A Sulfated Glycosaminoglycan Linkage Region is a Novel Type of Human Natural Killer-1 (HNK-1) Epitope Expressed on Aggrecan in Perineuronal Nets.
A Sulfated Glycosaminoglycan Linkage Region is a Novel Type of Human Natural Killer-1 (HNK-1) Epitope Expressed on Aggrecan in Perineuronal Nets.
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DOI：
10.1371/journal.pone.0144560
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Oka S
中科院分区：
文献类型：
--
作者：
Yabuno K;Morise J;Kizuka Y;Hashii N;Kawasaki N;Takahashi S;Miyata S;Izumikawa T;Kitagawa H;Takematsu H;Oka S
人类自然杀伤细胞-1（HNK-1）碳水化合物（HSO 3 -3GlcAβ1-3Galβ1-4GlcNAc-R）在大脑中高度表达，是学习和神经可塑性所需的。我们先前证明，HNK-1表位的表达在GlcAT-P（B3 gat 1）基因敲除小鼠中大部分被消除，GlcAT-P（B3 gat 1）是HNK-1生物合成所需的主要葡萄糖醛酸转移酶，但仍保留在这些突变小鼠的特定区域，如神经元周网（PNN）。考虑到PNNs主要由硫酸软骨素蛋白聚糖（CSPGs）组成并调节神经可塑性，建议PNNs中HNK-1的GlcAT-P非依赖性表达在神经可塑性中发挥作用。然而，GlcAT-P-不相关HNK-1表位的功能、结构、载体糖蛋白和生物合成途径尚不清楚。在这项研究中，我们确定了一个独特的HNK-1结构的聚集蛋白聚糖在PNNs。为了确定新型HNK-1的生物合成途径，我们产生了GlcAT-S（B3 gat 2）敲除小鼠，GlcAT-S是HNK-1生物合成所需的另一种葡萄糖醛酸转移酶。然而，与单GlcAT-P敲除小鼠相比，GlcAT-P和GlcAT-S双敲除小鼠没有表现出HNK-1表达降低，表明PNN中HNK-1表位的不寻常的生物合成途径。从不表达GlcAT-P和-S的培养细胞中纯化聚集蛋白聚糖，并使用液相色谱/质谱（LC/MS）确定新的HNK-1表位的结构，作为糖胺聚糖（GAG）的硫酸化连接区，HSO 3-GlcA-Gal-Gal-Xyl-R。综上所述，我们提出了一个假设的模型，其中GlcAT-I，唯一的葡糖醛酸转移酶所需的合成的GAG连接，也是负责生物合成的新HNK-1聚集蛋白聚糖。这些结果可能导致发现HNK-1表位在神经可塑性中的新作用。
Human natural killer-1 (HNK-1) carbohydrate (HSO3-3GlcAβ1-3Galβ1-4GlcNAc-R) is highly expressed in the brain and required for learning and neural plasticity. We previously demonstrated that expression of the HNK-1 epitope is mostly abolished in knockout mice for GlcAT-P (B3gat1), a major glucuronyltransferase required for HNK-1 biosynthesis, but remained in specific regions such as perineuronal nets (PNNs) in these mutant mice. Considering PNNs are mainly composed of chondroitin sulfate proteoglycans (CSPGs) and regulate neural plasticity, GlcAT-P-independent expression of HNK-1 in PNNs is suggested to play a role in neural plasticity. However, the function, structure, carrier glycoprotein and biosynthetic pathway for GlcAT-P-irrelevant HNK-1 epitope remain unclear. In this study, we identified a unique HNK-1 structure on aggrecan in PNNs. To determine the biosynthetic pathway for the novel HNK-1, we generated knockout mice for GlcAT-S (B3gat2), the other glucuronyltransferase required for HNK-1 biosynthesis. However, GlcAT-P and GlcAT-S double-knockout mice did not exhibit reduced HNK-1 expression compared with single GlcAT-P-knockout mice, indicating an unusual biosynthetic pathway for the HNK-1 epitope in PNNs. Aggrecan was purified from cultured cells in which GlcAT-P and -S are not expressed and we determined the structure of the novel HNK-1 epitope using liquid chromatography/mass spectrometry (LC/MS) as a sulfated linkage region of glycosaminoglycans (GAGs), HSO3-GlcA-Gal-Gal-Xyl-R. Taken together, we propose a hypothetical model where GlcAT-I, the sole glucuronyltransferase required for synthesis of the GAG linkage, is also responsible for biosynthesis of the novel HNK-1 on aggrecan. These results could lead to discovery of new roles of the HNK-1 epitope in neural plasticity.