Mechanosensitive HEG1-NOTCH1 signals governs endothelial cell function in the pathogenesis of pulmonary hypertension
L Hu, J Xu, Y Ji, S Zhuang, B Kojonazarov, J Liu, Y ZhangAbstract
Background
Endothelial cells (ECs) adapted mechanosensitivity to flow shear-stress are critical for vascular homeostasis. HEG1 as an endothelial mechanosensitive gene exerts anti-hypertensive and atheroprotective effects, yet its regulation of pulmonary endothelial function for pulmonary hypertension (PH) pathogenesis and the underlined mechanisms are not fully clarified.
Methods
Human plasma and lung samples were collected for association of plasma-HEG1 levels and pulmonary artery (PA) wall shear-stress(WSS), pulmonary hemodynamics, and WSS was analyzed by computational fluid dynamics with 3D CT angiography. EC-specific Heg1 deletion mice were generated for PH study using PA for nitric oxide (NO) production and two-photon intravital imaging for vascular permeability. Proteomics, transcriptomics, molecular interaction assay and single magnetic tweezers were applied to identify the regulatory pathways involved.
Results
Reduced plasma HEG1 levels, in parallel with decreased expression in lower-flow PAECs, correlated with lower PA-WSS of PH patients, but negatively with pulmonary hemodynamic parameters mPAP/PVR/PCWP. EC-specific Heg1 deletion mice developed PH due to impaired NO-mediated vasodilation and vascular hyperpermeability from defective endothelial integrity. Mechanistic studies identified HEG1 extracellular domain (Heg1-ECD), the EGF-like-domain/Dll1-1008ser site, for mechanosensitive activation of Notch1 signal that regulated intracellular calcium homeostasis for endothelial NO synthase (eNOS) phosphorylation and further NO production, as well as adherent proteins for endothelial integrity. In contrast, EC-specific Heg1-ECD overexpression restored endothelial dysfunction and ameliorated PH progression.
Conclusions
HEG1-NOTCH1 signaling regulation of endothelial NO and integrity advances understanding of flow-mediated endothelial dysfunction in PH pathogenesis, meanwhile provides opportunities of plasma HEG1 as biomarker monitoring PH progression and of developing diagnostic/therapeutic strategies.Graph abstract