Structures, Functions and Medical Meaning of Lysosomal Cysteine Protease Inhibitors

纯化了溶酶体半胱氨酸蛋白酶、组织蛋白酶B、H和L，测定了组织蛋白酶B和H的氨基酸序列和碳水化合物结构，并对三种组织蛋白酶在不同器官和外周血中的分布和定位进行了检测。组织蛋白酶B在巨噬细胞、Kupffer细胞等吞噬细胞中含量极高，在炎性巨噬细胞中被诱导数倍。三种组织蛋白酶在肝细胞、胰岛细胞和脑中有不同的定位。对内源性半胱氨酸蛋白酶抑制剂胱抑素< α >和< β >进行了测序，并证实了它们在不同组织中的分布。胱抑素- < β >的半胱氨酸残基（cys-3）通过与谷胱甘肽形成混合二硫参与抑制活性的调节：游离形式有活性，谷胱甘肽化形式无活性。抑制剂的混合二硫化物的形成显示发生在培养细胞中，可能是通过酶促反应。研究了不同营养和激素条件下肝脏自噬和异噬的不同调控与三种组织蛋白酶在肝细胞中的不同定位有关。在远端有边缘液泡的肌病和Duchnne型肌营养不良等肌肉萎缩疾病的肌纤维中显示出明显的自噬加速和组织蛋白酶的升高，这表明在这些疾病中抑制半胱氨酸组织蛋白酶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.