Mechanical ventilation induces alterations of the ubiquitin-proteasome pathway in the diaphragm
Mechanical ventilation induces alterations of the ubiquitin-proteasome pathway in the diaphragm
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DOI：
10.1152/japplphysiol.00993.2004
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发表时间：
2005-04-01
影响因子：
3.3
通讯作者：
Powers, SK
中科院分区：
文献类型：
--
作者：
DeRuisseau, KC;Kavazis, AN;Powers, SK
长时间机械通气(MV)会导致横隔膜萎缩，部分原因是蛋白分解增加。这些实验验证了MV诱导的横隔膜蛋白分解伴随着泛素蛋白酶体途径(UPP)关键成分表达增加的假说。为了验证这一假设，我们研究了延长MV对UPP组分的影响，并测定了20S蛋白酶体的胰酶样肽和氨基谷氨酸肽水解性。成年SD大鼠分为对照组和12h机械通气组(n=7/组)。MV动物麻醉、气管切开、室内空气呼吸12h，对照组急性麻醉，但不暴露于MV。与对照组相比，MV动物的两种泛素连接酶、肌肉萎缩F-box(+8.3倍)和肌环指1(+19.0倍)的横隔膜mRNA水平升高。但MV对14-kDa泛素结合酶、多聚泛素、蛋白酶体激活复合体PA28和20Sα亚基7的表达水平无明显影响。14-kDa泛素结合酶和蛋白酶体激活复合体PA28的蛋白表达水平无明显变化，但20Sα亚基7的蛋白表达水平下降(-17.7%)。MV可增加隔膜胰酶样活性(+31%)，但不改变肽基谷氨酰胺水解酶活性。最后，与对照组相比，MV增加了隔膜肌原纤维(+24.9%)和胞浆(+54.7%)部分的泛素-蛋白质结合物。这些结果与以下假设相一致，即延长MV会增加UPP内关键成分的横隔膜水平，20S蛋白酶体活性的增加有助于MV诱导的横隔膜蛋白分解和萎缩。
Prolonged mechanical ventilation (MV) results in diaphragmatic atrophy due, in part, to an increase in proteolysis. These experiments tested the hypothesis that MV-induced diaphragmatic proteolysis is accompanied by increased expression of key components of the ubiquitinproteasome pathway (UPP). To test this postulate, we investigated the effect of prolonged MV on UPP components and determined the trypsin-like and peptidylglutamyl peptide hydrolyzing activities of the 20S proteasome. Adult Sprague- Dawley rats were assigned to either control or 12-h MV groups ( n = 7/group). MV animals were anesthetized, tracheostomized, and ventilated with room air for 12 h. Animals in the control group were acutely anesthetized but not exposed to MV. Compared with controls, MV animals demonstrated increased diaphragmatic mRNA levels of two ubiquitin ligases, muscle atrophy F-box ( + 8.3-fold) and muscle ring finger 1 ( + 19.0-fold). However, MV did not alter mRNA levels of 14-kDa ubiquitin-conjugating enzyme, polyubiquitin, proteasome-activating complex PA28, or 20S alpha-subunit 7. Protein levels of 14-kDa ubiquitin- conjugating enzyme and proteasome-activating complex PA28 were not altered following MV, but 20S alpha-subunit 7 levels declined ( - 17.7%). MV increased diaphragmatic trypsin-like activity ( + 31%) but did not alter peptidylglutamyl peptide hydrolyzing activity. Finally, compared with controls, MV increased ubiquitin- protein conjugates in both the myofibrillar ( + 24.9%) and cytosolic ( + 54.7%) fractions of the diaphragm. These results are consistent with the hypothesis that prolonged MV increases diaphragmatic levels of key components within the UPP and that increases in 20S proteasome activity contribute to MV-induced diaphragmatic proteolysis and atrophy.