Role of microRNA-126-5p in myocardial injury induced by doxorubicin / 中国病理生理杂志

AIM:To observe the expression of microRNA-126-5p during myocardial injury and its role in myo-cardial cell injury induced by adriamycin(also called doxorubicin, DOX).METHODS: The BALB/c mouse model of DOX-induced acute and chronic myocardial injury was established via intraperitoneal injection of DOX.HE staining was applied to observe the morphological changes of myocardial tissues.Lactate dehydrogenase(LDH)in serum was detected and PowerLab system was used to detect the influence of DOX on the changes of ±dp/dtmax.The expression of microRNA-126-5p in injured myocardial tissues and the H 9c2 cells exposed to DOX was detected by real-time PCR.Gain-and loss-of-function experiments were conducted to detect the role of microRNA-126-5p in H9c2 cells treated with DOX on LDH release and caspase-3 activation.RESULTS:In acute and chronic DOX myocardial damage models in mice,HE staining showed disarranged myocardial fibers, dissolved myofibril and inflammatory cell infiltration.Higher serum LDH level and lower ±dp/dtmaxin DOX-treated mice than those in normal mice were found.Compared with the normal mice, the expression level of microRNA-126-5p was significant increased in the myocardium with DOX-induced injury.Similarly,the expression level of microRNA-126-5p was significant increased in the H9c2 cells treated with DOX.In addition, over-expression of microRNA-126-5p decreased cell viability and promoted apoptosis,while microRNA-126-5p ablation promoted the viability and inhibited the apoptosis of H9c2 cells.CONCLUSION:The microRNA-126-5p expression is up-regulated in myocar-dial injury induced by DOX,and microRNA-126-5p inhibits cell viability and promotes apoptosis induced by DOX.

MicroRNA Profiling of Transgenic Mice with Myocardial Overexpression of Nucleolin / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>Myocardial-protection mechanisms exerted by NCL might be mediated by the miRNAs identified in this study.</p>

Zinc oxide nanoparticles inhibits Ca2+-ATPase1 expression induced by UVB irradiation in human lens epithelial cells / 眼科新进展

Objective To investigate the effect of ZnO nanoparticles on the expressions of plasma membrane calcium ATPasel (PMCA1) of human lens epithelial cell B-3 (HLEB-3) at both mRNA and protein levels in the presence and absence of ultraviolet B (UVB) irradiation.Methods HLEB-3 was cultured in RPMI 1640 medium,and the cytotoxic effect of different concentrations of ZnO (0 μg · mL-1,2.5 μg · mL-1,5.0μg · mL-1,10.0 μg · mL-1) on HLEB-3 was investigated in the presence and absence of UVB irradiation.DAPI staining was used to monitor the effect of ZnO on HLECB-3 nuclei,and cell apoptosis was evaluated using annexin V-FITC/PI staining in the presence and absence of UVB irradiation.In addition,the intracellular calcium ion (Ca2 +)levels were assayed using Fluo-3/AM staining,and the expression levels of both PMCA1 mRNA and protein within HLEB-3 were detected by real-time PCR and Western blot,respectively.Results DAPI staining showed that the ZnO-treated HLEB-3 displayed a concentration-dependent apoptosis,and UVB irradiation could further aggravate the cytotoxic effect of ZnO on HLEB-3.In addition,in the presence of UVB irradiation,concentration gradient of ZnO (2.5 μg · mL-1,5.0 μg · mL-1,10.0 μg · mL-1) increased the intracellular calcium ion levels [from (156.34 ±4.59) nmol · L-1 to (173.88 ±7.17)umol · L-1,(289.02 ± 9.09) nmol · L-1,(488.36 ± 48.16) nmol · L 1,respectively] and upregulated HLEB-3 apoptosis,with statistical difference (all P ＜ 0.05).Moreover,the expression level of PMCA1 in the 2.5 μg · mL-1,5.0 μg · mL-1,10.0 μg · mL-1 ZnO-treated epithelial cells was accordingly 0.75,0.57 and 0.41 as much as that in the 0μg · mL-1 ZnO-treated cells in the absence of UVB irradiation (all P ＜ 0.05),and was accordingly 0.64,0.24 and 0.09 in the present of UVB irradiation,with significant difference (all P ＜ 0.05).Conclusion Both ZnO nanoparticle and UVB irradiation can exert cosuppression effect on HLEB-3 via calcium-mediated signaling pathway,indicating it has great potential for the treatment of posterior capsular opacification with UVB irradiation.

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 / 中南大学学报(医学版)

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 / 中南大学学报(医学版)

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 / 中南大学学报(医学版)

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 / 中南大学学报(医学版)

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 / 中南大学学报(医学版)

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.

HSP70 inhibits smac release from the mitochondria and protects against H2O2-induced apoptosis in C2C12 myogenic cells / 中南大学学报(医学版)

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 / 中南大学学报(医学版)

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.