Mechanism of Shikonin on spinal cord injury in rats based on TNFR/RIPK1 pathway / 中国骨伤

OBJECTIVE@#To explore the effect of shikonin on the recovery of nerve function after acute spinal cord injury(SCI) in rats.@*METHODS@#96 male Sprague-Dawley(SD)rats were divided into 4 groups randomly:sham operation group (Group A), sham operation+shikonin group (Group B), SCI+ DMSO(Group C), SCI+shikonin group (Group D).The acute SCI model of rats was made by clamp method in groups C and D . After subdural catheterization, no drug was given in group A. rats in groups B and D were injected with 100 mg·kg-1 of shikonin through catheter 30 min after modeling, and rats in group C were given with the same amount of DMSO, once a day until the time point of collection tissue. Basso-Beattie-Bresnahan(BBB) scores were performed on 8 rats in each group at 6, 12, and 3 d after moneling, and oblique plate tests were performed on 1, 3, 7 and 14 d after modeling, and then spinal cord tissues were collected. Eight rats were intraperitoneally injected with propidine iodide(PI) 1 h before sacrificed to detection PI positive cells at 24 h in each group. Eight rats were sacrificed in each group at 24 h after modeling, the spinal cord injury was observed by HE staining.The Nissl staining was used to observe survivor number of nerve cells. Western-blot technique was used to detect the expression levels of Bcl-2 protein and apoptosis related protein RIPK1.@*RESULTS@#After modeling, BBB scores were normal in group A and B, but in group C and D were significantly higher than those in group A and B. And the scores in group D were higher than those in group C in each time point (P<0.05). At 12 h after modeling, the PI red stained cells in group D were significantly reduced compared with that in group C, and the disintegration of neurons was alleviated(P<0.05). HE and Nissl staining showed nerve cells with normal morphology in group A and B at 24h after operation. The degree of SCI and the number of neuronal survival in group D were better than those in group C, the difference was statistically significant at 24h (P<0.05). The expression of Bcl-2 and RIPK1 proteins was very low in group A and B;The expression of RIPK1 was significantly increased in Group C and decreased in Group D, with a statistically significant difference (P<0.05);The expression of Bcl-2 protein in group D was significantly higher than that in group C (P<0.05).@*CONCLUSION@#Shikonin can alleviate the pathological changes after acute SCI in rats, improve the behavioral score, and promote the recovery of spinal nerve function. The specific mechanism may be related to the inhibition of TNFR/RIPK1 signaling pathway mediated necrotic apoptosis.

Progress in study on the final executor of necroptosis MLKL and its inhibitors / 中南大学学报(医学版)

Necroptosis is one of the regulated cell death, which involves receptor interacting protein kinase (RIPK) 1/RIPK3/mixed lineage kinase domain like protein (MLKL) signaling pathway. Among them, MLKL is the final execution of necroptosis. The formation of RIPK1/RIPK3/MLKL necrosome induces the phosphorylated MLKL, and the activated MLKL penetrates into the membrane bilayer to form membrane pores, which damages the integrity of the membrane and leads to cell death. In addition to participating in necroptosis, MLKL is also closely related to other cell death, such as NETosis, pyroptosis, and autophagy. Therefore, MLKL is involved in the pathological processes of various diseases related to abnormal cell death pathways (such as cardiovascular diseases, neurodegenerative diseases and cancer), and may be a therapeutic target of multiple diseases. Understanding the role of MLKL in different cell death can lay a foundation for seeking various MLKL-related disease targets, and also guide the development and application of MLKL inhibitors.

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.

