Functional Analysis of Galectin-9 and Purification of Galectin-9 Binding Molecules on Cell Surface

1. 半乳糖凝集素-9 （Gal-9）是一种独特的嗜酸性粒细胞激活因子，不同于其他已确定的化学引诱剂（J Immunol, 2002），并且发现连接肽不参与其功能（糖生物学，2002）。IFN诱导内皮细胞和成纤维细胞中Gal-9的上调，其表面表达的Gal-9与嗜酸性粒细胞的选择性粘附有关（J Leukocyte Biol, 2002; J Immunol, 2002）。我们还发现Gal-9诱导肿瘤细胞聚集和凋亡，如黑色素瘤和乳腺癌，高表达的Gal-9与这些患者更好的预后有关（Int J cancer, 2002; 25^ the > San Antonio breast cancer Symposium）。因此，免疫组织化学分析可以用于判断肿瘤患者的预后，特别是在远处转移的情况下。在Jurkat T细胞系中，PMA诱导Ga-1-9的产生和释放，MMP参与了Ga-1-9的释放（Glycobiology, 2002）。我们正在继续研究利用肥大细胞和巨噬细胞产生和释放Gal-9。乳糖的存在抑制了Gal-9诱导的细胞凋亡，这表明Gal-9结合分子（带β -半乳糖苷的糖蛋白）存在于细胞表面。我们发现Gal-9通过钙-calpain-caspase途径诱导细胞凋亡（J Immunol, 2003 in press）。目前，我们纯化了参与ga -9诱导的细胞凋亡的Gal-9结合分子候选分子，并明确了哪个分子是参与细胞凋亡的Gal-9结合分子。

1. Galectin-9 (Gal-9) is a unique eosinophil activation factor differing from other identified chemoattractants (J Immunol, 2002), and the linker peptide is found not to be involved in its function (Glycobiology, 2002). IFN induced up-regulation of Gal-9 in endothelial cells and fibroblasts, and the expressed Gal-9 on their surface is associated with selective adhesion of eosinophils (J Leukocyte Biol, 2002; J Immunol, 2002). We also found that Gal-9 induces aggregation and apoptosis of tumor cells such as melanoma and breast cancer, and higher Gal-9 expression is linked to better prognosis of those patients (Int J Cancer, 2002; 25^<th> San Antonio Breast Cancer Symposium). Thus, immunohistochemical analysis can be used for determining the prognosis of tumor patients, especially in remote metastasis.2. Production and release of Ga-1-9 is induced by PMA in Jurkat T cell line, and an MMP is involved in the release (Glycobiology, 2002). We are continuing the study on the production and release of Gal-9 using mast cells and macrophages.3. Apoptosis induced by Gal-9 is suppressed by the presence of lactose indicating that Gal-9 binding molecules (glycoprotein with beta-galactoside) is present on the surface. We found that Gal-9 induces apoptosis through calcium-calpain-caspase pathway (J Immunol, 2003 in press). Now, we have purified the candidates of Gal-9 binding molecule involving in Ga-9-induced apoptosis, and clarifying which molecule is the Gal-9 binding molecule for the apoptosis.