Transcription and processing of primary microRNAs are coupled by Elongator complex in Arabidopsis

Area of Science:

• Plant molecular biology
• Gene regulation
• Biochemistry

Background:

• MicroRNAs (miRNAs) are small non-coding RNAs regulating gene expression.
• miRNA biogenesis involves transcription of primary miRNAs (pri-miRNAs) by RNA polymerase II (RNAPII) and processing by Dicer or Dicer-like (DCL) proteins.

Purpose of the Study:

• To investigate the role of the Elongator complex in miRNA biogenesis in Arabidopsis.
• To elucidate how Elongator influences pri-miRNA transcription and processing.

Main Methods:

• Analysis of RNAPII occupancy at miRNA loci in wild-type and Elongator-mutant Arabidopsis.
• Assessment of pri-miRNA transcription levels.
• Investigation of Elongator interaction with the DCL1-containing Dicing complex.
• Examination of DCL1 localization within nuclear Dicing bodies.
• Chromatin immunoprecipitation assays to detect pri-miRNA and DCL1 association with miRNA gene chromatin.

Main Results:

• Disruption of the Elongator complex significantly reduces RNAPII occupancy and pri-miRNA transcription.
• Elongator interacts with the DCL1-containing Dicing complex.
• Absence of Elongator impairs DCL1 localization in nuclear Dicing bodies.
• Both pri-miRNA transcripts and DCL1 associate with miRNA gene chromatin.
• Elongator deficiency compromises the chromatin association of DCL1.

Conclusions:

• The Elongator complex plays a dual role in miRNA biogenesis, influencing both transcription and processing of pri-miRNAs.
• Elongator likely couples the transcription and processing steps of miRNA biogenesis.
• This study reveals a novel function for Elongator in regulating gene expression through miRNA pathways.