Inhibition of TAK1 aggravates airway inflammation by increasing RIPK1 activity and promoting macrophage death in a mouse model of toluene diisocyanate-induced asthma / 南方医科大学学报

OBJECTIVE@#To explore the effect of transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1) on toluene diisocyanate (TDI)-induced allergic airway inflammation in mice.@*METHODS@#Thirty-two mice were randomly divided into AOO group, AOO+5Z-7-Oxozeaenol group, TDI group, and TDI+5Z-7-Oxozeaenol group. Another 32 mice were randomly divided into AOO group, TDI group, TDI +5Z-7-Oxozeaenol group, and TDI +5Z-7-Oxozeaenol + Necrostatin-1 group. TAK1 inhibitor (5Z-7-Oxozeaenol, 5 mg/kg) and/or RIPK1 inhibitor (Necrostatin-1, 5 mg/kg) were used before each challenge. Airway responsiveness, airway inflammation and airway remodeling were assessed after the treatments. We also examined the effect of TDI-human serum albumin (TDI-HSA) conjugate combined with TAK1 inhibitor on the viability of mouse mononuclear macrophages (RAW264.7) using CCK8 assay. The expressions of TAK1, mitogen-activated protein kinase (MAPK) and receptor interacting serine/threonine protease 1 (RIPK1) signal pathway in the treated cells were detected with Western blotting. The effects of RIPK1 inhibitor on the viability of RAW264.7 cells and airway inflammation of the mouse models of TDI-induced asthma were evaluated.@*RESULTS@#TAK1 inhibitor aggravated TDI-induced airway inflammation, airway hyper responsiveness and airway remodeling in the mouse models (P < 0.05). Treatment with TAK1 inhibitor significantly decreased the viability of RAW264.7 cells, which was further decreased by co-treatment with TDI-HSA (P < 0.05). TAK1 inhibitor significantly decreased the level of TAK1 phosphorylation and activation of MAPK signal pathway induced by TDI-HSA (P < 0.05). Co-treatment with TAK1 inhibitor and TDI-HSA obviously increased the level of RIPK1 phosphorylation and caused persistent activation of caspase 8 (P < 0.05). RIPK1 inhibitor significantly inhibited the reduction of cell viability caused by TAK1 inhibitor and TDI-HSA (P < 0.05) and alleviated the aggravation of airway inflammation induced by TAK1 inhibitors in TDI-induced mouse models (P < 0.05).@*CONCLUSION@#Inhibition of TAK1 aggravates TDI-induced airway inflammation and hyperresponsiveness and may increase the death of macrophages by enhancing the activity of RIPK1 and causing persistent activation of caspase 8.

RIP1-dependent linear and nonlinear recruitments of caspase-8 and RIP3 respectively to necrosome specify distinct cell death outcomes

There remains a significant gap in our quantitative understanding of crosstalk between apoptosis and necroptosis pathways. By employing the SWATH-MS technique, we quantified absolute amounts of up to thousands of proteins in dynamic assembling/de-assembling of TNF signaling complexes. Combining SWATH-MS-based network modeling and experimental validation, we found that when RIP1 level is below ~1000 molecules/cell (mpc), the cell solely undergoes TRADD-dependent apoptosis. When RIP1 is above ~1000 mpc, pro-caspase-8 and RIP3 are recruited to necrosome respectively with linear and nonlinear dependence on RIP1 amount, which well explains the co-occurrence of apoptosis and necroptosis and the paradoxical observations that RIP1 is required for necroptosis but its increase down-regulates necroptosis. Higher amount of RIP1 (>~46,000 mpc) suppresses apoptosis, leading to necroptosis alone. The relation between RIP1 level and occurrence of necroptosis or total cell death is biphasic. Our study provides a resource for encoding the complexity of TNF signaling and a quantitative picture how distinct dynamic interplay among proteins function as basis sets in signaling complexes, enabling RIP1 to play diverse roles in governing cell fate decisions.

Expression and clinical significance of receptor-interacting protein serine-threonine kinases 1 in the nucleus pulposus of patients with lumbar disc herniation / 中国骨伤

