Activation Dynamics and Signaling Properties of Notch3 Receptor in the Developing Pulmonary Artery

Abstract

Notch3 signaling is fundamental for arterial specification of systemic vascular smooth muscle cells (VSMCs). However, the developmental role and signaling properties of the Notch3 receptor in the mouse pulmonary artery remain unknown. Here, we demonstrate that Notch3 is expressed selectively in pulmonary artery VSMCs, is activated from late fetal to early postnatal life, and is required to maintain the morphological characteristics and smooth muscle gene expression profile of the pulmonary artery after birth. Using a conditional knock-out mouse model, we show that Notch3 receptor activation in VSMCs is Jagged1-dependent. In vitro VSMC lentivirus-mediated Jagged1 knockdown, confocal localization analysis, and co-culture experiments revealed that Notch3 activation is cell-autonomous and occurs through the physical engagement of Notch3 and VSMC-derived Jagged1 in the interior of the same cell. Although the current models of mammalian Notch signaling involve a two-cell system composed of a signal-receiving cell that expresses a Notch receptor on its surface and a neighboring signal-sending cell that provides membrane-bound activating ligand, our data suggest that pulmonary artery VSMC Notch3 activation is cell-autonomous. This unique mechanism of Notch activation may play an important role in the maturation of the pulmonary artery during the transition to air breathing.Lung development involves the integration of multiple signaling pathways to ensure coordinated growth and differentiation of airway and vascular structures (1). The initial event in vessel development is the formation of basic tubular structures from endothelial precursors (2). Under the influence of PDGF-␤ and Wnt signaling (3, 4), formation of mature vessels occurs by the stepwise recruitment, growth, and differentiation of mesenchymal precursors into a circumferential mural cell layer composed of smooth muscle cells and pericytes (5).It is noteworthy that the lung vascular system is subjected to a dramatic switch at birth, from a low-flow, low-pressure fetal state to a high-flow, higher pressure postnatal state (1). Although it recognized as an essential feature of the transition from intrauterine life, the timing and identification of signals that control how lung vascular cells adapt to this changeover remain unclear. The involvement of Notch signals in multiple aspects of vessel development led us to investigate the role of this pathway during this transition period.The Notch signaling pathway is highly conserved across species, controlling cell fate decisions and tissue patterning during development (6). In classical Notch signaling, a cell surface Notch receptor is activated by binding with a membranebound ligand delivered by a neighboring signal-sending cell (7). This interaction initiates a series of proteolytic cleavages that release the Notch intracellular domain into the cytoplasm of the signal-receiving cell before translocation to the nucleus and induction of target gene transcription (8, 9).Of the four mammalian Notch receptors, Notch3...

A New Approach for the Study of Lung Smooth Muscle Phenotypes and Its Application in a Murine Model of Allergic Airway Inflammation

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Regulation of Vascular Smooth Muscle Cell Phenotype in Three-Dimensional Coculture System by Jagged1-Selective Notch3 Signaling

“…20,22,23 Notch3 is the primary receptor that is expressed by VSMCs and its ligand Jagged1 is predominantly expressed by vascular ECs. 19,24,25 Notwithstanding a number of in-vivo-gene-knockout experiments that demonstrate the role of EC-mediated Notch signaling during vascular development and maturity, [26][27][28] it is unknown whether Notch signaling is activated in vitro in 3D cultures to induce the VSMC contractile phenotype. 29 The objectives of the current work were, therefore, threefold: (1) to establish ligand presentation modes on the transcriptional activation of VSMC-specific genes, (2) to develop a 3D coculture model using human coronary artery smooth muscle cell (HCASMCs) and human coronary artery endothelial cell (HCAECs) on porous synthetic scaffolds, and (3) to investigate EC-mediated Notch signaling pathway in 3D cultures and induction of HCASMC contractile phenotype.…”

Notch3-Jagged signaling controls the pool of undifferentiated airway progenitors

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