Functional evidence that cell surface galectin-3 mediates homotypic cell adhesion.
Functional evidence that cell surface galectin-3 mediates homotypic cell adhesion.
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DOI：
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发表时间：
1995-08
期刊：
影响因子：
11.2
通讯作者：
Hidenori Inohara;A. Raz
中科院分区：
文献类型：
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作者：
Hidenori Inohara;A. Raz
半乳糖凝集素-3（Gal-3）是一种β-半乳糖苷结合蛋白，M（r）约为30，000。细胞表面Gal-3被假定参与转移期间循环中肿瘤细胞的同型聚集，其通过附着于互补血清糖蛋白而起作用，所述互补血清糖蛋白充当相邻细胞之间的交联桥。为了检验这一假设，使用编码Gal-3的杆状病毒重组株感染缺乏内源性Gal-3的Sf 9昆虫细胞。免疫印迹和间接免疫荧光研究表明，重组病毒感染赋予Gal-3在Sf 9细胞上的表达，并且Gal-3定位于细胞表面以及细胞质中。用重组病毒感染的sf 9细胞在外源糖蛋白（即，无唾液酸胎球蛋白），而未感染或用野生型病毒感染的对照细胞则没有。乳糖和抗Gal-3抗体的Fab'片段显著抑制细胞间聚集。此外，在无唾液酸胎球蛋白的存在下，用重组病毒感染的Sf 9细胞与未感染的细胞的共悬浮导致Gal-3表达细胞的优先细胞-细胞粘附。这些结果直接证明了细胞表面Gal-3分子通过分支的可溶性互补糖缀合物桥接来介导同型细胞粘附的能力。
Galectin-3 (Gal-3) is a beta-galactoside-binding protein with M(r) approximately 30,000. Cell surface Gal-3 is postulated to be involved in homotypic aggregation of tumor cells in the circulation during metastasis through attachment to a complementary serum glycoprotein(s), which serves as a cross-linking bridge between adjacent cells. To test this hypothesis a recombinant strain of baculovirus encoding Gal-3 was used to infect Sf9 insect cells, which lack endogenous Gal-3. Immunoblotting and indirect immunofluorescence studies revealed that the infection with recombinant virus conferred Gal-3 expression on Sf9 cells, and the Gal-3 was localized on the cell surface as well as in the cytoplasm. Sf9 cells infected with recombinant virus underwent homotypic aggregation in the presence of exogenous glycoprotein (i.e., asialofetuin), whereas control cells uninfected or infected with wild-type virus did not. Lactose and Fab' fragments of anti-Gal-3 antibodies markedly inhibited the cell-cell aggregation. Moreover, cosuspension of Sf9 cells infected with the recombinant virus with uninfected cells in the presence of asialofetuin resulted in a preferential cell-cell adhesion of the Gal-3-expressing cells. These results directly demonstrate the ability of cell surface Gal-3 molecules to mediate homotypic cell adhesion by bridging through branched, soluble complementary glycoconjugates.