OBJECTIVE@#To investigate the expression and clinical significance of receptor interacting protein serine-threonine kinases 1 (RIPK1) in the nucleus pulposus of patients with lumbar disc herniation (LDH).@*METHODS@#Nucleus pulposus tissue specimens of 40 patients with LDH patients underwent surgical treatment from January 2016 to January 2018 as the case group, and nucleus pulposus tissue specimens of 30 patients with lumbar spine fracture underwent surgical treatment at the same time as the control group. The expression of RIPK1 mRNA and protein of receptor interaction were detected by polymerase chain reaction (PCR) and Western blot, respectively. The expression of RIPK1 protein in the nucleus pulposus were detected by immunohistochemical staining. The concentrations of RIPK1 and tumor necrosis factor-α (TNF-α) in nucleus pulposus were detected by ELISA method. The relationship between the concentrations of RIPK1, TNF-α in nucleus pulposus and the Pearce grade of LDH patients was analyzed by one-way ANOVA. The correlation between RIPK1 and TNF-α was analyzed by Pearson.@*RESULTS@#RIPK1 was weakly positively expressed in nucleus pulposus of control group, and RIPK1 protein was positively or strongly positively expressed in case group. The expression of RIPK1 mRNA in nucleus pulposus of case group was higher than that of control group (@*CONCLUSION@#The expression levels of RIPK1 mRNA and protein in the intervertebral disc tissues of LDH patients are higher than those of normal intervertebral disc tissues, and increased with the increase of Pearce grade, which may be an important factor involved in LDH inflammatory disease.

Plasma levels of receptor interacting protein kinase-3 correlated with coronary artery disease / 中华医学杂志(英文版)

BACKGROUND@#Necroptosis plays an important role in human atherosclerosis and atheroma development. Since receptor interacting protein kinase-3 (RIP3) acts as a key mediator of necroptosis, this study aimed to explore its relationship between plasma RIP3 levels and coronary artery disease (CAD) and discover a potential new biomarker for screening CAD subtypes and severity.@*METHODS@#A total of 318 patients with CAD who had coronary angiography and 166 controls in Peking Union Medical College Hospital from September 2017 to January 2018 were enrolled in this study. Patients with CAD were divided into three subgroups: patients with stable coronary artery disease (SCAD), patients with unstable angina (UA), and patients with myocardial infarction (MI). The severity of atherosclerosis was determined by Gensini score (GSS). Logistic regression was used to determine the relationship between plasma RIP3 levels and CAD. The correlation between plasma RIP3 and GSS was calculated using multiple linear regression models.@*RESULTS@#Overall, plasma RIP3 levels were significantly higher than serum RIP3 levels. Plasma RIP3 levels in patients with CAD were significantly higher than those in controls. Plasma RIP3 levels were strongly associated with CAD (odds ratio: 6.00, 95% confidence interval 3.04-11.81; P < 0.001). Plasma RIP3 levels increased linearly from controls to patients with SCAD, then patients with UA, and finally to patients with MI. We found a significantly positive correlation between proportion of cases of acute coronary syndrome in subjects and their plasma RIP3 level quartile. Plasma RIP3 levels were also associated with GSS (B 0.027; standard error 0.012; P < 0.05).@*CONCLUSIONS@#Plasma RIP3 levels were independently associated with CAD. Plasma RIP3 levels could potentially supplement clinical assessment to screen CAD and determine CAD severity.

LRRK2 enhances Nod1/2-mediated inflammatory cytokine production by promoting Rip2 phosphorylation

The innate immune system is critical for clearing infection, and is tightly regulated to avert excessive tissue damage. Nod1/2-Rip2 signaling, which is essential for initiating the innate immune response to bacterial infection and ER stress, is subject to many regulatory mechanisms. In this study, we found that LRRK2, encoded by a gene implicated in Crohn's disease, leprosy and familial Parkinson's disease, modulates the strength of Nod1/2-Rip2 signaling by enhancing Rip2 phosphorylation. LRRK2 deficiency markedly reduces cytokine production in macrophages upon Nod2 activation by muramyl dipeptide (MDP), Nod1 activation by D-gamma-Glu-meso-diaminopimelic acid (iE-DAP) or ER stress. Our biochemical study shows that the presence of LRRK2 is necessary for optimal phosphorylation of Rip2 upon Nod2 activation. Therefore, this study reveals that LRRK2 is a new positive regulator of Rip2 and promotes inflammatory cytokine induction through the Nod1/2-Rip2 pathway.

