HUMAN BLOOD MONOCYTE RECEPTOR EXPRESSION AND MODULATION

描述：初步数据是广泛的。论证了 信号传导的模式和受体连接的后果，通过 三种Fc受体（Fc γ RI、II和III以及受体A、B、C 同种型）在Ca++、酪氨酸 磷酸化，受体的胞质尾区及其 与γ链和δ链的相互作用。使用瞬时转染 具有野生型和诱变的Fc受体的COS细胞构建了 申请人显示了细胞质尾区的酪氨酸磷酸化 Fc γ RII或γ或 链是完全连接所必需的 和通过Fc受体的吞噬作用。 此外，跨膜和 细胞外结构域的分子，虽然他们调节 配体对受体的亲和力，不实质性影响 信号和功能性后果。 酪氨酸 磷酸化通过活化和结合几种src- 相关的蛋白酪氨酸激酶（PTK），申请人证明了 Syk的结合和激活，在吞噬细胞中最为一致， PTK与γ链（具有Fc γ RI和Fc γ RIII）和PTK与γ链（具有Fc γ RI和Fc γ RIII）的结合。 FcgRII的胞质尾区。 论证了syk的重要性 通过Syk通过与以下物质共转染来刺激FCRI吞噬作用的能力 COS中的伽马链。 此外，很清楚的是， FcgammaRII的胞质尾区中基序Y-Xn-L和所有 除了缺乏Fc γ RI的其他受体， 完整的吞噬信号。此外，在共同体中， 用Fc γ RI和γ链转染COS，而Fc RI 单独能够结合IgG并通过提高胞质 Ca++，该信号不足以允许吞噬作用;然而， 与γ链共转染导致γ链磷酸化 和Fc γ RI的吞噬能力。具体而言， 申请人构造了函数替换的增益，其通过添加 适当数量和长度的含Y基序， 表达感受态Fc γ RII，其单独+/-γ链 能传递完整的吞噬信号。 补充初步 研究表明这种Fc受体在健康和疾病中的重要性 细胞因子对受体的调节，一些证据表明PKC Ca++介导的信号通过Fc γ RI对分泌是重要的。

DESCRIPTION: The preliminary data is extensive. It demonstrates that the mode of signalling and the consequences of receptor ligation via the three Fc receptors (FcgammaRI, II, and III and the receptors' A,B,C isoforms) differs with respect to the roles of Ca++, tyrosine phosphorylation, the cytoplasmic tail of the receptor and its interaction with gamma and delta chains. Using transient transfections of COS cells with wild type and mutagenized Fc receptor constructs the Applicant shows tyrosine phosphorylation of either the cytoplasmic tail of FcgammaRII or the gamma or chain are required for complete ligation and phagocytosis via the Fc receptors. Further the transmembrane and the extracellular domains of the molecule, although they regulate the affinity of ligand for receptor, do not materially affect signalling and the functional consequences. The tyrosine phosphorylation occurs via activation and binding of any of several src- related protein tyrosine kinases (PTK) and the Applicant demonstrated the binding and activation, most consistently in phagocytes, of the Syk PTK to the gamma chain (with the FcgammaRI and FcgammaRIII) and the cytoplasmic tail of the FcgRII. The importance of syk is demonstrated by ability of syk to stimulate FCRI phagocytosis via cotransfection with gamma chain in COS. Further, it is clear the exact number and placement of the motif Y-Xn-L in the cytoplasmic tail of the FcgammaRII and all other receptors, except the FcgammaRI where it is lacking, is critical for the complete phagocytic signal. Further it is clear in co- transfectants of COS with FcgammaRI and gamma chain that while the FcRI is alone competent to bind IgG and signal via elevation of cytosolic Ca++, this signal is insufficient to allow phagocytosis; however, cotransfection with gamma chain results in gamma chain phosphorylation and competence of the FcgammaRI for phagocytosis. In specific the Applicant constructed gain of function substitutions which by adding the appropriate number and length of the Y containing motif, a phagocytosis competent FcgammaRII was expressed, which alone +/- the gamma chain could transmit complete phagocytosis signal. Additional preliminary studies show the importance of this Fc receptors in health and disease the modulation of the receptor by cytokines, some evidence that the PKC and Ca++ mediated signal via the FcgammaRI is important for secretion.