Kitaura M, Suzuki N, Imai T, Takagi S, Suzuki R, Nakajima T, Hirai K, Nomiyama H, Yoshie O
Shionogi Institute for Medical Science, Osaka 566-0022, Kinki University School of Medicine, Osaka 589-8511, Japan.
J Biol Chem. 1999 Sep 24;274(39):27975-80. doi: 10.1074/jbc.274.39.27975.
Previously, we mapped the novel CC chemokine myeloid progenitor inhibitory factor 2 (MPIF-2)/eotaxin-2 to chromosome 7q11.23 (Nomiyama, H., Osborne, L. R., Imai, T., Kusuda, J., Miura, R., Tsui, L.-C., and Yoshie, O. (1998) Genomics 49, 339-340). Since chemokine genes tend to be clustered, unknown chemokines may be present in the vicinity of those mapped to new chromosomal loci. Prompted by this hypothesis, we analyzed the genomic region containing the gene for MPIF-2/eotaxin-2 (SCYA24) and have identified a novel CC chemokine termed eotaxin-3. The genes for MPIF-2/eotaxin-2 (SCYA24) and eotaxin-3 (SCYA26) are localized within a region of approximately 40 kilobases. By Northern blot analysis, eotaxin-3 mRNA was constitutively expressed in the heart and ovary. We have generated recombinant eotaxin-3 in a baculovirus expression system. Eotaxin-3 induced transient calcium mobilization specifically in CC chemokine receptor 3 (CCR3)-expressing L1.2 cells with an EC(50) of 3 nM. Eotaxin-3 competed the binding of (125)I-eotaxin to CCR3-expressing L1.2 cells with an IC(50) of 13 nM. Eotaxin-3 was chemotactic for normal peripheral blood eosinophils and basophils at high concentrations. Collectively, eotaxin-3 is yet another functional ligand for CCR3. The potency of eotaxin-3 as a CCR3 ligand seems, however, to be approximately 10-fold less than that of eotaxin. Identification of eotaxin-3 will further promote our understanding of the control of eosinophil trafficking and other CCR3-mediated biological phenomena. The strategy used in this study may also be applicable to identification of other unknown chemokine genes.
此前，我们将新型CC趋化因子髓系祖细胞抑制因子2（MPIF-2）/嗜酸性粒细胞趋化因子-2定位于染色体7q11.23（野山宏、奥斯本、今井、楠田纯司、三浦、徐立之、吉江孝夫，1998年，《基因组学》第49卷，第339 - 340页）。由于趋化因子基因往往成簇存在，因此在那些定位于新染色体位点附近可能存在未知趋化因子。基于这一假设，我们分析了包含MPIF-2/嗜酸性粒细胞趋化因子-2（SCYA24）基因的基因组区域，并鉴定出一种名为嗜酸性粒细胞趋化因子-3的新型CC趋化因子。MPIF-2/嗜酸性粒细胞趋化因子-2（SCYA24）和嗜酸性粒细胞趋化因子-3（SCYA26）的基因定位在大约40千碱基的区域内。通过Northern印迹分析，嗜酸性粒细胞趋化因子-3 mRNA在心脏和卵巢中组成性表达。我们在杆状病毒表达系统中制备了重组嗜酸性粒细胞趋化因子-3。嗜酸性粒细胞趋化因子-3特异性地诱导表达CC趋化因子受体3（CCR3）的L1.2细胞发生瞬时钙动员，其半数有效浓度（EC50）为3 nM。嗜酸性粒细胞趋化因子-3竞争性抑制125I-嗜酸性粒细胞趋化因子与表达CCR3的L1.2细胞的结合，其半数抑制浓度（IC50）为13 nM。嗜酸性粒细胞趋化因子-3在高浓度时对正常外周血嗜酸性粒细胞和嗜碱性粒细胞具有趋化作用。总体而言，嗜酸性粒细胞趋化因子-3是CCR3的又一功能性配体。然而，嗜酸性粒细胞趋化因子-3作为CCR3配体的效力似乎比嗜酸性粒细胞趋化因子低约10倍。嗜酸性粒细胞趋化因子-3的鉴定将进一步促进我们对嗜酸性粒细胞迁移控制及其他CCR3介导的生物学现象的理解。本研究中使用的策略也可能适用于鉴定其他未知趋化因子基因。
