The origin of exosomal miR-1246 in human cancer cells
The origin of exosomal miR-1246 in human cancer cells
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DOI：
10.1080/15476286.2019.1585738
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发表时间：
2019-03-25
期刊：
影响因子：
4.1
通讯作者：
Ding, Wei-Qun
中科院分区：
文献类型：
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作者：
Xu, Yi-Fan;Hannafon, Bethany N.;Ding, Wei-Qun
MIR-1246被认为是各种癌症类型的肿瘤。然而，miR-1246的起源和生物发生仍然存在争议，这往往导致对其检测和生物学功能的误解，并不可避免地掩盖其作用机制。利用下一代小RNA测序、CRISPR-Cas9基因敲除、siRNA敲除和PolyA Tail SYBR qRT-PCR，我们研究了外体miR-1246在人类癌细胞模型系统中的生物发生。我们发现miR-1246在来自人类癌细胞的外体中高度富含，并且它起源于RNU2-1，RNU2-1是一种小的核RNA，也是剪接体U2复合体的基本成分。DROSHA和DICER的敲除并没有降低外体miR-1246的水平，表明外体miR-1246是以DROSHA和DICER非依赖的方式产生的。RNase A对细胞裂解物的直接消化和RNU2-1结合蛋白SMB/B‘的敲除表明外体miR-1246是RNU2-1的降解产物。此外，RUN2-1转录本中的GCAG基序被证明介导了癌症外体中miR-1246的丰富。我们得出结论，exosome miR-1246是通过非规范的microRNA生物发生过程降解RNU2-1而来的。这些发现揭示了人类癌细胞中肿瘤的起源，为理解miR-1246的检测和生物学功能提供了指导。
miR-1246 is considered an oncomiR in various cancer types. However, the origin and biogenesis of miR-1246 remain controversial which often leads to misinterpretation of its detection and biological function, and inevitably masking its mechanisms of action. Using next generation small RNA sequencing, CRISPR-Cas9 knockout, siRNA knockdown and the poly-A tailing SYBR qRT-PCR, we examined the biogenesis of exosomal miR-1246 in human cancer cell model systems. We found that miR-1246 is highly enriched in exosomes derived from human cancer cells and that it originates from RNU2-1, a small nuclear RNA and essential component of the U2 complex of the spliceosome. Knockdown of Drosha and Dicer did not reduce exosomal miR-1246 levels, indicating that exosomal miR-1246 is generated in a Drosha- and Dicer-independent manner. Direct digestion of cellular lysate by RNase A and knockdown of the RNU2-1 binding protein SmB/B' demonstrated that exosomal miR-1246 is a RNU2-1 degradation product. Furthermore, the GCAG motif present in the RUN2-1 transcript was shown to mediate miR-1246 enrichment in cancer exosomes. We conclude that exosome miR-1246 is derived from RNU2-1 degradation through a non-canonical microRNA biogenesis process. These findings reveal the origin of an oncomiR in human cancer cells, providing guidance in understanding miR-1246 detection and biological function.