晚期糖基化终末产物可通过调节V-ATPase a3与ClC-7影响破骨细胞的泌酸功能

Advanced glycation end products modulate osteoclastic acidification by inhibiting the expression of V-ATPase a3 and ClC-7

背景:晚期糖基化终末产物对破骨细胞骨吸收功能的影响存在争议,作者的前期研究表明晚期糖基化终末产物作用于破骨细胞前体可显著抑制骨吸收功能,但关于其对破骨细胞泌酸功能的影响尚不明晰。目的:探究晚期糖基化终末产物对破骨细胞泌酸功能的影响及其机制。方法:以15μg/L的RANKL对破骨细胞前体RAW 264.7进行定向诱导(正常组),实验组中另加入50-400 mg/L不等的晚期糖基化终末产物及对照用牛血清白蛋白(100 mg/L)。通过骨吸收实验验证晚期糖基化终末产物对骨吸收的抑制效应,并以吖啶橙染色观察晚期糖基化终末产物对破骨细胞泌酸功能的影响;进一步检测质子泵V-ATPase a3及氯离子通道ClC-7的表达情况,分析晚期糖基化终末产物影响破骨细胞泌酸的相关机制。结果与结论:(1)晚期糖基化终末产物组的骨吸收面积较正常组显著减少(P<0.05);(2)吖啶橙染色显示晚期糖基化终末产物组的红色荧光(620 nm)强度较正常组显著减少(P<0.05),抑制程度随着刺激浓度的增高而加重;(3)免疫细胞化学染色、蛋白质免疫印迹及PCR发现,晚期糖基化终末产物组的V-ATPase a3及ClC-7表达量均较正常组显著下降(P<0.05);(4)综上结果表明,晚期糖基化终末产物作用于破骨细胞前体可显著抑制破骨细胞的泌酸功能,其机制可能与晚期糖基化终末产物抑制了质子泵V-ATPase a3及氯离子通道ClC-7的表达相关。

BACKGROUND：The effect of advanced glycation end products （AGEs） on bone resorption is controversial. Our previous study has shown that bone resorption is significantly inhibited when AGEs present with pre-osteoclast cells RAW 264.7, while the effect of AGEs on osteoclastic acidification remains unknown. OBJECTIVE：To investigate the effect of AGEs on osteoclastic acidification and the underlying mechanism. METHODS：RAW 264.7 cells were induced by RANKL （15μg/L;normal group） to generate osteoclasts, and AGEs （50-400 mg/L;experimental group） or bovine serum albumin （100 mg/L;control group） were added at the beginning of the induction. The effect of AGEs on bone resorption was evaIuated by anaIyzing the area of bone resorption on the Osteo Assay Surface plates, and the effect of AGEs on osteoclastic acidification was evaluated by acridine orange staining. Furthermore, the expression levels of V-ATPase a3 and CIC-7 were detected to investigate the underlying mechanism. RESULTS AND CONCLUSION：The bone resorption area in the AGEs group was significantly decreased compared with the normal group （P〈0.05）. Acridine orange staining reveaIed that the red fluorescence （620 nm） intensity in the AGEs group was significantly decreased compared with the normal group （P〈0.05）, and this inhibitory effect became obvious with the increase of AGEs concentration. Immunocytochemistry, western blot assay and PCR findings showed that the expression levels of V-ATPase a3 and CIC-7 in the AGEs group were decreased significantly compared with the normal group （P〈0.05）. To conclude, AGEs exert inhibitory effect on osteoclastic acidification, probably by inhibiting the expression of V-ATPase a3 and CIC-7.