Innovation Research Center for Special Food-Medicine and Biochemical Engineering, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 Xidazhi Street, Nangang District, Harbin, China.
Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, 157 Baojian Road, Nangang District, Harbin, China.
Food Funct. 2022 Jan 4;13(1):398-410. doi: 10.1039/d1fo02583j.
γ-Tocotrienol (γ-T3), an isoprenoid phytochemical, has shown the promotion of osteoblast proliferation and differentiation in our previous study. In this study, its underlying mechanism was investigated through regulating the Wnt/β-catenin signaling pathway in MC3T3-E1 cells. Comparative experiment results showed that γ-T3, not α-tocopherol (α-TOC) increased more significantly the viability and differentiation in MC3T3-E1 cells. After that, the cells were incubated with 10 mM LiCl, or 4 μM γ-T3 with or without 1 μM XAV-939. γ-T3 at 4 μM stimulated the Wnt/β-catenin signaling pathway by increasing the expression and nuclear accumulation of β-catenin, and the expressions of their downstream factors, such as cyclin-D1, c-Myc, BMP2 and BMP-4 in MC3T3-E1 cells. γ-T3 not only upregulated the viability, induced G0/G1 to the S phase, and promoted the expressions of PCNA (Proliferating Cell Nuclear Antigen) and Ki-67, but also increased ALP activity and the expressions of ON, OPN and OCN. Moreover, the effects of γ-T3 on the MC3T3-E1 cells resembled the actions of LiCl, an activator of the Wnt/β-catenin signaling pathway. Notably, all these effects of γ-T3 on the MC3T3-E1 cells were completely blocked by the Wnt/β-catenin signaling pathway inhibitor XAV-939. Our data demonstrated that γ-T3 can target β-catenin to enhance the Wnt/β-catenin signaling pathway, which led to increased expressions of the downstream cell proliferation and cell cycle-associated (cyclin D1 and c-myc), and cell differentiation-associated (BMP-2 and BMP-4) target genes, and ultimately promoted MC3T3-E1 cell proliferation and differentiation. Therefore, γ-T3 may be a potential agent to prevent and reverse osteoporosis due to its safety and powerful abilities of osteogenesis.
γ-生育三烯酚（γ-T3）是一种类异戊二烯植物化学物质，在我们之前的研究中已显示出促进成骨细胞增殖和分化的作用。在这项研究中，通过调节 MC3T3-E1 细胞中的 Wnt/β-连环蛋白信号通路来研究其潜在机制。比较实验结果表明，γ-T3（而非α-生育酚（α-TOC））可更显著地提高 MC3T3-E1 细胞的活力和分化。之后，用 10mM LiCl 或 4μMγ-T3 与或不与 1μM XAV-939 孵育细胞。4μMγ-T3 通过增加β-连环蛋白的表达和核积累，以及其下游因子 cyclin-D1、c-Myc、BMP2 和 BMP-4 的表达，刺激 Wnt/β-连环蛋白信号通路。γ-T3 不仅上调了细胞活力，诱导 G0/G1 进入 S 期，并促进 PCNA（增殖细胞核抗原）和 Ki-67 的表达，还增加了碱性磷酸酶（ALP）活性和 ON、OPN 和 OCN 的表达。此外，γ-T3 对 MC3T3-E1 细胞的作用类似于 Wnt/β-连环蛋白信号通路激活剂 LiCl 的作用。值得注意的是，Wnt/β-连环蛋白信号通路抑制剂 XAV-939 完全阻断了γ-T3 对 MC3T3-E1 细胞的所有这些作用。我们的数据表明，γ-T3 可以靶向β-连环蛋白来增强 Wnt/β-连环蛋白信号通路，从而导致下游细胞增殖和细胞周期相关（cyclin D1 和 c-myc）和细胞分化相关（BMP-2 和 BMP-4）靶基因的表达增加，最终促进 MC3T3-E1 细胞的增殖和分化。因此，γ-T3 由于其安全性和强大的成骨能力，可能是预防和逆转骨质疏松症的潜在药物。
