中文摘要：

目的观察氧化低密度脂蛋白（oxidized LDL，Ox-LDL）刺激对体外培养的小鼠肾小球足细胞清道夫受体A（scavenger receptor A，SR—A）表达的影响，并初步探讨其可能的分子机制。方法体外培养小鼠条件永生性足细胞，以不同浓度Ox-LDL刺激足细胞24h及以20mg／LOx-LDL干预不同时间，酶法检测细胞内胆固醇含量，采用实时荧光定量PCR、Western印迹法检测正常对照组、Ox-LDL刺激组SR-A、nephrin、PTEN的mRNA和蛋白表达水平；DiI标记的氧化低密度脂蛋白（DiI-Ox-LDL）与足细胞共孵育，免疫荧光观察足细胞对脂质的摄取情况。进一步采用PTEN抑制剂bpv（hOpic）[dipotassium bisperoxo（5-hydroxypyridine-2-carboxyl）oxovanadate（V）]、PTEN siRNA以及PTEN腺病毒（adPTEN）双向调控PTEN的表达，观察SR—A、nephrin的表达、足细胞对脂质的摄取情况及细胞内胆固醇含量的变化。结果小鼠足细胞表达SR-A受体并介导脂质摄取；与对照组相比，Ox-LDL刺激上调足细胞SR—A表达的同时伴有PTEN、nephrin表达下降（均P〈0．05），且与Ox—LDL的浓度及作用时间相关；增加IWEN表达能抑制Ox—LDL诱导的SR—A表达水平上调和脂质摄取（均P〈0．05），降低细胞内胆固醇含量（P〈0．05），上调裂孔隔膜蛋白nephrin的表达（均P〈0．05）；与之相反，抑制PTEN表达能进一步上调Ox—LDL诱导的SR—A表达，促进脂质摄取，增加细胞内胆固醇含量（均P〈0．05），并进一步降低nephrin的表达（均P〈0．05）。结论Ox—LDL可能通过PTEN调控SR—A表达进而调控脂质摄取，导致足细胞损伤。

英文摘要：

Objective To evaluate the effect of oxidized LDL （Ox-LDL） on scavenger receptor A （SR-A） expression in mouse podocytes and to explore the possible mechanism. Methods The conditionally immortalized mouse podoeyte cell line was cultured in vitro and exposed to Ox-LDL of different concentrations for 24 h, or 20 mg/L Ox-LDL for different hours. Cell cholesterol accumulation was examined. Real-time quantity PCR and Western blotting were used to analyze the expression level of PTEN, SR- A and nephrin. Podocytes were incubated with DiI labeled Ox- LDL for 4 h and immunofluorescence was used to analyze lipid uptaking. To further confirm the relationship between PTEN and SR- A, PTEN inhibitor bpv （hOpic） [dipotassium bisperoxo （5- hydroxypyridine- 2-carboxyl） oxovanadate （V） ], PTEN siRNA and PTEN adenovirus （adPTEN） were used to dual-directional regulate PTEN expression, so as to observe the change of SR- A, nephrin, cell cholesterol accumulation and lipid uptake. Results SR-A was expressed on mouse podocyte and mediated podocyte lipid uptake. Compared with control group, Ox-LDL increased cell cholesterol accumulation, and up-regulated SR-A expression along with inhibited expression of PTEN and nephrin （P 〈 0.05）, which were correlate with dose and exposure time of Ox-LDL. Expression of PTEN significantly inhibits the expression level of SR -A and lipid uptake induced by Ox-LDL （P 〈 0.05）, thereby decreasing cell cholesterol accumulation, but up- regulating nephrin level （P 〈 0.05）. However, down- regulation of PTEN could cause opposite effect. Conclusion Ox-LDL up-regulates SR-A through decreasing the expression of PTEN, and contributes to podocyte injury.