地塞米松对离体培养肌管内长寿命蛋白降解的影响及其机制探讨  

Effects of dexamethasone on degradation of long-lived protein in cultured myotubes and its mechanism

作　　者：柴家科[1] 申传安[1] 姚咏明[1] 盛志勇[1] 

机构地区：[1]解放军第304医院全军烧伤研究所临床部,北京100037

出　　处：《感染．炎症．修复》2002年第4期209-211,共3页Infection Inflammation Repair

基　　金：国家自然科学基金项目(39970716);军队医药卫生"十五"重点课题(012095)

摘　　要：目的:研究地塞米松对体外培养的骨骼肌肌管内长寿命蛋白降解的影响及其可能的作用机制。方法:无菌分离 Wistar 大鼠(2d 龄)下肢肌肉,组织块培养法增殖、传代纯化成肌细胞,融合形成肌管。L-[3,5-~3H]-酪氨酸标记肌管蛋白后,随机分成两组,A 组:分别应用不含地塞米松(对照组)和含有地塞米松10nmol/L(A1组)、100nmol/L(A2组)、1000nmol/L(A3组)的培养液培养肌管,12h、24h、36h 和48h 后使用液体闪铄计数仪测定培养液和细胞内 L-[3,5-~3H]-酪氨酸的含量,计算肌管长寿命蛋白的降解率。B 组:分别应用含蛋白酶体抑制剂 MG132(50μmol/L,B1组)或含有 MG132(50μmol/L)和地塞米松100nmol/L(B2组)的培养液培养肌管24h,相同方法测定肌管长寿命蛋白降解率。结果:A1组、A2组和 A3组长寿命蛋白降解率均较对照组显著增加,差异有显著性(P<0.01)。A2组和 A3组长寿命蛋白降解率均较 A1组增加显著,差异有显著性(P<0.01)。A2组和 A3组间相比长寿命蛋白降解率差异无显著性(P>0.05)。B1组长寿命蛋白降解率较...Objective:To study the effects of dexamethasone on degradation of long-lived protein in myotubes and its potential mechanism.Methods;After isolating skeletal muscles from rat's lower limb under aseptic conditions, the myoblasts were proliferated through tissue-block culture.After passaged and purified,the myoblasts were fused into myotubes.The protein in myotubes was radiolabelled with L-[3,5-~3 H]tyrosine,and then the myotubes were divided into two groups.Group A was divided into three subgroups and control group;the myotubes were cultured in DMEM containing 10% FBS and 2mmol/L tyrosine with dexamethasone 0 nmol/L (control group), 10nmol/L(group A1),100nmol/L(group A2),1000nmol/L(group A3)respectively,and 12h,24h,36h,48h lat- er,the amounts of L-[3,5-~3 H]-tyrosine in culture medium and cells were determined and the degradation rates of long-lived protein were calculated.Group B was again divided into two subgroups.The myotubes were cultured in DMEM containing 10% FBS and 2mmol/L tyrosine with 50μmol/mL proteasome inhibitor MG132 as group B1, and 50μmol/mL MG132 and 100nmol/L dexamethasone as group B2.24h later,long-lived proteolytic rates were calculated by the same way as group A.Results;The long-lived proteolytic rate in group A1,group A2 and group A3 were increased significantly compared with that in control group (P<0.01),and that in group A2 and A3 were raised markedly compared with that in group A1 (P<0.01).There was no statistically significant difference between group A2 and group A3 (P>0.05).Long-lived proteolytic rate in group B1 was significantly lower than that in control group (P<0.01).The degradation rate of long-lived protein in group B2 was markedly lower than that in group A2 (P<0.01).Conclusion;The results suggest that the ubiquitin-proteasome system might be one of the important pathways for degradating long-lived protein in cultured myotubes.Dexamethasone could enhance the degradation of long-lived protein in cultured mytubes by activating ubiquitin proteasome pathway with dose-de- pendent

关 键 词：蛋白降解 肌管 骨骼肌 地塞米松 MG132 

分 类 号：R96[医药卫生—药理学]