• Natural Product Sciences
• /
• v.24 no.1
• /
• pp.59-65
• /
• 2018

An isoform of NADPH oxidase (NOX), NOX2 is a superoxide-generating enzyme involved in diverse pathophysiological events. Although its potential as a therapeutic target has been validated, there is no clinically available inhibitor. Herein, NOX2-inhibitory activity was screened with the constituents isolated from Schisandra chinensis, which has been reported to have antioxidant and reactive oxygen species (ROS)-scavenging effects. Among the partitions prepared from crude methanolic extract, a chloroform-soluble partition showed the highest NOX2-inhibitory activity in PLB-985 cell-based NOX2 assay. A total of twenty nine compounds (1 - 29) were identified from the chloroform fraction, including two first isolated compounds; dimethyl-malate (25) and 2-(2-hydroxyacetyl) furan (27) from this plants. Of these constituents, two compounds (gomisin T, and pregomisin) exhibited an NOX2-inhibitory effect with the $IC_{50}$ of $9.4{\pm}3.6$, and $62.9{\pm}11.3{\mu}M$, respectively. They are confirmed not to be nonspecific superoxide scavengers in a counter assay using a xanthine-xanthine oxidase system. These findings suggest the potential application of gomisin T (6) and other constituents of S. chinensis to inhibit NOX2.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.11
• /
• pp.1455-1463
• /
• 2014

In the past, reactive oxygen species (ROS) have been considered a harmful byproduct of aerobic metabolism. However, accumulating evidence implicates redox homeostasis, which maintains appropriate ROS levels, in cell proliferation and differentiation in plants and animals. Similarly, ROS generation and signaling are instrumental in fungal development and host-fungus interaction. In fungi, NADPH oxidase, a homolog of human $gp91^{phox}$, generates superoxide and is the main source of ROS. The mechanism of activation and signaling by NADPH oxidases in fungi appears to be largely comparable to those in plants and animals. Recent studies have shown that the fungal NADPH oxidase homologs NoxA (Nox1), NoxB (Nox2), and NoxC (Nox3) have distinct functions. In particular, these studies have consistently demonstrated the impact of NoxA on the development of fungal multicellular structures. Both NoxA and NoxB (but not NoxC) are involved in host-fungus interactions, with the function of NoxA being more critical than that of NoxB.

• Biomolecules & Therapeutics
• /
• v.28 no.1
• /
• pp.25-33
• /
• 2020

Several recent studies have reported that reactive oxygen species (ROS), superoxide anion and hydrogen peroxide (H₂O₂), play important roles in various cellular signaling networks. NADPH oxidase (Nox) isozymes have been shown to mediate receptor-mediated ROS generation for physiological signaling processes involved in cell growth, differentiation, apoptosis, and fibrosis. Detectable intracellular levels of ROS can be induced by the electron leakage from mitochondrial respiratory chain as well as by activation of cytochrome p450, glucose oxidase and xanthine oxidase, leading to oxidative stress. The up-regulation and the hyper-activation of NADPH oxidases (Nox) also likely contribute to oxidative stress in pathophysiologic stages. Elevation of the renal ROS level through hyperglycemia-mediated Nox activation results in the oxidative stress which induces a damage to kidney tissues, causing to diabetic nephropathy (DN). Nox inhibitors are currently being developed as the therapeutics of DN. In this review, we summarize Nox-mediated ROS generation and development of Nox inhibitors for therapeutics of DN treatment.

