Guerrero Fátima, Herencia Carmen, Almadén Yolanda, Martínez-Moreno Julio M, Montes de Oca Addy, Rodriguez-Ortiz María Encarnación, Diaz-Tocados Juan M, Canalejo Antonio, Florio Mónica, López Ignacio, Richards William G, Rodriguez Mariano, Aguilera-Tejero Escolástico, Muñoz-Castañeda Juan R
Instituto Maimónides para la Investigación Biomédica (IMIBIC). Hospital Reina Sofía. Universidad de Córdoba, Córdoba, Spain.
Lipid and Atherosclerosis Unit. IMIBIC/Reina Sofía University Hospital/University of Córdoba, and CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Córdoba, Spain.
PLoS One. 2014 Feb 27;9(2):e89179. doi: 10.1371/journal.pone.0089179. eCollection 2014.
Transforming growth factor-β (TGF-β) is a key cytokine during differentiation of mesenchymal stem cells (MSC) into vascular smooth muscle cells (VSMC). High phosphate induces a phenotypic transformation of vascular smooth muscle cells (VSMC) into osteogenic-like cells. This study was aimed to evaluate signaling pathways involved during VSMC differentiation of MSC in presence or not of high phosphate.
Our results showed that TGF-β induced nuclear translocation of Smad3 as well as the expression of vascular smooth muscle markers, such as smooth muscle alpha actin, SM22α, myocardin, and smooth muscle-myosin heavy chain. The addition of high phosphate to MSC promoted nuclear translocation of Smad1/5/8 and the activation of canonical Wnt/β-catenin in addition to an increase in BMP-2 expression, calcium deposition and alkaline phosphatase activity. The administration of TGF-β to MSC treated with high phosphate abolished all these effects by inhibiting canonical Wnt, BMP and TGF-β pathways. A similar outcome was observed in high phosphate-treated cells after the inhibition of canonical Wnt signaling with Dkk-1. Conversely, addition of both Wnt/β-catenin activators CHIR98014 and lithium chloride enhanced the effect of high phosphate on BMP-2, calcium deposition and alkaline phosphatase activity.
Full VSMC differentiation induced by TGF-β may not be achieved when extracellular phosphate levels are high. Moreover, TGF-β prevents high phosphate-induced osteogenesis by decreasing the nuclear translocation of Smad 1/5/8 and avoiding the activation of Wnt/β-catenin pathway.
转化生长因子-β（TGF-β）是间充质干细胞（MSC）分化为血管平滑肌细胞（VSMC）过程中的关键细胞因子。高磷诱导血管平滑肌细胞（VSMC）向成骨样细胞发生表型转化。本研究旨在评估在存在或不存在高磷的情况下，MSC向VSMC分化过程中涉及的信号通路。
我们的结果表明，TGF-β诱导Smad3的核转位以及血管平滑肌标志物的表达，如平滑肌α肌动蛋白、SM22α、心肌素和平滑肌肌球蛋白重链。向MSC中添加高磷除了增加骨形态发生蛋白-2（BMP-2）表达、钙沉积和碱性磷酸酶活性外，还促进Smad1/5/8的核转位和经典Wnt/β-连环蛋白的激活。用TGF-β处理经高磷处理的MSC可通过抑制经典Wnt、BMP和TGF-β信号通路消除所有这些效应。在用Dkk-1抑制经典Wnt信号后，在高磷处理的细胞中观察到类似的结果。相反，添加Wnt/β-连环蛋白激活剂CHIR98014和氯化锂增强了高磷对BMP-2、钙沉积和碱性磷酸酶活性的影响。
当细胞外磷水平较高时，TGF-β诱导的完全VSMC分化可能无法实现。此外，TGF-β通过降低Smad 1/5/8的核转位并避免Wnt/β-连环蛋白信号通路的激活来预防高磷诱导的成骨作用。
