Negative feedback regulation of Dicer-Like1 in Arabidopsis by microRNA-guided mRNA degradation.
Formation of microRNA (miRNA) requires an RNaseIII domain-containing protein, termed DICER-1 in animals and DICER-LIKE1 (DCL1) in plants, to catalyze processing of an RNA precursor with a fold-back structure. Loss-of-function dcl1 mutants of Arabidopsis have low levels of miRNA and exhibit a range of developmental phenotypes in vegetative, reproductive, and embryonic tissues. In this paper, we show that DCL1 mRNA occurs in multiple forms, including truncated molecules that result from aberrant pre-mRNA processing. Both full-length and truncated forms accumulated to relatively low levels in plants containing a functional DCL1 gene. However, in dcl1 mutant plants, dcl1 RNA forms accumulated to levels several-fold higher than those in DCL1 plants. Elevated levels of DCL1 RNAs were also detected in miRNA-defective hen1 mutant plants and in plants expressing a virus-encoded suppressor of RNA silencing (P1/HC-Pro), which inhibits miRNA-guided degradation of target mRNAs. A miRNA (miR162) target sequence was predicted near the middle of DCL1 mRNA, and a DCL1-derived RNA with the properties of a miR162-guided cleavage product was identified and mapped. These results indicate that DCL1 mRNA is subject to negative feedback regulation through the activity of a miRNA.
Center for Gene Research and Biotechnology, Oregon State University, Corvallis, OR 97331, USA.
Zhixin
Z
Xie
Kristin D
KD
Kasschau
James C
JC
Carrington
D017360:Arabidopsis / Q000235:genetics*; D002874:Chromosome Mapping; D017931:DNA Primers; D025461:Feedback, Physiological / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D008957:Models, Genetic; D020871:RNA Stability / Q000235:genetics*; D043244:Ribonuclease III / Q000235:genetics*
D017931:DNA Primers; D035683:MicroRNAs; D043244:Ribonuclease III