糖皮质激素通过 GSK3β 介导的成骨细胞凋亡诱导大鼠股骨头坏死。
Glucocorticoid induces osteonecrosis of the femoral head in rats through GSK3β-mediated osteoblast apoptosis.
机构信息
Department of Orthopedics, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.
Department of Orthopedics, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.
出版信息
Biochem Biophys Res Commun. 2019 Apr 9;511(3):693-699. doi: 10.1016/j.bbrc.2019.02.118. Epub 2019 Feb 28.
OBJECTIVE
One of the important causes of glucocorticoids (GCs)-induced osteonecrosis of the femoral head (ONFH) is osteoblast apoptosis. Glycogen synthase kinase 3β (GSK3β) has been reported to be related to dexamethasone (Dex)-induced osteoblast apoptosis. This study aimed to determine whether GSK3β plays role in GC-induced ONFH and investigate the underlying mechanism.
METHODS
18 male Sprague-Dawley rats were divided into 3 groups. Rats from ONFH group underwent lipopolysaccharide and methylprednisolone injection. Lithium chloride (LiCl, a GSK3β inhibitor) group were fed with LiCl solution. The control group were untreated. Osteonecrosis, apoptosis and bone loss were evaluated by HE staining, TUNEL staining and micro-CT respectively. Protein expressions were examined by western blotting. In addition, primary osteoblast cells were transfected by GSK3β-siRNA and related signaling pathway and proteins were examined.
RESULTS
ONFH group showed a relative high percentage of empty lacunae and apoptotic cells, whilst LiCl treatment markedly decreased the percentage. LiCl treatment decreased GC-induced bone loss. Immunoblot analysis for GSK3β showed decreased level of Ser9-phosphorylated GSK3β in ONFH group compared with control group. Knockdown of GSK3β by siRNA in primary osteoblast cells attenuated DEX-induced apoptosis and loss of mitochondrial transmembrane potential (Δψm). GSK3β knockdown also reversed the release of cytochrome C (Cyt C) from mitochondria to the cytosol. GSK3β decreased apoptosis-related protein expression both in vitro and in vivo.
CONCLUSION
Our findings suggest that GC induces ONFH in rats through GSK3β-mediated osteoblast apoptosis, with involvement of mitochondrial apoptotic pathway.
目的
糖皮质激素（GCs）诱导的股骨头坏死（ONFH）的重要原因之一是成骨细胞凋亡。糖原合酶激酶 3β（GSK3β）已被报道与地塞米松（Dex）诱导的成骨细胞凋亡有关。本研究旨在确定 GSK3β 是否在 GC 诱导的 ONFH 中发挥作用，并探讨其潜在机制。
方法
将 18 只雄性 Sprague-Dawley 大鼠分为 3 组。ONFH 组大鼠接受脂多糖和甲基强的松龙注射。氯化锂（LiCl，GSK3β 抑制剂）组给予 LiCl 溶液喂养。对照组大鼠未处理。通过 HE 染色、TUNEL 染色和 micro-CT 分别评估骨坏死、细胞凋亡和骨丢失。通过 Western blot 检测蛋白表达。此外，通过 GSK3β-siRNA 转染原代成骨细胞，检测相关信号通路和蛋白。
结果
ONFH 组出现相对较高比例的空陷窝和凋亡细胞，而 LiCl 处理显著降低了该比例。LiCl 处理减少了 GC 诱导的骨丢失。与对照组相比，ONFH 组 GSK3β 的 Ser9 磷酸化 GSK3β 水平降低。在原代成骨细胞中敲低 GSK3β 通过 siRNA 减弱了 DEX 诱导的细胞凋亡和线粒体跨膜电位（Δψm）的丧失。GSK3β 敲低还逆转了细胞色素 C（Cyt C）从线粒体向细胞质的释放。GSK3β 在体外和体内均降低了凋亡相关蛋白的表达。
结论
我们的研究结果表明，GC 通过 GSK3β 介导的成骨细胞凋亡诱导大鼠发生 ONFH，涉及线粒体凋亡途径。
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