IgG1 cytoplasmic tail is essential for cell surface expression in Igβ down-regulated cells.
IgG1 cytoplasmic tail is essential for cell surface expression in Igβ down-regulated cells.
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IgG1 胞质尾对于 Igβ 下调细胞的细胞表面表达至关重要。
DOI：
10.1016/j.bbrc.2014.02.037
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Masaki Hikida
中科院分区：
文献类型：
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作者：
Kagefumi Todo;Orie Koga;Miwako Nishikawa;Masaki Hikida
已经显示IgG 1 B细胞受体（BCR）的胞质尾区对于诱导T依赖性免疫应答是必需的。此外，已经揭示，IgG2a的胞质尾区中的独特酪氨酸残基具有在酪氨酸处被磷酸化的潜力，并且这种磷酸化调节BCR信号传导。然而，仍然不清楚IgG胞质尾区的这种磷酸化是否参与BCR表面表达的调节。为了解决这个问题，我们建立并分析了表达野生型或突变形式的IgG1 BCR的细胞系。结果发现，IgG 1 BCR在A20 B细胞系的表面上正常表达，不依赖于胞质尾区。相比之下，其胞质酪氨酸被模拟磷酸化酪氨酸的谷氨酸取代的IgG1 BCR在非B谱系细胞和IGβ下调的B细胞系的表面上最有效地表达。这些结果表明，当BCR相关信号分子（包括IGβ）下调时，IgG胞质尾区的酪氨酸残基对IgG BCR在细胞表面的有效表达起着至关重要的作用。
It has been shown that cytoplasmic tail of the IgG1 B cell receptors (BCRs) are essential for the induction of T-dependent immune responses. Also it has been revealed that unique tyrosine residue in the cytoplasmic tail of IgG2a has the potential of being phosphorylated at tyrosine and that this phosphorylation modulates BCR signaling. However, it still remains unclear whether such phosphorylation of IgG cytoplasmic tail is involved in the regulation of BCR surface expression. In order to approach the issue, we established and analyzed the cell lines which express wild-type or mutated forms of IgG1 BCR. As the result, we found that IgG1 BCR expressed normally on the surface of A20 B cell line independent of the cytoplasmic tail. In contrast, IgG1 BCR whose cytoplasmic tyrosine was replaced with glutamic acid which mimics phosphorylated tyrosine, was expressed most efficiently on the surface of non-B lineage cells and Igβ-down-regulated B cell lines. These results suggest that tyrosine residue in IgG cytoplasmic tail is playing a essential role for the efficient expression of IgG BCR on the cell surface when BCR associated signaling molecules, including Igβ, are down-regulated.