EVIDENCE FOR A DEFECTIVE THIOL PROTEASE INHIBITOR IN SKELETAL-MUSCLE OF MICE WITH HEREDITARY MUSCULAR-DYSTROPHY
EVIDENCE FOR A DEFECTIVE THIOL PROTEASE INHIBITOR IN SKELETAL-MUSCLE OF MICE WITH HEREDITARY MUSCULAR-DYSTROPHY
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DOI：
10.1139/o86-134
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发表时间：
1986-10-01
影响因子：
2.9
通讯作者：
WARNER, AH
中科院分区：
文献类型：
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作者：
GOPALAN, P;DUFRESNE, MJ;WARNER, AH
从营养不良60日龄雄性小鼠（品系129/ReJ-dy）后肢骨骼肌中分离纯化巯基蛋白酶抑制剂（TPI-d），并与正常60日龄雄性鼠仔后肢骨骼肌中提取的巯基蛋白酶抑制剂（TPI-n）进行了比较。虽然TPI-d和TPI-n在十二烷基硫酸钠-聚丙烯酰胺凝胶（相对质量为14,800）、分析等电聚焦凝胶（pI 4.5）和高效液相色谱柱上表现出相同的性能，但经等电聚焦纯化后，TPI-d不能抑制木瓜蛋白酶和组织蛋白酶B。然而，在纯化的TPI-d制剂中，等电点为4.9的成分最初掩盖了TPI-d的功能状态，当用木瓜蛋白酶和组织蛋白酶H和l进行检测时，这种抑制成分在TPI-n制剂中不存在。纯TPI-d也不能抑制组织蛋白酶B对肌球蛋白的体外水解，而TPI-n完全阻断组织蛋白酶B催化的肌球蛋白水解。考虑到巯基蛋白酶（尤其是组织蛋白酶B）在细胞内蛋白质代谢中的核心作用，以及肌肉中不受控制的巯基蛋白酶活性可能导致肌肉蛋白质分解和营养不良，我们的数据表明，一种修饰的（缺陷的）巯基蛋白酶抑制剂（TPI-d）可能是患有遗传性疾病的小鼠营养不良基因的最终产物之一。
The thiol protease inhibitor (TPI-d) from hind-limb skeletal muscle of dystrophic 60-day-old male mice (strain 129/ReJ-dy) has been purified to apparent homogeneity and compared with the thiol protease inhibitor (TPI-n) from hind-limb skeletal muscle of normal 60-day-old male littermates. While both TPI-d and TPI-n displayed identical properties on sodium dodecyl sulfate-polyacrylamide gels (14,800 relative mass), analytical isoelectric focusing gels (pI 4.5), and high performance liquid chromatography columns, TPI-d was unable to inhibit papain and cathepsin B after purification by isoelectric focusing. However, a component in the purified TPI-d preparation with an isoelectric point of 4.9 initially masked the functional state of TPI-d, using papain when assayed with the test proteases papain and cathepsin H and L. This inhibitory component was absent from TPI-n preparations. Pure TPI-d was also unable to inhibit in vitro myosin hydrolysis by cathepsin B, whereas TPI-n completely blocked cathepsin B catalyzed myosin hydrolysis. Given the central role of the thiol proteases, especially cathepsin B, in intracellular protein metabolism and the possibility that uncontrolled thiol protease activity in muscle leads to muscle protein breakdown and dystrophy, our data suggest that a modified (defective) thiol protease inhibitor (TPI-d) may be (one of) the end product(s) of the dystrophy gene in mice with the hereditary form of the disease.