Molecular Signaling Pathways Controlling Vascular Tube Morphogenesis and Pericyte-Induced Tube Maturation in 3D...

Area of Science:

• Cell Biology
• Molecular Biology
• Vascular Biology

Background:

• Endothelial cells (ECs) form capillary networks through tubulogenesis, creating lumens within vascular guidance tunnels.
• Pericytes are recruited to EC tubes, and basement membrane deposition aids in tube maturation.

Purpose of the Study:

• To elucidate the molecular mechanisms governing EC tubulogenesis and EC-pericyte tube coassembly.
• To identify key signaling pathways and growth factors essential for capillary network formation.

Main Methods:

• Utilized defined serum-free models to study human EC tubulogenesis.
• Investigated the roles of specific molecules including integrins, MT1-MMP, Rho GTPases, Ras GTPases, and their downstream effectors.
• Analyzed growth factor signaling pathways, including PKC, Src, Raf, Mek, and Erk kinases.

Main Results:

• EC tubulogenesis involves integrins, MT1-MMP, extracellular matrix, Rho/Ras GTPases, and kinase cascades.
• Five exogenous growth factors (SCF, IL-3, SDF-1α, FGF-2, insulin) are required for EC tubulogenesis and coassembly with pericytes.
• EC-derived PDGF-BB and HB-EGF are essential for pericyte recruitment and basement membrane assembly.
• Vascular Endothelial Growth Factor (VEGF) does not directly induce EC tubulogenesis but primes ECs by upregulating key receptors and signaling molecules.

Conclusions:

• EC tubulogenesis is regulated by intricate molecular signaling networks controlling lumen expansion, vacuole formation, and cytoskeletal polarity.
• A defined cocktail of growth factors and EC-derived signals orchestrates capillary network formation and pericyte integration.
• VEGF acts upstream to enhance EC responsiveness to tubulogenic stimuli, highlighting a complex regulatory hierarchy in angiogenesis.