• The Plant Pathology Journal
• /
• v.38 no.4
• /
• pp.345-354
• /
• 2022

NADPH oxidase (Nox) complexes are known to play essential roles in differentiation and proliferation of many filamentous fungi. However, the functions of Noxs have not been elucidated in Colletotrichum species. Therefore, we set out to characterize the roles of Nox enzymes and their regulators in Colletotrichum scovillei, which causes serious anthracnose disease on pepper fruits in temperate and subtropical and temperate region. In this study, we generated targeted deletion mutants for CsNox1, CsNox2, CsNoxR, and CsNoxD via homologous recombination. All deletion mutants were normal in mycelial growth, conidiation, conidial germination, and appressorium formation, suggesting that CsNox1, CsNox2, CsNoxR, and CsNoxD are not involved in those developmental processes. Notably, conidia of 𝜟Csnox2 and 𝜟Csnoxr, other than 𝜟Csnox1 and 𝜟Csnoxd, failed to cause anthracnose on intact pepper fruits. However, they still caused normal disease on wounded pepper fruits, suggesting that Csnox2 and CsnoxR are essential for penetration-related morphogenesis in C. scovillei. Further observation proved that 𝜟Csnox2 and 𝜟Csnoxr were unable to form penetration peg, while they fully developed appressoria, revealing that defect of anthracnose development by 𝜟Csnox2 and 𝜟Csnoxr resulted from failure in penetration peg formation. Our results suggest that CsNox2 and CsNoxR are critical for appressorium-mediated penetration in C. scovillei-pepper fruit pathosystem, which provides insight into understanding roles of Nox genes in anthracnose disease development.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.12
• /
• pp.2984-2988
• /
• 2009

A gene (PH0311) encoding a hypothetical protein from the genome sequence data of the hyperthermophilic archaeon Pyrococcus horikoshii OT3 was cloned and over-expressed in Escherichia coli. The purified recombinant protein was found to possess FAD-dependent NADH oxidase activity, although it lacked sequence homology to any other known general NADH oxidase family. The product of the PH0311 gene was thus designated PhNOX (NADH oxidase from Pyrococcus horikoshii), with an estimated molecular weight of 84 kDa by gel filtration and 22 kDa by SDS-PAGE, indicating it to be a homotetramer of 22 kDa subunits. PhNOX catalyzed the oxidation of reduced ${\beta}$-NADH with subsequent formation of $H_2O_2$ in the presence of FAD as a cofactor, but not ${\alpha}$-NADH, ${\alpha}$-NADPH, or ${\beta}$-NADPH. PhNOX showed high affinity for ${\beta}$-NADH with a Km value of 3.70 ${\mu}$M and exhibited optimum activity at pH 8.0 and 95$^{\circ}C$ as it is highly stable against high temperature.

• Journal of Periodontal and Implant Science
• /
• v.36 no.4
• /
• pp.863-878
• /
• 2006

Porphyromonas gingivalis는 치주질환을 야기하는 독성세균으로서, 구강상피세포에 p. gingivalis가 감염되었을 때, 세포형태에 변화를 초래함으로 인해 방어기작이 작동하게 된다. 치주질환과 관련되어 생성된 활성 산소종의 소거에 관여하는 항산화성분은 p. gingivalis 이 감염된 구강상피세포에서 그 분포와 발현수준이 달라지리라 예상된다. 따라서 이번 연구에서는 구강상피세포(KB 세포)에 p. gingivalis가 감염되었을 때 야기되는 활성산소종과 이를 소거하는 역할을 하는 항산화단백들의 역할들을 규명하고자 하였다. 활성산소종 형성을 조절하는 NADPH oxidase 중 NOX4와 Rac1 전사체는 구강상피세포에서 p. gingivalis세균에 의해 증가하였으며 $gp91^{phox}$, Rac2, $p47^{phox}$와 $p67^{phox}$는 세균에 의한 변화가 관찰되지 않았다. 반면에 $p40^{phox}$ 전사체는 감소하는 경향을 보였다. NOX1 전사체는 p. gingivalis 처리 30분 후 감소하였다가 60분 후에는 다시 증가하는 양상을 보였다. 같은 시간에 NOX 활성화 단백인 NOXA1은 감소하고, NOX 구성단백질인 NOXO1은 증가하는 경향을 보였다. p. gingivalis가 감염된 구강상피세포를 방어하는 항산화단백 발현수준을 평가한 결과, SOD1, 2, 3 모두 p. gingivalis 처리시간에 따라 증가하는 양상을 보였다. GPx 발현 양상도 SOD와 유사하게 나타났다. $H_2O_2$를 소거하는 Prx는 감염된 KB 세포에서 Prx4와 Prx5가 4-6배 증가하는 것을 알 수 있었다. 반면 endocytosis 과정 중 $H_2O_2$ 생산은 변화되지 않았다. 이번 연구의 결과, p. gingivalis의 감염은 KB 세포의 NOX4와 Rac1의 NADPH oxidase 발현을 증가시켰으며, NOX1은 NOXA1과 NOXO1의 조절에 의해 영향을 받음을 알 수 있었다. 또한 항산화기작으로는 SOD, GPx, Prx가 증가하였는데, 이것은 Prx4와 Prx5가 중요한 역할을 할 것을 시사하였다.

