Nicorandil alleviates cardiac remodeling and dysfunction post -infarction by up-regulating the nucleolin/autophagy axis.

OBJECTIVE: The present study aimed to investigate whether the drug nicorandil can improve cardiac remodeling after myocardial infarction (MI) and the underlying mechanisms. METHODS: Mouse MI was established by the ligation of the left anterior descending coronary artery and H9C2 cells were cultured to investigate the underlying molecular mechanisms. The degree of myocardial collagen (Col) deposition was evaluated by Masson's staining. The expressions of nucleolin, autophagy and myocardial remodeling-associated genes were measured by Western blotting, qPCR, and immunofluorescence. The apoptosis of myocardial tissue cells and H9C2 cells were detected by TUNEL staining and flow cytometry, respectively. Autophagosomes were observed by transmission electron microscopy. RESULTS: Treatment with nicorandil mitigated left ventricular enlargement, improved the capacity of myocardial diastolic-contractility, decreased cardiomyocyte apoptosis, and inhibited myocardial fibrosis development post-MI. Nicorandil up-regulated the expression of nucleolin, promoted autophagic flux, and decreased the expressions of TGF-ß1 and phosphorylated Smad2/3, while enhanced the expression of BMP-7 and phosphorylated Smad1 in myocardium. Nicorandil decreased apoptosis and promoted autophagic flux in H2O2-treated H9C2 cells. Autophagy inhibitors 3-methyladenine (3MA) and chloroquine diphosphate salt (CDS) alleviated the effects of nicorandil on apoptosis. Knockdown of nucleolin decreased the effects of nicorandil on apoptosis and nicorandil-promoted autophagic flux of cardiomyocytes treated with H2O2. CONCLUSIONS: Treatment with nicorandil alleviated myocardial remodeling post-MI through up-regulating the expression of nucleolin, and subsequently promoting autophagy, followed by regulating TGF-ß/Smad signaling pathway.

The role of PSGL-1 in pathogenesis of systemic inflammatory response and coagulopathy in endotoxemic mice.

INTRODUCTION: Endotoxemia often results in systemic inflammatory response syndrome (SIRS), coagulation disturbance and acute lung injury (ALI), and such a condition is associated with the activation of platelets, leukocytes and vascular endothelial cells (VECs). P-selectin glycoprotein ligand 1 (PSGL-1) is a key regulatory molecule in the activation of platelets, leukocytes and VECs. However, it still remains largely unexplored whether PSGL-1 plays an important role in SIRS, coagulation dysfunction and ALI of endotoxemia. In the present study, we aimed to study the role of PSGL-1 in above-mentioned situations using endotoxemic mice. MATERIALS AND METHODS: An endotoxemia model was established in BALB/c mice via lipopolysaccharide (LPS) administration. Moreover, the mice were simultaneously injected with PSGL-1 antibody for intervention. The survival rate, morphologic changes of lung tissues, platelet-leukocyte adhesion, tissue factor expression on leukocytes, fibrinogen deposition in lung tissues, serum levels of inflammatory factors and the activation of VECs were determined. RESULTS: The results showed that the aggregation and recruitment of platelets and leukocytes in lung tissues, the expression of tissue factor on leukocytes, the serum levels of inflammatory factors, the activation of VECs, and the fibrinogen deposition in lung tissues were increased in endotoxemic mice, which were significantly alleviated by administration of PSGL-1 antibody. Moreover, blockade of PSGL-1 markedly increased survival rate, and alleviated coagulation disturbance and lung injury in endotoxemic mice. CONCLUSIONS: Taken together, PSGL-1 played an important role in pathogenesis of SIRS and coagulation dysfunction and ALI in endotoxemic mice.

Clopidogrel reduces lipopolysaccharide-induced inflammation and neutrophil-platelet aggregates in an experimental endotoxemic model.

