Endoplasmic reticulum and cis-Golgi localization of human T-lymphotropic virus type 1 p12I:: Association with calreticulin and calnexin
Endoplasmic reticulum and cis-Golgi localization of human T-lymphotropic virus type 1 p12I:: Association with calreticulin and calnexin
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DOI：
10.1128/jvi.75.16.7672-7682.2001
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发表时间：
2001-08-01
影响因子：
5.4
通讯作者：
Lairmore, MD
中科院分区：
文献类型：
--
作者：
Ding, W;Albrecht, B;Lairmore, MD
人类嗜T淋巴细胞病毒I型（Human T-lymphotropic virus type I，HTLV-1）是一种复杂的逆转录病毒，在pX区的4个开放阅读框（ORF I ~ IV）中编码调控和辅助基因。我们已经证明了编码p12（I）的pX ORF I表达在建立兔模型中的HTLV-1感染和在静止的原代淋巴细胞中的最佳病毒感染性中的重要作用。这些数据表明，p12（I）可以增强淋巴细胞活化，从而促进病毒感染。为了进一步确定p12（I）在细胞活化中的作用，我们通过多种方法，包括免疫荧光共聚焦显微镜、电子显微镜和亚细胞分级，表征了p12（I）在转染的293 T细胞和HeLa-Tat细胞中的亚细胞定位。在此，我们证明p12（I）积累在内质网（ER）和顺式高尔基体。用放线菌酮（阻断从头蛋白质合成）和布雷菲德菌素A（破坏ER至高尔基体蛋白质转运）处理后，p12（I）的位置没有变化，表明蛋白质保留在ER和顺式高尔基体中。此外，使用免疫共沉淀试验，我们确定了p12（I）与钙网蛋白和钙连接蛋白（调节钙储存的常驻ER蛋白）的直接结合。我们的研究结果表明，p12（I）直接结合参与钙介导的细胞信号传导的关键调控蛋白，并表明p12（I）在通过激活宿主细胞建立HTLV-1感染中的作用。
Human T-lymphotropic virus type I (HTLV-1) is a complex retrovirus encoding regulatory and accessory genes in four open reading frames (ORF I to IV) of the pX region. We have demonstrated an important role of pX ORF I expression, which encodes p12(I), in establishment of HTLV-1 infection in a rabbit model and for optimal viral infectivity in quiescent primary lymphocytes. These data indicated that p12(I) may enhance lymphocyte activation and thereby promote virus infection. To further define the role of p12(I) in cell activation, we characterized the subcellular localization of p12(I) in transfected 293T cells and HeLa-Tat cells by multiple methods, including immunofluorescence confocal microscopy, electron microscopy, and subcellular fractionation. Herein, we demonstrate that p12(I) accumulates in the endoplasmic reticulum (ER) and cis-Golgi apparatus. The location of p12(I) was unchanged following treatments with both cycloheximide (blocking de novo protein synthesis) and brefeldin A (disrupting ER-to-Golgi protein transport), indicating that the protein is retained in the ER and cis-Golgi. Moreover, using coimmunoprecipitation assays, we identify the direct binding of p12(I) with both calreticulin and calnexin, resident ER proteins which regulate calcium storage. Our results indicate that p12(I) directly binds key regulatory proteins involved in calcium-mediated cell signaling and suggest a role of p12(I) in the establishment of HTLV-1 infection by activation of host cells.