THE LENGTH OF 5'-UNTRANSLATED LEADER SEQUENCES INFLUENCES DISTRIBUTION OF 3-HYDROXY-3-METHYLGLUTARYL-COENZYME-A REDUCTASE MESSENGER-RNA IN POLYSOMES - EFFECTS OF LOVASTATIN, OXYSTEROLS, AND MEVALONATE
THE LENGTH OF 5'-UNTRANSLATED LEADER SEQUENCES INFLUENCES DISTRIBUTION OF 3-HYDROXY-3-METHYLGLUTARYL-COENZYME-A REDUCTASE MESSENGER-RNA IN POLYSOMES - EFFECTS OF LOVASTATIN, OXYSTEROLS, AND MEVALONATE
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DOI：
10.1006/abbi.1995.1491
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发表时间：
1995-10-01
影响因子：
3.9
通讯作者：
PEFFLEY, DM
中科院分区：
文献类型：
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作者：
GAYEN, AK;PEFFLEY, DM
仓鼠 3-羟基-3-甲基戊二酰辅酶 A (HMG-CoA) 还原酶的转录本在长度上存在异质性，这种异质性是由于 5'-非翻译前导 (UTL) 序列的长度变化造成的，这些序列是由第一个外显子内的交替剪接以及交替转录起始位点产生的。由于 mRNA 5'-UTL 序列在调节翻译效率中发挥作用，因此在来自叙利亚仓鼠细胞系 C100 的总细胞 RNA 和多核糖体中测量了 HMG-CoA 还原酶转录物的水平和分布。细胞用单独洛伐他汀、洛伐他汀和 25-羟基胆固醇 (25-OH C) 或洛伐他汀、25-OH C 和甲羟戊酸处理，这三种治疗方案用于早期研究证明非甾醇介导的 HMG-CoA 还原酶合成翻译控制 [D, M, Peffley (1992) Somat。细胞分子。热内特. [18, 19-32]，当在相同条件下通过 5'-延伸分析测量还原酶 mRNA 时，具有 41 至 81 个碱基范围的 5'-UTL 区域的转录物水平减少了约 4 至 8 倍，相反，长度为 93 至 100 个碱基的 5'-UTL 区域的转录物没有减少，并且具有约 300-400 个碱基的 5'-UTL 区域的转录物水平长度增加两倍，单独添加 25-OH C 或同时添加 25-OH C 和甲羟戊酸到洛伐他汀处理的细胞中，通过 RNase 保护测定测定，总细胞 RNA 中的 HMG-CoA 还原酶 mRNA 水平降低了五倍，与对照核糖体蛋白 S17 mRNA 没有观察到类似的变化 通过蔗糖梯度分级制备代表翻译失活的单体和翻译活性多聚体的线粒体后上清液从用标准三种处理孵育的细胞中，由于许多 mRNA 的 5'-UTL 序列在调节翻译效率方面发挥作用，我们从每个级分中分离出 RNA，并通过 5'-延伸分析测量还原酶转录本的水平。在所有三种条件下，长度为 41-103 个碱基的 5'-UTL 序列的转录本主要与包含多核糖体的致密蔗糖级分相关，相比之下，前导序列为 300 至 400 的还原酶转录本碱基几乎完全与含有单体的密度较低的蔗糖级分相关。这些结果表明，单个还原酶转录物的水平和多核糖体分布均受到 5'-UTL 序列长度的影响。 (C) 1995 学术出版社
Transcripts for hamster 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase are heterogeneous in length, This heterogeneity is due to variations in the length of 5'-untranslated leader (UTL) sequences, which are generated by both alternate splicing within the first exon as well as alternate transcription start sites. Because mRNA 5'-UTL sequences have a role in regulating translational efficiency, the level and distribution of HMG-CoA reductase transcripts were measured in both total cellular RNA and polysomes from the Syrian hamster cell line C100, Cells were treated with either lovastatin alone, lovastatin and 25-hydroxycholesterol (25-OH C), or lovastatin, 25-OH C, and mevalonate, three treatment regimens used in an earlier study to demonstrate nonsterol-mediated translational control of HMG-CoA reductase synthesis [D, M, Peffley (1992) Somat. Cell Mol. Genet. 18, 19-32], When reductase mRNA was measured by 5'-extension analysis under the same conditions, levels of transcripts with 5'-UTL regions ranging from 41 to 81 bases were reduced approximately four- to eightfold, In contrast, transcripts with 5'-UTL regions 93 to 100 bases in length were not reduced, and transcripts with 5'-UTL regions approximately 300-400 bases in length increased twofold, The addition of 25-OH C alone or both 25-OH C and mevalonate to lovastatin-treated cells lowered HMG-CoA reductase mRNA levels fivefold in total cellular RNA as determined by RNase protection assay, No comparable change was observed with control ribosomal protein S17 mRNA Postmitochondrial supernatants representing both translationally inactive monosomes and translationally active polysomes were prepared by sucrose gradient fractionation from cells incubated with the standard three treatments, Because 5'-UTL sequences of many mRNAs have a role in regulating translational efficiency we isolated RNA from each fraction and measured levels of reductase transcripts by 5'-extension analysis, Under all three conditions, transcripts with 5'-UTL sequences 41-103 bases in length were primarily associated with dense sucrose fractions that contain polysomes, In contrast, reductase transcripts with leader sequences 300 to 400 bases were almost exclusively associated with the less dense sucrose fractions containing monosomes, These results indicate that both the level and polysome distribution of individual reductase transcripts are influenced by the length of 5'-UTL sequences. (C) 1995 Academic Press, Inc.