Mignatti P, Morimoto T, Rifkin D B
Department of Cell Biology, New York University Medical Center, New York.
Proc Natl Acad Sci U S A. 1991 Dec 15;88(24):11007-11. doi: 10.1073/pnas.88.24.11007.
Basic fibroblast growth factor (bFGF), a protein with angiogenic, mitogenic, and chemotactic properties, lacks a signal sequence and is not secreted via the classical secretory pathway. However, the growth factor is known to act extracellularly. Since no defined mechanism for bFGF release has been described, it has been suggested that this growth factor is released from dead or damaged cells. To test this hypothesis we characterized the effect of exogenously added bFGF and neutralizing antibody on the migration of single, isolated NIH 3T3 cells transfected with bFGF cDNA. Under these conditions the observed cell cannot be affected by bFGF derived from other cells. Cells were seeded onto colloidal gold-coated coverslips at a density of one cell per coverslip. A cell migrating on this substrate produces a track free of refringent gold particles that is measured by an image analyzer. The results showed that cell motility directly correlated with the amount of bFGF released from the migrating cells. Affinity-purified anti-bFGF antibody, but not irrelevant IgG, reduced the level of migration of the bFGF transfectants to that of the control cells transfected with the vector alone, showing that bFGF stimulates migration of the cell that releases it. Thus, bFGF is secreted by viable cells and mediates cell functions via a "true" autocrine mechanism.
碱性成纤维细胞生长因子（bFGF）是一种具有血管生成、促有丝分裂和趋化特性的蛋白质，它缺乏信号序列，不会通过经典分泌途径分泌。然而，已知这种生长因子在细胞外发挥作用。由于尚未描述bFGF释放的明确机制，有人提出这种生长因子是从死亡或受损细胞中释放出来的。为了验证这一假设，我们对外源添加的bFGF和中和抗体对转染了bFGF cDNA的单个分离的NIH 3T3细胞迁移的影响进行了表征。在这些条件下，观察到的细胞不会受到来自其他细胞的bFGF的影响。将细胞以每盖玻片一个细胞的密度接种到胶体金包被的盖玻片上。在这种基质上迁移的细胞会产生一条没有折射金颗粒的轨迹，该轨迹由图像分析仪测量。结果表明，细胞运动性与迁移细胞释放的bFGF量直接相关。亲和纯化的抗bFGF抗体而非无关的IgG，将bFGF转染细胞的迁移水平降低到仅用载体转染的对照细胞的迁移水平，表明bFGF刺激释放它的细胞的迁移。因此，bFGF由活细胞分泌，并通过“真正的”自分泌机制介导细胞功能。
