AN ELEMENT IN THE BOVINE PAPILLOMAVIRUS LATE 3' UNTRANSLATED REGION REDUCES POLYADENYLATED CYTOPLASMIC RNA LEVELS
AN ELEMENT IN THE BOVINE PAPILLOMAVIRUS LATE 3' UNTRANSLATED REGION REDUCES POLYADENYLATED CYTOPLASMIC RNA LEVELS
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DOI：
10.1128/jvi.65.11.5806-5812.1991
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发表时间：
1991-11-01
影响因子：
5.4
通讯作者：
BAKER, CC
中科院分区：
文献类型：
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作者：
FURTH, PA;BAKER, CC
表达的两个牛乳头瘤病毒1型（BPV-1）晚期基因，L1和L2，编码的两个衣壳蛋白，是有限的终末分化的角质形成细胞在牛纤维乳头瘤。 这种表达模式由晚期启动子的活性和对分化较差的细胞中晚期区域表达的抑制决定。 在非允许性细胞中必须抑制L1和L2 mRNA的产生，因为晚期区域可能从早期区域启动子转录。 晚期区域的核径流分析已经证明，在非允许细胞中，在早期区域起始的高达95%的转录物终止于晚期多聚腺苷酸化位点上游的晚期区域内（C. C. Baker和J. Noe，J. Virol. 63：3529-3534，1989）。 然而，包括晚期多聚腺苷酸化位点的初级转录物很少被加工成mRNA。 在这项研究中，我们使用表达载体来表征在非允许细胞中具有活性的抑制元件，该抑制元件位于3'非翻译区（3' UTR）的晚期。 虽然晚期多聚腺苷酸化位点在这些细胞中是功能性的，但晚期3 'UTR中的53-bp元件降低了多聚腺苷酸化细胞质RNA的水平。 当以有义方向克隆到CAT表达载体的3 'UTR中时，该元件抑制氯霉素乙酰转移酶（CAT）表达6至10倍。 当将片段克隆到poly（A）位点的下游、CAT编码序列上游的内含子中或3 'UTR中的反义方向时，未观察到对表达的阻断。 当从BPV-1 L1表达载体中删除相同的片段时，mRNA水平增加了6倍。 使用BPV-1 L1表达载体的放线菌素D追踪实验表明，该元件不会使细胞质多腺苷酸化RNA不稳定。 因此，该元件必须在成熟mRNA到达细胞质之前起作用。 提供的数据与对核稳定性的影响和/或多聚腺苷酸化或核转运的抑制一致。
Expression of the two bovine papillomavirus type 1 (BPV-1) late genes, L1 and L2, coding for the two capsid proteins, is limited to terminally differentiated keratinocytes in bovine fibropapillomas. This pattern of expression is determined both by the activity of the late promoter and by the inhibition of late region expression in less well differentiated cells. Inhibition of L1 and L2 mRNA production in nonpermissive cells must occur since the late region potentially could be transcribed from early region promoters. Nuclear runoff analysis of the late region has demonstrated that up to 95% of transcripts which are initiated in the early region in nonpermissive cells terminate within the late region upstream of the late polyadenylation site (C. C. Baker and J. Noe, J. Virol. 63:3529-3534, 1989). However, very few of the primary transcripts which include the late polyadenylation site are processed into mRNA. In this study, we have used expression vectors to characterize an inhibitory element active in nonpermissive cells which is located in the late 3' untranslated region (3'UTR). While the late polyadenylation site is functional in these cells, a 53-bp element in the late 3'UTR reduces levels of polyadenylated cytoplasmic RNA. This element inhibited chloramphenicol acetyltransferase (CAT) expression 6- to 10-fold when cloned in the sense orientation into the 3'UTR of a CAT expression vector. No block to expression was seen when the fragment was cloned immediately downstream of the poly(A) site, in an intron upstream of the CAT coding sequence, or in an antisense orientation in the 3'UTR. When the same fragment was deleted from a BPV-1 L1 expression vector, a sixfold increase in mRNA levels was seen. Actinomycin D chase experiments using BPV-1 L1 expression vectors indicated that the element does not destabilize cytoplasmic polyadenylated RNA. Therefore, the element must act before the mature mRNA reaches the cytoplasm. The data presented are consistent with effects on nuclear stability and/or inhibition of polyadenylation or nuclear transport.