Repurposed hnRNPC binds mature mRNAs and safeguards the mitotic transcriptome

Area of Science:

• Molecular Biology
• Cell Biology
• RNA Metabolism

Background:

• RNA metabolism is broadly suppressed during mitosis.
• The mitotic transcriptome is generally preserved for daughter cells.
• The role of RNA-binding proteins in mitosis is not fully understood.

Purpose of the Study:

• To characterize the role of heterogeneous nuclear ribonucleoprotein C (hnRNPC) during mitosis.
• To investigate the RNA-binding properties and functions of mitotic hnRNPC.

Main Methods:

• Cell cycle synchronization
• RNA sequencing (RNA-seq)
• Fluorescent crosslinking and immuno-precipitation (fCLIP)
• Density gradient centrifugation

Main Results:

• Mitotic hnRNPC forms distinct low-density (LD) and high-density (HD) complexes.
• hnRNPC binds to a significant portion of expressed genes, including pre-mRNA and mature mRNA.
• LD-hnRNPC complexes interact with introns and spliceosomes, while HD-hnRNPC complexes associate with poly-ribosomes and mature mRNAs.
• Downregulation of hnRNPC negatively impacts the abundance of its mitotic targets.

Conclusions:

• Mitotic hnRNPC acts as a global stabilizer of both pre-mRNA and mRNA.
• hnRNPC plays a critical role in maintaining RNA homeostasis during cell division.