Structures, Functions and Medical Meaning of Lysosomal Cysteine Protease Inhibitors

我们纯化了溶酶体半胱氨酸蛋白酶、组织蛋白B、组织蛋白H和L，测定了组织蛋白B和组织蛋白H的氨基酸序列和糖类结构，并对三种组织蛋白在各器官和外周血细胞中的分布和定位进行了研究。组织蛋白酶B在巨噬细胞和枯否细胞等吞噬细胞中含量极高，在炎性巨噬细胞中可被诱导数倍。三种组织蛋白在肝细胞、胰岛细胞和脑中的定位不同。测定了内源性半胱氨酸蛋白酶抑制剂半胱氨酸氨基转移酶抑制剂的序列，并证明了它们在不同的组织中的分布。半胱氨酸基残基(Cys-3)通过与谷胱甘肽形成混合二硫键参与抑制活性的调节：游离态是活性的，谷胱甘肽是非活性的。该抑制剂的混合二硫化物的形成被证明发生在培养细胞中，推测是通过酶反应。研究了不同营养和激素条件下肝脏自噬和异噬的不同调节机制，并与三种组织蛋白在肝细胞中的不同定位有关。在肌肉衰减性疾病，如远端肌病伴边缘空泡和Duchnne型肌营养不良的肌纤维中，自噬显著加速和组织蛋白的升高，提示半胱氨酸组织蛋白在这些疾病中的抑制有望抑制肌肉萎缩的进展。

We purified lysosomal cysteine proteinases, cathepsins B, H and L and determined the amino acid sequences and carbohydrate structures of cathepsin B and H. Distributions and localizations of three cathepsis in various organs and peripheral blood cells were examined. The content of cathepsin B is extremely high in phagocytes such as macrophages and Kupffer cells and it is induced several fold in inflammatory macrophages. Different localizations of three cathepsins were shown in hepatocytes, pancreatic islet cells and brain. Cystatin <alpha> and <beta> , endogenous cysteine proteinase inhibitors were sequenced and their different tissue distributions were demonstrated. A cysteinyl residue (cys-3) of cystatin- <beta> is involved in regulation of the inhibitory activity by formation of mixed disulfide with glutathione: free form is active and the glutathionated form is inactive. The formation of mixed disulfide of the inhibitor was shown to occur in cultured cells, presumably by the enzymatic reaction. Different regulation of autophagy and heterophagy in liver under various nutritional and hormonal conditions was studied in relating with different localizations of three cathepsins in hepatocytes. Marked accerelation of autophagy and elevation of cathepsins were shown in myofibers of muscle wasting diseases such as distal myopathy with rimmed vacuole and Duchnne type muscle dystrophy, suggesting that the inhibition of cysteine cathepsins in these diseases is expected to supress the progression of muscle atrophy.