Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Puschino, Institutskaya st., 3, 142290, Russia.
Faculty of Fundamental Medicine, MV Lomonosov Moscow State University, 119991 Moscow, Russia.
Cell Signal. 2020 Jun;70:109590. doi: 10.1016/j.cellsig.2020.109590. Epub 2020 Feb 26.
Fas-ligand/CD178 belongs to the TNF family proteins and is the well-characterized inducer of cell death. We showed previously that the interaction of Fas-ligand and caveolin-1 is necessary for Fas-ligand translocation to rafts, and the subsequent induction of Fas-ligand-dependent cell death. Both molecules can undergo phosphorylation, however the role of the phosphorylation state of Fas-ligand and caveolin-1 in their physical association, and consequently in of Fas - mediated cell death induction is currently unknown. In this study, we show that in control cells Fas-ligand interaction with caveolin-1 is not observed, and both molecules are phosphorylated. The intracellular part of Fas-ligand was shown to form a complex with p59Fyn-kinase. Upon cell death activation, the expression and activity of p59Fyn-kinase decreases substantially, leading to the disruption of Fas-ligand - p59Fyn-kinase association, dephosphorylation of Fas-ligand and caveolin-1, and formation of a complex between them (Fas-ligand - caveolin-1). The analysis of the effects of kinase and phosphatase inhibitors revealed that phosphorylation of Fas-ligand and caveolin-1 at tyrosine residues suppressed Fas-mediated cell death. Thus, dephosphorylation of Fas-ligand and caveolin-1 is critical for triggering Fas-ligand-mediated apoptotic pathway and cell death execution.
Fas-配体/CD178 属于 TNF 家族蛋白，是一种已知的细胞死亡诱导因子。我们之前的研究表明，Fas-配体与窖蛋白-1的相互作用对于 Fas-配体向筏的易位以及随后诱导 Fas-配体依赖性细胞死亡是必需的。这两种分子都可以发生磷酸化，但是 Fas-配体和窖蛋白-1磷酸化状态在它们的物理结合中的作用，以及在 Fas 介导的细胞死亡诱导中的作用目前尚不清楚。在本研究中，我们发现在对照细胞中未观察到 Fas-配体与窖蛋白-1的相互作用，并且这两种分子都发生了磷酸化。Fas-配体的细胞内部分与 p59Fyn-激酶形成复合物。在细胞死亡激活后，p59Fyn-激酶的表达和活性显著降低，导致 Fas-配体与 p59Fyn-激酶的关联被破坏，Fas-配体和窖蛋白-1去磷酸化，并形成它们之间的复合物（Fas-配体-窖蛋白-1）。激酶和磷酸酶抑制剂的分析表明，Fas-配体和窖蛋白-1酪氨酸残基的磷酸化抑制 Fas 介导的细胞死亡。因此，Fas-配体和窖蛋白-1的去磷酸化对于触发 Fas-配体介导的凋亡途径和细胞死亡执行至关重要。
