AtXRN4 Affects the Turnover of Chosen miRNA*s in Arabidopsis.

Yan Liu,Xiaoming Zhang,Wenrui Gao,Shuangyang Wu,Yaqiu Chen,Junliang Guo,Lu Lu,Shuzhen Men

doi:10.3390/plants9030362

Abstract

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 miRNA*s levels are significantly increased in xrn4 mutant plants. However, the accumulation of the primary miRNAs (pri-miRNAs) and miRNA precursors (pre-miRNAs) were generally unchanged in xrn4 mutant plants which indicates that AtXRN4 contributes the degradation of some miRNA*s. Moreover, AtXRN4 interacts with Arabidopsis 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.

Highlights

Small RNAs are 20–30 nucleotide noncoding RNAs that regulate the expression of target genes at the transcription or post-transcription levels [1,2]
AtXRN4 contains all the conserved exoribonuclease motifs (Figure S2) and showed a mild phenotype with serrated leaves (Figure S3b), multiple fruits emanate from the same node (Figure S3c), and late flowering (Figure S3d) which have described previously [24,31] Because of the important functions of AtXRN4 in mRNA degradation, we hypothesized that AtXRN4 may contribute to the turnover of plant Small RNA (sRNA)
AtXRN4 interacts with AtAGO2 overlapped with the RFP signals (Figure 5c)

Summary

Introduction

Small RNAs (sRNAs) are 20–30 nucleotide (nt) noncoding RNAs that regulate the expression of target genes at the transcription or post-transcription levels [1,2]. The homeostasis of sRNAs is tightly regulated at the transcription and post-transcription levels [3,4]. The transcription and processing of microRNAs (miRNAs), a major sRNA for both animals and plants, have been well studied, the degradation mechanisms of miRNAs and other sRNAs remain unclear. 30 ends of sRNA duplexes are methylated by HUA Enhancer 1 (HEN1), which is a critical step in miRNA stabilization. The methylation of 30 ends protects sRNAs from being degraded by 30 truncation and uridylation [5].

Methods

Results

Conclusion