Structure-based discovery and in vitro validation of inhibitors of chloride intracellular channel 4 protein.

The use of computer-aided methods have continued to propel accelerated drug discovery across various disease models, interestingly allowing the specific inhibition of pathogenic targets. Chloride Intracellular Channel Protein 4 (CLIC4) is a novel class of intracellular ion channel highly implicated in tumor and vascular biology. It regulates cell proliferation, apoptosis and angiogenesis; and is involved in multiple pathologic signaling pathways. Absence of specific inhibitors however impedes its advancement to translational research. Here, we integrate structural bioinformatics and experimental research approaches for the discovery and validation of small-molecule inhibitors of CLIC4. High-affinity allosteric binders were identified from a library of 1615 Food and Drug Administration (FDA)-approved drugs via a high-performance computing-powered blind-docking approach, resulting in the selection of amphotericin B and rapamycin. NMR assays confirmed the binding and conformational disruptive effects of both drugs while they also reversed stress-induced membrane translocation of CLIC4 and inhibited endothelial cell migration. Structural and dynamics simulation studies further revealed that the inhibitory mechanisms of these compounds were hinged on the allosteric modulation of the catalytic glutathione (GSH)-like site loop and the extended catalytic ß loop which may elicit interference with the catalytic activities of CLIC4. Structure-based insights from this study provide the basis for the selective targeting of CLIC4 to treat the associated pathologies.

Effect of Panax Notoginseng Saponins on Breast Cancer Cell Line 4T1 in Tumor-bearing Mice Through MEKK1/SEK1/JNK1/AP-1 Pathway / 中国实验方剂学杂志

Objective:To explore the potential mechanisms of Panax Notoginseng Saponins （PNS） on growth inhibition of breast cancer cell line 4T1 in tumor-bearing mice by investigating the mitogen-activated protein kinase kinase kinase 1 （MEKK1）/stress activated protein kinase （SAPK）/extracellular regulated protein kinases （Erk） Kinase （SEK1）/c-Jun N-terminal kinase 1 （JNK1）/activator protein-1 （AP-1） signaling pathways. Method:The 4T1 breast cancer mice model was established. Forty-eight mice with successful modeled and randomly divided into the low， medium and high-dose PNS groups （10， 20， 40 mg·kg-1） and the model control group （12 mice in each group）. The PNS groups received intraperitoneal injection with dosage of 10 mL·kg-1， while the controlled group was given the same dosage of saline. After administration with PNS for 28 days， tumor tissues were isolated， weighed， sliced and homogenized. Tumor cell apoptosis was detected by TdT mediated-dUTP nick end labeling （TUNEL） staining. The mRNA expressions of MEKK1， SEK1， JNK1 and AP-1 in tumor tissue were detected by Real-time polymerase chain reaction（Real-time PCR）. The protein expressions of MEKK1， SEK1， JNK1 and AP-1 in tumor tissue were detected by immunofluorescence staining and Western blot. Result:Compared with model group， the tumor weights of medium-dose and high-dose PNS groups were decreased significantly （P<0.05）. TUNEL staining showed that the number of apoptotic tumor cells increased with the rise of dosage of PNS （P<0.05）. The medium-dose and high-dose PNS groups showed a significant increase in the mRNA expressions of MEKK1， SEK1， JNK1 and AP-1 as well as the protein expressions of MEKK1， SEK1， JNK1 and AP-1 in tumor tissues （P<0.05）， with statistically significant differences （P<0.05）. Conclusion:PNS could inhibit the tumor growth of breast cancer cell line 4T1 in tumor-bearing mice， which may be related to the activation of MEKK1/SEK1/JNK1/AP-1 signaling pathways.

Radiation-Induced Endothelial Vascular Injury: A Review of Possible Mechanisms.

In radiation therapy for cancer, the therapeutic ratio represents an optimal balance between tumor control and normal tissue complications. As improvements in the therapeutic arsenal against cancer extend longevity, the importance of late effects of radiation increases, particularly those caused by vascular endothelial injury. Radiation both initiates and accelerates atherosclerosis, leading to vascular events like stroke, coronary artery disease, and peripheral artery disease. Increased levels of proinflammatory cytokines in the blood of long-term survivors of the atomic bomb suggest that radiation evokes a systemic inflammatory state responsible for chronic vascular side effects. In this review, the authors offer an overview of potential mechanisms implicated in radiation-induced vascular injury.

Xihuang pill promotes apoptosis of Treg cells in the tumor microenvironment in 4T1 mouse breast cancer by upregulating MEKK1/SEK1/JNK1/AP-1 pathway.

OBJECTIVE: To determine the role of the MEKK1/SEK1/JNK1/AP-1 pathway in the action of Xihuang pill (XHP) in reducing regulatory T (Treg) cell numbers in the tumor microenvironment in a 4T1 mouse breast cancer model, and to clarify the anti-tumor mechanism of XHP in breast cancer. METHODS: We established a mouse 4T1 breast cancer model. Model mice were administered XHP for 2 weeks, and tumor tissues were then removed, weighed, sliced, and homogenized. Treg cells in the tumor microenvironment were isolated by magnetic cell sorting and analyzed by immunohistochemistry and flow cytometry. Treg cell apoptosis was detected by TdT-mediated dUTP nick end labeling. mRNA expression levels of MEKK1, SEK1, JNK1, and AP-1 in Treg cells in the tumor microenvironment were detected by quantitative real-time PCR and their protein expression levels were detected by immunofluorescence staining and western blot. RESULTS: Tumor weights were significantly lower in the XHP groups compared with the untreated control group. The overall number of Treg cells in the tumor microenvironment decreased while the number of apoptotic Treg cells increased with increasing doses of XHP. mRNA and protein expression levels of MEKK1, SEK1, JNK1, and AP-1 in Treg cells in the tumor microenvironment increased with increasing doses of XHP. CONCLUSION: XHP might promote Treg cell apoptosis in the tumor microenvironment and further inhibit the tumor growth of 4T1 mouse breast cancer. The mechanism of XHP may be related to upregulation of gene and protein expression of MEKK1, SEK1, JNK1, and AP-1 in Treg cells in the tumor microenvironment.

