Small GTPase Rap1 Is Essential for Mouse Development and Formation of Functional Vasculature

Area of Science:

• Molecular Biology
• Developmental Biology
• Genetics

Background:

• Small GTPase Rap1 regulates fundamental cellular processes like adhesion, proliferation, and polarity.
• Rap1 signaling is conserved across species and plays roles in stem cell, leukocyte, and vascular cell functions.
• Rap1 is implicated in maintaining epithelial and endothelial cell junction integrity and linked to diseases like cerebral cavernous malformations.

Purpose of the Study:

• To investigate the role of the Rap1 signaling network in mammalian development.
• To characterize the phenotypes of mice with total and vascular-specific knockouts of Rap1a and Rap1b.

Main Methods:

• Generation of murine total and vascular-specific Rap1a, Rap1b, and double knockout (Rap1) mice.
• Phenotypic analysis of knockout embryos at various developmental stages.

Main Results:

• The majority of total Rap1 knockout mice die before embryonic day 10.5, indicating a critical role in early development.
• Approximately 50% of Tie2-double Rap1 knockout embryos exhibit normal vasculature initially, while the other 50% show tissue degeneration and vascular abnormalities.
• No Tie2-double Rap1 knockout embryos are observed at embryonic day 15.5, with hemorrhages suggested as the cause of death.

Conclusions:

• At least one Rap1 allele is essential for development before vascular system formation.
• Rap1 function in endothelial cells is required for the life-supporting functions of the vasculature.
• Rap1 plays a critical role in epithelial morphogenesis and vascular development.