Activation of Notch signaling by soluble Dll4 decreases vascular permeability via a cAMP/PKA-dependent pathway

Abstract

The Notch ligand delta-like ligand 4 (Dll4), upregulated by VEGF, is a key regulator of vessel morphogenesis and function, controlling tip and stalk cell selection during sprouting angiogenesis. Inhibition of Dll4 results in hypersprouting, nonfunctional, poorly perfused vessels, suggesting a role for Dll4 in the formation of mature, reactive, functional vessels, with low permeability and able to restrict fluid and solute exchange. We tested the hypothesis that Dll4 controls transvascular fluid exchange. A recombinant protein expressing only the extracellular portion of Dll4 [soluble Dll4 (sDll4)] induced Notch signaling in endothelial cells (ECs), resulting in increased expression of vascular-endothelial cadherin, but not the tight junctional protein zonula occludens 1, at intercellular junctions. sDll4 decreased the permeability of FITC-labeled albumin across EC monolayers, and this effect was abrogated by coculture with the γ-secretase inhibitor N-[ N-(3,5-difluorophenacetyl)-l-alanyl]- S-phenylglycine t-butyl ester. One of the known molecular effectors responsible for strengthening EC-EC contacts is PKA, so we tested the effect of modulation of PKA on the sDll4-mediated reduction of permeability. Inhibition of PKA reversed the sDll4-mediated reduction in permeability and reduced expression of the Notch target gene Hey1. Knockdown of PKA reduced sDLL4-mediated vascular-endothelial cadherin junctional expression. sDll4 also caused a significant decrease in the hydraulic conductivity of rat mesenteric microvessels in vivo. This reduction was abolished upon coperfusion with the PKA inhibitor H89 dihydrochloride. These results indicate that Dll4 signaling through Notch activation acts through a cAMP/PKA pathway upon intercellular adherens junctions, but not tight junctions, to regulate endothelial barrier function. NEW & NOTEWORTHY Notch signaling reduces vascular permeability through stimulation of cAMP-dependent protein kinase A.

Long non-coding RNA UCA1 promotes malignant phenotypes of renal cancer cells by modulating the miR-182-5p/DLL4 axis as a ceRNA

“…Delta-like ligand 4 (DLL4), one of the ligands of Notch receptors, is predominantly expressed in the endothelial cells and has been shown to play a pivotal role in regulating tumor angiogenesis [38][39][40][41][42][43][44][45]. Some studies reveal a role for DLL4 in tumorigenesis in several cancers, including T acute lymphoblastic leukemia (T-ALL) [46], and glioblastoma [47] etc.…”

“…Some studies reveal a role for DLL4 in tumorigenesis in several cancers, including T acute lymphoblastic leukemia (T-ALL), and glioblastoma etc. [37][38][39][40][41][42][43][44][45][46][47]. DLL4 is one of the ligands of Notch 1.…”

Enhanced notch signaling modulates unproductive revascularization in response to nitric oxide‐angiopoietin signaling in a mouse model of peripheral ischemia

“…We have previously shown that activation of Notch signaling by soluble Dll4 (sDll4) decreases vascular permeability, mainly due to an increased expression of VE‐Cadherin at intercellular junctions, and thus we used an adenovirus (Ad.sDll4) to promote early vessel maturation in the hindlimb ischemia mouse model, in order to assess its effect on recovery of blood flow. Firstly, to confirm that sDll4 was able to induce angiogenesis as well, we used an in vitro angiogenesis assay, where co‐cultured fibroblasts and ECs were treated with adenovirus‐conditioned media, stained, and imaged (Figure ).…”

“…Ad.sDll4 gives rise to the over‐expression of the extracellular portion of Delta‐like ligand 4, which is sufficient to activate Notch signaling, nuclear translocation of NICD, and Hes/Hey upregulation in ECs …”

Serum delta‐like 4 levels: A possible association with interstitial lung disease in systemic sclerosis

“…We failed to detect any association of serum Dll4 levels with organ involvement other than ILD and vascular manifestations (Table 1). Soluble Dll4 serves as an activator or inhibitor of neovascularization in a context-dependent manner in vivo and in vitro, 3,4 but serum Dll4 levels did not correlate with any vascular complications, suggesting the minimal effect of soluble Dll4 on SSc vasculopathy. On the other hand, the association of serum Dll4 levels with ILD suggests the potential role of Notch/Dll4 pathway in CD4 + T-cell differentiation in the lung.…”