Internal initiation of translation of the TrkB mRNA is mediated by multiple regions within the 5′ leader
Internal initiation of translation of the TrkB mRNA is mediated by multiple regions within the 5′ leader
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DOI：
10.1093/nar/gki605
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发表时间：
2005-01-01
影响因子：
14.9
通讯作者：
Krushel, L
中科院分区：
文献类型：
--
作者：
Dobson, T;Minic, A;Krushel, L
编码神经营养因子受体TrkB的树突定位mRNA的翻译调节对突触功能具有重要影响。我们研究了TrkB mRNA是否通过内部起始进入位点（IRES）翻译。人TrkB 50前导序列来源于选择性启动子和选择性剪接的使用，但所有50个前导序列共享一个共同的外显子。将全长50前导序列以及共同外显子插入到双顺反子荧光素酶构建体的顺反子间区域中，产生了从这些顺反子产生的荧光素酶活性，其等于或高于从脑心肌炎病毒IRES观察到的活性。此外，抑制离体和体外裂解物中的帽依赖性翻译对含有TrkB 50前导序列的mRNA的翻译仅具有最小的影响。解剖50前导序列表明，IRES位于所有TrkB 50前导序列共有的外显子中。此外，从2到25 nt的六个区域被确定为促进或抑制IRES活性。两者合计，这些结果表明，50领导人的人TrkB mRNA含有多个顺式元件，调节内部启动翻译，这种机制可能有助于显着的TrkB mRNA在神经元树突的翻译。
Translational regulation of the dendritically localized mRNA encoding for the neurotrophin receptor TrkB has important ramifications for synaptic function. We examined whether the TrkB mRNA is translated through an internal initiation entry site (IRES). The human TrkB 50 leaders are derived from the use of alternative promoters and alternative splicing, but all 50 leaders share a common exon. Insertion of a full-length 50 leader, as well as the common exon into the intercistronic region of a dicistronic luciferase construct, yielded luciferase activity generated from these condcistron that was either equivalent or higher than that observed from the encephalomyocarditis virus IRES. Moreover, inhibiting cap-dependent translation ex vivo and in in vitro lysates had only a minimal effect on the translation of mRNA containing the TrkB 50 leader. Dissecting the 50 leader showed that the IRES is located in the exon common to all TrkB 50 leaders. Moreover, six regions ranging from 2 to 25 nt were identified that either promoted or inhibited IRES activity. Taken together, these results suggest that the 50 leader of the human TrkB mRNA contains multiple cis-elements that regulate internal initiation of translation and that this mechanism may contribute significantly to the translation of the TrkB mRNA in neuronal dendrites.