Platelet activation contributes to organs failure in inflammation and plays an important role in endotoxemia. Clopidogrel inhibits platelet aggregation and activation. However, the role of clopidogrel in modulating inflammatory progression of endotoxemia remains largely unexplored. Therefore, we investigated the role of clopidogrel on the activation of platelet and leukocytes in lipopolysaccharide (LPS)-induced inflammation in mice. Animals were treated with clopidogrel or vehicle before LPS induction. The expression of neutrophil-platelet aggregates and platelet activation and tissue factor was determined. Immunofluorescence was used to analyze platelet-leukocyte interactions and tissue factor (TF) expression on leukocytes. Clopidogrel pretreatment markedly decreased lung damage, inhibited platelet-neutrophil aggregates and TF expression. In addition, clopidogrel reduced thrombocytopenia and affected the number of circulating white blood cell in endotoxemia mice. Moreover, clopidogrel also reduced platelet shedding of CD40L and CD62P in endotoxemic mice. Taken together, clopidogrel played an important role through reducing platelet activation and inflammatory process in endotoxemia.

Puerarin prevents vascular endothelial injury through suppression of NF-κB activation in LPS-challenged human umbilical vein endothelial cells.

OBJECTIVE: In the present study, we aimed to explore the effects of puerarin on vascular endothelial cell injury induced by lipopolysaccharide (LPS) and its underlying mechanisms. METHODS: The cell viability and morphological changes were assessed using the cell counting kit-8 (CCK-8) assay and 4´,6-diamidino-2-phenylindole (DAPI) staining, respectively. The levels of tumor necrosis factor-alpha (TNF-α), interleukin-1ß (IL-1ß), monocyte/macrophage chemotactic protein-1 (MCP-1), IL-8, intercellular cell adhesion molecule-1 (ICAM-1), thrombomodulin (TM) and plasminogen activator inhibitor-1 (PAI-1) in cell culture supernatant were determined by the enzyme-linked immunosorbent assay (ELISA). The neutrophils adhesion to endothelial cells were examined by myeloperoxidase activity assay. The nuclear translocation of nuclear factor-κB p65 (NF-κB p65) was assessed by immunofluorescence analysis. RESULTS: Compared with the control group, LPS challenge significantly injured human umbilical vein endothelial cells (HUVECs) and increased the levels of TNF-α, IL-1ß, MCP-1, IL-8, ICAM-1, TM and PAI-1 in the cell culture supernatants. The neutrophils adhesion to endothelial cells were significantly increased in LPS-challenged HUVECs. Moreover, LPS challenge increased the nuclear translocation of NF-κB p65. However, puerarin pre-treatment attenuated the vascular endothelial injury and reduced the levels of TNF-α, IL-1ß, MCP-1, IL-8, ICAM-1, TM and PAI-1 in cell supernatants of LPS-challenged HUVECs. In addition, the neutrophils adhesion to HUVECs induced by LPS were also decreased by puerarin pre-treatment. Furthermore, puerarin pre-treatment reduced the nuclear translocation of NF-κB p65 elicited by LPS. CONCLUSIONS: Puerarin prevented LPS-induced vascular endothelial injury, the mechanism of which might be related to the suppression of NF-κB activation and subsequently altered levels of inflammatory factors and coagulation-related factors.

MicroRNA Profiling of Transgenic Mice with Myocardial Overexpression of Nucleolin.

BACKGROUND: Nucleolin (NCL) is the most abundant RNA-binding protein in the cell nucleolus and plays an important role in chromatin stability, ribosome assembly, ribosomal RNA maturation, ribosomal DNA transcription, nucleocytoplasmic transport, and regulation of RNA stability and translation efficiency. In addition to its anti-apoptotic properties, the underlying mechanisms associated with NCL-related roles in different cellular processes remain unclear. In this study, the effect of NCL on microRNA (miRNA) expression was evaluated by generating transgenic mice with myocardial overexpression of NCL and by analyzing microarrays of mature and precursor miRNAs from mice. METHODS: Using microinjection of alpha-MyHc clone 26-NCL plasmids, we generated transgenic mice with myocardial overexpression of NCL firstly, and then mature and precursor miRNAs expression profiles were analyzed in NCL transgenic mice (n = 3) and wild-type (WT) mice (n = 3) by miRNA microarrays. Statistical Package for the Social Sciences version 16.0 software (SPSS, Inc., Chicago, IL, USA) was used to perform Student's t-test, and statistical significance was determined at P < 0.05. RESULTS: Several miRNAs were found to be differentially expressed, of which 11 were upregulated and 4 were downregulated in transgenic mice with myocardial overexpression of NCL compared to those in WT mice. Several differentially expressed miRNAs were subsequently confirmed and quantified by real-time quantitative reverse transcription-polymerase chain reaction. Bioinformatics analysis was used for the prediction of miRNA targets. Furthermore, in vitro experiments showed that NCL regulated miR-21 expression following hydrogen peroxide preconditioning. CONCLUSIONS: Myocardial-protection mechanisms exerted by NCL might be mediated by the miRNAs identified in this study.

