Abstract
Aims: β-catenin has been shown to be regulated by inducible nitric oxide synthase (NOS) in endothelial cells. We investigated here whether β-catenin interacts with and regulates endothelial NOS (eNOS) and whether eNOS activation promotes β-catenin signaling.
Methods and Results: We identified β-catenin as a novel eNOS binding protein in human umbilical vein endothelial cells (HUVECs) by mass spectroscopy and western blot analyses of β-catenin and eNOS immunoprecipitates. This was confirmed by in situ proximity ligation assay. eNOS activity, assessed by cGMP production and eNOS phosphorylation (Ser1177), was enhanced in β-catenin−/- mouse pulmonary endothelial cells (MPECs) relative to wild type MPECs. eNOS activation (using adenosine, salbutamol, thrombin or histamine), or application of an NO donor (spermine NONOate) or cGMP-analogue (8-bromo-cGMP) caused nuclear translocation of β-catenin in HUVEC as shown by western blotting of nuclear extracts. Exposure to spermine NONOate, 8-bromo-cGMP or sildenafil (a phosphodiesterase type 5 inhibitor) also increased the expression of β-catenin-dependent transcripts, IL-8 and cyclin D1. Stimulation of wild type MPECs with basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), spermine NONOate, 8-bromo-cGMP or sildenafil increased tube length relative to controls in an angiogenesis assay. These responses were abrogated in β-catenin−/- MPECs, with the exception of that to bFGF which is NO-independent. In C57BL/6 mice, subcutaneous VEGF-supplemented Matrigel plugs containing β-catenin−/- MPECs exhibited reduced angiogenesis compared to plugs containing wild type MPECs. Angiogenesis was not altered in bFGF-supplemented Matrigel.
Conclusions: These data reveal bidirectional cross talk and regulation between the NO-cGMP and β-catenin signaling pathways.
Methods and Results: We identified β-catenin as a novel eNOS binding protein in human umbilical vein endothelial cells (HUVECs) by mass spectroscopy and western blot analyses of β-catenin and eNOS immunoprecipitates. This was confirmed by in situ proximity ligation assay. eNOS activity, assessed by cGMP production and eNOS phosphorylation (Ser1177), was enhanced in β-catenin−/- mouse pulmonary endothelial cells (MPECs) relative to wild type MPECs. eNOS activation (using adenosine, salbutamol, thrombin or histamine), or application of an NO donor (spermine NONOate) or cGMP-analogue (8-bromo-cGMP) caused nuclear translocation of β-catenin in HUVEC as shown by western blotting of nuclear extracts. Exposure to spermine NONOate, 8-bromo-cGMP or sildenafil (a phosphodiesterase type 5 inhibitor) also increased the expression of β-catenin-dependent transcripts, IL-8 and cyclin D1. Stimulation of wild type MPECs with basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), spermine NONOate, 8-bromo-cGMP or sildenafil increased tube length relative to controls in an angiogenesis assay. These responses were abrogated in β-catenin−/- MPECs, with the exception of that to bFGF which is NO-independent. In C57BL/6 mice, subcutaneous VEGF-supplemented Matrigel plugs containing β-catenin−/- MPECs exhibited reduced angiogenesis compared to plugs containing wild type MPECs. Angiogenesis was not altered in bFGF-supplemented Matrigel.
Conclusions: These data reveal bidirectional cross talk and regulation between the NO-cGMP and β-catenin signaling pathways.
| Original language | English |
|---|---|
| Pages (from-to) | 116-126 |
| Journal | Cardiovascular Research |
| Volume | 104 |
| Issue number | 1 |
| Early online date | 25 Jul 2014 |
| DOIs | |
| Publication status | Published - 1 Oct 2014 |