Constitutive Musashi1 expression impairs mouse postnatal development and intestinal homeostasis

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• Musashi1 (Msi1) is an evolutionarily conserved RNA-binding protein regulating genes crucial for development.
• Understanding Msi1's role in postnatal development is essential for comprehending growth and organogenesis.

Purpose of the Study:

• To generate and characterize a novel mouse model for inducible, temporal, and tissue-specific Msi1 overexpression.
• To investigate the effects of Msi1 overexpression on postnatal mouse development, focusing on organ growth and cellular differentiation.

Main Methods:

• Generation of a conditional Msi1-overexpressing mouse model.
• Inducible overexpression of Msi1 in approximately 5-week-old mice.
• Analysis of organ-to-body proportions, intestinal morphology, cell proliferation, and differentiation markers.

Main Results:

• Ubiquitous Msi1 induction led to growth delay, altered organ proportions, and premature death.
• Msi1 overexpression resulted in shortened intestines, reduced intestinal epithelial cell proliferation, and impaired villi/crypt growth.
• Reduced Cdc20 expression and altered Notch signaling (increased Hes1:Atoh1 ratio) were observed, impacting intestinal cell differentiation, particularly in the ileum.

Conclusions:

• Msi1 plays a significant role in postnatal development across multiple organs in mice.
• Altered Notch signaling contributes to intestinal defects observed in Msi1-overexpressing mice.
• The developed mouse model is a valuable tool for further Msi1 research in various tissue contexts.