Claus V, Jahraus A, Tjelle T, Berg T, Kirschke H, Faulstich H, Griffiths G
Max Planck Institute for Medical Research, Heidelberg, Germany.
J Biol Chem. 1998 Apr 17;273(16):9842-51. doi: 10.1074/jbc.273.16.9842.
In this study we take advantage of recently developed methods using J774 macrophages to prepare enriched fractions of early endosomes, late endosomes, dense lysosomes, as well as phagosomes of different ages enclosing 1-micron latex beads to investigate the steady state distribution and trafficking of lysosomal enzyme activity between these organelles. At steady state these cells appear to possess four different cellular structures, in addition to phagolysosomes, where acid hydrolases were concentrated. The first site of hydrolase concentration was the early endosomes, which contained the bulk of the cellular cathepsin H. This enzyme was acquired by phagosomes significantly faster than the other hydrolases tested. The second distinct site of lysosomal enzyme concentration was the late endosomes which contain the bulk of cathepsin S. The third and fourth large pools of hydrolases were found in two functionally distinct types of dense lysosomes, only one of which was found to be secreted in the presence of chloroquine or bafilomycin. Among this secreted pool was soluble furin, generally considered only as a membrane-bound trans-Golgi network resident protein. Thus, the organelles usually referred to as "lysosomes" in fact encompass a growing family of highly dynamic but functionally distinct endocytic organelles.
在本研究中，我们利用最近开发的方法，使用J774巨噬细胞来制备富含早期内体、晚期内体、致密溶酶体以及包裹1微米乳胶珠的不同年龄吞噬体的组分，以研究这些细胞器之间溶酶体酶活性的稳态分布和运输。在稳态下，除了溶酶体（酸性水解酶在其中浓缩）外，这些细胞似乎拥有四种不同的细胞结构。水解酶浓缩的第一个位点是早期内体，其含有大部分细胞组织蛋白酶H。该酶被吞噬体获取的速度明显快于所测试的其他水解酶。溶酶体酶浓缩的第二个不同位点是晚期内体，其含有大部分组织蛋白酶S。水解酶的第三和第四大池存在于两种功能不同的致密溶酶体类型中，其中只有一种在氯喹或巴弗洛霉素存在的情况下被分泌。在这个分泌池中存在可溶性弗林蛋白酶，通常仅被认为是一种驻留在反式高尔基体网络中的膜结合蛋白。因此，通常被称为“溶酶体”的细胞器实际上包含一个不断增长的高度动态但功能不同的内吞细胞器家族。
