Asada Ken, Canestrari Emanuele, Fu Xiuping, Li Zhi, Makowski Edward, Wu Yen-Ching, Mito Jeffrey K, Kirsch David G, Baraban Jay, Paroo Zain
Cell Rep. 2014 Nov 20;9(4):1471-81. doi: 10.1016/j.celrep.2014.10.021.
Genetic defects in the microRNA (miRNA) generating enzyme, dicer, are increasingly linked to disease. Loss of miRNA in dicer deficiency is thought to be due to loss of miRNA-generating activity. Here, we demonstrate a catabolic mechanism driving miRNA depletion in dicer deficiency. We developed a Dicer-antagonist assay revealing a pre-miRNA degrading enzyme that competes with pre-miRNA processing. We purified this pre-miRNA degrading activity using an unbiased chromatographic procedure and identified the ribonuclease complex Translin/Trax (TN/TX). In wild-type dicer backgrounds, pre-miRNA processing was dominant. However, in dicer-deficient contexts, TN/TX broadly suppressed miRNA. These findings indicate that miRNA depletion in dicer deficiency is due to the combined loss of miRNA-generating activity and catabolic function of TN/TX. Importantly, inhibition of TN/TX mitigated loss of both miRNA and tumor suppression with dicer haploinsufficiency. These studies reveal a potentially druggable target for restoring miRNA function in cancers and emerging dicer deficiencies.
微小RNA（miRNA）生成酶Dicer中的基因缺陷与疾病的关联日益密切。Dicer缺陷导致的miRNA缺失被认为是由于miRNA生成活性丧失所致。在此，我们展示了一种在Dicer缺陷中驱动miRNA耗竭的分解代谢机制。我们开发了一种Dicer拮抗剂检测方法，揭示了一种与前体miRNA加工竞争的前体miRNA降解酶。我们使用无偏色谱法纯化了这种前体miRNA降解活性，并鉴定出核糖核酸酶复合物Translin/Trax（TN/TX）。在野生型Dicer背景下，前体miRNA加工占主导地位。然而，在Dicer缺陷的情况下，TN/TX广泛抑制miRNA。这些发现表明，Dicer缺陷中miRNA的耗竭是由于miRNA生成活性的丧失以及TN/TX的分解代谢功能共同作用的结果。重要的是，抑制TN/TX减轻了Dicer单倍体不足导致的miRNA丢失和肿瘤抑制能力丧失。这些研究揭示了一个潜在的可药物靶向，用于恢复癌症中miRNA功能以及新兴的Dicer缺陷。
