Extended core 1 and core 2 branched O-glycans differentially modulate sialyl Lewis x-type L-selectin ligand activity
Extended core 1 and core 2 branched O-glycans differentially modulate sialyl Lewis x-type L-selectin ligand activity
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DOI：
10.1074/jbc.m212756200
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发表时间：
2003-03-14
影响因子：
4.8
通讯作者：
Fukuda, M
中科院分区：
文献类型：
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作者：
Mitoma, J;Petryniak, B;Fukuda, M
已经确定核心 2 支链 O-聚糖中的唾液酸路易斯 x 充当 E-和 P-选择素配体。最近，人们发现扩展核心1 O-聚糖中的6-磺基唾液酸基Lewis x，NeuNAcalpha2-->3Gal-beta1-->4(Fucalpha1-->3(sulfo-->6))GlcNAc,beta1--> 3Galbeta1-->3Gal-NAcalpha1-->Ser/Thr，在高内皮细胞中充当L-选择素配体小静脉。当存在核心 1 延伸酶时，可以合成延伸的核心 1 O-聚糖。在这项研究中，我们首先表明 beta1,3-N-乙酰氨基葡萄糖转移酶-3 (beta3GlcNAcT-3) 几乎完全负责七个不同 beta3GlcNAcT 中核心 1 的延伸，从而作用于附着在 PSGL-1 上的核心 1 O-聚糖。我们发现编码 beta3GLcNAcT-3 的转录本在人中性粒细胞和淋巴细胞中表达，但其水平低于编码核心 2)beta1,6-N-乙酰氨基葡萄糖转移酶 I (Core2GlcNAcT-1) 的转录本。中性粒细胞还表达编码岩藻糖基转移酶VII (FucT-VII)和Core2GlcNAcT-1的转录本，而淋巴细胞仅表达少量编码FucT-VII的转录本。为了确定唾液酸路易斯 x 在扩展核心 1 O-聚糖中的作用，稳定转染中国仓鼠卵巢 (CHO) 细胞以表达 PSGL-1、FucT-VII 以及 beta3GlcNAcT-3 或 Core2GlcNAcT-1。聚糖结构分析表明，这些转染细胞中表达的 PSGL-1 在扩展核心 1 和核心 2 支链 O-聚糖中携带相当量的唾液酸 Lewis x。在滚动测定中，在延伸的核心 1 O-聚糖中表达唾液酸 Lewis x 的 CHO 细胞支持中性粒细胞和淋巴细胞的显着程度的剪切依赖性束缚和滚动，尽管少于在核心 2 分支 O-聚糖中表达唾液酸 Lewis x 的 CHO 细胞。这些结果表明，扩展核心 1 O-聚糖中的唾液酸路易斯 x 可以充当 L-选择素配体，并可能参与中性粒细胞对与活化内皮细胞结合的中性粒细胞的粘附。
It has been established that sialyl Lewis x in core 2 branched O-glycans serves as an E- and P-selectin ligand. Recently, it was discovered that 6-sulfosialyl Lewis x in extended core 1 O-glycans, NeuNAcalpha2-->3Gal-beta1-->4(Fucalpha1-->3(sulfo-->6))GIcNAc,beta1--> 3Galbeta1-->3Gal-NAcalpha1-->Ser/Thr, functions as an L-selectin ligand in high endothelial venules. Extended core 1 O-glycans can be synthesized when a core 1 extension enzyme is present. In this study, we first show that beta1,3-N-acetylglucosaminyltransferase-3 (beta3GlcNAcT-3) is almost exclusively responsible for core 1 extension among seven different beta3GlcNAcTs and thus acts on core 1 O-glycans attached to PSGL-1. We found that transcripts encoding beta3GLcNAcT-3 were expressed in human neutrophils and lymphocytes but that their levels were lower than those of transcripts encoding core 2)beta1,6-N-acetylglucosaminyltransferase I (Core2GlcNAcT-1). Neutrophils also expressed transcripts encoding fucosyltransferase VII (FucT-VII) and Core2GlcNAcT-1, whereas lymphocytes expressed only small amounts of transcripts encoding FucT-VII. To determine the roles of sialyl Lewis x in extended core 1 O-glycans, Chinese hamster ovary (CHO) cells were stably transfected to express PSGL-1, FucT-VII, and either beta3GlcNAcT-3 or Core2GlcNAcT-1. Glycan structural analyses disclosed that PSGL-1 expressed in these transfected cells carried comparable amounts of sialyl Lewis x in extended core 1 and core 2 branched O-glycans. In a rolling assay, CHO cells expressing sialyl Lewis x in extended core 1 O-glycans supported a significant degree of shear-dependent tethering and rolling of neutrophils and lymphocytes, although less than CHO cells expressing sialyl Lewis x in core 2 branched O-glycans. These results indicate that sialyl Lewis x in extended core 1 O-glycans can function as an L-selectin ligand and is potentially involved in neutrophil adhesion on neutrophils bound to activated endothelial cells.