High glucose-induced jagged 1 in endothelial cells disturbs notch signaling for angiogenesis: a novel mechanism of diabetic vasculopathy.

Angiogenesis is a multistep process which is orchestrated by intercellular signaling. We developed an in vitro model of human angiogenesis to identify a pathologic angiogenesis and intercellular signaling in high glucose condition. We co-cultivated human endothelial cells (ECs) and smooth muscle cells (SMCs) in a spheroid on an SMC monolayer for 7 days either in high glucose or in control condition. We analyzed vascular growth and expression of notch or its ligands with confocal microscopy. Abnormal angiogenesis by high glucose condition was characterized by (1) increased sprouting and branching (high glucose vs. normal: number of sprouts 20.3±1.5 vs. 13.7±2.9, p=0.024; number of branching points 7.6±2.5 vs. 2.3±2.1, p=0.047), (2) decreased vascular diameter (diameter of the tubes 13.4±6. 1μm vs. 19.1±8.8 μm, p=0.012) and (3) destabilization of the tubes. We identified that high glucose induced jagged 1 and suppressed notch1 in ECs whereas it did not affect Dll4. Constitutive jagged 1 overexpression or inhibition of notch1 in ECs induced abnormal angiogenesis as the high glucose condition did. Endothelial-specific shRNA targeting jagged 1 rescued the aberrant angiogenesis in high glucose condition. High glucose condition induced an abnormal endothelial intercellular signaling leading to aberrant angiogenesis. It is a novel mechanism of diabetic microvasculopathy which can be a therapeutic target beyond glucose control.

Yoon CH ，Choi YE ，Koh SJ ，Choi JI ，Park YB ，Kim HS ... -  《-》

Endothelial Jagged1 antagonizes Dll4 regulation of endothelial branching and promotes vascular maturation downstream of Dll4/Notch1.

Notch signaling controls cardiovascular development and has been associated with several pathological conditions. Among its ligands, Jagged1 and Dll4 were shown to have opposing effects in developmental angiogenesis, but the underlying mechanism and the role of Jagged1/Notch signaling in adult angiogenesis remain incompletely understood. The current study addresses the importance of endothelial Jagged1-mediated Notch signaling in the context of adult physiological angiogenesis and the interactions of Jagged1 and Dll4 on angiogenic response and vascular maturation processes. The role of endothelial Jagged1 in wound healing kinetics and angiogenesis was investigated with endothelial-specific Jag1 gain-of-function and loss-of-function mouse mutants (eJag1OE and eJag1cKO). To study the interactions between the 2 Notch ligands, genetic mouse models were combined with pharmacological inhibition of Dll4 or Jagged1, respectively. Jagged1 overexpression in endothelial cells increased vessel density, maturation, and perfusion, thus accelerating wound healing. The opposite effect was seen in eJag1cKO animals. Interestingly, Dll4 blockade in these animals led to an increase in vascular density but induced a greater decrease in perivascular cell coverage. However, Jagged1 inhibition in Dll4 gain-of-function (eDll4OE) mutants, with reduced angiogenesis, further diminished angiogenic growth and hampered perivascular cell coverage. Our findings suggest that as Dll4 blocks endothelial activation through Notch1 signaling, it also induces Jagged1 expression. Jagged1 then blocks Dll4 signaling through Notch1, allowing endothelial activation by vascular endothelial growth factor and endothelial layer growth. Jagged1 also initiates maturation of the newly formed vessels, possibly by binding and activating endothelial Notch4. Importantly, mice administered with a Notch4 agonistic antibody mimicked the mural cell phenotype of eJag1OE mutants without affecting angiogenic growth, which is thought to be Notch1 dependent. Endothelial Jagged1 is likely to operate downstream of Dll4/Notch1 signaling to activate Notch4 and regulate vascular maturation. Thus, Jagged1 not only counteracts Dll4/Notch in the endothelium but also generates a balance between angiogenic growth and maturation processes in vivo.

Pedrosa AR ，Trindade A ，Fernandes AC ，Carvalho C ，Gigante J ，Tavares AT ，Diéguez-Hurtado R ，Yagita H ，Adams RH ，Duarte A ... -  《-》

Soluble Jagged-1 inhibits neointima formation by attenuating Notch-Herp2 signaling.

Caolo V ，Schulten HM ，Zhuang ZW ，Murakami M ，Wagenaar A ，Verbruggen S ，Molin DG ，Post MJ ... -  《-》

Vascular smooth muscle Notch signals regulate endothelial cell sensitivity to angiogenic stimulation.

Yang K ，Proweller A 《-》

Regulation of multiple angiogenic pathways by Dll4 and Notch in human umbilical vein endothelial cells.

Harrington LS ，Sainson RC ，Williams CK ，Taylor JM ，Shi W ，Li JL ，Harris AL ... -  《MICROVASCULAR RESEARCH》