|ZFIN ID: ZDB-PUB-120718-11|
|Source:||Circulation research 111(5): 564-574 (Journal)|
|Registered Authors:||Flynn, Edward J., Jin, Suk-Won, Schmitt, Chris|
|Keywords:||angiogenesis, endothelial cells, bone morphogenetic protein, low density lipoprotein receptor-related protein 1, endocytosis|
|PubMed:||22777006 Full text @ Circ. Res.|
Rationale: Among the extracellular modulators of Bmp (bone morphogenetic protein) signaling, Bmper (Bmp endothelial cell precursor-derived regulator) both enhances and inhibits Bmp signaling. Recently we found that Bmper modulates Bmp4 activity via a concentration-dependent, endocytic trap-and-sink mechanism.
Objective: To investigate the molecular mechanisms required for endocytosis of the Bmper/Bmp4 and signaling complex and determine the mechanism of Bmper’s differential effects on Bmp4 signaling.
Methods and Results: Using an array of biochemical and cell biology techniques, we report that LRP1 (Low density lipoprotein receptor-related protein 1), a member of the LDL receptor family, acts as an endocytic receptor for Bmper and a co-receptor of Bmp4 to mediate the endocytosis of the Bmper/Bmp4 signaling complex. Furthermore, we demonstrate that LRP1-dependent Bmper/Bmp4 endocytosis is essential for Bmp4 signaling, as evidenced by the phenotype of lrp1-deficient zebrafish, which have abnormal cardiovascular development and decreased Smad1/5/8 activity in key vasculogenic structures.
Conclusions: Together, these data reveal a novel role for LRP1 in the regulation of Bmp4 signaling by regulating receptor complex endocytosis. In addition, these data introduce LRP1 as a critical regulator of vascular development. These observations demonstrate Bmper's ability to fine-tune Bmp4 signaling at the single-cell level, unlike the spatial regulatory mechanisms applied by other Bmp modulators.