Energy-ubiquitin-dependent muscle proteolysis during sepsis in rats is regulated by glucocorticoids
Energy-ubiquitin-dependent muscle proteolysis during sepsis in rats is regulated by glucocorticoids
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DOI：
10.1172/jci118421
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发表时间：
1996-01-15
影响因子：
15.9
通讯作者：
Hasselgren, PO
中科院分区：
文献类型：
--
作者：
Tiao, G;Fagan, J;Hasselgren, PO
最近的研究表明，脓毒症引起的肌肉蛋白分解增加主要反映了能量泛素依赖的蛋白质分解。我们验证了糖皮质激素在脓毒症时激活骨骼肌中能量泛素依赖的蛋白分解途径的假说。采用盲肠结扎和穿刺法建立大鼠脓毒症模型或假手术组，16h后测定肌肉蛋白分解率。用糖皮质激素受体拮抗剂RU 38486或Vehicle对脓毒症大鼠和假手术大鼠进行干预。在其他实验中，正常大鼠皮下注射地塞米松(2.5或10 mg/kg)。以酪氨酸和3-甲基组氨酸的释放为指标，测定孵育的指长伸肌的总蛋白和肌原纤维蛋白分解。在2-脱氧葡萄糖和2，4-二硝基苯酚耗尽能量的孵育肌肉中，确定了能量依赖的蛋白质分解。用Northern和Western印迹法分别检测肌肉泛素mRNA和游离泛素和结合泛素的水平。RU 38486抑制脓毒症引起的总蛋白和肌原纤维能量依赖性蛋白分解率的增加，并钝化泛素基因水平和游离泛素的增加。部分，但不是全部，脓毒症引起的泛素蛋白结合物的变化可被RU 38486抑制。正常大鼠注射地塞米松可增加能量依赖性蛋白分解和泛素mRNA水平。结果提示，糖皮质激素在脓毒症时调节骨骼肌中能量泛素依赖的蛋白分解途径。
Recent studies suggest that sepsis-induced increase in muscle proteolysis mainly reflects energy-ubiquitin-dependent protein breakdown. We tested the hypothesis that glucocorticoids activate the energy-ubiquitin-dependent proteolytic pathway in skeletal muscle during sepsis. Rats underwent induction of sepsis by cecal ligation and puncture or were sham-operated and muscle protein breakdown rates were measured 16 h later. The glucocorticoid receptor antagonist RU 38486 or vehicle was administered to groups of septic and sham-operated rats. In other experiments, dexamethasone (2.5 or 10 mg/kg) was injected subcutaneously in normal rats. Total and myofibrillar proteolysis was determined in incubated extensor digitorum longus muscles as release of tyrosine and 3-methylhistidine, respectively. Energy-dependent proteolysis was determined in incubated muscles depleted of energy with 2-deoxyglucose and 2,4-dinitrophenol. Levels of muscle ubiquitin mRNA and free and conjugated ubiquitin were determined by Northern and Western blot, respectively. RU 38486 inhibited the sepsis-induced increase in total and myofibrillar energy-dependent protein breakdown rates and blunted the increase in ubiquitin mRNA levels and free ubiquitin. Some, but not all, sepsis-induced changes in ubiquitin protein conjugates were inhibited by RU 38486. Injection of dexamethasone in normal rats increased energy-dependent proteolysis and ubiquitin mRNA levels. The results suggest that glucocorticoids regulate the energy-ubiquitin-dependent proteolytic pathway in skeletal muscle during sepsis.