Venous identity requires BMP signalling through ALK3

Area of Science:

• Vascular Biology
• Cellular and Molecular Biology
• Developmental Biology

Background:

• Venous endothelial cells differ functionally and molecularly from arterial cells.
• Venous identity is actively regulated transcriptionally, not a default state.
• The specific mechanisms controlling venous identity remain largely unknown.

Purpose of the Study:

• To investigate the role of signaling pathways in establishing venous endothelial cell identity.
• To identify the molecular regulators responsible for venous-specific gene expression.
• To elucidate the mechanisms controlling venous development and Ephb4 expression.

Main Methods:

• Utilized genetic manipulation in mouse and zebrafish models.
• Perturbed transforming growth factor-beta (TGF-β) and bone morphogenetic protein (BMP) signaling pathways.
• Analyzed venous endothelium-specific enhancers and SMAD binding motifs.
• Investigated the expression of the venous-specific gene Ephb4.

Main Results:

• BMP signaling, specifically via ALK3/BMPR1A and SMAD1/SMAD5, controls venous identity.
• Disruptions in BMP and TGF-β signaling led to abnormal vein formation and loss of Ephb4 expression.
• SMAD1/5 binding was enriched at the Ephb4 enhancer, crucial for its expression.
• BMP/SMAD-mediated Ephb4 expression necessitates the ALK3/BMPR1A receptor.

Conclusions:

• BMP signaling is essential for establishing Ephb4 expression and venous vasculature development.
• Active BMP/SMAD signaling pathways are required for maintaining venous endothelial cell identity.
• This study reveals a key molecular mechanism underlying venous development and distinctness from arterial cells.