The evidence for a microRNA product of human DROSHA gene

MicroRNAs are short RNA molecules that regulate function and stability of a large subset of eukaryotic mRNAs. In the main pathway of microRNA biogenesis, a short “hairpin” is excised from a primary transcript by ribonuclease DROSHA, followed by additional nucleolytic processing by DICER and inclusion of the mature microRNA into the RNA-induced silencing complex. We report that a microRNA-like molecule is encoded by human DROSHA gene within a predicted stem-loop element of the respective transcript. This putative mature microRNA is complementary to DROSHA transcript variant 1 and can attenuate expression of the corresponding protein. The findings suggest a possibility for a negative feedback loop, wherein DROSHA processes its own transcript and produces an inhibitor of its own biosynthesis.

微小RNA（MicroRNAs）是一类短链RNA分子，可调控真核生物中大量信使RNA（mRNA）的功能与稳定性。在微小RNA生成的主要通路中，核糖核酸酶DROSHA会从初级转录本中剪切出一段短“发夹”结构，随后经由DICER完成后续的核酸水解加工，并将成熟的微小RNA组装进入RNA诱导沉默复合体（RNA-induced silencing complex）。本研究发现，人类DROSHA基因在其对应转录本的预测茎环结构区域内编码了一类类微小RNA分子。该推定的成熟微小RNA可与DROSHA转录本变体1互补，并能减弱对应蛋白的表达水平。上述研究结果提示存在一种负反馈环路的可能性：DROSHA可加工自身转录本并生成其生物合成的抑制剂。