KAPOSI?S SARCOMA-ASSOCIATED HERPESVIRUS K1 SIGNALOSOME

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。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，部分由局部炎症细胞因子的产生引起。ks相关疱疹病毒（KSHV）的K1淋巴细胞受体样蛋白通过其细胞质免疫受体酪氨酸基激活基序（ITAM）有效地转导细胞外信号，引发细胞活化事件。为了进一步描述K1介导的信号转导，我们纯化了K1信号复合物并鉴定了其细胞成分。刺激后，K1 ITAM被酪氨酸有效磷酸化，随后通过磷酸化的酪氨酸残基与细胞Src同源性2 （SH2）信号蛋白Lyn、Syk、p85、PLC2、RasGAP、Vav、SH2结构域蛋白酪氨酸磷酸酶¿和Grab2相互作用。突变分析表明，K1 ITAM的每个酪氨酸残基都以不同的方式与细胞信号蛋白相互作用。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的增加，NF-AT和AP0-1转录因子活性的激活以及炎症细胞因子的产生。这些结果表明，KSHV K1有效地招募一组细胞中含有sh2的信号分子，形成K1信号体，引发下游信号转导并诱导炎症细胞因子的产生。

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.