Anticorpos conformacionais para PKCs clássicas e suas aplicações / Conformational antibodies against classical PKCs and their applications

A família proteína quinases C (PKC) é composta por dez isoenzimas, as quais são capazes de fosforilar resíduos de serina e treonina. A ativação dessas quinases envolve mudanças conformacionais, como a remoção do pseudo-substrato do sítio ativo e associação dessas enzimas com lipídeos em membranas biológicas. Além disso, três fosforilações são importantes para a maturação/ enovelamento da enzima e não estão associadas com o estado de ativação das cPKCs. Apesar dessas quinases estarem envolvidas em vários processos patológicos, como carcinogênese e doenças cardiovasculares, ainda não se estabeleceu a relação entre estado de ativação das PKCs com essas doenças. Isso se deve, em parte, à ausência de ferramentas que possibilitam a distinção das formas ativas e inativas das PKCs. Na presente tese, baseando-se em mudanças conformacionais sofridas pelas PKCs durante o processo de ativação, dois anticorpos contra cPKCs ativas foram racionalmente desenvolvidos, sendo um anticorpo policlonal (anti-C2Cat) e outro monoclonal (4.8E). O anticorpo anti-C2Cat foi desenvolvido a partir de imunização de coelhos com um peptídeo localizado na região de interação entre os domínios C2 e catalítico na PKC inativa. Já o anticorpo monoclonal 4.8E foi produzido após a imunização de camundongos Balb/ C com extrato de proteínas proveniente de células HEK293T superexpressando formas constitutivamente ativas da PKCßI. A seletividade de anti-C2Cat e 4.8E por cPKCs ativas foi demonstrada por ensaios de ELISA e de imunoprecipitação, sendo que os anticorpos sempre apresentaram maior afinidade por cPKCs ativas purificadas, superexpressas ou mesmo as endógenas. O anticorpo anti-C2Cat foi capaz de monitorar a dinâmica espaço-temporal da ativação das cPKCs em linhagens de neuroblastoma (Neuro-2A e SK-N-SH) estimuladas com PMA, morfina, ATP ou glutamato por diferentes tempos. Ainda, um maior conteúdo de cPKCs ativas foi detectado por anti-C2Cat na linhagem de câncer de mama MDA-MB-231 (triplo- negativa) do que em células MCF-7 (ER+). Em acordo com esses dados, anti-C2Cat identificou uma maior ativação de cPKCs em tumores mais agressivos de câncer de mama (subtipo triplo-negativo) do que em tumores menos agressivos (ER+, subtipo luminal). Os anticorpos conformacionais anti-C2Cat e 4.8E foram aplicados para elucidar vias de sinalização que levam à carcinogênese em células MDA-MB-231, por meio da realização de ensaios de co-imunoprecipitação, seguida pela identificação das proteínas por espectrometria de massas. Usando essa abordagem, os resultados sugerem que as cPKCs ativas possam estar envolvidas com a tradução de proteínas envolvidas na migração celular, como actina. Em conjunto, os resultado obtidos na presente tese demonstram duas formas racionais de desenvolver anticorpos contra cPKCs ativas, sendo que algumas aplicações para estas ferramentas foram demonstradas. Estratégias baseadas em mudanças conformacionais, similares às apresentadas aqui, poderão ser utilizadas para a produção racional de anticorpos contra outras quinases ou proteínas

