替米沙坦在细胞周期依赖性蛋白激酶5介导的过氧化物酶体增殖物激活受体γ磷酸化调节脂联素表达中的作用

Effect of telmisartan on cyclin-dependent kinase 5-mediated peroxisome proliferator-activated receptors γ phosphorylation regulates adiponectin expression

目的研究替米沙坦在细胞周期依赖性蛋白激酶（CDK）5介导的过氧化物酶体增殖物激活受体（PPAR）γ磷酸化水平上升、调节3T3-L1脂肪细胞脂联素表达的机制。方法诱导至转化率达到80%的3T3-L1脂肪细胞以不同浓度肿瘤坏死因子（TNF）-α（10、50、100 ng/ml，分别为T10、T50、T100组）刺激1h，T100组以替米沙坦不同剂量（0.1、5、10 μmol/L，分别为Tel0.1、Tel5、Tel10组）干预24 h后利用Western blotting法检测CDK5、p35蛋白表达水平和PPARγ磷酸化水平；实时荧光定量聚合酶链反应检测CDK5、p35、PPARγ mRNA表达变化；酶联免疫吸附试验法（ELISA）检测培养基上清脂联素释放变化。构建并包装携带p35基因的逆转录病毒感染3T3-L1细胞，以空载体病毒为对照，同时设置CDK5抑制剂组，检测CDK5、p35/p25、磷酸化PPARγ（pPPARγ）及脂联素表达。实验数据以±s表示，多组间比较采用单因素方差分析。结果与未处理组相比，T10、T50、T100组CDK5 mRNA及蛋白相对表达量差异无统计学意义（均P〉0.05）；T50、T100组p35 mRNA（2.11±0.66、2.71±0.59比1.22±0.35；q=3.77、4.91）及蛋白（0.32±0.02、0.45±0.04比0.09±0.01；q=2.19、4.55）相对表达量显著上升（均P〈0.05）；各组PPARγ mRNA及蛋白相对表达量差异均无统计学意义（均P〉0.05），T50、T100组pPPARγ/PPARγ显著上升（0.21±0.03、0.47±0.04比0.11±0.02；q=3.89、6.91），脂联素释放显著下降（1.56±0.34、1.07±0.12比2.36±0.55；q=6.32、6.99，均P〈0.05）；替米沙坦干预后，与T100组相比，各组CDK5、p35 mRNA及蛋白相对表达量差异均无统计学意义（均P〉0.05）；Tel5、Tel10组pPPARγ/PPARγ显著降低（0.11±0.03、0.05±0.01比0.38±0.02；q=4.91、5.22），脂联素释放显著上升（1.71±0.26、1.92±0.17比1.11±0.05；q=5.77、6.43，均P〈0.05）；过表达p35可检出p25表达，同时显著上调pPPARγ/PPARγ（0.87±0.12比0.07±0.02，q=9.13）并下调脂联素释放（1.39±0.12比2.21±0.33，q=5.67），抑制剂组pPPARγ/PPARγ下降（0.15±0.01比0.87±0.12，q=3.14），脂联素释放上升（1.95±0.24比1.39±0.12，q=4.99），差异均具有统计学意义（均P〈0.05）。结论替米沙坦能够抑制CDK5过度激活导致的PPARγ磷酸化，调节3T3-L1脂肪细胞脂联素表达。

Objective To study the mechanism of telmisartan on peroxisome proliferator-activated receptors （PPAR） γ phosphorylation mediated by cyclin-dependent kinase （CDK） 5 and regulation of adiponectin expression in 3T3-L1 adipocytes.Methods 3T3-L1 with differentiation rate above 80% adipocytes were stimulated with different concentrations of tumor necrosis factor （TNF）-α （10, 50, 100 ng/ml for T10, T50, and T100 groups respectively） for 1 h. Different doses of telmisartan （0.1, 5, 10 μmol/L） treated T100 group for 24 h. The expression of CDK5 and p35 protein and the PPARγ phosphorylation levels were detected with Western blotting; Quantitative real-time polymerase chain reaction （qPCR） assessed CDK5, p35, PPARγ gene expression changes. Enzyme-linked immunosorbent assay （ELISA） was used to measure adiponectin concentration. 3T3-L1 cells were constructed and packaged with retroviruses carrying the p35 gene. The empty vector virus was used as a control and a CDK5 inhibitor group was set up to detect the CDK5, p35/p25, phosphorylation levels of PPARγ and the adiponectin level. Data were expressed in ±s, data among multiple groups were compared using One-Way ANOVA.Results Compared with untreated group, the relative expression levels of CDK5 mRNA and protein in the T10, T50, and T100 groups were not statistically different （all P〉0.05）. The relative expression of p35 mRNA （2.11±0.66, 2.71±0.59 vs 1.22±0.35, q=3.77, 4.91） and protein （0.32±0.02, 0.45±0.04 vs 0.09±0.01, q=2.19, 4.55） in the T50 and T100 groups were up-regulated, the differences were statistically significant （all P〈0.05）. There was no significant difference in the relative expression of PPARγ mRNA and protein among each group （all P〉0.05）. pPPARγ/PPARγ was increased in the T50 and T100 groups （0.21±0.03, 0.47±0.04 vs 0.11±0.02, q=3.89, 6.91） while adiponectin concentration was decreased （1.56±0.34, 1.07±0.12 vs 2.36±0.55, q=6.32, 6.99, all P〉0.05）. After telmisartan intervention there was no significant difference in the relative mRNA and protein expression levels of CDK5 and p35 compared with the T100 group （all P〉0.05）. Tel5 and Tel10 groups had significant decreases in pPPARγ/PPARγ （0.11±0.03, 0.05±0.01 vs 0.38±0.02, q=4.91, 5.22） and increase in adiponectin release （1.71±0.06, 1.92±0.27 vs 1.11±0.05, q=5.77, 6.43） （all P〈0.05）. Over-expression of p35 led to p25 expression, elevation of pPPARγ/PPARγ （0.87±0.12 vs 0.07±0.02, q=9.13） and down-regulation of adiponectin （1.39±0.12 vs 2.21±0.33, q=5.67）. In the inhibitor group, pPPARγ/PPARγ significantly decreased （0.15±0.01 vs 0.87±0.12, q=3.14） and adiponectin increased （1.95±0.24 vs 1.39±0.12, q=4.99） （all P〈0.05）.Conclusion Telmisartan regulates 3T3-L1 adipocyte adiponectin expression by inhibiting PPARγ phosphorylation induced by CDK5 overactivation.