Arabidopsis AAR2, a conserved splicing factor in eukaryotes, acts in microRNA biogenesis

Area of Science:

• Molecular Biology
• Plant Science
• Genetics

Background:

• MicroRNAs (miRNAs) are crucial regulators of plant growth and development.
• miRNA biogenesis is tightly controlled by microprocessor complex components.

Purpose of the Study:

• To investigate the role of Arabidopsis AAR2, a splicing factor homolog, in miRNA biogenesis.
• To elucidate the interaction between AAR2 and the microprocessor complex component HYL1.

Main Methods:

• Yeast and human homolog analysis.
• Interaction studies of AAR2 with HYL1 in various cellular compartments.
• Analysis of HYL1 abundance and dicing body formation in aar2 mutants.
• RNA decay assays to assess pri-miRNA stability.

Main Results:

• AAR2 interacts with HYL1 in the cytoplasm, nucleus, and dicing bodies.
• Mutations in AAR2 lead to reduced active HYL1 and fewer HYL1-labeled dicing bodies.
• Pri-miRNA accumulation is impaired in aar2 mutants due to accelerated degradation.
• This degradation is HYL1-dependent, suggesting a negative role for HYL1 in miRNA biogenesis.

Conclusions:

• AAR2 plays a dual role in promoting miRNA biogenesis and pre-messenger RNA splicing.
• AAR2's function in miRNA biogenesis involves stabilizing pri-miRNAs.
• The study uncovers a previously unrecognized negative regulatory role of HYL1 in miRNA biogenesis.