Identification of novel RARbeta2 transcript variants with short 5'-UTRs in normal and cancerous breast epithelial cells.
Identification of novel RARbeta2 transcript variants with short 5'-UTRs in normal and cancerous breast epithelial cells.
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在正常和癌性乳腺上皮细胞中鉴定具有短 5-UTR 的新型 RARbeta2 转录物变体。
DOI：
10.1038/sj.onc.1208284
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Christov,Konstantin
中科院分区：
文献类型：
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作者：
Peng,Xinjian;Mehta,RajendraG;Tonetti,DebraA;Christov,Konstantin
RARβ2作为一种推定的肿瘤抑制基因在乳腺癌和其他肿瘤中的功能意义已被研究。其转录物的长5 ' -未翻译区（5 ' -UTR）具有多个开放阅读帧（uorf），被认为是翻译的调控单元。在这里，我们首次在正常和恶性乳腺上皮细胞中发现了具有短5 ' - utr的RARβ2转录变异体。对这些细胞中RARβ2 mRNA的5 ' -RACE分析表明，存在与已知RARβ2序列相同的短RARβ2转录变体，但缺乏全长5 ' -UTR中存在的所有uorf。通过RT-PCR分析，我们发现5 ' -UTR短转录本和全长转录本的表达都是由维甲酸介导的，而细胞敏感性优先与RARβ2短转录本变体在维甲酸的作用下上调有关。转染和体外翻译实验表明，短的5 ' -UTR对翻译没有抑制作用，而全长5 ' -UTR的存在对翻译的抑制作用为60%。此外，RARβ2全长5′-UTR区未检测到启动子活性。我们的数据表明，具有短5 ' -UTR的RARβ2转录物变体可能是RARβ2蛋白翻译的主要转录物，也是类维生素a在乳腺癌预防和治疗研究中的潜在靶点。
Functional significance of RARβ2 as a putative tumor suppressor gene has been studied in breast cancer and other tumors. The long 5′-untranslated region (5′-UTR) of its transcript with multiple open-reading frames (uORFs) is considered as a regulatory unit for translation. Here, for the first time we identified RARβ2 transcript variants with short 5′-UTRs in both normal and malignant breast epithelial cells. The 5′-RACE analysis of RARβ2 mRNA in these cells demonstrated the existence of short RARβ2 transcript variants that are identical to the sequence of known RARβ2, but lack all the uORFs present in the full-length 5′-UTR. By RT–PCR analysis, we found that the expression of both transcripts with short and full-length 5′-UTR is mediated by retinoic acid, while cellular sensitivity is preferentially correlated to upregulation of short RARβ2 transcript variants in response to retinoic acid. The transfection and in vitro translation assay indicated that the short 5′-UTR has no inhibitory effects on translation, while the presence of full-length 5′-UTR inhibited translation by 60%. In addition, no promoter activity was detectable in RARβ2 full-length 5′-UTR region. Our data suggest that the RARβ2 transcript variants with short 5′-UTR may serve as major transcripts for RARβ2 protein translation as well as potential targets for retinoids in breast cancer prevention and therapy studies.