BMP-9 Induced Endothelial Cell Tubule Formation and Inhibition of Migration Involves Smad1 Driven Endothelin-1 Production

Abstract

BackgroundBone morphogenetic proteins (BMPs) and their receptors, such as bone morphogenetic protein receptor (BMPR) II, have been implicated in a wide variety of disorders including pulmonary arterial hypertension (PAH). Similarly, endothelin-1 (ET-1), a mitogen and vasoconstrictor, is upregulated in PAH and endothelin receptor antagonists are used in its treatment. We sought to determine whether there is crosstalk between BMP signalling and the ET-1 axis in human pulmonary artery endothelial cells (HPAECs), possible mechanisms involved in such crosstalk and functional consequences thereof.Methodology/Principal FindingUsing western blot, real time RT-PCR, ELISA and small RNA interference methods we provide evidence that in HPAECs BMP-9, but not BMP-2, -4 and -6 significantly stimulated ET-1 release under physiological concentrations. This release is mediated by both Smad1 and p38 MAPK and is independent of the canonical Smad4 pathway. Moreover, knocking down the ALK1 receptor or BMPR II attenuates BMP-9 stimulated ET-1 release, whilst causing a significant increase in prepro ET-1 mRNA transcription and mature peptide release. Finally, BMP-9 induced ET-1 release is involved in both inhibition of endothelial cell migration and promotion of tubule formation.Conclusions/SignificanceAlthough our data does not support an important role for BMP-9 as a source of increased endothelial ET-1 production seen in human PAH, BMP-9 stimulated ET-1 production is likely to be important in angiogenesis and vascular stability. However, increased ET-1 production by endothelial cells as a consequence of BMPR II dysfunction may be clinically relevant in the pathogenesis of PAH.

Circulating Bmp10 acts through endothelial Alk1 to mediate flow-dependent arterial quiescence

“…However, changes in expression of cxcr4a and edn1 cannot fully explain defects in vessel architecture resulting from loss of alk1. Although ALK1 signaling can repress CXCR4 or induce EEN1 in cultured endothelial cells (Star et al, 2010;Park et al, 2012;Young et al, 2012), supporting our in vivo data, previous work has demonstrated that increased cxcr4a is not necessary nor is loss of edn1 sufficient for AVM development , and additional work has demonstrated that concomitant increase in cxcr4a and loss of edn1 is insufficient to generate AVMs (E. Rochon and B.L.R., unpublished). Thus, further work is required to define the molecular mechanisms and cellular behaviors that lead to arterial enlargement in the absence of alk1.…”

BMP9-regulated angiogenic signaling plays an important role in the osteogenic differentiation of mesenchymal progenitor cells

“…Endochondral bone formation occurs in close spatial and temporal association and proximity to capillary invasion, so that angiogenesis and osteogenesis must be tightly coupled (Olsen et al, 2000;Wan et al, 2010;Wang et al, 2007). Conflicting results have implicated BMP9 as either an angiogenesis inducer in endothelial cells (Castonguay et al, 2011;Cunha et al, 2010;Mitchell et al, 2010;Park et al, 2012;Scharpfenecker et al, 2007;Suzuki et al, 2010;Yao et al, 2012) or as a potent anti-angiogenic factor (David et al, 2008). Although it is well recognized that osteogenic and angiogenic pathways are well coordinated during bone formation (Wan et al, 2010), it is unclear how these processes are linked in MSCs stimulated by osteogenic factors, such as BMPs.…”

Nuclear IL-33 regulates soluble ST2 receptor and IL-6 expression in primary human arterial endothelial cells and is decreased in idiopathic pulmonary arterial hypertension

“…Cell lysates were prepared as described previously [27] and were precipitated using cold acetone, and air-dried. The resulting pellets were dissolved in 50ul 1XSDS sample buffer and cleared by centrifugation.…”