The protein kinase C family (PKC) is composed of ten isoenzymes, which are capable of phosphorylating serine and threonine amino acid residues. PKC activation involves conformational changes, such as removing the pseudo-substrate from the active site and binding of the enzyme to lipids in biological membranes. In addition, PKC undergoes three phosphorylations that are important for the maturation/ folding of the enzyme and are not linked with activation status. Despite the fact that these kinases are involved in various pathological processes, such as carcinogenesis and cardiovascular disease, a relationship between PKC activation status with these diseases has not yet been established. This is partly due to the lack of tools to detect active PKC in tissue samples. In this thesis, based on conformational changes suffered by PKC during its activation, two antibodies against active cPKCs were rationally developed; a polyclonal antibody (anti-C2Cat) and a monoclonal (4.8E). Anti-C2Cat was produced after immunization of rabbits with a peptide located at the interface between the C2 and catalytic domains of cPKCs in an inactive PKC. The monoclonal antibody 4.8E was produced after immunization of Balb/C mice with total lysates from HEK293T cells overexpressing constitutively active forms of PKCßI. The anti-C2Cat and 4.8E specificity by active cPKCs was demonstrated by ELISA and immunoprecipitation assays, where the antibodies always showed higher affinity to active cPKCs. Anti-C2Cat was able to detect the temporal and spatial dynamics of cPKC activation upon receptor (morphine, ATP or glutamate) or phorbol ester stimulation in neuroblastoma lines (Neuro-2A and SK-N-SH). Futhermore, anti-C2Cat is able to detect active PKC in human tissues. Higher levels of active cPKC were observed in the more aggressive triple negative breast cancer tumors as compared to the less aggressive estrogen receptor positive tumors. Also, both antibodies were applied to study signaling pathways that lead to carcinogenesis in MDA-MB-231 cells by performing co-immunoprecipitation and mass spectrometry. Using this approach, the results suggest that active cPKCs may be involved in translation of proteins involved in cell migration, such as actin. Taken together, the results obtained in this thesis showed two rational ways to develop antibodies against active cPKCs and some applications for these tools were demonstrated. Strategies based on conformational changes, similar to those presented herein may be used for rational production of antibodies against other kinases and proteins

Activation of necroptosis in a rat model of acute respiratory distress syndrome induced by oleic acid / 生理学报

The present study was aimed to investigate the role of necroptosis in the pathogenesis of acute respiratory distress syndrome (ARDS). The rat model of ARDS was induced by intravenous injection of oleic acid (OA), and observed for 4 h. The lung injury was evaluated by arterial blood gas, lung wet-dry weight ratio (W/D) and histological analyses. Simultaneously, bronchoalveolar lavage fluid (BALF) was collected for total and differential cell analysis and total protein determination. Tumor necrosis factor alpha (TNF-α) level in BALF was determined with a rat TNF-α ELISA kit. Expressions of receptor interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like protein (MLKL) in lung tissue were determined by Western blot and immunohistochemical staining. The interaction between RIPK1 and RIPK3 was explored by immunoprecipitation. The results showed that, compared with those in control group, total white blood cells count (WBC), polymorphonuclear percentage (PMN%), total protein concentration, TNF-α level in BALF, W/D, and the alveolar-arterial oxygen tension difference (P(A-a)O) in OA group were significantly increased at 4 h after OA injection. Western blot and immunostaining further showed remarkably increased expressions of RIPK1, RIPK3 and MLKL in lung tissue from OA group. Additionally, immunoprecipitation results indicated an enforced interaction between RIPK1 and RIPK3 in OA group. Collectively, the TNF-α level in BALF and the RIPK1-RIPK3-MLKL signaling pathway in lung tissue were found to be upregulated and activated with the process of ARDS. These findings implicate that RIPK1/RIPK3-mediated necroptosis plays a possible role in the pathogenesis of ARDS, which may provide a new idea to develop novel drugs for the therapy of ARDS.

Programmed necrosis: a new target for ischemia reperfusion injury / 中南大学学报(医学版)

Recent years, the researchers have found a new type of cell death, referred to programmed necrosis or necroptosis, which involves the death receptor and the ligand binds and is initiated under the inhibition of apoptosis pathway. Programmed necrosis possesses the morphological features of typical necrosis accompanied by inflammation. The receptor interacting protein kinase 1/3(RIPK1/3) can be inhibited by the specific inhibitors, such as necrostatin-1. RIPK1/3 could regulate programmed necrosis and play a key role in the process. The significance of programmed necrosis in ischemia-reperfusion injury (IRI) has been attracted great attention at present. Simultaneously, a series of studies have found it also involves in the IRI of heart, kidney, brain and retina.

