Research progress in RIPK3 and its inhibitors / 中国药理学通报

Receptor-interacting serine/threonine-protein kinase 3(RIPK3),a member of the RIP kinase family,plays an important role in cell death,especially in necroptosis. In addition,RIPK3 is also involved in apoptosis and pyroptosis,suggesting that RIPK3 may be the intersection of multiple cell death and it possesses the potential to be a target for precise regulation of cell death. According to the kinase binding mode,current RIPK3 inhibitors can be classified into type ,type Ⅱ and other types. This review summarizes the research progress in the role of RIPK3 in cell death and its inhibitors,which is of great significance in seeking drugs for the treatment of injury-related diseases.

Atractylodin induces programmed necrosis of non-small cell lung cancer A549 cells and inhibits xenograft growth in nude mice by activating the RIPK1/RIPK3/MLKL signaling pathway / 中国肿瘤生物治疗杂志

@#目的：探讨苍术素（ATR）通过调节受体相互作用蛋白激酶（RIPK）1/RIPK3/混合谱系激酶结构域样（MLKL）信号通路对非小细胞肺癌（NSCLC）A549细胞程序性死亡及裸鼠移植瘤生长的影响。方法：使用0~160 μmol/L的ATR处理A549细胞，MTT法检测细胞存活率以确定后续实验给药浓度。使用ATR和/或RIPK1抑制剂Nec-1（necrostatin-1）、caspase抑制剂Z-VAD-FMK处理A549细胞，验证ATR是否诱导A549细胞发生程序性坏死。将A549细胞分为对照组、ATR-L组、ATR-M组、ATR-H组（分别用0、10、20、40 μmol/L ATR处理）、ATR+Nec-1组（40 μmol/L ATR+50 μmol/L Nec-1处理），处理24 h后，采用PI单染及Hoechst33342/PI双染法检测细胞死亡情况、透射电镜观察细胞死亡形态、DCFH-DA荧光探针法检测细胞内ROS水平、JC-1染色法检测线粒体膜电位、WB法检测细胞中RIPK1/RIPK3/MLKL信号通路相关蛋白质的表达水平。构建A549细胞裸鼠移植瘤模型，用10 mg/kg ATR（溶于玉米油中）对裸鼠灌胃给药5周，观察ATR对移植瘤生长的影响，WB法检测移植瘤组织中RIPK1/RIPK3/MLKL信号通路相关蛋白质的表达水平。结果：10~160 μmol/L的ATR可显著抑制A549细胞增殖，选择10、20、40 μmol/L的ATR进行后续实验。ATR组A549细胞存活率显著低于对照组（P<0.01）和ATR+Nec-1组（P<0.01），而ATR+z-VAD组细胞存活率显著低于z-VAD组（P<0.01），说明ATR可诱导A549细胞发生程序性坏死而非凋亡。与对照组比较，ATR处理组A549细胞发生肿胀，线粒体内脊消失呈空泡化，细胞内容物向外泄漏，细胞核聚集，表现为坏死特征，ATR-L组、ATR-M组、ATR-H组A549细胞死亡率、ROS水平及p-RIPK1、p-RIPK3、p-MLKL表达水平均显著升高，线粒体膜电位显著降低（均P<0.01），且呈药物浓度依赖性；与ATR-H组比较，ATR+Nec-1组细胞死亡率、ROS及p-RIPK1、p-RIPK3、p-MLKL表达水平降低，线粒体膜电位显著升高（均P<0.01）。裸鼠移植瘤实验结果显示，与对照组比较，ATR组裸鼠移植瘤体积、移植瘤质量均降低（P<0.05，或P<0.01），而与瘤组织中p-RIPK1、p-RIPK3、p-MLKL蛋白表达水平均显著升高（均P<0.01）。结论：ATR可能通过激活RIPK1/RIPK3/MLKL信号通路诱导A549细胞发生程序性坏死，抑制A549细胞及其裸鼠移植瘤的生长。

Effects and mechanisms of total flavones of Abelmoschus manihot in inhibiting podocyte necroptosis and renal fibrosis in diabetic kidney disease / 中国中药杂志

