Alk2/ACVR1 and Alk3/BMPR1A Provide Essential Function for Bone Morphogenetic Protein-Induced Retinal Angiogenesis

Area of Science:

• Molecular Biology
• Developmental Biology
• Ophthalmology

Background:

• Bone morphogenetic protein (BMP) signaling is increasingly recognized for its role in regulating angiogenesis.
• Understanding the specific functions of BMP receptors in early postnatal angiogenesis is critical for identifying therapeutic targets.

Purpose of the Study:

• To define the function of BMP receptors in regulating early postnatal angiogenesis.
• To analyze the role of endothelial-specific deletion of BMP receptor components (BMP type 2 receptor [BMPR2], activin receptor-like kinase 1 [ALK1], ALK2, and ALK3) in mouse retinal vessels.

Main Methods:

• Generated mice with inducible, endothelial-specific deletion of BMP receptor components: Bmpr2, Alk1, Alk2, and Alk3.
• Analyzed the impact of receptor deletion on retinal vascular development in postnatal mice.
• Examined expression patterns of BMP ligands and receptors in the retina.

Main Results:

• Postnatal deletion of Bmpr2 in endothelial cells significantly reduced angiogenic sprouts and attenuated radial expansion of retinal vessels.
• Endothelial-specific deletion of Alk2/acvr1 or Alk3/Bmpr1a also caused delayed radial expansion, similar to Bmpr2 deletion.
• Proangiogenic BMP ligands and BMP receptors are highly expressed in postnatal retinas.

Conclusions:

• BMP signaling, coordinated by ALK2/ACVR1, ALK3/BMPR1A, and BMPR2, is an essential proangiogenic cue for retinal vessel development.
• These findings highlight the critical role of specific BMP receptor components in regulating postnatal retinal angiogenesis.