Fibrillin-1 regulates endothelial sprouting during angiogenesis.

Area of Science:

• Molecular Biology
• Vascular Biology
• Extracellular Matrix Biology

Background:

• Fibrillin-1 is an extracellular matrix protein essential for microfibril assembly and tissue integrity, particularly in blood vessels.
• Mutations in the fibrillin-1 gene cause Marfan syndrome, leading to cardiovascular, ocular, and skeletal abnormalities.
• The role of fibrillin-1 in angiogenesis, the formation of new blood vessels, is not fully understood.

Purpose of the Study:

• To investigate the role of fibrillin-1 in angiogenesis and its potential compromise in Marfan syndrome.
• To explore the molecular mechanisms by which fibrillin-1 regulates endothelial cell behavior during angiogenesis.
• To assess the therapeutic potential of fibrillin-1 fragments in correcting Marfan syndrome-associated angiogenic defects.

Main Methods:

• Utilized a mouse retina vascularization model and cell culture experiments.
• Analyzed fibrillin-1 and MAGP1 localization and deposition in angiogenic tissues.
• Investigated the impact of fibrillin-1 deficiency on VEGF-A/Notch and Smad signaling pathways.
• Administered a recombinant C-terminal fibrillin-1 fragment to Marfan syndrome model mice.
• Performed mass spectrometry to identify proteins interacting with the fibrillin-1 fragment, including ADAMTS1.

Main Results:

• Fibrillin-1 is present at the angiogenic front, colocalizing with MAGP1.
• Marfan syndrome model mice (Fbn1C1041G/+) exhibited reduced MAGP1, impaired endothelial sprouting, and altered tip cell identity.
• Fibrillin-1 deficiency disrupted VEGF-A/Notch and Smad signaling, affecting endothelial cell phenotype acquisition.
• Treatment with a fibrillin-1 fragment restored normal angiogenesis and corrected defects in Marfan syndrome model mice.
• The fibrillin-1 fragment altered the expression of proteins, including the metalloprotease ADAMTS1.

Conclusions:

• Fibrillin-1 acts as a dynamic signaling platform regulating endothelial cell specification and matrix remodeling during angiogenesis.
• Mutant fibrillin-1 impairs angiogenesis through disrupted signaling pathways and matrix composition.
• Pharmacological intervention using a C-terminal fibrillin-1 fragment can rescue angiogenic defects in Marfan syndrome models.
• Fibrillin-1, MAGP1, and ADAMTS1 are key regulators of endothelial sprouting, with implications for Marfan syndrome understanding and treatment.