McCallinhart Patricia E, Biwer Lauren A, Clark Olivia E, Isakson Brant E, Lilly Brenda, Trask Aaron J
Center for Cardiovascular Research, The Heart Center, The Research Institute at Nationwide Children's Hospital, Columbus, OH, United States.
Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, United States.
Front Physiol. 2020 Feb 4;11:29. doi: 10.3389/fphys.2020.00029. eCollection 2020.
Myoendothelial junctions (MEJs) within the fenestrae of the internal elastic lamina (IEL) are critical sites that allow for endothelial cell (EC) - vascular smooth muscle cell (VSMC) contact and communication. Vascular Notch signaling is a critical determinant of normal vasculogenesis and remodeling, and it regulates cell phenotype via contact between ECs and VSMCs. To date, no studies have linked Notch signaling to the MEJ despite it requiring cell-cell contact. Furthermore, very little is known about Notch in the adult coronary circulation or the localization of Notch signaling and activity within the mature intact blood vessel.
We tested the hypothesis that vascular Notch signaling between ECs and VSMCs occurs at MEJs.
Notch receptor and ligand immunofluorescence was performed in human coronary EC and VSMC co-cultures across transwell inserts ( MEJs) and in the intact mouse coronary circulation. Human coronary VSMC Notch activity induced by human coronary ECs at the MEJ was assessed using a CBF-luciferase construct. We observed Jagged1, Notch1, Notch2, and Notch3 expression within the and MEJs. We also demonstrated a 3-fold induction ( < 0.001) of human coronary VSMC Notch signaling by ECs at the MEJ, which was completely blocked by the Notch inhibitor, DAPT ( < 0.01).
We demonstrate for the first time in mature blood vessels that Notch receptors and ligands are expressed within and are active at coronary MEJs, demonstrating a previously unrecognized mode of Notch signaling regulation between the endothelium and smooth muscle.
内弹性膜（IEL）窗孔内的肌内皮连接（MEJ）是允许内皮细胞（EC）与血管平滑肌细胞（VSMC）接触和通讯的关键部位。血管Notch信号是正常血管生成和重塑的关键决定因素，它通过EC与VSMC之间的接触来调节细胞表型。迄今为止，尽管Notch信号需要细胞间接触，但尚无研究将Notch信号与MEJ联系起来。此外，对于成人冠状动脉循环中的Notch以及成熟完整血管内Notch信号和活性的定位知之甚少。
我们检验了EC与VSMC之间的血管Notch信号发生在MEJ的假说。
在跨孔插入物（MEJ）上的人冠状动脉EC和VSMC共培养物以及完整的小鼠冠状动脉循环中进行Notch受体和配体免疫荧光检测。使用CBF-荧光素酶构建体评估人冠状动脉EC在MEJ处诱导的人冠状动脉VSMC Notch活性。我们在IEL和MEJ内观察到Jagged1、Notch1、Notch2和Notch3的表达。我们还证明，EC在MEJ处可使人冠状动脉VSMC Notch信号诱导3倍增加（P<0.001），而Notch抑制剂DAPT可完全阻断这种增加（P<0.01）。
我们首次在成熟血管中证明，Notch受体和配体在冠状动脉MEJ内表达并具有活性，这表明内皮与平滑肌之间存在一种先前未被认识的Notch信号调节模式。
