Liu Yan, Gao Wenrui, Wu Shuangyang, Lu Lu, Chen Yaqiu, Guo Junliang, Men Shuzhen, Zhang Xiaoming
State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China.
Plants (Basel). 2020 Mar 13;9(3):362. doi: 10.3390/plants9030362.
Small RNA (sRNA) turnover is a key but poorly understood mechanism that determines the homeostasis of sRNAs. Animal XRN genes contribute the degradation of sRNAs, AtXRN2 and AtXRN3 also contribute the pri-miRNA processing and miRNA loop degradation in plants. However, the possible functions of the plant XRN genes in sRNA degradation are far from known. Here, we find that AtXRN4 contributes the turnover of plant sRNAs in Arabidopsis thaliana mainly by sRNA-seq, qRT-PCR and Northern blot. The mutation of AtXRN4 alters the sRNA profile and the accumulation of 21 nt sRNAs was increased. Some miRNAs levels are significantly increased in mutant plants. However, the accumulation of the primary miRNAs (pri-miRNAs) and miRNA precursors (pre-miRNAs) were generally unchanged in mutant plants which indicates that AtXRN4 contributes the degradation of some miRNAs. Moreover, AtXRN4 interacts with Argonaute 2 (AtAGO2). This interaction takes place in Processing bodies (P-bodies). Taken together, our observations identified the interaction between XRN4 with AtAGO2 and suggested that plant XRN4 also contributes the turnover of sRNAs.
小RNA（sRNA）周转是决定sRNA稳态的关键机制，但人们对此了解甚少。动物XRN基因参与sRNA的降解，拟南芥中的AtXRN2和AtXRN3也参与植物中初级微小RNA（pri-miRNA）的加工和微小RNA环的降解。然而，植物XRN基因在sRNA降解中的可能功能却鲜为人知。在此，我们通过sRNA测序、定量逆转录聚合酶链反应（qRT-PCR）和Northern杂交发现，拟南芥中的AtXRN4主要参与植物sRNA的周转。AtXRN4的突变改变了sRNA图谱，21核苷酸（nt）sRNA的积累增加。在突变体植物中，一些微小RNA星号链（miRNAs）的水平显著增加。然而，在突变体植物中，初级微小RNA（pri-miRNAs）和微小RNA前体（pre-miRNAs）的积累通常没有变化，这表明AtXRN4参与了一些miRNAs的降解。此外，AtXRN4与AGO2蛋白（AtAGO2）相互作用。这种相互作用发生在加工小体（P小体）中。综上所述，我们的观察结果确定了XRN4与AtAGO2之间的相互作用，并表明植物XRN4也参与sRNA的周转。
