Endolysosomes Are the Principal Intracellular Sites of Acid Hydrolase Activity.
Endolysosomes Are the Principal Intracellular Sites of Acid Hydrolase Activity.
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DOI：
10.1016/j.cub.2016.06.046
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发表时间：
2016-09-12
期刊：
影响因子：
9.2
通讯作者：
Luzio, J. Paul
中科院分区：
文献类型：
--
作者：
Bright, Nicholas A.;Davis, Luther J.;Luzio, J. Paul
大分子从哺乳动物细胞表面的内吞递送以供溶酶体酸水解酶降解需要通过早期内体运输到晚期内体，随后是晚期内体和溶酶体之间的瞬时（接触）或完全融合。瞬时或完全融合导致内溶酶体的形成，内溶酶体是溶酶体由其重新形成的杂合细胞器。我们已经使用了合成的膜可渗透的组织蛋白酶底物，其在蛋白水解裂解后释放荧光报告，以及酸性磷酸酶细胞化学来鉴定哪些内吞隔室是酸性水解酶活性的。我们发现，内溶酶体是酸性水解酶底物被切割的主要细胞器，内溶酶体也积累了亲酸探针，并可以从末端储存溶酶体，这是酸性水解酶失活，不积累亲酸探针区分。使用活细胞显微镜，我们已经证明，融合事件，形成内溶酶体，酸水解酶活性的发病之前。通过蔗糖和转化酶摄取实验，我们还表明，酸水解酶活性的内溶酶体和酸水解酶失活的末端储存溶酶体存在于动态平衡中。我们的结论是，终端内吞隔室是由酸水解酶活性，酸性内溶酶体和酸水解酶失活，非酸性，终端存储溶酶体，这是连接和功能在一个溶酶体再生周期。晚期内体-溶酶体融合产生酸性的、组织蛋白酶活性的内溶酶体。末端储存溶酶体是组织蛋白酶失活的，而不是酸性的。提供证据表明，末端内吞区室由酸水解酶活性的酸性内溶酶体和酸水解酶失活的非酸性末端储存溶酶体组成，它们在溶酶体再生循环中连接并起作用。
The endocytic delivery of macromolecules from the mammalian cell surface for degradation by lysosomal acid hydrolases requires traffic through early endosomes to late endosomes followed by transient (kissing) or complete fusions between late endosomes and lysosomes. Transient or complete fusion results in the formation of endolysosomes, which are hybrid organelles from which lysosomes are re-formed. We have used synthetic membrane-permeable cathepsin substrates, which liberate fluorescent reporters upon proteolytic cleavage, as well as acid phosphatase cytochemistry to identify which endocytic compartments are acid hydrolase active. We found that endolysosomes are the principal organelles in which acid hydrolase substrates are cleaved. Endolysosomes also accumulated acidotropic probes and could be distinguished from terminal storage lysosomes, which were acid hydrolase inactive and did not accumulate acidotropic probes. Using live-cell microscopy, we have demonstrated that fusion events, which form endolysosomes, precede the onset of acid hydrolase activity. By means of sucrose and invertase uptake experiments, we have also shown that acid-hydrolase-active endolysosomes and acid-hydrolase-inactive, terminal storage lysosomes exist in dynamic equilibrium. We conclude that the terminal endocytic compartment is composed of acid-hydrolase-active, acidic endolysosomes and acid hydrolase-inactive, non-acidic, terminal storage lysosomes, which are linked and function in a lysosome regeneration cycle. Late endosome-lysosome fusion creates acidic, cathepsin-active endolysosomes Terminal storage lysosomes are cathepsin inactive and not acidic Fusion events creating endolysosomes precede the onset of cathepsin activity A lysosome regeneration cycle links endolysosomes and terminal storage lysosomes Bright et al. provide evidence that the terminal endocytic compartment is composed of acid-hydrolase-active, acidic endolysosomes and acid hydrolase-inactive, non-acidic, terminal storage lysosomes, which are linked and function in a lysosome regeneration cycle.
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发表时间：
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期刊：
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影响因子：
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