Merck KGaA, Darmstadt, Germany.
Merck KGaA, Darmstadt, Germany.
Exp Cell Res. 2020 Oct 15;395(2):112236. doi: 10.1016/j.yexcr.2020.112236. Epub 2020 Aug 13.
Sprifermin is a human recombinant fibroblast growth factor 18 (rhFGF18) in clinical development for knee osteoarthritis. Previously, we demonstrated that sprifermin exerts an anabolic effect on chondrocytes in 3D culture with cyclic but not permanent exposure. Here, we hypothesized that permanent exposure to sprifermin de-sensitizes the cells. To test this, a combination of Western-blot and cell staining methods was used. We demonstrate that sprifermin is transiently internalized in chondrocytes along with a transient increase in ERK1/2 activation. We also show that sprifermin is intracellularly degraded, probably together with its receptor FGFR3, thus preventing further stimulation. However, incubation without sprifermin re-sensitizes the cells. Finally, we show that sprifermin endocytosis is clathrin- and dynamin-independent and that receptor activation is not necessary for sprifermin's endocytosis. In this study, we link the role of endocytosis to the cell response and elucidate for the first time a de-sensitization phenomenon to a FGF.
Sprifermin 是一种处于临床开发阶段的人重组成纤维细胞生长因子 18（rhFGF18），用于治疗膝骨关节炎。此前，我们的研究表明，Sprifermin 对 3D 培养的软骨细胞具有合成代谢作用，但其作用具有周期性而非永久性。在这里，我们假设 Sprifermin 的永久性暴露会使细胞脱敏。为了验证这一点，我们采用了 Western blot 和细胞染色相结合的方法。研究结果表明，Sprifermin 会与 ERK1/2 激活的短暂增加一起被瞬时内化到软骨细胞中。我们还表明，Sprifermin 会在细胞内降解，可能与其受体 FGFR3 一起被降解，从而阻止进一步的刺激。然而，没有 Sprifermin 的孵育会使细胞重新敏感。最后，我们表明 Sprifermin 的内化与网格蛋白和动力蛋白无关，并且受体的激活对于 Sprifermin 的内化不是必需的。在这项研究中，我们将内化作用与细胞反应联系起来，并首次阐明了成纤维细胞生长因子的脱敏现象。
