RIPK3羟基化在程序性坏死中的作用及维生素C诱导的RIPK3羟基化在乳腺癌治疗中的应用

Apoptosis and necroptosis are the two main forms of programmed cell death (PCD). RIPK3, a critical regulator of necroptosis, binds to RIPK1 and activate its downstream substrates such as PYGL, GLUL, GLUD1, MLKL, PGAM5, and then initiates the necroptosis. RIPK3 contains a LXXLAP motif that is recognized and proline-hydroxylated by PHDs. Here we report the proline-hydroxylation of RIPK3. Vitamin C, a cofactor of PHDs, promotes the hydroxylation of RIPK3. Differently, the inhibitor of PHDs (DMOG) inhibits the hydroxylation of RIPK3. We also found that vitamin C can induce the cell death like TNF/zVAD and this effect is dependent on RIPK3. This study will determine the mechanisms by which proline-hydroxylation of RIPK3 affects necroptosis. Meanwhile, we will determine whether vitamin C can induce RIPK3-dependent necroptosis of human breast cancer cells in vivo. This study will uncover a new mechanism of necroptosis and provide a new idea for the anti-tumor effect of vitamin C.

细胞程序性死亡分为凋亡和程序性坏死两种，其中RIPK3是细胞程序性坏死重要的调控因子。RIPK1结合RIPK3进一步激活其下游底物如PYGL、GLUL、GLUD1、MLKL、PGAM5，进而启动程序性坏死。RIPK3含有LXXLAP的氨基酸序列，而此序列是脯氨酸羟基化酶（PHDs）特异性识别并发生脯氨酸羟基化的特征序列。我们证实RIPK3存在脯氨酸羟基化修饰，这种修饰被PHDs辅因子维生素C所促进，相反却能被PHDs抑制剂DMOG所抑制；我们还发现维生素C能发挥与TNF/zVAD一样诱导细胞发生依赖于RIPK3的细胞死亡。本研究将继续探讨RIPK3脯氨酸羟基化修饰对程序性坏死的影响，深入探索其发生脯氨酸羟基化修饰的机制；同时也通过体内实验验证维生素C是否能诱导乳腺癌细胞产生依赖于RIPK3的程序性坏死。本研究有助于阐明程序性细胞坏死的新机制，也为维生素C抗肿瘤作用提供了新思路。