Fang Li, Shen Zhijie, Zhang Yinzhuang, Mao Zhuoni, Huang Dan, Lou Chenyu
Cardiovascular Department Second Ward, The Affiliated Changsha Hospital of Xiangya School of Medicine, Central South University, Changsha, China.
Biol Direct. 2025 Feb 26;20(1):24. doi: 10.1186/s13062-025-00615-0.
Nucleolin (NCL) plays an important regulatory role in angiotensin II (Ang II)-induced phenotypic switching of vascular smooth muscle cells (VSMCs). The aim of this study was to discuss its potential regulatory mechanisms.
We investigated if the pathways involving Ang II type 1 receptor (AT1R) and PKC/MAPK are responsible for Ang II's effects on VSMC phenotypic switching. Ang II upregulated NCL expression and activated the PKC/MAPK signaling pathway to induce VSMC phenotypic switching. In addition, Ang II promoted the translocation of NCL from the nucleus to the cell membrane. NCL was shown to bind to AT1R, whereas the binding of NCL to AT1R was greatly attenuated after the deletion of the GAR region. In addition, when peptide-N-glycosidase F (PNGase F) was applied, the N-glycosylation of NCL protein and the phenotypic switching of VSMC were inhibited. Ang II-induced AT1R internalization, whereas overexpression of NCL delayed Ang II-induced AT1R internalization by inhibiting AT1R phosphorylation and recruited Rab4 and Rab11 to promote recycling, and knockdown of NCL showed the opposite effect and reversal of AT1R binding by the use of rasarfin reversed the effects of sh-NCL. In in vivo experiments, knockdown of NCL expression inhibited Ang II-induced blood pressure rise and vasculopathy.
Our study demonstrates that NCL promotes Ang II-mediated phenotypic switching of VSMCs by regulating AT1R internalization function.
核仁素（NCL）在血管紧张素II（Ang II）诱导的血管平滑肌细胞（VSMC）表型转换中起重要调节作用。本研究旨在探讨其潜在的调节机制。
我们研究了涉及血管紧张素II 1型受体（AT1R）和蛋白激酶C/丝裂原活化蛋白激酶（PKC/MAPK）的信号通路是否介导Ang II对VSMC表型转换的影响。Ang II上调NCL表达并激活PKC/MAPK信号通路以诱导VSMC表型转换。此外，Ang II促进NCL从细胞核向细胞膜的转位。结果显示NCL与AT1R结合，而在缺失GAR区域后，NCL与AT1R的结合显著减弱。此外，当应用肽-N-糖苷酶F（PNGase F）时，NCL蛋白的N-糖基化和VSMC的表型转换受到抑制。Ang II诱导AT1R内化，而NCL的过表达通过抑制AT1R磷酸化延迟Ang II诱导的AT1R内化，并募集Rab4和Rab11以促进再循环，敲低NCL则显示相反的效果，并且使用rasarfin逆转AT1R结合可逆转sh-NCL的作用。在体内实验中，敲低NCL表达可抑制Ang II诱导的血压升高和血管病变。
我们的研究表明，NCL通过调节AT1R内化功能促进Ang II介导的VSMC表型转换。
