[Mechanism study of platelet derived growth factor receptor alpha on the bidirectional differentiation regulation of glioma-associated oncogene homolog 1-positive mesenchymal stem cells in mice]

Abstract

Objective: To investigate the role of platelet derived growth factor receptor alpha (PDGFRα) on bidirectional differentiation of glioma-associated oncogene homolog 1-positive mesenchymal stem cells (Gli1+-MSC). Methods: Breeding double reporter transgenic mice ROSAmT/mG/Gli1-Cre^ERt2/PDGFRα^fl (Experimental group) and ROSA^mT/mG/Gli1-Cre^ERt2 (Control group), 20 mice in each of the two groups at four weeks of age were selected, MSC were isolated from the mouse aortic epithelium. After tamoxifen inducement, the two groups of Gli1⁺-MSC were screened by green fluorescent protein (GFP) labeling and flow cytometry sorting. PDGFRα was conditionally knocked out in the experimental group, and the control group Gli1⁺-MSC expressed PDGFRα normally. The two groups of Gli1⁺-MSC were subjected to adipogenic induction and fibrogenic induction, the Western blotting was performed to detect PDGFRα, adipocyte markers [perilipin and CCAAT/enhancer binding protein alpha (C/EBPα)] and fibrogenic markers [alpha smooth muscle actin (α-SMA) and fibroblast-specific protein 1 (FSP-1)] and semi-quantitative analysis was performed. The degree of cellular adipose differentiation after bidirectional induction of Gli1+-MSC in both groups was observed by oil red O staining and analyzed semi-quantitatively. Results: After tamoxifen induction, Gli1⁺-MSC could be accurately isolated from flow cytometry by GFP labeling. Via adipogenic differentiation, the expression of PDGFRα in the experimental group (0.017±0.002) was significantly lower than that in the control group (0.184±0.012) (t=25.48，P=0.002). The protein expressions of perilipin (3.138±0.414) and C/EBPα (3.565±0.289) were significantly higher than those in the control group (2.312±0.218 and 2.179±0.103, respectively) (t=6.21，P=0.025；t=6.69，P=0.022). Thus, the knock-out of PDGFRα enhanced the adipogenic differentiation ability of Gli1⁺-MSC. After fibrogenesis induction, the protein expressions of PDGFRα, α-SMA and FSP-1 in the experimental group (0.030±0.001, 0.932±0.177 and 0.276±0.020, respectively) were significantly lower than those in the control group (0.439±0.006, 1.352±0.170 and 0.835±0.097, respectively) (t=149.40, P<0.001; t=66.38,P<0.001; t=11.41,P<0.08). This suggested that the knock-out of PDGFRα significantly inhibited Gli1⁺-MSC differentiation toward fibroblasts. After bidirectional induction, significantly less adipocyte formation was seen in the control group and more in the experimental group. Quantitative analysis showed that the amount of oil red O staining in the experimental group (0.461±0.042) was significantly higher than that in the control group (0.017±0.007) after bidirectional induction (t=23.20, P<0.01). Conclusions: PDGFRα plays an important role in the regulation of bidirectional differentiation of vascular adventitial Gli1+-MSC.