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. 2017 Jul 21;31(11):4720–4733. doi: 10.1096/fj.201700193RR

Figure 2.

Figure 2.

Distinct BMP type I receptor complexes determine endothelial BMP signaling. A) HUVECs, HAECs, and HPMECs were serum starved and subsequently stimulated with 10 nM BMP2 or BMP6 for 45 min. Cell lysates were analyzed by immunoblot with the indicated antibodies. B, C) Quantification of pSMAD1/5/8 : GAPDH (B) and pp38 : GAPDH (C) signal intensity ratio. Means ± sd; n = 3. D) Representative images of SMAD1 and p38 location in HUVECs after 30 min BMP2 or BMP6 treatment. Scale bars, 20 µm. E) Bar chart shows mean normalized expression (MNE) of BMP receptor transcript levels in HUVECs, HAECs, and HPMECs normalized to GAPDH. Means ± sem; n = 3. F) Immunoblot analysis of indicated proteins in HPMECs upon siRNA-mediated knockdown of ALK3 and subsequent BMP2 or BMP6 stimulation for 45 min. G) Scheme illustrating the two modes of receptor oligomerization (preformed complex/PFC and BMP2-induced signaling complex/BISC) resulting in the induction of SMAD1/5 and p38 pathways, respectively. H) Immunoblot analysis of indicated proteins in HUVECs upon siRNA-mediated knockdown of ALK1/2 and subsequent BMP2 stimulation for 45 min. I) Quantification of pSMAD1/5 : GAPDH signal intensity ratio. Means ± sd; n = 4. *P < 0.05, **P < 0.005, ***P < 0.001 vs. control or as indicated; #P < 0.05 vs. BMP2-treated si-scr control.