The Role of HEN1 in MicroRNA Biogenesis in Arabidopsis

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

MicroRNAs (miRNAs), single-stranded RNAs of usually 21-25 nucleotides in length found in diverse eukaryotes, act as sequence-specific regulators of gene expression during normal growth and development. miRNAs are processed, by an RNAse III enzyme named Dicer, from longer transcripts that fold into stem-loop structures with the miRNAs being in the double-stranded regions. In addition to Dicer, two classes of proteins of unknown molecular functions, Argonaute and HEN1, have been implicated in miRNA biogenesis. The temporally or spatially restricted expression of many miRNAs suggests that miRNA biogenesis is tightly regulated during development. However, little is known about the pathway or the regulation of miRNA biogenesis. The goal of this research is to dissect the role of HEN1 in miRNA biogenesis using molecular genetic and biochemical approaches. In particular, this research will follow clues from previous observations, such as the accumulation of a potential miRNA precursor in a dicer mutant and the presence of heterogeneous miRNA species in the hen1-1 mutant to probe the potential roles of HEN1 in miRNA biogenesis, such as production, stabilization, or nuclear export of miRNA precursors or miRNAs. This investigation will shed light on the molecular function of HEN1, a pioneer protein with homologs from metazoans, in miRNA biogenesis and also provide insights into the poorly understood miRNA biogenesis process in plants, such as the steps involved to process the primary transcript to the mature miRNA and the subcellular locations of the processing steps.