目标:淫羊藿苷,一种8-异戊二烯化的类黄酮苷,是一种合成代谢剂,可以通过不依赖配体的激活成骨细胞中的雌激素受体α(ERα)来促进成骨,从而发挥快速的雌激素作用。然而,对它的直接细胞靶标知之甚少,其保护作用,和骨髓基质细胞(BMSCs)对微重力的细胞粘附活性。在本研究中,通过整合素受体α5β1,连接蛋白43和CAMs的参与,检查了淫羊藿苷在微重力下对成骨和细胞粘附的影响。
收集BMSCs用于实验和RNA测序分析,以检查淫羊藿苷的作用机制及其在刺激成骨中的直接细胞靶标。
结果:结果表明,淫羊藿苷通过激活连接蛋白-43(Cx43)和Ras同源家族成员A(RhoA)和Rac家族小GTP酶1(Rac1)介导的信号通路,诱导了细胞粘附分子(CAM)的表达,并保护了微重力诱导的BMSCs肌动蛋白细胞骨架破坏和成骨活性丧失。计算机分子对接技术和竞争性固相结合ELISA测定证实淫羊藿苷可能是整合素α5β1(α5β1)的直接配体,它还可以增加整合素α5β1的蛋白表达,以进行机械传感。
结论:我们的发现表明淫羊藿苷可以通过与整合素α5β1结合直接激活细胞粘附信号,这为整合素α5β1配体作为一种防止卸载诱导的骨丢失的药物的开发开辟了新的途径。
OBJECTIVE: Icariin, an 8-prenylated flavonoid glycoside, is an anabolic agent that could exert rapid estrogenic actions via ligand-independent activation of estrogen receptor alpha (ERα) in osteoblastic cells to promote osteogenesis. However, relatively little is known about its direct cellular target, its protective effects, and cell adhesion activities in bone marrow stromal cells (BMSCs) against microgravity. In the present study, the effects of icariin on osteogenesis and cell adhesion under microgravity were examined with the involvement of integrin receptor α5β1, connexin 43, and CAMs.
METHODS: Icariin was orally administered to 6-month-old ovariectomized (OVX) Sprague-Dawley (SD) rats for 3 months through daily intake of phytoestrogen-free rodent diets containing icariin at 2 different dosages (50 and 500 ppm). BMSCs were harvested for experiments and RNA-sequencing analysis to examine the mechanism of action of icariin and its direct cellular target in stimulating osteogenesis.
RESULTS: The results revealed that icariin induced the expression of cell adhesion molecules (CAMs) and protected against microgravity-induced disruption of actin cytoskeleton and the loss of osteogenic activities in BMSCs through the activation of connexin-43 (Cx43) and Ras homolog family member A (RhoA) and Rac family small GTPase 1 (Rac1)-mediated signaling pathways. Computerized molecular docking techniques and the competitive solid-phase binding ELISA assay confirmed that icariin could be a direct ligand of integrin alpha 5 beta 1 (α5β1), and it could also increase the protein expression of integrin α5β1 for mechanosensing.
CONCLUSIONS: Our findings suggest that icariin could directly activate cell adhesion signaling by binding to integrin α5β1, which opens up new avenues for the development of integrin α5β1 ligand as an agent to protect against unloading-induced bone loss.