Staneviciene Inga, Sadauskiene Ilona, Lesauskaite Vaiva, Ivanoviene Laima, Kasauskas Artūras, Ivanov Leonid
Laboratory of Pathochemistry, Institute for Biomedical Research, Kaunas University of Medicine, Eiveniu 4, 50009 Kaunas, Lithuania.
Medicina (Kaunas). 2008;44(2):131-8.
The aim of this study was to evaluate in vivo the effects of cadmium and zinc ions on translational machinery and death of mouse liver cells.
Outbred mice received intraperitoneal injections of cadmium chloride solution (1.4 micromoles cadmium per 1 kg of body weight) and/or zinc sulfate solution (4.8 micromoles zinc per kg of body weight) three times per week for six weeks. Analogical volume of saline solution was injected to the control mice. Protein synthesis was evaluated by incorporation of [(14)C]-labeled leucine into peptides and proteins. Total tRNAs were isolated using deproteinized extract of liver tissue. Postmitochondrial supernatant was as a source of leucyl-tRNA synthetase. Activities of tRNA(Leu) and leucyl-tRNA synthetase were measured by an aminoacylation reaction using [(14)C]-labeled leucine. Liver cell apoptosis was detected by TUNEL assay using in situ cell death detection kit.
A decrease in incorporation of [(14)C]-labeled leucine into proteins was detected in liver, kidney, and heart as well as diminution of tRNA(Leu) acceptor activity in cadmium-exposed liver. Cadmium caused activation of the leucyl-tRNA synthetase and induced liver cell apoptosis. Pretreatment of mice with zinc sulfate solution favored to protection of protein synthesis and acceptor activity of tRNA(Leu) against cadmium-induced inhibition. Under co-exposure of mouse liver to cadmium and zinc, activity of the leucyl-tRNA synthetase was at the level of control. Zinc did not influence TUNEL-positive cell number in cadmium-exposed mouse liver.
Under subacute intoxication of mice by cadmium, zinc ions protect the translation machinery against inhibition, but do not decrease the number of apoptotic cells in the liver.
本研究旨在评估镉离子和锌离子对小鼠肝细胞翻译机制及细胞死亡的体内影响。
远交群小鼠每周腹腔注射氯化镉溶液（每千克体重1.4微摩尔镉）和/或硫酸锌溶液（每千克体重4.8微摩尔锌）3次，共6周。给对照小鼠注射等量的生理盐水。通过将[¹⁴C]标记的亮氨酸掺入肽和蛋白质中来评估蛋白质合成。使用肝组织的脱蛋白提取物分离总tRNA。线粒体后上清液作为亮氨酰 - tRNA合成酶的来源。使用[¹⁴C]标记的亮氨酸通过氨酰化反应测量tRNA（Leu）和亮氨酰 - tRNA合成酶的活性。使用原位细胞死亡检测试剂盒通过TUNEL法检测肝细胞凋亡。
在肝脏、肾脏和心脏中检测到[¹⁴C]标记的亮氨酸掺入蛋白质减少，镉暴露的肝脏中tRNA（Leu）受体活性降低。镉导致亮氨酰 - tRNA合成酶活化并诱导肝细胞凋亡。用硫酸锌溶液预处理小鼠有利于保护蛋白质合成和tRNA（Leu）的受体活性免受镉诱导的抑制。在小鼠肝脏同时暴露于镉和锌的情况下，亮氨酰 - tRNA合成酶的活性处于对照水平。锌不影响镉暴露的小鼠肝脏中TUNEL阳性细胞数。
在小鼠镉亚急性中毒情况下，锌离子保护翻译机制免受抑制，但不减少肝脏中凋亡细胞的数量。
