Campos Alexandre H, Wang Wenli, Pollman Matthew J, Gibbons Gary H
Cardiovascular Research Institute, Morehouse School of Medicine, Atlanta, Ga 30310, USA.
Circ Res. 2002 Nov 29;91(11):999-1006. doi: 10.1161/01.res.0000044944.99984.25.
The Notch family of receptors and ligands plays an important role in cell fate determination, vasculogenesis, and organogenesis. Mutations of the Notch-3 receptor result in an arteriopathy that predisposes to early-onset stroke. However, the functional role of the Notch signaling pathway in adult vascular smooth muscle cells (VSMCs) is poorly characterized. This study documents that the Notch-3 receptor, the ligand Jagged-1, and the downstream transcription factor, HESR-1, are expressed in the normal adult rat carotid artery, and that this expression is modulated after vascular injury. In cultured VSMCs, both angiotensin II and platelet-derived growth factor (PDGF) markedly downregulated Notch-3 and Jagged-1 through ERK-dependent signaling mechanisms and prevented the glycosylation of Jagged-1. The downregulation of Jagged-1 and Notch-3 was associated with a decrease in CBF-1-mediated gene transcription activation and a fall in the mRNA levels of the downstream target transcription factor HESR-1. To test the hypothesis that the Notch pathway was coupled to growth regulation, we generated VSMC lines overexpressing the constitutively active form of Notch-3 (A7r5-N3IC). These cells exhibited a biphasic growth behavior in which the growth rate was retarded during the subconfluent phase and failed to decelerate at postconfluence. The lack of cell-cycle arrest in postconfluent A7r5-N3IC was associated with an attenuated upregulation of the cell-cycle inhibitor p27(kip) relative to control cells. This study documents the regulation of the Jagged-1 and Notch-3 genes in VSMCs by growth factor stimulation as well as a role for Notch-3 as a determinant of VSMC growth.
Notch受体和配体家族在细胞命运决定、血管生成和器官发生中发挥着重要作用。Notch-3受体的突变会导致一种易引发早发性中风的动脉病变。然而，Notch信号通路在成年血管平滑肌细胞（VSMC）中的功能作用却鲜为人知。本研究证明，Notch-3受体、配体Jagged-1和下游转录因子HESR-1在正常成年大鼠颈动脉中表达，且这种表达在血管损伤后会受到调节。在培养的VSMC中，血管紧张素II和血小板衍生生长因子（PDGF）均通过ERK依赖性信号机制显著下调Notch-3和Jagged-1，并阻止Jagged-1的糖基化。Jagged-1和Notch-3的下调与CBF-1介导的基因转录激活减少以及下游靶转录因子HESR-1的mRNA水平下降有关。为了验证Notch通路与生长调节相关的假设，我们构建了过表达组成型活性形式Notch-3（A7r5-N3IC）的VSMC系。这些细胞表现出双相生长行为，即在亚汇合期生长速率减慢，而在汇合后未能减速。与对照细胞相比，汇合后A7r5-N3IC细胞缺乏细胞周期停滞与细胞周期抑制剂p27(kip)的上调减弱有关。本研究证明了生长因子刺激对VSMC中Jagged-1和Notch-3基因的调节作用，以及Notch-3作为VSMC生长决定因素的作用。
