damage in various lung diseases. To investigate whether the Nox2 isoform of Nox is involved in the progression of PHMG-induced lung damage, we studied the contribution of Nox2 in PHMG-induced lung injury in Nox2-deficient mice. We treated wild-type (WT) and Nox2 knockout mice with a single intratracheal instillation of 1.1 mg/kg PHMG and sacrificed them after 14 days. We analyzed lung histopathology and the number of total and differential cells in the bronchoalveolar lavage fluid. In addition, the expressions of cytokines, chemokines, and profibrogenic genes were analyzed in the lung tissues. Based on our results, Nox2-deficient mice showed less PHMG-induced pulmonary damage than WT mice, as indicated by parameters such as body weight, lung weight, total cell count, cytokine and chemokine levels, fibrogenic mediator expression, and histopathological findings. These findings suggest that Nox2 may have the potential to contribute to PHMG-induced lung injury and serves as an essential signaling molecule in the development of PHMG-induced pulmonary fibrosis by regulating the expression of profibrogenic genes.