Identification of genes induced by mechanical stress in osteocytes

机械应力是预防骨质疏松的重要因素之一，被认为是控制骨吸收和骨形成的重要因素。骨细胞是骨组织中数量最多的细胞，对机械应力的反应比成骨细胞和破骨细胞更敏感。我们研究了与机械应力相关的基因，以揭示机械应力在骨细胞中的作用。我们在MLO-Y 4-A2细胞中鉴定了机械应力刺激下环氧合酶-2基因5'侧翼区的顺式作用元件和反式作用因子。NF-IL 6、CREB、API是与环氧合酶-2基因5'侧翼区的顺式作用元件结合并诱导环氧合酶-2 mRNA表达的反式作用因子。这些因子可作为探索细胞质膜机械应力传感器的标志物。（准备出版）2。我们研究了流体剪切力对MLO-Y 4-A2骨细胞样细胞中甲状旁腺激素（PTH）受体的诱导作用。RT-PCR分析表明，MLO-Y 4-A2细胞在流体切应力作用下，PTH受体mRNA表达在7 h时增加了约6.2倍。用启动子/增强子结构域的Lusiferase测定考虑了应激负荷对PTH受体的转录调节。启动子/增强子结构域的缺失分析表明，含有P1区的结构域与PTH受体的诱导相关。流体剪切力可使考克斯-2诱导的上游信号ERK-1磷酸化。ERK激酶抑制剂U-0126对PTH受体的诱导无明显抑制作用。这些结果表明，流体剪切应力是通过与ERK/考克斯-2/PGE 2不同的信号通路在转录调控下由PTH受体诱导的。（准备出版）3。我们还鉴定了其他受机械应力诱导的基因，如雌激素受体α、CD 44抗原、ODF。我们还在MLO-Y 4-A2骨细胞样细胞中鉴定了一些未鉴定的基因。我们继续分析这些基因

The mechanical stress is one of important factor to prevent osteoporosis and is considered to control bone resorption and formation. Osteocytes are most abundant cells in bone, and seem to more responsive to the mechanical stress than osteoblast or osteoclast. We investigated the genes relating to mechanical stress to reveal a role of mechanical stress in osteocytes.1. We identified cis-acting elements and trans-acting factors on 5' flanking regions of cyclooxygenase-2 gene stimulated by mechanical stress in MLO-Y4-A2 cells. NF-IL6, CREB, API were identified as trans-acting factors which bound to cis-acting elements of 5' flanking regions of cyclooxygenase-2 gene and induced cyclooxygenase-2 mRNA. These factors should be used as markers exploring machano-sensor of mechanical stress on plasma membrane of cells. (preparing for publication)2. We investigated the induction of parathyroid hormone (PTH) receptor by fluid shear stress in MLO-Y4-A2 osteocyte-like cells. When the fluid shear stress was exposed to MLO-Y4-A2 cells, PTH receptor mRNA was increased by about 6.2 times at 7 h analyzed by RT-PCR. Lusiferase assay with the promoter/enhancer domain considered the transcriptional regulation of PTH receptor by stress loading. The deletion analysis of promoter/enhancer domain revealed that the domain containing P1 region was correlated to the induction of PTH receptor. The fluid shear stress phosphorylated ERK-1 which was an up-stream signaling of COX-2 induction. However, PTH receptor induction was not inhibited by U-0126, ERK kinase inhibitor. These results suggested that the fluid shear stress was induced PTH receptor under transcriptional controls through a different signaling pathway from ERK/COX-2/PGE2. (preparing for publication)3. We identified other genes induced by mechanical stress, such as estrogen receptor α, CD44 antigen, ODF. We also identified some unidentified genes in MLO-Y4-A2 osteocyte-like cells. We have continued to analyzed these genes