BACKGROUND Brains express structurally unique glycans, including human natural killer-1 (HNK-1), which participate in development and high-order functions. However, the regulatory mechanisms of expression of these brain-specific glycans are largely unknown. We examined whether arginine methylation, another type of protein modification essential for neural development, impacts the expression of various glycans in the developing brain. METHODS We analyzed several types of glycans, including the HNK-1 epitope, in the cerebellum and cerebral cortex from mice with nervous system-specific knockout of protein arginine methyltransferase 1 (PRMT1). We also analyzed the expression levels of glycosyltransferases responsible for HNK-1 and of HNK-1 carrier glycoproteins by quantitative RT-PCR and western blotting. RESULTS Among several glycans, expression of HNK-1 glycan was strikingly upregulated in the PRMT1-deficient cerebellum. Furthermore, such upregulation was found in the cerebellum but not in the cerebral cortex. Regarding the mechanisms, we demonstrated that the mRNA level and activity of the responsible glycosyltransferase (B3gat1) were elevated in the knockout cerebellum. We also showed that the expression of HNK-1 carrier glycoproteins such as neural cell adhesion molecule (NCAM), L1 and AMPA receptor subunit GluA2 were also increased in the PRMT1-deficient cerebellum. CONCLUSIONS Loss of arginine methylation leads to an increase in HNK-1 glycan in the developing cerebellum but not in the cerebral cortex via upregulation of the biosynthetic enzyme and carrier glycoproteins. GENERAL SIGNIFICANCE PRMT1 is a novel regulator of HNK-1 glycan production in the cerebellum. Mechanisms involving crosstalk between glycosylation and arginine methylation are suggested to occur.

中文翻译：

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PRMT1缺陷型脑中HNK-1聚糖的区域特异性上调。

背景技术大脑表达结构独特的聚糖，包括人类自然杀手1（HNK-1），其参与发育和高级功能。但是，这些脑特异性聚糖的表达调控机制在很大程度上是未知的。我们检查了精氨酸甲基化（对神经发育至关重要的另一种蛋白质修饰）是否会影响发育中的大脑中各种聚糖的表达。方法我们分析了精氨酸甲基转移酶1（PRMT1）的神经系统特异性敲除小鼠的小脑和大脑皮层中的几种类型的聚糖，包括HNK-1表位。我们还通过定量RT-PCR和Western印迹分析了负责HNK-1和HNK-1载体糖蛋白的糖基转移酶的表达水平。结果在几种聚糖中，PRNK1缺陷型小脑中HNK-1聚糖的表达显着上调。此外，在小脑而不是在大脑皮层中发现了这种上调。关于机制，我们证明了在敲除小脑中mRNA水平和负责的糖基转移酶（B3gat1）的活性均升高。我们还表明，在PRMT1缺陷型小脑中，HNK-1载体糖蛋白（如神经细胞粘附分子（NCAM），L1和AMPA受体亚基GluA2）的表达也有所增加。结论精氨酸甲基化的丧失会通过生物合成酶和载体糖蛋白的上调导致发育中的小脑中HNK-1聚糖的增加，而不是大脑皮层中的HNK-1聚糖的增加。一般意义PRMT1是小脑中HNK-1聚糖生产的新型调节剂。