Kuganesan Nishanth, Dlamini Samkeliso, Tillekeratne L M Viranga, Taylor William R
Department of Biological Sciences, University of Toledo, Toledo, Ohio, USA.
Department of Medicinal and Biological Chemistry, University of Toledo, Toledo, Ohio, USA.
Cell Biochem Funct. 2025 Jun;43(6):e70085. doi: 10.1002/cbf.70085.
Tumor suppressor RB is a central regulator of cell cycle progression. By binding to E2F transcription factors, RB can inhibit transcription of E2F target genes to cause cell cycle arrest. Cyclin dependent kinases (CDK) regulate the interaction of RB/E2F by phosphorylating RB at multiple sites. Previously, we observed that CDK2, RB and E2F inhibit ferroptosis. Ferroptosis is a non-apoptotic, iron-dependent form of cell death characterized by toxic lipid peroxidation. Here, we investigate whether RB is a downstream target of CDK activity in the regulation of ferroptosis. We approach this question by overexpressing wild-type (WT) RB or a mutant RB that cannot be phosphorylated by CDKs (RBΔCDK) followed by analysis of ferroptosis. Overexpressing WT-RB reduced sensitivity to ferroptosis while the RBΔCDK mutant increased sensitivity. As we previously found, increasing CDK2 expression reduced ferroptotic sensitivity. This reduction persisted in cells expressing RBΔCDK. However, WT-RB blocked the ability of CDK2 to inhibit ferroptosis. These observations suggest that at least part of the mechanism by which CDK2 inhibits ferroptosis is by phosphorylating RB.
肿瘤抑制因子RB是细胞周期进程的核心调节因子。通过与E2F转录因子结合，RB可抑制E2F靶基因的转录，从而导致细胞周期停滞。细胞周期蛋白依赖性激酶（CDK）通过在多个位点磷酸化RB来调节RB/E2F的相互作用。此前，我们观察到CDK2、RB和E2F可抑制铁死亡。铁死亡是一种非凋亡性、铁依赖性的细胞死亡形式，其特征是有毒的脂质过氧化。在此，我们研究RB是否是CDK活性在调节铁死亡过程中的下游靶点。我们通过过表达野生型（WT）RB或不能被CDK磷酸化的突变型RB（RBΔCDK），然后分析铁死亡来探讨这个问题。过表达WT-RB降低了对铁死亡的敏感性，而RBΔCDK突变体则增加了敏感性。正如我们之前所发现的，增加CDK2的表达降低了铁死亡敏感性。这种降低在表达RBΔCDK的细胞中持续存在。然而，WT-RB阻断了CDK2抑制铁死亡的能力。这些观察结果表明，CDK2抑制铁死亡的机制至少部分是通过磷酸化RB来实现的。
