Effect of Fluid Shear Stress on the expression of bone markers in MLO-Y4 Osteocyte-Like Cells

Abstract

的通過研究MLO-Y4骨細胞受流體剪切力作用前后骨性標志物在mRNA水平的表達變化,探討機械力影響骨組織代謝中骨細胞的作用。方法以小鼠成骨細胞(MOB)為參照,逆轉錄聚合酶鏈式反應(RT-PCR)檢測MLO-Y4細胞在體外培養條件下,以及受流體剪切力作用0.5 h,1 h,2 h,4 h,6 h,12 h,24 h后骨性標志物在mRNA水平的表達特征和變化。結果以MOB為參照,在mRNA水平,體外培養條件下MLO-Y4細胞骨鈣素(OCN)、堿性磷酸酶(ALP)和骨橋蛋白(OPN)高表達;破骨細胞分化因子(RANKL)、骨保護因子(OPG)低表達,但RANKL/OPG比值明顯高于MOB。受流體剪切力作用后,MLO-Y4細胞ALP、OCN表達降低;RANKL和OPN表達增加;OPG隨加力時間也有一定變化。結論 MLO-Y4細胞具有分化終末骨細胞的特點;流體剪切力作用后,RANKL/OPG比值以及ALP、OCN和OPN等骨性標志物的表達發生變化,為其參與機械力信號到生物信號的傳導過程提供了間接證據。 Objective Objective To study the expression of several bone markers in osteocytes (MLO-Y4) and osteoblast (MOB) also the effect from fluid shear stress in osteocytes. Methods Reverse transcription-polymerase chain reaction analysis indicate the expression differences between MLO-Y4 cells and MOB cells also before and after fluid shear stress in MLO-Y4 cells. Results MLO-Y4 cells appear to express relatively greater amounts of mRNA for osteocalsin (OCN), osteopontin (OPN) and alkaline phosphatase (ALP) but less amounts for osteoprotegerin (OPG) than MOB cells. Although the receptor activator of nuclear factor kappa B ligand (RANKL) mRNA expression is more in MOB, the ratio of RANKL to OPG mRNA is greater in the MLO-Y4 cells. Fluid shear stress up regulates the expression of RANKL and OPN mRNA but down regulates ALP and OCN mRNA expression significantly in MLO-Y4 cells and also make some changes in OPG. Conclusions The properties of MLO-Y4 cell’s are more like osteocytes than osteobiast. The expression of ALP,OCN,OPN and the ratio of RANKL/OPG in MLO-Y4 ceils changed when exposed to fluid shear stress, which suggest osteocytes play a very important role in bone remodlling.