ANTIOXIDANT DEFENSE OF TWO PEROXIREDOXIN MEMBERS FROM BLACK ROCKFISH Sebastes schlegelii WITH THEIR MOLECULAR PROFILING AND TISSUE SPECIFIC EXPRESSIONAL PROFILE  

Marine aquatic organisms are vulnerable to different oxidative stress and constant attack from free radicals. Excessive level of reactive oxygen species (ROS) in the cells creates a state of oxidative stress, which can cause protein oxidation, lipid peroxidation, DNA strand breaks, DNA base modifications and cell death. Peroxiredoxins (Prxs) are considered as essential components of antioxidant defenses to reduce the excessive levels of ROS. Here, we report the antioxidant activity of Prx4 and Prx5 from black rockfish (Sebastes schlegelii) with their molecular features and tissue specific transcriptional profiles. Each nucleotide sequence of SsPrx4 and SsPrx5 bears a coding sequence (CDS) of 789 bp and 573 bp, respectively which coded into a putative peptide of 262 aa (29 kDa) and 190 aa (20 kDa). Characteristic peroxiredoxin super family domain and two cysteine residues were identified in both SsPrx molecules. 100 µg/mL recombinant proteins of SsPrxs (rSsPrx4 and rSsPrx5) were significantly increased the human THP-1 cell survival rate under H₂O₂ (400 µmol) oxidative stress (Fig. 1X). In addition, 100 µg/mL both rSsPrx4 and rSsPrx5 were significantly reduced the intracellular ROS generation in human THP-1 cells upon H₂O₂ (400 µmol) oxidative stress (Fig. 1Y). These findings affirm the antioxidant activity of the rSsPrx4 and rSsPrx5 via redox activity between H₂O₂ and peroxiredoxins.

The qPCR results indicated that SsPrx4 and SsPrx5 were ubiquitously expressed in fourteen different tissues isolated from healthy rockfish with highest expression in liver and ovary, respectively. Collective results of SsPrx4 and SsPrx5 were revealed that, those two rockfish genes are belongs to teleostean peroxiredoxin family. Indeed, our findings suggest that SsPrx4 and SsPrx5 are potential antioxidants and may crucial for the black rockfish cell protection under ROS mediated oxidative stress environment.