Ischemic postconditioning protects cardiomyocytes against ischemia/reperfusion injury by inducing MIP2.

Cardiomyocytes can resist ischemia/reperfusion (I/R) injury through ischemic postconditioning (IPoC) which is repetitive ischemia induced during the onset of reperfusion. Myocardial ischemic preconditioning up-regulated protein 2 (MIP2) is a member of the WD-40 family proteins, we previously showed that MIP2 was up-regulated during ischemic preconditioning (IPC). As IPC and IPoC engaged similar molecular mechanisms in cardioprotection, this study aimed to elucidate whether MIP2 was up-regulated during IPoC and contributed to IPoC-mediated protection against I/R injury. The experiment was conducted on two models, an in vivo open chest rat coronary artery occlusion model and an in vitro model with H9c2 myogenic cells. In both models, 3 groups were constituted and randomly designated as the sham, I/R and IPoC/hypoxia postconditioning (HPoC) groups. In the IPoC group, after 45 min of ischemia, hearts were allowed three cycles of reperfusion/ischemia phases (each of 30 s duration) followed by reperfusion. In the HPoC group, after 6 h of hypoxia, H9c2 cells were subjected to three cycles of 10 minute reoxygenation and 10 minute hypoxia followed by reoxygenation. IPoC significantly reduced the infarct size, plasma level of Lactate dehydrogenase and creatine kinase MB in rats. 12 h after the reperfusion, MIP2 mRNA levels in the IPoC group were 10 folds that of the sham group and 1.4 folds that of the I/R group. Increased expression of MIP2 mRNA and attenuation of apoptosis were similarly observed in the HPoC group in the in vitro model. These effects were blunted by transfection with MIP2 siRNA in the H9c2 cells. This study demonstrated that IPoC induced protection was associated with increased expression of MIP2. Both MIP2 overexpression and MIP2 suppression can influence the IPoC induced protection.

[Effect of Krüppel-like factor 4 overexpression on heat stress-induced apoptosis of Raw264.7 macrophages].

OBJECTIVE: To observe the effect of Krüppel-like factor 4 (KLF4) overexpression on heat stress-induced apoptosis of Raw264.7 macrophages. METHODS: The fragment containing full length mouse KLF4 cDNA coding sequence was inserted into the pcDNA3.1 vector and Raw264.7 macrophages were transfected with pcDNA3.1-KLF4 plasmids using lipofectamine.The expression of KLF4 was examined by Western blot in the Raw264.7 macrophages stably transfected with pcDNA3.1- KLF4 plasmids. Raw264.7 cells transfected with pcDNA3.1 and pcDNA3.1-KLF4 were exposed to heat stress (42 degrees C) for 1h and recovered at 37 degrees C for 12h. Flow cytometry, Hoechest 33258 staining assay, and DNA ladder assays were performed to assess the apoptosis. RESULTS: The KLF4 overexpressed Raw264.7 macrophages were established. After the heat stress, flow cytometry showed that apoptotic cells increased significantly in KLF4 overexpressed cells compared with the vector control; Hoechest 33258 staining was characterized with classical changes including apoptotic body, and nuclear condensation. Agarose gel electrophoresis showed that "DNA ladder" could be observed clearly. CONCLUSION: KLF4 overexpression can increase heat stress-induced apoptosis of Raw264.7 macrophages.

[HSF1 inhibits heat stress-induced apoptosis in Raw264.7 macrophages].

