KAPOSI?S SARCOMA-ASSOCIATED HERPESVIRUS K1 SIGNALOSOME

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。卡波西肉瘤(KS)是一种多灶性血管生成肿瘤，似乎是一种增生性疾病，部分原因是局部产生炎性细胞因子。KS相关疱疹病毒的K1淋巴细胞受体样蛋白通过其胞浆免疫受体酪氨酸激活基序(ITAM)有效地传递细胞外信号以诱导细胞激活事件。为了进一步阐明K1介导的信号转导，我们纯化了K1信号复合体，并鉴定了其细胞成分。在刺激下，K1ITAM被有效地酪氨酸磷酸化，随后通过其磷酸化的酪氨酸残基与含有细胞Src同源2(SH2)的信号蛋白Lyn、Syk、P85、PLC2、RasGAP、Vav、SH2结构域蛋白酪氨酸磷酸酶和Grab 2相互作用。突变分析表明，K1ITAM的每个酪氨酸残基以不同的方式参与了与细胞信号蛋白的相互作用。因此，这些相互作用导致细胞信号转导活性显著增强，表现为细胞酪氨酸磷酸化和细胞内钙动员增加，核因子-AT和AP0-1转录因子活性激活，以及炎性细胞因子的产生。这些结果表明，KSHV K1有效地招募了一组含有SH2的细胞内信号分子形成K1信号体，从而引发下游信号转导和诱导炎性细胞因子的产生。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Kaposi's sarcoma (KS) is a multifocal angiogenic tumor and appears to be a hyperplastic disorder caused, in part, by local production of inflammatory cytokines. The K1 lymphocyte receptor-like protein of KS-associated herpesvirus (KSHV) efficiently transduces extracellular signals to elicit cellular activation events through its cytoplasmic immunoreceptor tyrosine-based activation motif (ITAM). To further delineate K1-mediated signal transduction, we purified K1 signaling complexes and identified its cellular components. Upon stimulation, the K1 ITAM was efficiently tyrosine phosphorylated and subsequently interacted with cellular Src homology 2 (SH2)-containing signaling proteins Lyn, Syk, p85, PLC2, RasGAP, Vav, SH2 domain-containing protein tyrosine phosphatase ¿, and Grab2 through its phosphorylated tyrosine residues. Mutational analysis demonstrated that each tyrosine residue of K1 ITAM contributed to the interactions with cellular signaling proteins in distinctive ways. Consequently, these interactions led to the marked augmentation of cellular signal transduction activity, evidenced by the increase of cellular tyrosine phosphorylation and intracellular calcium mobilization, the activation of NF-AT and AP0-1 transcription factor activities, and the production of inflammatory cytokines. These results demonstrate that KSHV K1 effectively recruits a set of cellular SH2-containing signaling molecules to form the K1 signalosome, which elicits downstream signal transduction and induces inflammatory cytokine production.