Streptozotocin-induced diabetes increases disulfide bond formation on cardiac ryanodine receptor (RyR2)
Streptozotocin-induced diabetes increases disulfide bond formation on cardiac ryanodine receptor (RyR2)
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DOI：
10.1124/jpet.102.046201
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发表时间：
2003-06-01
影响因子：
3.5
通讯作者：
Dincer, UD
中科院分区：
文献类型：
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作者：
Bidasee, KR;Nallani, K;Dincer, UD
在先前的研究中，我们发现，在链脲佐菌素诱导的糖尿病(6D)6周后，大鼠心脏中2型兰尼定受体钙释放通道(RyR2)的表达没有明显变化。然而，这种蛋白与[H-3]ryanodine结合的能力受到了损害。因此，活性的丧失是由于糖尿病导致RyR2上翻译后修饰的增加。在本研究中，研究了糖尿病对一种修饰的影响，即反应性巯基氧化状态的变化。6D的RyR2蛋白结合的[H-3]ryanodine比对照(6C)的RyR2少42.3+/-7.6。在糖尿病4周后开始2周的胰岛素治疗，结合的丢失最小(6C的77.8+/-5.5%)。用2 mM二硫苏糖醇体外处理RyR2，可使[H-3]ryanodine结合量增加60.8+/-5.3%。二硫苏糖醇使RyR2的[H-3]ryanodine结合量增加16.8+/-4.3%。试剂焦酚与6C RyR2上不同类别的自由巯基相互作用，产生两种主要作用。当浓度小于或等于10um时，它使RyR2失活(减少[H-3]ryanodine结合)，而当浓度较高时，它激活RyR2(增加[H-3]ryanodine结合)。该试剂不能从6d起激活RyR2。虽然胰岛素处理的动物的RyR2被低浓度的焦酚灭活，但在较高浓度时只有部分激活。这些数据表明，糖尿病引起的RyR2功能障碍可能部分是由于相邻的巯基之间形成二硫键所致，这些变化可被胰岛素治疗减弱。
In a previous study, we showed that after 6 weeks of streptozotocin-induced diabetes (6D), expression of type 2 ryanodine receptor calcium-release channels (RyR2) did not change significantly in rat hearts. However, the ability of this protein to bind [H-3]ryanodine was compromised. Loss in activity therefore resulted from diabetes-induced increases in post-translational modifications on RyR2. In the present study, the effects of diabetes on one type of modification, namely, changes in oxidative state of reactive sulfhydryls was investigated. RyR2 protein from 6D bound 42.3 +/- 7.6 less [H-3] ryanodine than RyR2 from controls (6C). The loss in binding was minimized with 2 weeks of insulin treatment initiated after 4 weeks of diabetes (77.8 +/- 5.5% of 6C). Pretreating RyR2 from 6D with 2 mM dithiothreitol in vitro increases [H-3] ryanodine binding by 60.8 +/- 5.3%. Dithiothreitol pretreatment of RyR2 from 6C increased [H-3] ryanodine binding by 16.8 +/- 4.3%. The reagent pyrocoll interacts with distinct classes of free sulfhydryl groups on 6C RyR2 to induce two major effects. At concentrations less than or equal to10 muM, it deactivates RyR2 (decreases [H-3] ryanodine binding), whereas at higher concentrations it activates them (increases [H-3] ryanodine binding). This reagent was unable to activate RyR2 from 6D. Although RyR2 from insulin-treated animals was deactivated by low concentrations of pyrocoll, it was only partially activated at higher concentrations. These data suggest that the dysfunction of RyR2 induced by diabetes may be due in part to formation of disulfide bonds between adjacent sulfhydryl groups and that these changes were attenuated with insulin treatment.