锌对小鼠组织MT-1基因转录及MT蛋白表达的影响

Effect of Zn on MT-1 gene transcription and metallothionein (MT) protein expression in mice

目的 :研究锌对小鼠各脏器金属硫蛋白 (MT)基因表达的影响。方法 :将小鼠随机分为注锌组和对照组 ,注锌后不同时间或不同剂量锌注射后 16 h断头处死动物 ,取一定量肝、脑、胸腺及脾脏组织制成匀浆 ,采用 Northern blot及 10 9Cd- hem饱和法测定组织 MT基因转录及蛋白表达的变化。结果 :时程研究表明 ,锌 10 mg/ kg腹腔注射后 2 h,小鼠肝脏及脾脏 MT- 1m RNA水平明显升高 ,4 h达峰值 ,分别为对照组的 5 .30和 2 .92倍 ,2 4 h恢复至正常水平 ;其 MT蛋白表达迟于 MT- 1m RNA水平升高 ,注锌后 8～ 2 4 h肝脏及脾脏 MT蛋白含量均比对照组明显升高 (P<0 .0 5或 P<0 .0 0 1) ,2 4 h达峰值 ,72 h恢复至正常水平。注射不同剂量锌后小鼠肝脏及脾脏 MT- 1m RNA水平 (4h)和 MT蛋白含量 (16 h)均呈剂量依赖性增加。小鼠腹腔注射锌 2 .5～ 10 mg/ kg 16 h,小鼠肝脏或脾脏 MT含量或锌5～ 10 mg/ kg注射后脾脏 MT含量均显著高于对照组 (P<0 .0 1或 P<0 .0 0 1)。但注射锌后脑及胸腺MT- 1m RNA水平及 MT蛋白含量均无明显变化经。结论 :锌诱导小鼠组织 MT合成具有明显的组织器官特异性。

Objective:To study the effect of Zn on MT protein and MT 1 mRNA levels in mouse organs. Methods: Mice were randomly divided into Zn intraperitoneal injection and control groups.MT 1 mRNA and MT levels of mouse organs were detected by Northern blot and 109 Cd hem saturation method at different time points after Zn injection and at 4 h or 16 h after different dose Zn injection.Results:Time course experiment showed that MT 1 mRNA level of liver and spleen increased at 2~16 h after injection with Zn 10 mg/kg .bw and reached a peak at 4 h which was 5.30 and 2.92 times as high as control respectively and returned to normal level at 24 h;MT protein expression was obviously later than MT 1 mRNA increase after Zn injection.MT protein levels of liver and spleen markedly increased from 8 to 48 h after injection with Zn 10 mg/kg and there was significant difference in comparison with control ( P <0 05 or P <0 001),and MT contents of liver and spleen reached a peak at 24 h and returned to normal level at 72 h.MT 1 mRNA or MT protein increases of liver and spleen at 4 h or 16 h after different dose injection was dose dependent.MT protein levels in liver injected with Zn 2.5~10 mg/kg and in spleen with Zn 5~10 mg/kg were obviously higher than control ( P <0 01~0 001).But MT protein expression in brain and thymus had no markedly change after Zn injection.Conclusion:MT synthesis in liver and spleen could rapidly be induced by Zn in mice and increased in a dose dependent manner,but not in thymus and brain.It was suggested that Mt induction by Zn was obviously tissue specific.And MT induced by Zn was regulated through MT 1 gene transcription.pleen markedly increa