OBJECTIVE: To observe the effect of heat shock factor 1 (HSF1) on heat stress-induced apoptosis in Raw264.7 macrophages. METHODS: Raw264.7 cells transfected with pcDNA3.1 and pcDNA3.1-HSF1 were exposed to heat stress (42.5 degrees C +/- 0.5 degrees C) for 1 h and recovered at 37 degrees C for 6, 9, 12, and 24 h respectively. Flow cytometry (FCM), Hoechst 33258 staining and DNA ladder assays were performed to assess the apoptosis. RESULTS: After heat stress, FCM showed that apoptotic cells were increased significantly and reached the peak at 9 h in Raw 264.7 cells transfected with pcDNA3.1, and were characterized with classical morphologic changes including apoptotic body and nuclear condensation. Agarose gel electrophoresis showed that "DNA ladder" could be observed clearly at 6, 9, and 12 h after the heat stress. But the overexpression of HSF1 could reduce the number of apoptotic cells and inhibit DNA fragmentation. CONCLUSION: HSF1 can inhibit heat stress-induced apoptosis in Raw264.7 macrophages.

[Immortalization of embryonic fibroblasts in heat shock transcription factor 1 knockout mouse].

OBJECTIVE: To establish immortalized embryonic fibroblast lines in heat shock transcription factor 1 (HSF1) HSF1-/- and HSF1+/+ mice and to provide experimental models to study the function of HSF1. METHODS: A mammalian expression vector (pSV3neo) containing the SV40 large T antigen was used to transfect the HSF1-/- and HSF1+/+ mouse embryonic fibroblast using Lipofectamine 2000. Colonies were screened by G418 and expanded to immortalized cell lines. PCR was used to detect the integration of the large T antigen with genome in the mouse embryonic fibroblast. Expression of SV40 large T antigen gene in expanded cells was identified by RT-PCR. HSP70 expression was examined by Western blot in the embryonic fibroblast lines. RESULTS: The stable growth and serial propagation were observed in the HSF1-/- and HSF1+/+ cell lines for six months. The mRNA of SV40 T antigen gene expressed in the two cell lines. HSP70 expression could not be induced in the heat-treated HSF1-/- mouse embryo fibroblasts. CONCLUSION: The immortalized cells of HSF1+/+ and HSF1-/- mouse embryo fibroblasts are successfully established.

[Effect of HSP72 on acute injury of neonatal cardiomyocytes induced by oxidative stress].

OBJECTIVE: To explore the protective effect of HSP72 on the acute injury of cardiomyocyte induced by oxidative stress. METHODS: Cardiomyocytes of neonatal rats treated with heat shock (42 degrees C, 30 min, recovery for 6 h) to induce the expression of HSP72 and HSP72 antisense oligonucleotide was transformed to block the expression of HSP72. 0.5 mmol/L (final concentration) H2O2 was added into the culture medium to mimic oxidative stress, and to induce the acute injury of neonatal cardiomyocytes. The release of LDH and the total protein synthesis were applied to evaluate the injury of cardiomyocyte of neonatal rats. RESULTS: Oxidative stress could significantly increase the release of LDH, and inhibit the total protein synthesis. By inducing the expression of HSPs, heat shock pretreatment significantly reduced the release of LDH and relieved the oxidative stress-mediated inhibition of total protein synthesis. Moreover, HSP7-2 anti-sense oligonucleotide could remarkably block the protective effect of heat shock pretreatment on the cellular injuries induced by H2O2. CONCLUSION: HSP72 plays a most important role in the acute injury of cardiomyocyte mediated by oxidative stress.

[Characteristics and expression of Mip5, a novel gene associated with myocardial ischemia/reperfusion in rats].

OBJECTIVE: To determine the characteristics of a novel gene Mip5 (GenBank accession number AY553870) and its expression under physiological and pathological conditions. METHODS: The characteristics of Mip5 were analyzed by bioinformatic programs including BLAST, spidey, psort, ClustalW and so on. RT-PCR was performed to detect Mip5 expression. RESULTS: Bioinformatic analysis showed that Mip5 gene lied in the 13th chromosome and contained 8 exons and 7 introns, its open reading frame contained 909 bp and its protein production was 302 amino acid residues including 6 kelth domains. Under normal conditions, MIP5 expressed abundantly in the heart, brain and kidney, but its expression could not be detected in the liver and muscle. Expression of Mip5 gene was increased significantly after ischemia-reperfusion compared with the sham groups, and reached its peak at 3 h and recovered at 12 h after the reperfusion. Conclusion Mip5 gene is a novel gene containing a putative open reading frame of 302 amino acids residues and may play an important role in rat cardiomyocytes suffering ischemia processing.

