Searching for substrates of lysosomal cathepsins

为了寻找组织蛋白酶D的底物，用双向凝胶电泳法分离了组织蛋白酶D缺陷小鼠(CD-/-)和对照仔鼠的全脑裂解产物。用质谱仪(MS)鉴定了CD-/-小鼠脑组织中增加的几种蛋白质。然而，免疫组织化学分析显示，在CD-/-脑中，一些已鉴定的蛋白质富含在活跃的小胶质细胞或星形胶质细胞中。我们还发现，组织蛋白酶C的蛋白含量和活性都增加了，组织蛋白酶C是一种溶酶体蛋白，据报道在体内被组织蛋白D切割。然而，在CD-/-脑中激活的小胶质细胞中也检测到组织蛋白酶C。

For the discovery of substrates for cathepsin D, whole brain lysates from cathepsin D deficient (CD-/-) and the control littermate mice were separated by two-dimensional gel electrophoresis. Several proteins increased in CD-/- mouse brains were identified by mass spectrometry (MS). However immunohistochemical analyses revealed that some of the identified proteins were enriched in active microglia or astrocytes in CD-/- brains. We also found that the protein amount and activity of cathepsin C, whic h is a lysosomal protease and reported to be cleaved by cathepin D in vivo, was increased. However cathepsin C was also detected in activated microglia in CD-/- brains.