• Toxicological Research
• /
• v.30 no.3
• /
• pp.149-157
• /
• 2014

Smoking is one of the most serious but preventable causes of cardiovascular disease (CVD). Key aspects of pathological process associated with smoking include endothelial dysfunction, a prothrombotic state, inflammation, altered lipid metabolism, and hypoxia. Multiple molecular events are involved in smoking-induced CVD. However, the dysregulations of reactive oxygen species (ROS) generation and metabolism mainly contribute to the development of diverse CVDs, and NADPH oxidase (NOX) has been established as a source of ROS responsible for the pathogenesis of CVD. NOX activation and resultant ROS production by cigarette smoke (CS) treatment have been widely observed in isolated blood vessels and cultured vascular cells, including endothelial and smooth muscle cells. NOX-mediated oxidative stress has also been demonstrated in animal studies. Of the various NOX isoforms, NOX2 has been reported to mediate ROS generation by CS, but other isoforms were not tested thoroughly. Of the many CS constituents, nicotine, methyl vinyl ketone, and ${\alpha}$,${\beta}$-unsaturated aldehydes, such as, acrolein and crotonaldehyde, appear to be primarily responsible for NOX-mediated cytotoxicity, but additional validation will be needed. Human epidemiological studies have reported relationships between polymorphisms in the CYBA gene encoding p22phox, a catalytic subunit of NOX and susceptibility to smoking-related CVDs. In particular, G allele carriers of A640G and $-930^{A/G}$ polymorphisms were found to be vulnerable to smoking-induced cardiovascular toxicity, but results for C242T studies are conflicting. On the whole, evidence implicates the etiological role of NOX in smoking-induced CVD, but the clinical relevance of NOX activation by smoking and its contribution to CVD require further validation in human studies. A detailed understanding of the role of NOX would be helpful to assess the risk of smoking to human health, to define high-risk subgroups, and to develop strategies to prevent or treat smoking-induced CVD.

• IMMUNE NETWORK
• /
• v.11 no.3
• /
• pp.169-174
• /
• 2011

Background: NADPH oxidase (NOX) modulates cell proliferation, differentiation and immune response through generation of reactive oxygen species. Particularly, NOX2 is recently reported to be important for regulating Treg cell differentiation of CD4+ T cells. Methods: We employed ovalbumin-induced airway inflammation in wild-type and NOX2-deficient mice and analyzed tissue histopathology and cytokine profiles. Results: We investigated whether NOX2-deficiency affects T cell-mediated airway inflammation. Ovalbumin injection which activates T cell-mediated allergic response increased airway inflammation in wild-type mice, as evidenced by increased immune cell infiltration, allergic cytokine expression, and goblet cell hyperplasia in the lung. Interestingly, NOX2 knockout (KO) mice were more susceptible to allergen-induced lung inflammation compared to wild-type mice. Immune cells including neutrophils, lymphocytes, macrophages, and eosinophils were drastically infiltrated into the lung of NOX2 KO mice and mucus secretion was substantially increased in deficiency of NOX2. Furthermore, inflammatory allergic cytokines and eotaxin were significantly elevated in NOX2 KO mice, in accordance with enhanced generation of inflammatory cytokines interleukin-17 and interferon-${\gamma}$ by CD4+ T cells. Conclusion: These results indicate that NOX2 deficiency favorably produces inflammatory cytokines by T cells and thus increases the susceptibility to severe airway inflammation.

