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Defective fluid shear stress mechanotransduction mediates hereditary hemorrhagic telangiectasia

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ABSTRACT

Mutations of the endothelial BMP9/10 receptors Alk1 and endoglin are associated with vascular malformations in hereditary hemorrhagic telangiectasia (HHT). Baeyens et al. report that fluid flow potentiates BMP activation of Alk1 signaling to stabilize blood vessels. HHT lesions thus result from a defect in a synergistic mechanical/biochemical signaling pathway.

No MeSH data available.


Related in: MedlinePlus

Potentiation of BMP9 responses by FSS. (A) Representative Western blot of Smad1/5/8 phosphorylation in response to the indicated concentrations of BMP9 in serum-free media with or without flow for 45 min (n = 4, two-way ANOVA; ***, P < 0.001; ****, P < 0.0001, BMP9 EC50: 56 pg/ml without flow, 3.6 pg/ml with flow). (B) Representative Western blot of Smad1/5/8 phosphorylation in response to 12 dynes/cm2 for 45 min in the presence or absence of two blocking antibodies against BMP9 and BMP10 (each at 100 ng/ml). (C) Association of endoglin-GFP with endogenous Alk1 in response to 1 ng/ml BMP9 or 12 dynes/cm2 flow for 15 min. GFP-tagged proteins were captured with a GFP-trap and immunoprecipitations analyzed by immunoblotting (IB) as indicated.
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fig3: Potentiation of BMP9 responses by FSS. (A) Representative Western blot of Smad1/5/8 phosphorylation in response to the indicated concentrations of BMP9 in serum-free media with or without flow for 45 min (n = 4, two-way ANOVA; ***, P < 0.001; ****, P < 0.0001, BMP9 EC50: 56 pg/ml without flow, 3.6 pg/ml with flow). (B) Representative Western blot of Smad1/5/8 phosphorylation in response to 12 dynes/cm2 for 45 min in the presence or absence of two blocking antibodies against BMP9 and BMP10 (each at 100 ng/ml). (C) Association of endoglin-GFP with endogenous Alk1 in response to 1 ng/ml BMP9 or 12 dynes/cm2 flow for 15 min. GFP-tagged proteins were captured with a GFP-trap and immunoprecipitations analyzed by immunoblotting (IB) as indicated.

Mentions: To investigate the mechanisms by which shear stress activates Smad signaling, we first addressed whether the effect of flow was independent of BMPs. FBS contains significant amounts of these factors, which would still be present at low levels in medium containing 0.2% serum. Therefore, cells were examined in serum-free medium containing 0.2% BSA and supplemented with various concentrations of BMP9. Without BMP9, flow failed to detectably activate Smad1, whereas addition of as little as 1 pg/ml BMP9 conferred sensitivity (Fig. 3 A). At high levels of BMP9, Smad signaling was activated without flow. BMP9 EC50 was shifted from ∼60 pg/ml without flow to ∼3.5 pg/ml with flow. Addition of BMP9 and BMP10 inhibitory antibodies to medium containing 0.2 FBS efficiently blocked the flow-dependent activation of Smad1 (Fig. 3 B), confirming the requirement for BMPs. Thus, FSS activates this pathway by potentiating responses to soluble BMP9/BMP10.


Defective fluid shear stress mechanotransduction mediates hereditary hemorrhagic telangiectasia
Potentiation of BMP9 responses by FSS. (A) Representative Western blot of Smad1/5/8 phosphorylation in response to the indicated concentrations of BMP9 in serum-free media with or without flow for 45 min (n = 4, two-way ANOVA; ***, P < 0.001; ****, P < 0.0001, BMP9 EC50: 56 pg/ml without flow, 3.6 pg/ml with flow). (B) Representative Western blot of Smad1/5/8 phosphorylation in response to 12 dynes/cm2 for 45 min in the presence or absence of two blocking antibodies against BMP9 and BMP10 (each at 100 ng/ml). (C) Association of endoglin-GFP with endogenous Alk1 in response to 1 ng/ml BMP9 or 12 dynes/cm2 flow for 15 min. GFP-tagged proteins were captured with a GFP-trap and immunoprecipitations analyzed by immunoblotting (IB) as indicated.
© Copyright Policy - openaccess
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5037412&req=5

fig3: Potentiation of BMP9 responses by FSS. (A) Representative Western blot of Smad1/5/8 phosphorylation in response to the indicated concentrations of BMP9 in serum-free media with or without flow for 45 min (n = 4, two-way ANOVA; ***, P < 0.001; ****, P < 0.0001, BMP9 EC50: 56 pg/ml without flow, 3.6 pg/ml with flow). (B) Representative Western blot of Smad1/5/8 phosphorylation in response to 12 dynes/cm2 for 45 min in the presence or absence of two blocking antibodies against BMP9 and BMP10 (each at 100 ng/ml). (C) Association of endoglin-GFP with endogenous Alk1 in response to 1 ng/ml BMP9 or 12 dynes/cm2 flow for 15 min. GFP-tagged proteins were captured with a GFP-trap and immunoprecipitations analyzed by immunoblotting (IB) as indicated.
Mentions: To investigate the mechanisms by which shear stress activates Smad signaling, we first addressed whether the effect of flow was independent of BMPs. FBS contains significant amounts of these factors, which would still be present at low levels in medium containing 0.2% serum. Therefore, cells were examined in serum-free medium containing 0.2% BSA and supplemented with various concentrations of BMP9. Without BMP9, flow failed to detectably activate Smad1, whereas addition of as little as 1 pg/ml BMP9 conferred sensitivity (Fig. 3 A). At high levels of BMP9, Smad signaling was activated without flow. BMP9 EC50 was shifted from ∼60 pg/ml without flow to ∼3.5 pg/ml with flow. Addition of BMP9 and BMP10 inhibitory antibodies to medium containing 0.2 FBS efficiently blocked the flow-dependent activation of Smad1 (Fig. 3 B), confirming the requirement for BMPs. Thus, FSS activates this pathway by potentiating responses to soluble BMP9/BMP10.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Mutations of the endothelial BMP9/10 receptors Alk1 and endoglin are associated with vascular malformations in hereditary hemorrhagic telangiectasia (HHT). Baeyens et al. report that fluid flow potentiates BMP activation of Alk1 signaling to stabilize blood vessels. HHT lesions thus result from a defect in a synergistic mechanical/biochemical signaling pathway.

No MeSH data available.


Related in: MedlinePlus