• Journal of Marine Bioscience and Biotechnology
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• v.14 no.1
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• pp.33-42
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• 2022

Tacrolimus, a type of macrolide produced by Streptomyces tsukubaensis, is widely used as an immunosuppressant. However, continuous exposure to tacrolimus causes oxidative stress in normal cells, ultimately inducing cell injury. Therefore, this study investigated whether luthione, a reduced glutathione, could inhibit tacrolimus-induced cytotoxicity in olive flounder (hirame) natural embryo (HINAE) cells. According to the results, luthione significantly inhibited tacrolimus-induced reduction in cell viability in a concentration-dependent manner. Additinally, although luthione unaffected autophagy by tacrolimus, tacrolimus-induced apoptosis was significantly suppressed in the presence of luthione. Luthione also markedly blocked DNA damage in tacrolimus-treated HINAE cells, associated with the inhibition of reactive oxygen species (ROS) generation. Additionally, tacrolimus cytotoxicity in HINAE cells was correlated with increased inflammatory response, also attenuated by luthione. Collectively, these results show that at least luthione protects HINAE cells against tacrolimus-induced DNA damage, apoptosis, and inflammation, but not autophagy, by scavenging ROS. Although additional in-vivo studies are required, this study's results can be used as a basis for utilizing luthione to reduce the toxicity of fish cells caused by excessive immune responses.

• Journal of Life Science
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• v.27 no.11
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• pp.1369-1375
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• 2017

The purpose of this study was to investigate the cellular characterization of phospholipase C-${\delta}1$ in olive flounders (Paralichthys olivaceus). In general, phospholipase C signaling pathways are distributed in nuclei at plasma membranes and in cytoplasms, although the pathways' nuclear localization mechanisms are unclear. P. olivaceus duplicates type-A PoPLC-${\delta}1$ (PoPLC-${\delta}1A$), which has a high similarity to the human isoform PLC-${\delta}$; type-B PoPLC-${\delta}1$ (PoPLC-${\delta}1B$ [Sf]), which has a low similarity to the human isoform PLC-${\delta}$ and the alternative splice variant PoPLC-${\delta}1B$ (Lf), which has a nuclear localization signal (NLS) and a nuclear export signal (NES) for nuclear imports and exports, respectively. This study confirmed the effects of the cellular localization and translocation of GFP-tagged PoPLC-${\delta}1A$, PoPLC-${\delta}1B$ (Sf) and PoPLC-${\delta}1B$ (Lf). It administered treatments of $Ca^{2+}$ ionophore ionomycin and endoplasmic reticulum (ER)-$Ca^{2+}$ pump inhibitor thapsigargin to hirame natural-embryo (HINAE) cells. A laser-scanning confocal microscope was used. GFP-tagged PoPLC-${\delta}1A$ was distributed to the cellular organelles, rather than to the cytoplasms and cytomembranes, when PoPLC-${\delta}1B$ (Lf) and PoPLC-${\delta}1B$ (Sf) were localized at the plasma membranes. The treatments of ionomycin and thapsigargin showed the accumulation of PoPLC-${\delta}1A$ in the nuclei when PoPLC-${\delta}1B$ (Lf) nucleocytoplasmic shuttling and PoPLC-${\delta}1B$ (Sf) nucleocytoplasmic shuttling were not observed. The results were the first evidence that PoPLC-${\delta}1A$, which contains functional, intact NES sequences, has a main role in nucleocytoplasmic shuttling and translocation in fish.