Tyrosine 112 of latent membrane protein 2A is essential for protein tyrosine kinase loading and regulation of Epstein-Barr virus latency
Tyrosine 112 of latent membrane protein 2A is essential for protein tyrosine kinase loading and regulation of Epstein-Barr virus latency
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DOI：
10.1128/jvi.72.10.7796-7806.1998
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发表时间：
1998-10-01
影响因子：
5.4
通讯作者：
Longnecker, R
中科院分区：
文献类型：
--
作者：
Fruehling, S;Swart, R;Longnecker, R
EB病毒潜伏膜蛋白2 A(LMP2 A)在潜伏感染EB病毒的B淋巴细胞膜上表达，阻断EB病毒永生化B细胞的BCR信号转导。LMP2A氨基末端结构域是LMP2A介导的阻断BCR信号转导所必需的，它含有8个酪氨酸残基。Syk蛋白酪氨酸激酶(PTK)与LMP2A的结合发生在LMP2A型免疫受体酪氨酸激活基序的两个酪氨酸上，并推测Lyn PTK与LMP2A型酪氨酸112(Y112)的YEEA氨基酸基序有关。为了检测Lyn PTK与LMP2A的特异性关联，将一组含有LMP2A突变的LMP2AcDNA表达载体导入EBV阴性的B细胞系，并分析Lyn和LMP2A的免疫共沉淀。Lyn与野生型LMP2A和其他LMP2A突变结构相关联，但在LMP2A残基Y112(LMP2AY112F)包含酪氨酸(Y)到苯丙氨酸(F)突变的LMP2A结构中，Lyn关联丢失。接下来，将LMP2AY112F突变基因重组到EBV基因组中，获得稳定的淋巴细胞样细胞系(LCLS)。对LMP2AY112F LCLS中BCR介导的信号转导的分析表明，LMP2AY112F LCLS中LMP2A介导的BCR信号转导缺失。此外，在LMP2AY112F LCLS中，LMP2AY112F中没有LMP2A的酪氨酸磷酸化。综上所述，这些数据表明LMP2AY112残基在LMP2A阻断BCR介导的信号转导的能力中的重要性，并将该残基的作用及其与Lyn PTK的相互作用作为LMP2A磷酸化、PTK负载和参与BCR介导的信号转导中的PTKs下调所必需的。
Latent membrane protein 2A (LMP2A) of Epstein-Barr virus (EBV) is expressed on the plasma membrane of B lymphocytes latently infected with EBV and blocks B-cell receptor (BCR) signal transduction in EBV-immortalized B cells in vitro. The LMP2A amino-terminal domain that is essential for the LMP2A-mediated block on BCR signal transduction contains eight tyrosine residues. Association of Syk protein tyrosine kinase (PTK) with LMP2A occurs at the two tyrosines of the LMP2A immunoreceptor tyrosine-based activation motif, and it is hypothesized that Lyn PTK associates with the YEEA amino acid motif at LMP2A tyrosine 112 (Y112). To examine the specific association of Lyn PTK to LMP2A, a panel of LMP2A cDNA expression vectors containing LMP2A mutations were transfected into an EBV-negative B-cell line and analyzed for Lyn and LMP2A coimmunoprecipitation. Lyn associates with wild-type LMP2A and other LMP2A mutant constructs, but Lyn association is lost in the LMP2A construct containing a tyrosine (Y)-to-phenylalanine (F) mutation at LMP2A residue Y112 (LMP2AY112F). Next, the LMP2AY112F mutation was recombined into the EBV genome to generate stable lymphoblastoid cell lines (LCLs) transformed with the LMP2AY112F mutant virus. Analysis of BCR-mediated signal transduction in the LMP2AY112F LCLs revealed loss of the LMP2A-mediated block in BCR signal transduction. In addition, LMP2A was not tyrosine phosphorylated in LMP2AY112F LCLs. Together these data indicate the importance of the LMP2A Y112 residue in the ability of LMP2A to block BCR-mediated signal transduction and place the role of this residue and its interaction with Lyn PTK as essential to LMP2A phosphorylation, PTK loading, and down-modulation of PTKs involved in BCR-mediated signal transduction.