Developmental Changes in the Activation of Signal Transduction Pathway via JNK in Rat Hippocampus after Kainic Acid-Induced Seizure / 신경정신의학

OBJECTIVE: We observed the developmental pattern of activation of MAPK signal transduction pathways known to be activated by electroconvulsive shock(ECS) in young rat hippocampus after kainic acid(KA)-induced seizure. METHODS: We used the method of immunoblotting for examining the basal protein amount and basal level of phosphorylation of MAPK kinase(SAPK/ERK kinase -1, SEK-1), MAPK(c-Jun N terminal protein kinase, JNK), transcription factor(c-Jun) and immediate early gene proteins(Fos) in rat hippocampus at postnatal day 7, 14, and 21, respectively. We also examined the changes of phosphorylation of those proteins after kainic acid-induced seizure in the same way. RESULTS: The basal protein amounts of SEK-1, JNK, and c-Jun did not show age-dependent changes and basal level of phosphorylation of JNK and c-Jun remains unchanged throughout the early developmental period. The basal level of phosphorylation of SEK-1 was peaked at postnatal 7 days and then decreased with aging. After kainic acid-induced seizure, the change of phosphorylation of JNK was not observed but those of SEK-1 and c-Jun increased after postnatal day 14. The expression of Fos was observed at postnatal day 7 and also increased with aging. CONCLUSION: These results show that the MAPK signal transduction system in rat hippocampus matures in accordance with aging, but the process of maturation differs depending specific proteins. This study suggests the signal transduction cascade(SEK-1 - JNK - c-Jun - Fos) which is well established in cell line studies may not be applied to rat hipposcampus because we could not observe the activation of JNK after KA-induced seizure in young rat hippocampus.

The Roles of SEK1 in Nitric Oxide (NO) Induced Apoptsis of RAW264.7 cells / 대한면역학회지

Nitric oxide (NO) induces apoptotic cell death in murine RAW 264.7 macrophages. To elucidate the roles of SEK1/MKK4, a upstream kinase for both c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) and p38 kinase, on NO-induced apoptosis, we generated clones of RAW 264.7 cells which stably overexpressd kinase inactive SEK1 (RAW/SEK1-Kl) or wild type SEK1 (RAW/SEK1-WT). Treatment of kinase inactive SEK1 transfected RAW 264.7 cells (RAW/SEK1-Kl) with sodium nitroprusside (SNP), a NO generating agent, significantly decreased the cell viability up to 20% of RAW control cells which were treated with the same amount of SNP. However, RAW/SEK1-WT cells were less susceptible to NO induced apoptosis. For a while, caspase-3 like activity in NO treated RAW/SEK1-Kl cells was significantly increased with parallell to apoptotic death rate. However, caspase1 like activity was not affected by NO in any transfectants. The NO induced apoptosis in RAW/SEK1-Kl cells was significantly prevented by the addition of caspase-3 like inhibitor (N-Ac- DEVD-CHO). In addition, the phosphotransferase activity of JNK1 in NO-treated RAW/SEK1-WT is significantly increased, but not in RAW/SEK1-Kl cells. These results suggest that SEK1 may play anti-apoptotic role in RAW cells from NO-induced apoptosis.

The Role of Sek1 in Protecting NO-induced Apoptosis in H9c2 cells by Inhibiting Caspase 3 Activation / 대한해부학회지

The stress activated protein kinase, or Jun N-terminal kinase (SAPKs/JNKs), is activated in response to a variety of cellular stresses such as changes in osmolarity and metabolism, DNA damage, heat shock, ischemia, and inflammatory cytokines. Sek1 (JNKK/MKK4) is a direct activator of SAPKs/JNKs in response to environmental stresses or mitogenic factors. Thus, this study was conducted to investigate the role of Sek1 on nitric oxide (NO) induced apoptotic signaling pathway in H9c2 cell. The viability of SNP (Sodium Nitroprusside) treated inactive Sek1 kinase transfectants [Sek1/KI H9c2] is significantly decreased and SNP induce DNA fragmentation in Sek1/KI H9c2. Interestingly, concomitantly with SNP induced injuries, caspase 3-like activity is increased but caspase 1 like activity is not changed in Sek1/KI H9c2. Whereas wild type Sek1 kinase transfectants [Sek1/WT H9c2] is less susceptible to SNP induced apoptosis. In Sek1/KI H9c2, the injuries and DNA fragmentation by SNP is protected by adding Ac-DEVD-AMC, caspase 3 inhibitor. In conclusion, these results suggest that Sek1 plays a role in protecting NO-induced apoptosis and DNA fragmentaion in H9c2 cells by inhibiting caspase 3-like activation.