Antagonistic effect of gingerols against TNF-α release, ROS overproduction and RIP3 expression increase induced by lectin from Pinellia ternata / 中国中药杂志

To explore the antagonistic effect of gingerols against the inflammation induced by lectin from Pinellia ternata. In this study, ELISA method was used to determine the effect of different extracts from gingerols on the release of inflammatory factor TNF-α from macrophages induced by lectin from P. ternata. The fluorescence probe was used to determine the effect of gingerols on the changes in ROS of macrophages induced by lectin from P. ternata. The western-blot method was applied to study the effect of gingerols on the increase in expression of cell receptor interacting protein RIP3 in macrophages induced by lectin from P. ternata. The scanning electron microscope (SEM) was used to study the effect of gingerols on morphological changes in macrophages induced by lectin from P. ternata. According to the results, gingerols can significantly inhibit the release of inflammatory factor from macrophages induced by lectin from P. ternata, ROS overproduction and increase in RIP3 expression. SEM results showed that gingerols can inhibit the cytomorphosis and necrocytosis induced by lectin from P. ternata. Fresh ginger's detoxication may be related to gingerols' effects in inhibiing release of inflammatory factor, ROS overproduction and increase in RIP3 expression caused by macrophages induced by lectin from P. ternata, which are mainly inflammatory development.

Preliminary Study of Necroptosis in Cardiac Hypertrophy Induced by Pressure Overload / 生物医学工程学杂志

The aim of this study was to observe whether necroptosis is involved in the process of cardiac hypertrophy induced by pressure overload. SD rats underwent transverse abdominal aortic constriction (TAC) operation for establishing cardiac hypertrophy model. The structure and function of the left ventricle of rats were evaluated via echocardiography, left ventricular mass index, the expression of markers of cardiac hypertrophy and histological detection. Real-time PCR and Western blot were used to measure the gene and protein expression of receptor interacting protein kinase 1 and 3 (RIPK1 and RIPK3, the necroptosis markers) respectively. Four weeks after TAC operation, rat model for cardiac hypertrophy was established. The experimental data showed that the gene and protein expressions of RIPK1 and RIPK3 in the rat heart hypertrophic tissues after TAC for 4 weeks were increased significantly compared with those in the sham group. HE staining showed cardiomyocytes injury and hypertrophy in the hearts of TAC rat models. By transmission electron microscope, we observed that mitochondria of cardiomyocytes were damaged seriously in the TAC models. Treatment with losartan used, the selective antagonist of angiotensin II type I receptor could improve the cardiac function of TAC rats. Moreover, losartan treatment decreased the expression of RIPK1 and RIPK3 in heart tissues of TAC rats. The results suggest that necroptosis occurrs in the process of cardiac hypertrophy with pressure overload, and losartan could alleviate the cardiac hypertrophy and inhibit necroptosis.

Effects of Inhibiting Necroptosis on H9c2 Cardiomyocytes Injury Induced by Hypoxia/Reoxygenation / 生物医学工程学杂志

The aim of this study is to construct specific shRNA expressing plasmids, and to observe their effects on H9c2 cardiomyocytes injury induced by hypoxia/reoxygenation (H/R). RIPK1 and RIPK3 are the key kinases mediating the process of necroptosis. Using recombinant DNA technology, we inserted the synthetic shRNA into pSUPER vector to construct RIPK1-shRNA or RIPK3-shRNA plasmid respectively. We transfected H9c2 cardiomyocytes with the two shRNA plasmids respectively, before we treated them with H/R stimulation. Then, we measured the relevant genes and proteins by real-time PCR and Western blot. Meanwhile,we detected the markers of necroptosis and cardiomyocytes injury. The results showed that inhibition of ripk1 or ripk3 gene expression by its specific shRNA might protect the cardiomyocytes injury induced by H/R stimulation.

