Appeddu P A, Shur B D
Department of Biochemistry and Molecular Biology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Proc Natl Acad Sci U S A. 1994 Mar 15;91(6):2095-9. doi: 10.1073/pnas.91.6.2095.
Despite the identification and characterization of cell surface receptors for the extracellular matrix, it is unknown how their relative expression and cytoskeletal association regulate cell migration. Previous studies have identified beta-1,4-galactosyltransferase (GalTase; EC 2.4.1.38) on the surface of migrating cells, where it mediates cell migration on basal lamina matrices by associating with the cytoskeleton and binding to N-linked oligosaccharides in the E8 domain of laminin. In this study, the function of GalTase during cell migration was examined directly by analyzing the migration rate of stably transfected cell lines in which the relative level of surface GalTase and its ability to associate with the cytoskeleton were altered. We show here that the cytoskeleton contains a limiting, saturable, number of binding sites for surface GalTase. Furthermore, the rate of cell migration was inversely related to the ability of surface GalTase to associate with the cytoskeleton. Elevating surface GalTase in excess of the number of cytoskeleton-binding sites reduced the rate of cell migration, whereas decreasing the amount of surface GalTase available to bind the cytoskeleton increased migration rates. These results show that the rate of cell migration on basal lamina is directly dependent upon the expression of surface GalTase and the ability of this protein to associate with a limiting number of cytoskeleton-binding sites.
尽管已经鉴定并表征了细胞外基质的细胞表面受体，但尚不清楚它们的相对表达和细胞骨架关联如何调节细胞迁移。先前的研究已经在迁移细胞表面鉴定出β-1,4-半乳糖基转移酶（GalTase；EC 2.4.1.38），它通过与细胞骨架结合并与层粘连蛋白E8结构域中的N-连接寡糖结合，介导细胞在基膜基质上的迁移。在本研究中，通过分析稳定转染细胞系的迁移速率，直接检测了GalTase在细胞迁移过程中的功能，在这些细胞系中，表面GalTase的相对水平及其与细胞骨架结合的能力发生了改变。我们在此表明，细胞骨架含有数量有限、可饱和的表面GalTase结合位点。此外，细胞迁移速率与表面GalTase与细胞骨架结合的能力呈负相关。将表面GalTase提升至超过细胞骨架结合位点的数量会降低细胞迁移速率，而减少可用于结合细胞骨架的表面GalTase的量则会提高迁移速率。这些结果表明，细胞在基膜上的迁移速率直接取决于表面GalTase的表达以及该蛋白与数量有限的细胞骨架结合位点结合的能力。
