Defining the molecular pathologies in cloaca malformation: similarities between mouse and human

Area of Science:

• Developmental biology
• Embryology
• Genetics

Background:

• Anorectal malformations (ARMs) are congenital disorders with varying severity.
• Severe ARMs, like cloaca malformation, suggest early embryonic defects.
• Investigating human embryonic cloaca development is challenging, necessitating animal models.

Purpose of the Study:

• To compare human and mouse embryonic cloaca development.
• To identify early molecular defects underlying severe ARMs.
• To correlate signaling pathway dysregulation with ARM severity.

Main Methods:

• Comparative analysis of human and mouse embryonic cloaca development.
• Utilized sonic hedgehog (Shh) knockout mouse models.
• Molecular analysis of epithelial and stromal tissues, including gene expression (Sox2, keratins) and signaling pathways (Shh, BMP).
• Comparison of mouse model findings with human ARM patient data.

Main Results:

• Identified early dorsal-ventral epithelial abnormalities in Shh knockout mouse embryos.
• Observed absence of Sox2 and aberrant keratin expression in Shh deficient cloaca.
• Found defective BMP signaling in the stroma of Shh knockout embryos.
• Demonstrated striking molecular parallels between the Shh mouse model and human ARM patients, including cloaca malformation.

Conclusions:

• Early mispatterning and differentiation defects of the embryonic cloaca are likely causes of severe human ARMs.
• Dysregulated Shh and BMP signaling pathways are correlated with severe ARMs in both mouse models and humans.
• The Shh mouse model serves as a valuable tool for studying severe anorectal malformations.