p56lck LFA-1 and PI3K but not SHP-2 interact with GM1- or GM3-enriched microdomains in a CD4-p56lck association-dependent manner
p56lck LFA-1 and PI3K but not SHP-2 interact with GM1- or GM3-enriched microdomains in a CD4-p56lck association-dependent manner
复制标题
DOI：
10.1042/bj20061061
复制
发表时间：
2007-03-15
影响因子：
4.1
通讯作者：
Mazerolles, Fabienne
中科院分区：
文献类型：
--
作者：
Barbat, Christiane;Trucy, Maylis;Mazerolles, Fabienne
我们先前的研究表明，由CD4配体结合诱导的CD4与G(M3)神经节苷脂的结合是下调粘附性所必需的，神经节苷脂富集区的聚集伴随着LFA-1(淋巴细胞功能相关抗原-1)、PI3K(磷脂酰肌醇3-激酶)和CD4的瞬时共定位。我们还发现这些蛋白与神经节苷脂共定位，神经节苷脂与神经节苷脂部分共定位于这些区域。在本研究中，我们表明，p56(Lek)、PI3K和LFA-I在神经节苷脂富集区的重新分布需要与CD4信号中的CD4-p56(Lek)关联，因为在表达不结合p56(Lek)的突变形式的CD4突变形式的T细胞系(A201)中没有观察到这些蛋白的聚集和募集。此外，我们还发现，尽管这些蛋白与GM和G(M3)的关联方式不同，但所有的关联都依赖于CD4-p56(Lek)的关联。神经节苷脂可以与这些在亲和力结合上不同的蛋白质结合，并可以在CD4信号转导后被修饰。我们的结果表明，通过这些联系，神经节苷脂暂时隔离这些蛋白，从而抑制LFA-I依赖的黏附。此外，虽然神经节苷脂的结构多样性可能允许与不同的蛋白质结合，但我们发现酪氨酸磷酸酶SHP-2(Src同源2结构域包含蛋白酪氨酸磷酸酶2)，也是下调LFA-I依赖的黏附所必需的，与PI3K和p56(Lek)瞬时和部分共定位在洗涤剂不溶的膜上，而不与G(M1)或G(M3)结合。我们认为，CD4与p56(Lek)的连接和结合，以及它们与G(M3)和/或G(M1)神经节苷脂的相互作用，可以诱导对CD4信号转导重要的不同蛋白质的募集，形成一个多分子信号转导复合体。
We previously showed that the association of CD4 and G(M3) ganglioside induced by CD4 ligand binding was required for the down-regulation of adhesion and that aggregation of gangliosideenriched domains was accompanied by transient co-localization of LFA-1 (lymphocyte function-associated antigen-1), PI3K (phosphoinositide 3-kinase) and CD4. We also showed that these proteins co-localized with the Gm, ganglioside that partially colocalized with Gm, in these domains. In the present study, we show that CD4-p56(lek) association in CD4 signalling is required for the redistribution of p56(lek), PI3K and LFA-I in ganglioside-enriched domains, since ganglioside aggregation and recruitment of these proteins were not observed in a T-cell line (A201) expressing the mutant form of CD4 that does not bind p56(lek). In addition, we show that although these proteins associated in different ways with Gm, and G(M3), all of the associations were dependent on CD4-p56(lek) association. Gangliosides could associate with these proteins that differ in affinity binding and could be modified following CD4 signalling. Our results suggest that through these associations, gangliosides transiently sequestrate these proteins and consequently inhibit LFA-I-dependent adhesion. Furthermore, while structural diversity of gangliosides may allow association with distinct proteins, we show that the tyrosine phosphatase SHP-2 (Src homology 2 domain-containing protein tyrosine phosphatase 2), also required for the down-regulation of LFA-I-dependent adhesion, transiently and partially co-localized with PI3K and p56(lek) in detergent-insoluble membranes without association with G(M1) or G(M3). We propose that CD4 ligation and binding with p56(lek) and their interaction with G(M3) and/or G(M1) gangliosides induce recruitment of distinct proteins important for CD4 signalling to form a multimolecular signalling complex.