RNA fate determination through cotranscriptional adenosine methylation and microprocessor binding

Area of Science:

• Molecular Biology
• Epigenetics
• RNA Biology

Background:

• Eukaryotic gene expression involves transcriptional and post-transcriptional regulation.
• Co-transcriptional regulation of nascent transcripts associated with chromatin is known in yeast but less understood in mammals.
• RNA interference (RNAi) machinery plays a role in co-transcriptional processing and decay.

Purpose of the Study:

• To investigate the conservation and mechanisms of co-transcriptional gene regulation in mammals.
• To determine the role of Dgcr8, Drosha, and Mettl3 in chromatin-associated RNA processing.
• To explore the impact of environmental stress on these regulatory pathways.

Main Methods:

• Chromatin immunoprecipitation (ChIP) in murine embryonic stem cells (mES).
• Analysis of Dgcr8 and Drosha association with chromatin and specific genes.
• Investigation of Mettl3's role in Dgcr8 recruitment and m⁶A modification.
• Assessment of gene expression changes under acute temperature stress.

Main Results:

• Dgcr8 and Drosha physically associate with chromatin at specific transcribed coding and noncoding genes in mES cells.
• Dgcr8 chromatin recruitment is dependent on both transcription and the methyltransferase Mettl3.
• Mettl3 catalyzes RNA N⁶-methyladenosine (m⁶A) modification.
• Acute temperature stress induces relocalization of Dgcr8 and Mettl3 to heat-shock genes.
• Co-transcriptional marking of mRNAs by m⁶A leads to subsequent RNA degradation.

Conclusions:

• A novel mechanism of co-transcriptional gene regulation exists in mammals involving Dgcr8, Drosha, and Mettl3.
• RNA N⁶-methyladenosine (m⁶A) acts as a critical mark initiating post-transcriptional RNA processing events.
• This pathway is dynamically regulated, particularly under stress conditions, impacting gene expression via RNA degradation.