The trans-Golgi network accessory protein p56 promotes long-range movement of GGA/clathrin-containing transport carriers and lysosomal enzyme sorting
The trans-Golgi network accessory protein p56 promotes long-range movement of GGA/clathrin-containing transport carriers and lysosomal enzyme sorting
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DOI：
10.1091/mbc.e07-02-0190
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发表时间：
2007-09-01
影响因子：
3.3
通讯作者：
Bonifacino, Juan S.
中科院分区：
文献类型：
--
作者：
Mardones, Gonzalo A.;Burgos, Patricia V.;Bonifacino, Juan S.
酸水解酶前体在反式高尔基体网络（TGN）处的分选是通过与甘露糖6-磷酸受体（MPR）结合并随后将水解酶-MPR复合物捕获到网格蛋白包被的囊泡或转运载体（TC）中来介导的，所述网格蛋白包被的囊泡或转运载体（TC）预定用于递送到内体。这种捕获依赖于三个单体网格蛋白衔接子（称为GGA）的功能。GGA包含C-末端“耳”结构域，其结合一组特定的辅助蛋白。在这里，我们表明，这些辅助蛋白，p56，共定位和物理相互作用的三个GGA在TGN。此外，GGA的过表达增强了p56与TGN的关联，并且RNA干扰（RNAi）介导的GGA的消耗降低了TGN关联和p56的总水平。RNAi介导的p56或GGA缺失导致酸性水解酶前体组织蛋白酶D不同程度的错分选。在p56缺失的情况下，这种错误分选与含GGA的TC的迁移率降低相关。用RNAi抗性p56构建体转染，而不是用缺乏GGA-耳相互作用基序的p56构建体转染，恢复了TC的移动性。我们的结论是，p56紧密合作的GGA的组织蛋白酶D的溶酶体的排序，可能是通过使运动的GGA含有TC。
The sorting of acid hydrolase precursors at the trans-Golgi network (TGN) is mediated by binding to mannose 6-phosphate receptors (MPRs) and subsequent capture of the hydrolase-MPR complexes into clathrin-coated vesicles or transport carriers (TCs) destined for delivery to endosomes. This capture depends on the function of three monomeric clathrin adaptors named GGAs. The GGAs comprise a C-terminal "ear" domain that binds a specific set of accessory proteins. Herein we show that one of these accessory proteins, p56, colocalizes and physically interacts with the three GGAs at the TGN. Moreover, overexpression of the GGAs enhances the association of p56 with the TGN, and RNA interference (RNAi)-mediated depletion of the GGAs decreases the TGN association and total levels of p56. RNAi-mediated depletion of p56 or the GGAs causes various degrees of missorting of the precursor of the acid hydrolase, cathepsin D. In the case of p56 depletion, this missorting correlates with decreased mobility of GGA-containing TCs. Transfection with an RNAi-resistant p56 construct, but not with a p56 construct lacking the GGA-ear-interacting motif, restores the mobility of the TCs. We conclude that p56 tightly cooperates with the GGAs in the sorting of cathepsin D to lysosomes, probably by enabling the movement of GGA-containing TCs.