Department of Orthopaedic Surgery, Ewha Womans University Medical Center, Ewha Womans University College of Medicine, 1071 Anyangcheon-ro, Yangcheon-gu, Seoul, 07985, South Korea.
Department of Orthopaedic Surgery, Konkuk University School of Medicine, 120-1 Neungdong-ro, Gwangjin-gu, Seoul, 143-729, South Korea.
J Bone Miner Metab. 2019 Sep;37(5):920-927. doi: 10.1007/s00774-019-00995-0. Epub 2019 Feb 21.
Despite the presence of vitamin D receptor (VDR) in skeletal muscle cells, the relationship between VDR expressions and muscle mass or function has not been well studied. The purpose of this study was to compare VDR gene and protein expression in the forearm muscle between sarcopenic and non-sarcopenic individuals who have sustained distal radius fractures. Twenty samples of muscle tissue from sarcopenic patients (mean age 63.4 ± 8.1 years) and 20 age- and sex-matched control tissues (62.1 ± 7.9 years) were acquired from the edge of dissected pronator quadratus muscle during surgery for distal radius fractures. The mRNA expression levels of VDR as well as the myokines of interest that may be associated with muscle mass change (myogenin and myostatin) were analyzed with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, Western blot assay and immunohistochemistry for VDR were performed. Sarcopenic patients showed a significantly lower level of gene expression for VDR and myogenin, but a greater level of gene expression for myostatin than the controls according to qRT-PCR analysis. The density of VDR protein expressions was 2.1 times greater, while that of myostatin was 2.6 times lower, in the control group than in the sarcopenic group according to Western blot analysis. On immunohistochemical analysis, the density of the cells expressing VDR was significantly decreased in the sarcopenic patients. Sarcopenic patients who sustained distal radius fractures presented lower vitamin D receptor gene and protein expression in skeletal muscles compared to non-sarcopenic individuals.
尽管骨骼肌细胞存在维生素 D 受体 (VDR)，但 VDR 表达与肌肉质量或功能之间的关系尚未得到很好的研究。本研究旨在比较患有桡骨远端骨折的肌少症和非肌少症个体前臂肌肉中的 VDR 基因和蛋白表达。从桡骨远端骨折手术中切开的旋前方肌边缘获得 20 例肌少症患者（平均年龄 63.4±8.1 岁）和 20 例年龄和性别匹配的对照组织（62.1±7.9 岁）的肌肉组织样本。采用实时定量逆转录聚合酶链反应 (qRT-PCR) 分析 VDR 以及可能与肌肉质量变化相关的肌因子（肌生成素和肌肉生长抑制素）的 mRNA 表达水平。此外，还进行了 VDR 的 Western blot 检测和免疫组织化学检测。根据 qRT-PCR 分析，肌少症患者的 VDR 和肌生成素基因表达水平显著降低，但肌肉生长抑制素基因表达水平显著升高。Western blot 分析显示，VDR 蛋白表达密度在对照组中比肌少症组高 2.1 倍，而肌肉生长抑制素蛋白表达密度在对照组中比肌少症组低 2.6 倍。免疫组织化学分析显示，VDR 表达细胞的密度在肌少症患者中显著降低。与非肌少症个体相比，患有桡骨远端骨折的肌少症患者骨骼肌中的维生素 D 受体基因和蛋白表达水平较低。
