Research for physiological roles of the CD47-SHPS-1 system.

SHPS-1是一种跨膜蛋白，其胞外区与CD47相互作用，其胞质区与酪氨酸磷酸酶SHP-1或SHP-2结合。CD47是一种五跨膜蛋白，最初被鉴定为整合素的结合伙伴。我们最近阐明了CD47和SHPS-1构成了一个细胞间通信系统（CD47-SHPS-1系统），在以下细胞功能中起重要作用。在本研究中，我们探讨了CD47-SHPS-1系统的生理作用。结果表明：(1)SHPS-1- shp -2复合物对黑色素瘤细胞和其他培养细胞的迁移具有正向调节作用，而CD47参与SHPS-1则阻止了这种调节作用。CD47参与SHPS-1也诱导了SHPS-1的去磷酸化和Rho活性增强，同时形成应力纤维和采用较少极化的形态。因此，CD47-SHPS-1系统可能有助于抑制细胞间接触的迁移。(2)与野生型小鼠相比，携带突变体SHPS-1缺失大部分细胞质区域（SHPS-1-Δcyto）小鼠的腹腔巨噬细胞（PEMs）对活化红细胞（rbc）的吞噬能力明显增加。相比之下，当CD47-null RBC作为吞噬靶点或存在SHPS-1阻断抗体时，WT和突变体之间没有观察到差异。因此，CD47（红细胞）对巨噬细胞上的SHPS-1的作用通过依赖于SHP-1的方式负向调节被活化的红细胞的吞噬。(3)在原代培养的海马神经元中，SHPS-1和CD47的定位方式不同；前者主要作用于轴突，后者主要作用于树突。体外培养的神经元中SHPS-1和CD47的表达也证实了这一观察结果。(4)在N1E-115神经母细胞瘤细胞中，CD47的强制表达诱导了神经突的延伸和丝足的形成，CD47- fc融合蛋白进一步增强了这一功能。这种调控涉及Rac和Cdc42的激活，以及含有β3亚基的整合素。少

SHPS-1 is a transmembrane protein whose extracellular region interacts with CD47 and whose cytoplasmic region binds the protein tyrosine phosphatases SHP-1 or SHP-2. CD47 is a penta-transmembrane protein, which was originally identified as a binding partner of integrin. We have recently elucidated that CD47 and SHPS-1 constitute an intercellular communication system (the CD47-SHPS-1 system), that plays important roles in the following cell functions. In this study, we investigated the physiological roles of CD47-SHPS-1 system. The results obtained are follows :(1)The SHPS-1-SHP-2 complex positively regulated the migration of melanoma cells and other cultured cells, however engagement of SHPS-1 by CD47 prevented such regulation. Engagement of SHPS-1 by CD47 also induced the dephosphorylation of SHPS-1 and enhanced Rho activity accompanied by formation of stress fibers and adoption of a less polarized morphology. Thus, the CD47-SHPS-1 system might thus contribute to the inhibition of cel … More l migration by cell-cell contact.(2)The phagocytosis of opsonoized red blood cells (RBCs) by peritoneal macrophages (PEMs) from mice bearing mutant SHPS-1 lacking most of cytoplasmic regions (SHPS-1-Δcyto) was markedly increased, compared wild-type PEMs. In contrast, the difference between WT and the mutant was not observed when CD47-null RBC was used as a phagocytotic target or in the presence of blocking antibodies of SHPS-1. Thus, the engagement of SHPS-1 (on macrophages) by CD47 (on RBCs) negatively regulates the phagocytosis of opsonized RBCs through a manner dependent of SHP-1.(3)In primary cultured hippocampal neurons, SHPS-1 and CD47 were localized in a different manner ; the former predominantly on axons and the latter on dendrites, respectively. Exogenous expression of SHPS-1 and CD47 in cultured neurons also confirmed this observation.(4)In N1E-115 neuroblastoma cells, forced expression of CD47 induced neurite extension and filopodium formation, those were further enhanced by CD47-Fc fusion protein. Such regulation involved the activation of Rac and Cdc42, and integrins containing the β3 subunit. Less