HLA-E surface expression depends on binding of TAP-dependent peptides derived from certain HLA class I signal sequences.
HLA-E surface expression depends on binding of TAP-dependent peptides derived from certain HLA class I signal sequences.
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DOI：
10.4049/jimmunol.160.10.4951
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发表时间：
1998-05
影响因子：
4.4
通讯作者：
N. Lee;D. Goodlett;A. Ishitani;H. Marquardt;D. Geraghty
中科院分区：
文献类型：
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作者：
N. Lee;D. Goodlett;A. Ishitani;H. Marquardt;D. Geraghty
以往的研究表明，人类白细胞抗原-E在淋巴母细胞系721.221细胞中有表达，但缺乏表面表达。为了确定控制表面表达的信号，我们利用来自人类白细胞抗原E基因和人类白细胞抗原A2基因的互补部分构建了一系列杂交基因。通过这种方式，鉴定出了一种人类白细胞抗原E的杂交体，命名为AEH，它与人类白细胞抗原E的不同之处在于用人类白细胞抗原A2信号序列替代了人类白细胞抗原E的前导肽。AEH基因转染LCL 721.221细胞可诱导HLAE表面表达。对与人类白细胞抗原-E结合的多肽的分析表明，从A2信号序列中衍生出的一个多聚体是主要的结合多肽。LCL 721.221细胞在不增加HLAE重链合成水平的情况下，也足以促进包括HLAG在内的某些I类基因的结合和表面表达。与HLAE结合的多肽由9个氨基酸组成，甲硫氨酸在第2位，亮氨酸在羧基末端，与前导序列衍生的多肽几乎相同，这些多肽是与小鼠Qa-1Ag结合的主要多肽。某些由苏氨酸位于第2位的人类白细胞抗原-B蛋白产生的信号肽仅略微上调0.221细胞中人类白细胞抗原-E的表面表达。对TAP阴性细胞系.134中的HLA-E多肽结合的检测表明，与HLA-E结合的多肽依赖于功能性的TAP异源二聚体，无论多肽是存在于顺式中，如AEH构建中，还是反式中，如.221细胞的I类转染体中。
Previous studies showed that HLA-E was expressed in lymphoblastoid cell line (LCL) 721.221 cells, but surface expression was lacking. To determine the signals controlling surface expression, we constructed a series of hybrid genes using complementary portions derived from the HLA-E and HLA-A2 genes. In this manner, a hybrid of HLA-E was identified, designated AEH, which differed from HLA-E by having the HLA-A2 signal sequence substituting for the HLA-E leader peptide. Transfection of LCL 721.221 cells with AEH induced HLA-E surface expression. Analysis of peptides bound to HLA-E revealed that a nonamer peptide derived from the A2 signal sequence was the predominant peptide bound. LCL 721.221 cells transfected with certain class I genes, including HLA-G, were also sufficient to promote peptide binding and HLA-E surface expression without increasing the level of HLA-E heavy chain synthesis. Peptides bound to HLA-E consisted of nine amino acids, with methionine at position 2 and leucine in the carboxyl-terminal position, and were nearly identical to the leader sequence-derived peptide previously shown to be a predominant peptide bound to the murine Qa-1 Ag. Signal peptides derived from certain HLA-B proteins with threonine in position 2 only marginally up-regulated HLA-E surface expression in .221 cells. An examination of HLA-E peptide binding in the TAP negative cell line .134 indicated that peptide binding to HLA-E was dependent on a functional TAP heterodimer regardless of whether peptide was available in cis, as in the AEH construct, or in trans, as in the class I transfectants of .221 cells.