14-3-3ζ-Mediated Stimulation of Oxidative Phosphorylation Exacerbates Oxidative Damage Under Hypothermic Oxygenated Conditions in Human Renal Tubular Cells (HK-2).

Cellular survival and death are at least partially regulated by the phosphorylation of proteins. A chaperon protein, 14-3-3ζ, regulates the activity of many proteins by covering the phosphorylation site within a 14-3-3 binding motif. Therefore, regulation of 14-3-3ζ activity may affect the fate of cells subjected to cold preservation and/or hypothermic oxygenated conditions. The present study assessed whether 14-3-3ζ protects cells from hypothermic oxygenation-induced injury and clarified its role in mitochondrial functions. Human renal tubular cell line HK-2 or 14-3-3ζ-overexpressed HK-2 (ζHK-2) cells were subjected to 72 hours of normoxic cold preservation in UW solution with or without antioxidants and hydroperoxides. Cellular death, adenosine triphosphate (ATP) content, and MTT catabolism were evaluated. Deferoxamine treatment reduced cellular death and augmented ATP content in both cell types. These indices were higher in ζHK-2, regardless of deferoxamine treatment. Exposure to hydroperoxides did not affect cellular death in either cell type, whereas hydroperoxide supplementation significantly reduced ATP content, except for low-dose hydrogen peroxide in HK-2 cells. MTT assay at normal state showed higher values in ζHK-2 cells, whereas it was impaired by hydroperoxides in both cell types. These results suggest that accumulation of hydroperoxides as a byproduct of the augmented oxidative phosphorylation by 14-3-3ζ overexpression causes mitochondrial dysfunction. In conclusion, despite possessing many potentially protective functions, 14-3-3ζ exacerbates cellular injury under hypothermic oxygenated conditions. 14-3-3ζ accelerates mitochondrial functions together with iron-dependent oxidative damage. Although further investigations are necessary, upregulation of 14-3-3ζ could be a method to maintain mitochondrial function under hypothermic oxygenated conditions, as shown in hypothermic machine preservation of renal grafts, when appropriate antioxidant treatment is administered.

Analysis of differential accumulation of winged bean Kunitz chymotrypsin inhibitor mRNA species by a sequence-specific termination method.

Winged bean Kunitz chymotrypsin inhibitor (WCI) is encoded by a multigene family and accumulation of its mRNA is restricted in mid-maturation stage seeds and tuberous roots. In this paper, we analyzed the accumulation of mRNA derived from each WCI gene using a novel method: sequence-specific termination analysis. The results demonstrated that the accumulation of each WCI mRNA was differentially regulated in winged bean plants.

Structure and regulated expression of Kunitz chymotrypsin inhibitor genes in winged bean [Psophocarpus tetragonolobus (L.) DC].

We analyzed the structure and the expression of Kunitz chymotrypsin inhibitor (WCI) genes in winged bean. WCI was encoded by a multigene family which comprised at least seven members. From their primary structures, four genes (WCI-2, WCI-3a, WCI-3b, and WCI-x) were expected to be functional ones and the other three (WCI-P1, WCI-P2, and WCI-P3) to be pseudogenes. The nucleotide sequences of the WCI-3a and WCI-3b genes were nearly identical, and they encoded the WCI-3 protein, the major chymotrypsin inhibitor in seeds. The WCI-2 gene also encoded the chymotrypsin inhibitor found in seeds and the WCI-x gene was expected to encode an unidentified chymotrypsin inhibitor. WCI messenger RNA and protein accumulated mainly in developing seeds and tuberous roots, small amounts of WCI mRNA being present in stems and pericarps. In seeds, transient accumulation of WCI mRNA was observed during the seed maturation period. These results suggest that the expression of WCI genes is regulated organ-specifically and developmentally in winged bean.