Bikfalvi A, Klein S, Pintucci G, Quarto N, Mignatti P, Rifkin D B
Department of Cell Biology, New York University Medical Center, New York 10016.
J Cell Biol. 1995 Apr;129(1):233-43. doi: 10.1083/jcb.129.1.233.
To study possible functional differences of the 18-kD and high molecular weight forms of basic fibroblast growth factor (bFGF), we have examined the effect of endogenous production of different bFGF forms on the phenotype of NIH 3T3 cells. Cells transfected with cDNAs coding for either 18-kD bFGF (18-kD bFGF) or all four molecular forms (18, 22, 22.5, 24 kD; wild type [WT] bFGF) exhibit increased migration and decreased FGF receptor number compared to parental cells. However, migration and FGF receptor number of cells transfected with a cDNA coding only for high molecular weight bFGF (22, 22.5, and 24 kD; HMW bFGF) were similar to that of parental cells transfected with vector alone. Cells expressing HMW, 18 kD, or WT bFGF grew to high saturation densities in 10% serum. However, only cells expressing HMW or WT bFGF grew in low serum. Cell surface or metabolic labeling of the different cell types followed by immunoprecipitation with anti-bFGF antibody showed primarily cell surface-associated 18-kD bFGF. In addition, when cells expressing exclusively HMW bFGF were transfected with a cDNA coding for 18-kD bFGF, migration was increased, bFGF receptors were down-regulated, and 18-kD bFGF was found on the cell surface. Cells expressing 18-kD bFGF transfected with a cDNA encoding FGF receptor-2 lacking the COOH-terminal domain (dominant negative bFGF receptor) exhibited a flat morphology and decreases in migration and saturation density. Cells expressing HMW bFGF transfected with the dominant negative bFGF receptor continued to grow to a high saturation density, proliferated in low serum, and exhibited no morphological changes. These results indicate that increased cell migration and FGF receptor down-regulation are mediated by the extracellular interaction of 18-kD bFGF with its cell surface receptor. Growth in low serum may be stimulated by the intracellular action of HMW bFGF through mechanisms independent of the presence of a cell surface receptor. Thus, the different molecular forms of bFGF may act through distinct but convergent pathways.
为了研究碱性成纤维细胞生长因子（bFGF）的18-kD和高分子量形式可能存在的功能差异，我们检测了不同bFGF形式的内源性产生对NIH 3T3细胞表型的影响。与亲代细胞相比，用编码18-kD bFGF（18-kD bFGF）或所有四种分子形式（18、22、22.5、24 kD；野生型[WT] bFGF）的cDNA转染的细胞迁移增加，FGF受体数量减少。然而，用仅编码高分子量bFGF（22、22.5和24 kD；HMW bFGF）的cDNA转染的细胞的迁移和FGF受体数量与仅用载体转染的亲代细胞相似。表达HMW、18 kD或WT bFGF的细胞在10%血清中生长至高饱和密度。然而，只有表达HMW或WT bFGF的细胞能在低血清中生长。对不同细胞类型进行细胞表面或代谢标记，然后用抗bFGF抗体进行免疫沉淀，结果显示主要是细胞表面相关的18-kD bFGF。此外，当仅表达HMW bFGF的细胞用编码18-kD bFGF的cDNA转染时，迁移增加，bFGF受体下调，并且在细胞表面发现了18-kD bFGF。用编码缺乏COOH末端结构域的FGF受体-2（显性负性bFGF受体）的cDNA转染表达18-kD bFGF的细胞，细胞呈现扁平形态，迁移和饱和密度降低。用显性负性bFGF受体转染表达HMW bFGF的细胞继续生长至高饱和密度，在低血清中增殖，且无形态学变化。这些结果表明，细胞迁移增加和FGF受体下调是由18-kD bFGF与其细胞表面受体的细胞外相互作用介导的。低血清中的生长可能是由HMW bFGF的细胞内作用通过独立于细胞表面受体存在的机制刺激的。因此，bFGF的不同分子形式可能通过不同但趋同的途径发挥作用。
