Alternative polyadenylation expands the mRNA isoform repertoire of human CD46
Alternative polyadenylation expands the mRNA isoform repertoire of human CD46
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DOI：
10.1016/j.gene.2017.05.004
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发表时间：
2017-08-20
期刊：
影响因子：
3.5
通讯作者：
Roca, Xavier
中科院分区：
文献类型：
--
作者：
Ly, Phuong Thao;Tang, Sze Jing;Roca, Xavier
选择性多聚腺苷酸化是调节哺乳动物基因表达的普遍机制。虽然串联3 '非编码区（3' UTR）多聚腺苷酸化改变表达水平，但内含子多聚腺苷酸化产生编码截短蛋白的较短转录物。内含子多聚腺苷酸化调节20%的基因，并且在受体酪氨酸激酶转录物中特别常见，产生可溶性阻遏物。在这里，我们报告，人CD 46，编码一个跨膜抑制补体和T细胞共刺激分子，表达多种亚型的交替聚腺苷酸化。我们通过5'内含子片段的RT-PCR以及通过功能性Ul敲低增加此类同种型，提供了在几个内含子处多腺苷酸化的证据。我们利用3'RACE技术定位了不同的内含子聚腺苷酸化位点，该技术可以产生可溶性或膜结合但无尾的CD 46。内含子聚腺苷酸化可以增加体液和组织中可溶性CD 46同种型的来源，这增加了癌症和自身免疫综合征的发病率。此外，3 'RACE在最后一个内含子和外显子中鉴定了三个多聚腺苷酸化位点，其具有缩短的3' UTR的转录物可以支持更高的CD 46表达。最后，3 'RACE揭示了CD 46假基因仅通过内含子2中的早期多聚腺苷酸化表达短转录本。总体而言，我们报告了各种各样的CD 46 mRNA亚型，可以产生新的蛋白质亚型，增加了CD 46的不同生理和病理作用。
Alternative polyadenylation is a prevalent mechanism regulating mammalian gene expression. While tandem 3'Untranslated-Region (3'UTR) polyadenylation changes expression levels, Intronic PolyAdenylation generates shorter transcripts encoding truncated proteins. Intronic PolyAdenylation regulates 20% of genes and is especially common in receptor tyrosine-kinase transcripts, generating soluble repressors. Here we report that human CD46, encoding a TransMembrane repressor of complement and T-cell co-stimulator, expresses multiple isoforms by alternative polyadenylation. We provide evidence for polyadenylation at several introns by RT-PCR of 5' intronic fragments, and by increase in such isoforms via functional Ul knockdown. We mapped various Intronic PolyAdenylation Sites by 3' Rapid Amplification of cDNA Ends (3'RACE), which could generate soluble or membrane-bound but tail-less CD46. Intronic PolyAdenylation could add to the source of soluble CD46 isoforms in fluids and tissues, which increase in cancers and autoimmune syndromes. Furthermore, 3'RACE identified three PolyAdenylation Sites within the last intron and exon, whose transcripts with shortened 3'UTRs could support higher CD46 expression. Finally, 3'RACE revealed that the CD46 Pseudogene only expresses short transcripts by early polyadenylation in intron 2. Overall, we report a wide variety of CD46 mRNA isoforms which could generate new protein isoforms, adding to the diverse physiological and pathological roles of CD46.