Genome-wide analysis of Musashi-2 targets reveals novel functions in governing epithelial cell migration

Area of Science:

• Molecular Biology
• Cell Biology
• RNA Biology

Background:

• Musashi-2 (Msi2) is an RNA-binding protein crucial for stem cell self-renewal and oncogenesis.
• Its precise mRNA targets and regulatory mechanisms in vivo remain largely uncharacterized.
• Understanding Msi2's function is vital for comprehending stem cell maintenance and cancer development.

Purpose of the Study:

• To identify Msi2's direct mRNA targets and binding sites in epithelial progenitor cells.
• To elucidate the molecular mechanisms by which Msi2 regulates target mRNAs.
• To investigate the role of Msi2 in epithelial cell growth and migration.

Main Methods:

• High-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (HITS-CLIP) to identify Msi2 binding sites.
• RNA sequencing (RNA-seq) and ribosome profiling to assess mRNA expression and translation efficiency.
• Functional assays to evaluate the impact of Msi2 loss on cell migration and focal adhesion formation.

Main Results:

• Msi2 predominantly binds to 3'UTRs of target mRNAs, recognizing multiple UAG motifs.
• Msi2 promotes the decay of targeted mRNAs without altering translation efficiency.
• Key Msi2 targets include regulators of cell motility, focal adhesion, and extracellular matrix interactions, alongside cell growth and survival factors.
• Loss of Msi2 leads to increased epithelial cell migration, enhanced focal adhesion numbers, and impaired cell growth.

Conclusions:

• Msi2 recognizes and represses specific mRNA targets primarily through promoting mRNA decay.
• Msi2 plays a significant role in restricting epithelial cell migration, in addition to its known functions in cell growth.
• These findings reveal a novel mechanism by which Msi2 controls cell motility and provide insights into its oncogenic functions.