Developmentally regulated changes in glucosidase II association with, and carbohydrate content of, the protein tyrosine phosphatase CD45
Developmentally regulated changes in glucosidase II association with, and carbohydrate content of, the protein tyrosine phosphatase CD45
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DOI：
10.4049/jimmunol.167.7.3829
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发表时间：
2001-10-01
影响因子：
4.4
通讯作者：
Ostergaard, HL
中科院分区：
文献类型：
--
作者：
Baldwin, TA;Ostergaard, HL
葡萄糖苷酶II（GII）以碳水化合物依赖性方式与CD45的外部结构域稳定相互作用。我们发现这种关联发生在未成熟细胞中，但在成熟T细胞中显著减少。使用甘露糖结合蛋白（MBP），在两个FACS分析和下拉测定，我们发现，MBP可以特异性地识别来自未成熟的，但不是成熟的T细胞的细胞表面CD45。胸腺细胞的分析表明，增加MBP结合和GII协会与CD45在双阳性胸腺细胞相比，无论是双阴性或单阳性胸腺细胞。同样，MBP识别的相同CD45库也可以与GII相关。对CD45和MBP之间相互作用基础的初步分析表明，MBP基于与葡萄糖的差异竞争结合CD45的两种不同糖型。最后，在通常不表达MBP配体的细胞中抑制GII活性导致细胞表面MBP配体（包括CD45）的显著增加。总之，这些数据表明，细胞表面CD45的葡萄糖含量的变化，胸腺细胞经历成熟的成熟T细胞，并可能受到GII相互作用。CD 45上细胞表面碳水化合物的这种变化可能会影响胸腺细胞的发育，这可能是通过胸腺细胞上的CD 45与基质细胞上的凝集素结合来实现的。
Glucosidase II (GII) stably interacts with the external domain of CD45 in a carbohydrate-dependent manner. We have found that the association occurs in immature cells, but is significantly reduced in mature T cells. Using mannose-binding protein (MBP), in both FACS analysis and pull-down assays, we find that MBP can specifically recognize cell surface CD45 from immature, but not mature T cells. Analysis of thymocytes reveals increased MBP binding and GII association with CD45 in double-positive thymocytes compared with either double-negative or single-positive thymocytes. As well, the same pool of CD45 recognized by MBP can also associate with GII. Initial analysis of the basis of the interaction between CD45 and MBP suggests MBP binds two different glycoforms of CD45 based on the differential competition with glucose. Finally, inhibition of GII activity in cells that do not normally express MBP ligands results in significant increases in cell surface MBP ligands, including CD45. Taken together, these data suggest that the glucose content of the cell surface CD45 changes as thymocytes undergo maturation to mature T cells, and may be regulated by GII interactions. Such changes in the cell surface carbohydrate on CD45 may affect the development of thymocytes, perhaps via binding of CD45 on thymocytes to lectins on stromal cells.