• Parasites, Hosts and Diseases
• /
• v.61 no.4
• /
• pp.388-396
• /
• 2023

Entamoeba histolytica is an enteric tissue-invasive protozoan parasite causing amoebic colitis and liver abscesses in humans. Amoebic contact with host cells activates intracellular signaling pathways that lead to host cell death via generation of caspase-3, calpain, Ca²⁺ elevation, and reactive oxygen species (ROS). We previously reported that various NADPH oxidases (NOXs) are responsible for ROS-dependent death of various host cells induced by amoeba. In the present study, we investigated the specific NOX isoform involved in ROS-dependent death of hepatocytes induced by amoebas. Co-incubation of hepatoma HepG2 cells with live amoebic trophozoites resulted in remarkably increased DNA fragmentation compared to cells incubated with medium alone. HepG2 cells that adhered to amoebic trophozoites showed strong dichlorodihydrofluorescein diacetate (DCF-DA) fluorescence, suggesting intracellular ROS accumulation within host cells stimulated by amoebic trophozoites. Pretreatment of HepG2 cells with the general NOX inhibitor DPI or NOX2-specific inhibitor GSK 2795039 reduced Entamoeba-induced ROS generation. Similarly, Entamoeba-induced LDH release from HepG2 cells was effectively inhibited by pretreatment with DPI or GSK 2795039. In NOX2-silenced HepG2 cells, Entamoeba-induced LDH release was also significantly inhibited compared with controls. Taken together, the results support an important role of NOX2-derived ROS in hepatocyte death induced by E. histolytica.

• Parasites, Hosts and Diseases
• /
• v.62 no.3
• /
• pp.270-280
• /
• 2024

Trichomoniasis is caused by a sexually transmitted flagellate protozoan parasite Trichomonas vaginalis. T. vaginalis-derived secretory products (TvSP) contain lipid mediators such as leukotriene B₄ (LTB₄) and various cysteinyl leukotrienes (CysLTs) which included LTC₄, LTD₄, and LTE₄. However, the signaling mechanisms by which T. vaginalis-induced CysLTs stimulate interleukin (IL)-8 production in human mast cells remain unclear. In this study, we investigated these mechanisms in human mast cells (HMC-1). Stimulation with TvSP resulted in increased intracellular reactive oxygen species (ROS) generation and NADPH oxidase 2 (NOX2) activation compared to unstimulated cells. Pre-treatment with NOX2 inhibitors such as diphenyleneiodonium chloride (DPI) or apocynin significantly reduced ROS production in TvSP-stimulated HMC-1 cells. Additionally, TvSP stimulation increased NOX2 protein expression and the translocation of p47^phox from the cytosol to the membrane. Pretreatment of HMC-1 cells with PI3K or PKC inhibitors reduced TvSP-induced p47^phox translocation and ROS generation. Furthermore, NOX2 inhibitors or NOX2 siRNA prevented CREB phosphorylation and IL-8 gene expression or protein secretion induced by TvSP. Pretreatment with a CysLTR antagonist significantly inhibited TvSP-induced ROS production, CREB phosphorylation, and IL-8 production. These results indicate that CysLT-mediated activation of NOX2 plays a crucial role in ROS-dependent IL-8 production in human mast cells stimulated by T. vaginalis-secreted CysLTs. These findings enhance our understanding of the inflammatory response in trichomoniasis and may inform the development of targeted therapies to mitigate this response.