MIGAL-Galilee Research Institute, POB 831, Kiryat Shmona 1101602, Israel.
Faculty of Sciences, Tel-Hai Academic College, Upper Galilee 1220800, Israel.
Biomolecules. 2020 Feb 13;10(2):293. doi: 10.3390/biom10020293.
The human small RNA miR-4443 is functionally involved in several types of cancer and in the biology of the immune system, downstream of insulin and leptin signaling. Next generation sequencing evidence and structural prediction suggest that miR-4443 is not produced via the canonical Drosha-Exportin 5-Dicer pathway of microRNA biogenesis. We tested this hypothesis by using qRT-PCR to measure miR-4443 and other microRNA levels in HCT-116 cells with Drosha, Exportin 5, and Dicer knockouts, as well as in the parental cell line. Neither of the knockouts decreased miR-4443 levels, while the levels of canonical microRNAs (miR-21 and let-7f-5p) were dramatically reduced. Previously published Ago2-RIP-Seq data suggest a limited incorporation of miR-4443 into RISC, in agreement with the functional studies. The miR-4443 locus shows conservation in primates but not in other mammals, while its seed region appears in additional microRNAs. Our results suggest that miR-4443 is a Drosha, Exportin 5, and Dicer-independent, non-canonical small RNA produced by a yet unknown biogenesis pathway.
人类小 RNA miR-4443 在几种类型的癌症和胰岛素及瘦素信号下游的免疫系统生物学中具有功能。下一代测序证据和结构预测表明，miR-4443 不是通过微 RNA 生物发生的典型 Drosha-Exportin 5-Dicer 途径产生的。我们通过使用 qRT-PCR 来测量 HCT-116 细胞中的 Drosha、Exportin 5 和 Dicer 敲除细胞以及亲本细胞系中的 miR-4443 和其他 microRNA 的水平来验证这个假说。敲除都没有降低 miR-4443 的水平，而典型的 microRNA（miR-21 和 let-7f-5p）的水平则显著降低。先前发表的 Ago2-RIP-Seq 数据表明 miR-4443 有限地被整合到 RISC 中，这与功能研究一致。miR-4443 基因座在灵长类动物中保守，但在其他哺乳动物中不保守，而其种子区出现在其他 microRNAs 中。我们的结果表明，miR-4443 是一种 Drosha、Exportin 5 和 Dicer 非依赖性的非典型小 RNA，由一个未知的生物发生途径产生。
