【摘要】 目的：探讨脂肪质量和肥胖相关基因（fat mass and obesity-associated gene,Fto）对糖尿病（diabetes mellitus,DM）小鼠主动脉平滑肌收缩功能异常的影响及其钙调控的作用机制。方法：利用Cre-lox P重组技术制备平滑肌特异性Fto基因敲除(smooth muscle-specific Fto gene knockout,Fto^SMKO)小鼠。实验分3组：野生型（wild-type,WT）组、DM模型组和Fto^SMKO-DM组，每组各15只。Fto^SMKO-DM组和DM组小鼠通过腹腔注射链脲佐菌素制备1型DM模型；WT组小鼠注射等体积柠檬酸-柠檬酸钠缓冲液。应用离体血管环张力测定技术，观察不同药物对3组小鼠主动脉平滑肌收缩反应的影响；采用Western blot技术检测小鼠主动脉组织FTO蛋白的表达水平。结果：（1）DM小鼠主动脉FTO蛋白的表达显著升高（P<0.01）。（2）平滑肌特异性敲除Fto后，FTO蛋白基本不表达（P<0.01）;DM组与WT组相比，空腹血糖水平显著升高（P<0.01），体重显著下降（P<0.05）;Fto^SMKO-DM组与DM组相比，小鼠的体重和空腹血糖水平无显著差异（P>0.05）。（3）DM组与WT组相比，苯肾上腺素诱导的主动脉平滑肌收缩反应性增强；其中，非L型钙通道和钙库操纵性钙通道（store-operated calcium channels,SOCC）介导的血管平滑肌收缩反应增强；1,4,5-三磷酸肌醇受体（inositol 1,4,5-trisphosphate receptors,IP₃R）介导肌浆网钙释放引起的血管平滑肌收缩反应增强；咖啡因激活兰尼碱受体（ryanodine receptors,Ry R）介导肌浆网钙释放诱导的血管平滑肌收缩反应减弱（P<0.05）。（4）Fto^SMKO-DM组与DM组相比，苯肾上腺素诱导的主动脉平滑肌收缩反应性显著降低；其中，非L型钙通道和SOCC介导钙内流诱导的血管平滑肌收缩反应显著降低（P<0.05）；咖啡因激活Ry R介导肌浆网钙释放诱导的血管平滑肌收缩反应显著上升（P<0.05），而IP₃R介导肌浆网钙释放诱导的血管平滑肌收缩反应不受影响（P>0.05）。结论：特异性敲除平滑肌Fto基因可降低DM小鼠主动脉平滑肌收缩高反应性，可能与FTO蛋白参与血管平滑肌的钙调控有关。更多还原

【Abstract】 AIM:To investigate the influence of fat mass and obesity-associated （Fto） gene on the aberrant contraction of aortic smooth muscle in diabetes mellitus （DM） mice,and to explore the mechanism of Fto gene underlying the calcium regulation.METHODS:Smooth muscle-specific Fto gene knockout (Fto^SMKO) mice were generated using Crelox P technology.The experiment involved 3 groups of mice:wild-type （WT） group,DM model group and Fto^SMKO-DM group,with 15 mice in each group.In DM group and Fto^SMKO-DM group,type 1 DM was induced by intraperitoneal injec‐tion of streptozotocin.The mice in WT group were injected with equal volume of citric acid-sodium citrate buffer solution.The influences of different drugs on the contraction responses of aortic smooth muscle in mice were analyzed using a multimyograph system.The expression level of FTO protein in the aortic tissues was detected by Western blot.RESULTS:（1） Compared with WT mice,the expression levels of FTO protein in the aortic tissues of DM mice were significantly in‐creased （P<0.01）.（2） The expression level of FTO protein in smooth muscle was significantly decreased after knockout of Fto gene （P<0.01）.Compared with WT group,the mice in DM group exhibited a significant decrease in body weight and a marked increase in fasting blood glucose level （P<0.05）.There were no noticeable differences in body weight or fasting blood glucose level between Fto^SMKO-DM group and DM group （P>0.05）.（3） The contraction responses of aortic smooth muscle in DM group were substantially increased by phenylephrine compared with WT group.Specifically,vaso‐constriction responses mediated by non-L-type calcium channels and store-operated calcium channels （SOCC） were signifi‐cantly enhanced in DM group.In addition,the responses mediated by inositol 1,4,5-trisphosphate receptors （IP₃R）,which facilitate calcium release from the sarcoplasmic reticulum,were significantly enhanced.However,the responses mediated by caffeine-activated ryanodine receptors （Ry R）,which also facilitate calcium release from the sarcoplasmic re‐ticulum,were significantly inhibited （P<0.05）.（4） Compared with DM group,the phenylephrine-induced contraction re‐sponses of aortic smooth muscle in Fto^SMKO-DM group were greatly weakened （P<0.05）.In particular,the vasoconstriction responses mediated by non-L-type calcium channels and SOCC in Fto^SMKO-DM group were greatly suppressed （P<0.05）,while those mediated by caffeine-activated Ry R were dramatically boosted （P<0.05）.However,IP₃R-mediated responses were not affected （P>0.05）.CONCLUSION:Smooth muscle-specific Fto gene knockout suppresses contractile hyperre‐sponsiveness in the aortic smooth muscle of DM mice,which may be attributed to involvement of FTO protein in calcium regulation in the vascular smooth muscle.更多还原