[Peroxiredoxins, a new family of antioxidant proteins]

Large yellow croaker peroxiredoxin IV protect cells against oxidative damage and apoptosis

Oxidative stress and inflammation lead to cell damage and are implicated in many disease states. High concentrations of hydrogen peroxide (H₂O₂) may mediate cells apoptosis by increasing intracellular reactive oxygen species (ROS) levels. In this study, we established a LYCK-PrxIV cell line (large yellow croaker head kidney cell line stably expressing peroxiredoxin IV). The level of nitric oxide (NO), superoxide anion and hydrogen peroxide (H₂O₂) in this LYCK-PrxIV cells were significantly lower than those in control cells of LYCK-pcDNA3.1 (LYCK cell line stably transfected by pcDNA3.1 vector). Additionally, when exposed to H₂O₂, cell apoptosis was significantly alleviated in LYCK-PrxIV than in control cells. Meanwhile, the ROS level and ATP content were maintained more stable in LYCK-PrxIV than in LYCK-pcDNA3.1. The over-expression of LcPrxIV in LYCK-PrxIV cells induced a declined mRNA expression of LcCXC, LcCC, LcIL-8 and LcTNF-α2, as well as an increase of LcIL-10 mRNA expression, when compared to LYCK-pcDNA3.1. On the other hand, the expression of chemokine LcCXC, LcCC and LcTNF-a2 increased in LYCK-pcDNA3.1 after H₂O₂ stimulation, while that of LcIL-8 and LcIL-10 decreased. The regualtion of gene expression in LYCK-PrxIV cells was almost the same as that in LYCK-pcDNA3.1, but the change fold was much more moderate. These results suggest that LcPrxIV may be an indispensable ROS scavenger protecting LYCK cells against oxidative damage as well as the subsequent apoptosis and inflammatory response, which provides a clue that LcPrxIV may be an assist in fish immune response.

Peroxiredoxin 5 Inhibits Glutamate-Induced Neuronal Cell Death through the Regulation of Calcineurin-Dependent Mitochondrial Dynamics in HT22 Cells

Glutamate is an essential neurotransmitter in the central nervous system (CNS). However, high glutamate concentrations can lead to neurodegenerative diseases. A hallmark of glutamate toxicity is high levels of reactive oxygen species (ROS), which can trigger Ca²⁺ influx and dynamin-related protein 1 (Drp1)-mediated mitochondrial fission. Peroxiredoxin 5 (Prx5) is a well-known cysteine-dependent peroxidase enzyme. However, the precise effects of Prx5 on glutamate toxicity are still unclear. In this study, we investigated the role of Prx5 in glutamate-induced neuronal cell death. We found that glutamate treatment induces endogenous Prx5 expression and Ca²⁺/calcineurin-dependent dephosphorylation of Drp1, resulting in mitochondrial fission and neuronal cell death. Our results indicate that Prx5 inhibits glutamate-induced mitochondrial fission through the regulation of Ca²⁺/calcineurin-dependent dephosphorylation of Drp1, and it does so by scavenging cytosolic and mitochondrial ROS. Therefore, we suggest that Ca²⁺/calcineurin-dependent mitochondrial dynamics are deeply associated with glutamate-induced neurotoxicity. Consequently, Prx5 may be used as a potential agent for developing therapies against glutamate-induced neurotoxicity and neurodegenerative diseases where it plays a key role.

Peroxiredoxin1, a novel regulator of pronephros development, influences retinoic acid and Wnt signaling by controlling ROS levels

Peroxiredoxin1 (Prdx1) is an antioxidant enzyme belonging to the peroxiredoxin family of proteins. Prdx1 catalyzes the reduction of H₂O₂ and alkyl hydroperoxide and plays an important role in different biological processes. Prdx1 also participates in various age-related diseases and cancers. In this study, we investigated the role of Prdx1 in pronephros development during embryogenesis. Prdx1 knockdown markedly inhibited proximal tubule formation in the pronephros and significantly increased the cellular levels of reactive oxygen species (ROS), which impaired primary cilia formation. Additionally, treatment with ROS (H₂O₂) severely disrupted proximal tubule formation, whereas Prdx1 overexpression reversed the ROS-mediated inhibition in proximal tubule formation. Epistatic analysis revealed that Prdx1 has a crucial role in retinoic acid and Wnt signaling pathways during pronephrogenesis. In conclusion, Prdx1 facilitates proximal tubule formation during pronephrogenesis by regulating ROS levels.

DACH1 inhibits the proliferation and invasion of lung adenocarcinoma through the downregulation of peroxiredoxin 3

In this study, we found the expression of Dachshund 1 (DACH1) is downregulated while peroxiredoxin 3 (PRX3) upregulated in both lung adenocarcinoma tissues and cells. Transfection of DACH1 can significantly downregulate PRX3 expression in targeting lung adenocarcinoma cells. Further experimental results demonstrated the evidence that overexpression of DACH1 resulted in significant retardation of in vitro proliferation and invasion of lung adenocarcinoma cells. Direct upregulation of PRX3 by co-transfection of PRX3 messenger RNA (mRNA) can prevent the above alteration caused by DACH1 transfection. Besides, lower DACH1 expression significantly correlated with tumor diameter and tumor invasion in all the 36 patients diagnosed with lung adenocarcinoma in our hospital during the past months. In conclusion, DACH1 can inhibit the proliferation and invasion of lung adenocarcinoma through the downregulation of PRX3. Decreased expression of DACH1 is involved in the initiation and development of lung cancer, which might be an adverse prognostic factor of lung adenocarcinoma.

Expression of candidate genes related to metabolism, immunity and cellular stress during massive mortality in the American oyster Crassostrea virginica larvae in relation to biochemical and physiological parameters

Quantification of mRNA of genes related to metabolism, immunity and cellular stress was examined in relation to a massive mortality event during the culture of American oyster larvae, Crassostrea virginica which was probably, in regard to previous microbiological analysis, induced by Vibrio infection. To document molecular changes associated with the mortality event, mRNA levels were compared to biochemical and physiological data, previously described in a companion paper. Among the 18 genes studied, comparatively to the antibiotic control, 10 showed a lower relative gene expression when the massive mortality occurred. Six of them are presumed to be related to metabolism, corroborating the metabolic depression associated with the mortality event suggested by biochemical and physiological analyses. Relationships between the regulation of antioxidant enzyme activities, lipid peroxidation, and the mRNA abundance of genes linked to oxidative stress, cytoprotection, and immune response are also discussed. Finally, we observed an increase in the transcript abundance of two genes involved in apoptosis and cell regulation simultaneously with mortality, suggesting that these processes might be linked.