Department of Cell Biology and Genetics, Faculty of Science, Palacky University in Olomouc, Slechtitelu 27, Olomouc, 783 71, Czech Republic.
Calcif Tissue Int. 2019 Dec;105(6):651-659. doi: 10.1007/s00223-019-00602-4. Epub 2019 Aug 30.
Some epidemiological studies suggested caffeine consumption as the cause for bone mineral density loss. Certain genes involved in this process are regulated by vitamin D receptor (VDR). Therefore, we investigated if caffeine can affect inducible expression of VDR-regulated genes, some of them being involved in bone mineralization process. By employing reporter gene assay, polymerase chain reaction, and western blotting, we monitored the VDR activity and expression in cell cultures of intestinal (LS180), osteosarcoma (HOS), and normal human osteoblasts in vitro. While caffeine stimulated calcitriol-inducible VDR-dependent nanoluciferase activity in stable reporter cell line IZ-VDRE (derived from LS180), it rather modulated mRNA levels of target genes, like CYP24A1, BGLAP, SPP1, and TNSF11 in LS180 and HOS cells. However, caffeine significantly decreased calcitriol-inducible CYP24A1, TNSF11, and SPP1 transcripts in osteoblasts. This decrease had non-linear U-shaped profile. Our in vitro data demonstrate biphasic action of caffeine on the expression of certain calcitriol-inducible VDR-regulated genes in normal human osteoblasts.
一些流行病学研究表明，咖啡因摄入是导致骨密度降低的原因。参与这一过程的某些基因受维生素 D 受体 (VDR) 调节。因此，我们研究了咖啡因是否会影响 VDR 调节基因的诱导表达，其中一些基因参与骨矿化过程。通过报告基因检测、聚合酶链反应和 Western blot，我们监测了肠道 (LS180)、骨肉瘤 (HOS) 和体外正常人类成骨细胞培养物中 VDR 的活性和表达。虽然咖啡因刺激稳定报告细胞系 IZ-VDRE (源自 LS180) 中钙三醇诱导的 VDR 依赖性纳米荧光素酶活性，但它调节了靶基因的 mRNA 水平，如 LS180 和 HOS 细胞中的 CYP24A1、BGLAP、SPP1 和 TNSF11。然而，咖啡因显著降低了成骨细胞中钙三醇诱导的 CYP24A1、TNSF11 和 SPP1 转录本。这种减少呈非线性 U 形。我们的体外数据表明，咖啡因对正常人成骨细胞中某些钙三醇诱导的 VDR 调节基因的表达具有双相作用。
