Signal Transduction of Paired Inhibitory Receptors of NK

这个项目涉及一组快速出现的免疫受体的研究。最近在小鼠和人类中发现了许多抑制性免疫受体家族。有趣的是，在这些抑制受体家族中，有一些蛋白质失去了抑制结构域。相反，这些受体在其跨膜区域内获得了带正电的酸，这表明它们可能与信号转导链相互作用并传递正信号。在本项目中，我们研究免疫细胞功能的阳性和阴性调节因子的信号转导和生物化学。通过对阳性受体的研究，我们等人证明了其中一些受体与新型信号转导链DAP12的关联。从那时起，我们一直在表征DAP12信号转导途径的生物化学。这项工作包括展示参与DAP12早期信号传导的激酶，描述所涉及的接头，以及研究这些途径的调控。此外，除了DAP12，我们正在开始对DAP10的研究，这是已知与NK细胞和单核细胞内受体相关的第二链，位于19号染色体上距离DAP12仅130 bp的地方。DAP10包含一个与DAP12不同的酪氨酸基序。该基序（Y*xNM）表明与磷脂酰肌醇3激酶（PI3K）和接头Grb2相互作用。我们现在正准备剖析DAP10的信号传导，以充分了解这些链在NK细胞、单核细胞和树突状细胞中的作用。我们对配对受体系统的研究现在已经很大程度上转移到骨髓细胞（TREM）上表达的触发受体的研究。TREM-1最近被证明参与导致感染性休克的信号放大。据报道，TREM-2参与树突状细胞的成熟。我们最近描述了TREM类转录-1，TREM簇中一个假定的抑制受体。通过RT-PCR在多种髓细胞中发现了TLT-1转录本，然而，northern blotting显示，TLT-1仅在血小板和骨髓中有丰富的表达。免疫组织化学和免疫荧光研究表明，骨髓TLT-1完全来源于巨核细胞。这一发现使TLT-1成为外周血血小板中第二种抑制受体（另一种是PECAM-1），也是唯一一种只在血小板和巨核细胞中表达的抑制受体。TLT-1在巨核细胞和血小板中的亚细胞定位和调控表明，TLT-1被巨核细胞预先包装到血小板α颗粒中，以便在血小板脱粒后快速表面表达。这些发现提示TLT-1可能参与了α颗粒和/或α - β的产生和释放

This project involves the study of a rapidly emerging group of immune receptors. Many families of inhibitory immune receptors have recently been identified in both mice and humans. Interestingly, within each of these inhibitory families of receptors, there are proteins that have lost the inhibitory domains. Instead these receptors have gained a positively charged acid within their transmembrane domain, suggesting that they may interact with signal transduction chains and transmit positive signals. In this project, we study the signal transduction and biochemistry of both the positive and negative regulators of immune cell function. Through the study of the positive receptors, we and others demonstrated the association of some of these receptors with the novel signal transduction chain DAP12. Since then we have been characterizing the biochemistry of the DAP12 signal transduction pathway. This work has included demonstration of the kinases involved in the early signaling of DAP12, delineation of the adaptors involved, and study of the regulation of these pathways. In addition, to DAP12, we are beginning the study of DAP10, a second chain known to associate with receptors within NK cells and monocytes that is located just 130 bp from DAP12 on Chromosome 19. DAP10 contains a tyrosine based motif unique from that of DAP12. This motif (Y*xNM) suggests interaction with both the phosphatidylinositol 3 kinase (PI3K) and the adaptor Grb2. We are now preparing to dissect the signaling of DAP10 in an effort to fully understand the role of these chains within NK cells, monocytes and dendritic cells. Our studies of paired receptor systems has now largely shifted to the study of the Triggering Receptors Expressed on Myeloid cells (TREM). TREM-1 has recently been shown to be involved in the amplification of signals leading to septic shock. TREM-2 has been reported to be involved in the maturation of dendritic cells. We recently described TREM Like Transcript-1, a putative inhibitory receptor within the TREM cluster. TLT-1 transcripts have been found in various myeloid cells by RT-PCR, however, northern blotting demonstrates abundant TLT-1 expression only in platelets and bone marrow. Immunohistochemical and immunofluorescence studies show that bone marrow TLT-1 is derived exclusively from megakaryocytes. This finding makes TLT-1 only the second inhibitory receptor described on peripheral blood platelets (the other being PECAM-1), and the only inhibitory receptor expressed exclusively in platelets and megakaryocytes. The subcellular localization and regulation of TLT-1 in megakaryocytes and platelets suggests that TLT-1 is prepackaged into the platelet alpha granules by megakaryocytes for rapid surface expression after platelet degranulation. These findings suggest TLT-1 may be involved in the production and release of alpha granules and/or the