Small interfering RNA-mediated RIP1 knockdown enhances L-OHP sensitivity of human oral squamous carcinoma cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of small interfering RNA-mediated receptor-interacting protein kinase 1 (RIP1) knockdown on the sensitivity of human oral squamous carcinoma cells to to oxaliplatin (L-OHP)-induced apoptosis and explore a new target for clinical treatment of oral squamous carcinoma.</p><p><b>METHODS</b>The viability of human oral squamous carcinoma cell line KB exposed to different concentrations (0, 0.25, 0.5, 1, 2, 4 µmol/L) of L-OHP were detected by MTT assay. PI/Annexin V staining was used to observe cell apoptosis in naive KB cells, cell and transfected with pSH1Si-RIP1 or with the empty plasmid. Western blotting was used to detect RIP1 expression in KB cells exposed to L-OHP and in cells transfected with pSH1Si-RIP1.</p><p><b>RESULTS</b>Exposure to L-OHP (1µmol/L) for 24, 48, 72 h resulted in KB cell survival rates of 67.66%, 55.17%, and 41.34%, respectively, but the cell apoptosis rate was only 9.6% following a 24-h exposure. KB cells transfected with pSH1Si-RIP1 showed an apoptotic rate of 9.4%, which increased to 29.1% following L-OHP exposure. RIP1 expression was first up-regulated and then down-regulated in KB cells treated with L-OHP, and was significantly reduced after cell transfection with pSH1Si-RIP1.</p><p><b>CONCLUSION</b>Suppression of RIP1 expression increases the apoptotic rate of human oral squamous carcinoma cells, suggesting the potential of RIP1 as a new candidate target for clinical treatment of oral squamous carcinoma.</p>

New components of the necroptotic pathway

Programmed necrosis, also known as necroptosis, has recently drawn great attention. As an important cellular regulation mechanism, knowledge of its signaling components is expanding. Necroptosisis demonstrated to be regulated by the RIP1 and RIP3 kinases, and its pathophysiological importance has been confirmed in a number of disease models. Here we review the new members of this necroptosis pathway, MLKL, PGAM5, Drp1 and DAI, and discuss some of their possible applications according to recent findings.

CUEDC2: an emerging key player in inflammation and tumorigenesis

CUE domain-containing 2 (CUEDC2) is a protein involved in the regulation of the cell cycle, inflammation, and tumorigenesis and is highly expressed in many types of tumors. CUEDC2 is phosphorylated by Cdk1 during mitosis and promotes the release of anaphase-promoting complex or cyclosome (APC/C) from checkpoint inhibition. CUEDC2 is also known to interact with IkB kinase α (IKKα) and IKKβ and has an inhibitory role in the activation of transcription factor nuclear factor-κB. Moreover, CUEDC2 plays an important role in downregulating the expression of hormone receptors estrogen receptor-α and progesterone receptor, thereby impairing the responsiveness of breast cancer to endocrine therapies. In this review, current knowledge on the multi-functions of CUEDC2 in normal processes and tumorigenesis are discussed and summarized.

Expression of caspase-8, receptor interacting protein and nuclear factor-kappaBp65 in oral lichen planus / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the expressions of caspase-8, receptor interacting protein (RIP) and nuclear factor (NF)-kappaBp65 in oral lichen planus (OLP) and their relationship with cell apoptosis.</p><p><b>METHODS</b>Immunohistochemical technique with SP method was used to detect the expressions of caspase-8, RIP and NF-kappaBp65 in 30 OLP cases and 15 normal oral mucosa specimens. Terminal deoxynucleotidyl transferase-mediated nucleotide shift enzyme (TdT) mediated d-UTP end labeling (TUNEL) was used for detecting the cell apoptotic index (AI) in 15 OLP cases and 5 nomal oral mucosa specimens.</p><p><b>RESULTS</b>Compared with the control group, the AI of epithelial cells (6.76 +/- 2.32) increased and the AI of lymphocytes (1.75 +/- 0.74)decreased in OLP (P < 0.01). The positive rate of caspase-8, RIP and NF-kappaBp65 of epithelial cells were 97% (29/30), 87% (26/30) and 93% (28/30) respectively, significantly higher in OLP than in normal control (P < 0.05). The positive rate of caspase-8, RIP and NF-kappaBp65 of lymphocytes were 100% (30/30, 90% (27/30) and 80% (24/30) respectively, significantly higher in OLP than in normal control (P < 0.01). A positive correlation was also observed between NF-kappaBp65 expression of lymphocytes and AI of epithelial cells.</p><p><b>CONCLUSIONS</b>Accelerated apoptosis of the keratinocytes and inhibition of lymphocyte apoptosis may coexist and contribute to the formation and progression of OLP. The over expression of caspase-8, RIP and NF-kappaBp65 in OLP may play a role in the pathogenesis of OLP.</p>

