Impaired hepatic apolipoprotein B and E translation in streptozotocin diabetic rats.
Impaired hepatic apolipoprotein B and E translation in streptozotocin diabetic rats.
复制标题
链脲佐菌素糖尿病大鼠肝载脂蛋白 B 和 E 翻译受损。
DOI：
10.1172/jci115731
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Fisher,EA
中科院分区：
文献类型：
--
作者：
Sparks,JD;Zolfaghari,R;Sparks,CE;Smith,HC;Fisher,EA
对链脲佐菌素诱导的大鼠糖尿病的研究表明，肝脏载脂蛋白B和载脂蛋白E的产生减少。为了确定减少是否与肝脏mRNAs的减少有关，我们用大鼠载脂蛋白B、载脂蛋白E和白蛋白cDNA探针对肝脏总RNA进行了印迹分析。糖尿病大鼠肝脏白蛋白基因表达水平下降到对照肝脏的48%，而载脂蛋白B和载脂蛋白E基因表达水平没有变化。糖尿病大鼠的翻译终止密码子(BSTOP)mRNA的比例平均为43%，与对照组水平相近。[35S]蛋氨酸在大鼠肝细胞原代培养中的长期标记实验和特异性免疫沉淀实验表明，糖尿病大鼠肝细胞产生载脂蛋白B和载脂蛋白E，白蛋白分别减少到对照组的37%、53%和23%。脉搏追踪研究和mRNA分析表明，糖尿病患者肝脏载脂蛋白B和载脂蛋白E的分泌减少主要是翻译受损而不是细胞内降解的结果。核糖体转运研究直接证实了糖尿病大鼠肝细胞载脂蛋白B和载脂蛋白E的mRNAs延伸率延长。这种影响在载脂蛋白BH(高分子量)上比在载脂蛋白BL(低分子量)上更明显。糖尿病大鼠经胰岛素治疗7d后，肝组织白蛋白基因表达水平恢复正常，载脂蛋白E基因表达水平无明显变化。相反，胰岛素治疗导致肝脏载脂蛋白B mRNA显著高于对照组水平。结果表明，在糖尿病状态下，肝脏白蛋白和载脂蛋白B的mRNA水平对胰岛素有反应。
Studies of streptozotocin-induced diabetes in rats have demonstrated that hepatic apo B and apo E production are reduced. To determine if reductions are related to decreases in hepatic mRNAs, we performed blotting analysis of total liver RNA with rat apo B, apo E, and albumin cDNA probes. The expected reduction in albumin mRNA levels to 48% of control livers occurred in diabetic rat liver, while apo B and apo E mRNA levels were unchanged. The proportion of translational stop codon (BSTOP) mRNA averaged 43% of total in diabetic rats similar to control levels. Long-term labeling experiments using [35S]methionine in primary cultures of rat hepatocytes and specific immunoprecipitations demonstrated production of apo B and apo E, and albumin by hepatocytes from diabetic rats was reduced to 37%, 53%, and 23% of controls. Pulse-chase studies, together with mRNA analyses, suggest that reduced hepatic secretion of apo B and apo E in diabetics is primarily a result of impaired translation and not intracellular degradation. Ribosome transit studies directly confirmed the prolonged elongation rates for apo B and apo E mRNAs in hepatocytes derived from diabetic rats. This effect was more pronounced on apo BH (higher molecular weight) than on apo BL (lower molecular weight). Treatment of diabetic rats with insulin for 7 d led to normalization of hepatic albumin mRNA levels with no substantial change in apo E mRNA levels. In contrast, insulin treatment resulted in significant increases in hepatic apo B mRNA over control levels. Results suggest hepatic albumin and apo B mRNA levels are responsive to insulin in the diabetic state.Images