[Roles of nuclear factor-kappaB in heat shock pretreatment to abate cardiomyocyte injury induced by hydrogen peroxide].

OBJECTIVE: To investigate the role of nuclear factor-kappaB (NF-kappaB) in heat shock pretreatment to abate cardiomyocyte injury induced by hydrogen peroxide (H(2)O(2)). METHODS: The primary generation of cultured neonatal rat cardiomyocytes were injured by exposure to 1 mmol/L H(2)O(2) for different durations. The total antioxidant in cardiomyocytes was detected. The changes in heat shock protein 70 (HSP70), alphaB-crystallin, inhibitor of NF-kappaB (I-kappaB) were assayed by Western-blotting. The translocation of NF-kappaB and HSP70 from cytoplasm to nucleus was observed by immunohistochemical analysis. RESULTS: (1)Compared with H(2)O(2) (1 mmol/L, 3 h) treated cells, cells subjected to heat shock pretreatment showed significant increase in total antioxidant capability (all P<0.01). (2)Western blot analysis demonstrated that heat shock pretreatment could induce expression of HSP70, alphaB-crystallin and I-kappaB. (3)Heat shock pretreatment inhibited H(2)O(2)-mediated I-kappaB degradation. (4)Immunohistochemical analysis showed that heat shock pretreatment could abate HSP70 and NF-kappaB translocation from cytoplasm to nucleus. CONCLUSION: Heat shock pretreatment could protect cardiomyocytes against H(2)O(2)-induced injury, and its mechanism might involve expression of HSP70, alphaB-crystallin and I-kappaB, which could inhibit H(2)O(2) -mediated NF-kappaB activation.

[HSP70 inhibits smac release from the mitochondria and protects against H2O2-induced apoptosis in C2C12 myogenic cells].

OBJECTIVE: To observe whether HSP70 could protect against H2O2-induced apoptosis in C2C12 myogenic cells by inhibiting Smac release from the mitochondria. METHODS: HSP70 gene and full length Smac gene was transiently transfected in C2C12 myogenic cells by lipofectamine and the protein levels of HSP70 and Smac were analysed by Western blotting. Hoechst 33 258 staining was used to examine cell morphological changes and to calculate percentage of apoptotic nuclei. DNA ladder pattern on agarose gel electrophoresis was used to observe the DNA fragmentation. Activities of caspase-3 and caspase-9 were assayed with Western blotting. The release of Smac from the mitochondria to the cytoplasm was observed by immunofluorescence. RESULTS: H2O2 ( 0.5 mmol/L ) activated caspase-3, caspase-9 8 h after the treatment and specific morphological changes of apoptosis 12 h after the treatment, and overexpression of Smac significantly promoted H2O2-induced activation of caspase-3, caspase-9 and apoptosis in C2C12 myogenic cells. HSP70 overexpression significantly inhibited H2O2-induced and Smac-promoted apoptosis, as shown by no specific DNA ladder pattern in agarose gel electrophoresis, decrease of percentage of apoptotic nuclei, and marked inactivation of caspase-3 and caspase-9. HSP70 could inhibit the release of Smac from the mitochondria to the cytoplasm 2 h after the treatment by H2O2. CONCLUSION: HSP70 inhibits Smac release from the mitochondria and protects against H2O2-induced apoptosis in C2C12 myogenic cells.

[Effect of nucleolin down-regulation on the proliferation and apoptosis in C2C12 cells].

OBJECTIVE: To clarify the effect of nucleolin on the proliferation and apoptosis in C2C12 cells. METHODS: After inhibiting the expression of nucleolin using antisense oligonucleotides, the cellular proliferation was determined by MTT, and the apoptosis was detected by flow cytometry (FCM) assays and DNA ladder assays. RESULTS: After being transfected with antisense oligonucleotides for 24 hours, Western blotting showed that the expression of nucleolin was repressed significantly. In cells treated with antisense oligonucleotides, the cellular proliferation was obviously inhibited; the apoptotic cell increased significantly; and the "DNA ladder" was clearly observed. But the sense and random oligonucleotides had no effect on the cellular proliferation and apoptosis. CONCLUSION: The down-regulation of nucleolin can inhibit the cellular proliferation and initiate the apoptosis in C2C12cells.