Expressions of receptor-interacting protein and caspase-8 in oral squamous cell carcinoma and oral precancerous lesions / 南方医科大学学报

<p><b>OBJECTIVE</b>To detect the expressions of receptor-interacting protein (RIP) and caspase-8 and investigate their roles in oral squamous cell carcinoma (OSCC) and oral precancerous lesions.</p><p><b>METHODS</b>SABC immunohistochemical methods were used to detect the expressions of RIP and caspase-8 in 22 specimens of OSCC, 14 specimens of oral lichen planus (OLP), 14 specimens of oral leukoplakia (OLK) and 10 specimens of normal oral mucosa (NOM).</p><p><b>RESULTS</b>The rate of weak or negative expression of RIP in normal mucosa was 50% (5/10). The rates of weak and positive expression of RIP in OLP, OLK and OSCC were 75% (36/50), and the rate of positive and strong expression of RIP was 63.7% (14/22) in OSCC, significantly higher that in the others groups (P<0.05). The rates of weak, positive and strong positive expression of caspase-8 in NOM, OLP, OLK and OSCC were 80% (8/10), 100% (14/14), 85.7% (12/14), and 100% (22/22), respectively.</p><p><b>CONCLUSION</b>Both RIP and caspase-8 may play important roles in the occurrence and progression of OSCC and oral precancerous lesions.</p>

Expression of TNF-alpha signaling adapter proteins in peripheral blood mononuclear cells in lupus nephritis patients of different TCM asthenia syndromes / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To investigate the mRNA expressions of the TNF adapter proteins, including TNF receptor-associated death domain protein (TRADD), Fas-associated death domain protein (FADD), receptor-interacting protein 1 (RIP-1) and TNF receptor-associated factor-2 (TRAF-2) in peripheral blood mononuclear cells (PBMCs) of lupus nephritis (LN) patients of various TCM asthenia syndromes. Methods Fifty-one inpatients with LN were differentiated according to TCM syndrome differentiation, 13 cases of yin-deficiency with inner heat syndrome (A); 26 cases of both qi-yin deficiency syndrome (B), 12 cases of Pi-Shen yang-deficiency syndrome (C). Peripheral venous blood samples from the 51 LN patients and 17 healthy subjects were collected to separate PBMCs. The mRNA expressions of TNF adapter molecules (TRADD, FADD, RIP-1 and TRAF-2), as well as Caspase-3 and interleukin-1beta (IL-1beta) were analyzed by quantitative real-time PCR and the differences among them were compared.</p><p><b>RESULTS</b>(1) As compared with the healthy subjects, expression of TRADD mRNA in patients of syndrome A, B and C was lowered to 0.54, 0.32, and 0.38-fold, respectively (P < 0.05, P < 0.01), showing insignificant difference among the three syndromes; (2) FADD mRNA lowered to 0.79, 0.62, and 0.72-fold respectively, only with significance shown in syndrome B (P < 0.05); (3) RIP-1 mRNA lowered to 0.79, 0.50, and 0.60-fold respectively with significance shown in syndrome B and C (P < 0.01, P < 0.05), and insignificant difference was shown among the three syndromes; (4) TRAF-2 lowered to 0.70, 0.52, and 0.50-fold respectively (P < 0.01, P < 0.01, P = 0.07), significance shown in syndrome B and C (P < 0.01), but with insignificant difference among the three; (5) Caspase-3 elevated in all patients of the three syndromes (all P < 0.01); (6) IL-1beta in syndrome A was apparently lower ed to the normal range and also lower than that in the other two syndromes (both P < 0.05).</p><p><b>CONCLUSIONS</b>Expressions of TRADD, FADD, RIP-1 and TRAF-2 mRNA decreased in all the patients of various TCM asthenia syndromes, the decrement in patients of syndrome B and C was lesser than that in syndrome A. These abnormal low expressions of signal proteins might be the substantial bases for asthenia syndromes of LN patients, and the apoptotic signal mediated by them may involve in the formation of asthenia syndrome in LN.</p>