Previous studies have shown that high blood glucose-induced chronic microinflammation can cause inflammatory podocyte injury in patients with diabetic kidney disease(DKD). Therein, necroptosis is a new form of podocyte death that is closely associated with renal fibrosis(RF). To explore the effects and mechanisms in vivo of total flavones of Abelmoschus manihot(TFA), an extract from traditional Chinese herbal medicine Abelmoschus manihot for treating kidney diseases, on podocyte necroptosis and RF in DKD, and to further reveal its scientific connotation with multi-pathway and multi-target, the authors randomly divided all rats into four groups: a namely normal group, a model group, a TFA group and a rapamycin(RAP) group. After the modified DKD rat models were successfully established, four group rats were given double-distilled water, TFA suspension and RAP suspension, respectively by gavage every day. At the end of the 4th week of drug treatment, all rats were sacrificed, and the samples of their urine, blood and kidneys were collected. And then, the various indicators related to podocyte necroptosis and RF in the DKD model rats were observed, detected and analyzed, respectively. The results indicated that, general condition, body weight(BW), serum creatinine(Scr), urinary albumin(UAlb), and kidney hypertrophy index(KHI) in these modified DKD model rats were both improved by TFA and RAP. Indicators of RF, including glomerular histomorphological characteristics, fibronectin(FN) and collagen type Ⅰ(collagen Ⅰ) staining extent in glomeruli, as well as the protein expression levels of FN, collagen Ⅰ, transforming growth factor-β1(TGF-β1) and Smad2/3 in the kidneys were improved respectively by TFA and RAP. Podocyte damage, including foot process form and the protein expression levels of podocin and CD2AP in the kidneys was improved by TFA and RAP. In addition, tumor necrosis factor-α(TNF-α)-mediated podocyte necroptosis in the kidneys, including the morphological characteristics of podocyte necroptosis, the extent and levels of the protein expression of TNF-α and phosphorylated mixed lineage kinase domain like pseudokinase(p-MLKL) was improved respectively by TFA and RAP. Among them, RAP had the better effect on p-MLKL. More importantly, the activation of the receptor interacting serine/threonine protein kinase 1(RIPK1)/RIPK3/MLKL signaling axis in the kidneys, including the expression levels of its key signaling molecules, such as phosphorylated receptor interacting serine/threonine protein kinase 1(p-RIPK1), p-RIPK3, p-MLKL and cysteinyl aspartate specific proteinase-8(caspase-8) was improved respectively by TFA and RAP. Among them, the effect of TFA on p-RIPK1 was superior. On the whole, in this study, the authors demonstrated that TFA alleviates podocyte necroptosis and RF in DKD through inhibiting the activation of the TNF-α-mediated RIPK1/RIPK3/MLKL signaling axis in diabetic kidneys. The authors' findings provide new pharmacological evidence to reveal the scientific connotation of TFA in treating RF in DKD in more depth.

Progress in RIPK3-mediated necroptosis involved in myocardial ischemia-reperfusion injury / 中国药理学通报

Aim Timely re establishment of coronary blood How in patients with myocardial infarction is the cornerstone of their treatment; however, substantial amount of damage can oecur as a consequence of reperfusion.In recent years it has been found that receptor interacting protein kinase 3 ( RIPK3 ) contributes remarkably to myocardial ischemia-reperfusion injury (MIRI).RIPK3 can regulate necroptosis through RIPK1/RIPK3/MLKL and CaMKII, respectively, and participate in the MIRI process.This artiele reviews the researeh progress of RIPK3-mediated ne¬ croptosis involved in MIRI from endoplasmic reticulum stress, mitochondrial fragmentation disturbanee, cardiac microvascular dysfunction and inflammation, and focuses on whether RIPK3 can be used as a new target for anti-MIRI, so as to provide a new strategy and choice for improving the clinical treatment effect and prognosis of ischemic heart disease.

Kinase activity of novel receptor interacting protein kinase 3 mutants / 上海交通大学学报（医学版）

Objective:To explore the kinase activity of novel receptor interacting protein kinase 3 (RIPK3) mutants. Methods:The four amino acids (Q84WDF87) of RIPK3 were mutated respectively and these mutants were co-transfected with mixed lineage kinase domain like pseudokinase (MLKL) into HEK293T cells. The auto-phosphorylation of these mutants at S232 and phosphorylation of MLKL at S345 were detected by Western blotting. The interaction between RIPK3 and MLKL was tested by co-immunoprecipitation. The oligomerization of MLKL was detected by non-reducing gel. Results:The kinase activities of RIPK3ΔQ84, RIPK3ΔW85 and RIPK3ΔD86 were effectively decreased. Nevertheless, the kinase activities of RIPK3Q84A/RIPK3Q84E, RIPK3W85Y and RIPK3D86A/RIPK3D86Y did not change markedly. The auto-phosphorylation of RIPK3W85A at S232 was decreased without affecting phosphorylation and oligomerization of MLKL. Conclusion:The amino acid site Q84, W85 or D86 plays a critical role in RIPK3 kinase activity. The kinase activity of RIPK3W85A is decreased, but it does not affect MLKL.