成纤维细胞生长因子 19 (FGF19) 已成为治疗骨骼代谢紊乱的新可能途径。然而,FGF19 对骨骼系统细胞周期进程的作用知之甚少。在这里,我们证明 FGF19 能够通过与 β-Klotho (KLB) 的相互作用来减少软骨细胞的增殖并导致细胞周期 G2 期停滞,β-Klotho (KLB) 是一种帮助 FGF19 与其受体连接的重要辅助蛋白。FGF19 通过调节 cdk1/cylinb1、chk1 和 gadd45a 的表达介导细胞周期停滞。然后我们证实FGF19与膜受体FGFR4的结合是FGF19介导的细胞周期停滞所必需的,并进一步证明FGF19介导的细胞周期停滞是通过p38/MAPK信号的激活来实现的。通过抑制剂实验,我们发现,即使存在 FGF19,抑制 FGFR4 也会导致 p38 信号传导下调。同时,抑制 p38 信号传导可减少 FGF19 诱导的软骨细胞的细胞周期停滞。此外,阻断p38信号传导有助于保留软骨细胞中被FGF19降低的cdk1和cyclinb1的表达,并降低软骨细胞中被FGF19增强的chk1和gadd45a的表达。总而言之,这项研究首次证明 FGF19 通过 FGFR4-p38/MAPK 轴诱导细胞周期停滞在 G2 期,并加深了我们对 FGF19 在软骨细胞细胞周期进展中的作用的理解。阻断p38信号传导有助于保留软骨细胞中被FGF19减少的cdk1和cyclinb1的表达,并减少软骨细胞中被FGF19增强的chk1和gadd45a的表达。总而言之,这项研究首次证明 FGF19 通过 FGFR4-p38/MAPK 轴诱导细胞周期停滞在 G2 期,并加深了我们对 FGF19 在软骨细胞细胞周期进展中的作用的理解。阻断p38信号传导有助于保留软骨细胞中被FGF19减少的cdk1和cyclinb1的表达,并减少软骨细胞中被FGF19增强的chk1和gadd45a的表达。总而言之,这项研究首次证明 FGF19 通过 FGFR4-p38/MAPK 轴诱导细胞周期停滞在 G2 期,并加深了我们对 FGF19 在软骨细胞细胞周期进展中的作用的理解。
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FGF19 induces the cell cycle arrest at G2-phase in chondrocytes
Fibroblast growth factor 19 (FGF19) has appeared as a new possible avenue in the treatment of skeletal metabolic disorders. However, the role of FGF19 on cell cycle progression in skeletal system is poorly understood. Here we demonstrated that FGF19 had the ability to reduce the proliferation of chondrocytes and cause cell cycle G2 phase arrest through its interaction with β-Klotho (KLB), an important accessory protein that helps FGF19 link to its receptor. FGF19-mediated cell cycle arrest by regulating the expressions of cdk1/cylinb1, chk1 and gadd45a. We then confirmed that the binding of FGF19 to the membrane receptor FGFR4 was necessary for FGF19-mediated cell cycle arrest, and further proved that FGF19-mediated cell cycle arrest was via activation of p38/MAPK signaling. Through inhibitor experiments, we discovered that inhibition of FGFR4 led to down-regulation of p38 signaling even in the presence of FGF19. Meanwhile, inhibiting p38 signaling reduced the cell cycle arrest of chondrocytes induced by FGF19. Furthermore, blocking p38 signaling facilitated to retain the expression of cdk1 and cyclinb1 that had been reduced in chondrocytes by FGF19 and decreased the expression of chk1 and gadd45a that had been enhanced by FGF19 in chondrocytes. Taking together, this study is the first to demonstrate that FGF19 induces cell cycle arrest at G2 phase via FGFR4-p38/MAPK axis and enlarges our understanding about the role of FGF19 on cell cycle progression in chondrocytes.