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

1.半乳糖凝集素-9(Galectin-9，Galectin-9，Gal-9)是一种独特的嗜酸性粒细胞激活因子，不同于其他已鉴定的趋化因子(J Invol，2002)，并且连接肽未被发现参与其功能(GlycoBiology，2002)。干扰素诱导内皮细胞和成纤维细胞Gal-9表达上调，其表面表达的Gal-9与嗜酸性粒细胞的选择性黏附有关(J白细胞生物学杂志，2002；J免疫杂志，2002)。我们还发现Gal-9诱导黑色素瘤和乳腺癌等肿瘤细胞的聚集和凋亡，并且Gal-9的高表达与这些患者更好的预后有关(Int J Cancer，2002；第25^<TH>圣安东尼奥乳腺癌研讨会)。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患者。PMA诱导Jurkat T细胞产生和释放Ga-1-9，而基质金属蛋白酶参与了这种释放(GlycoBiology，2002)。我们正在继续利用肥大细胞和巨噬细胞生产和释放Gal-9的研究。乳糖的存在抑制了Gal-9诱导的细胞凋亡，表明表面存在Gal-9结合分子(含β-半乳糖苷的糖蛋白)。我们发现Gal-9通过钙-钙蛋白酶-半胱氨酸天冬氨酸酶途径诱导细胞凋亡(《免疫学杂志》，2003)。现在，我们已经纯化了参与Ga-9诱导细胞凋亡的Gal-9结合分子的候选分子，并阐明了哪个分子是Gal-9诱导细胞凋亡的结合分子。

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.