[Impact of Pax-8 gene interference on mitochondrial function and cardiomyocyte apoptosis].

OBJECTIVE: To observe the effects of paired box gene 8 (Pax-8) silencing by RNA interference on mitochondrial function and cardiomyocytes apoptosis. METHODS: The cultured H9C2 (2-1) myocytes were divided into 3 groups: short interference RNA targeting Pax-8 (Pax-8 siRNA) group, non-specific siRNA group as the negative control (NC siRNA), and blank control group (BC siRNA). Fluorescence spectrophotometry was used to detect the activity of caspase-3. RT-PCR was performed to detect mRNA expression of Bcl2 and Bax. The protein expression of Bcl2, Bax and cytoplasm of Cytochrome was examined by Western blot. Changes of ΔΨm were detected by flow cytometry.ΔΨm with JC-1 monomer/polymer ratio was calculated for measuring mitochondrial depolarization proportion. RESULTS: Compared to NC siRNA and BC siRNA group (0.075 ± 0.021, 0.072 ± 0.019), the activity of caspase-3 in Pax-8 siRNA group (0.167 ± 0.012) was significantly increased (P < 0.05); Bcl2 mRNA and protein expression in Pax-8 siRNA group (0.61 ± 0.06, 0.94 ± 0.11) were significantly downregulated compared with NC siRNA group (0.90 ± 0.070, 1.39 ± 0.15) and BC siRNA group (0.94 ± 0.087, 1.49 ± 0.20) (P < 0.05); Bax mRNA and protein expression in Pax-8 siRNA group (1.05 ± 0.10, 1.25 ± 0.12) were markedly upregulated compared with NC siRNA group (0.72 ± 0.03, 0.99 ± 0.12) and BC siRNA group (0.64 ± 0.03, 0.92 ± 0.06), P < 0.05; cytosolic cytochrome expression in Pax-8 siRNA group (0.75 ± 0.14) was significantly upregulated compared with NC siRNA group (0.51 ± 0.06) and BC siRNA group (0.48 ± 0.07) (P < 0.05); JC-1 monomer/polymer ratio in Pax-8 siRNA group (0.163 ± 0.011) was significantly increased compared with NC siRNA group (0.092 ± 0.015) and BC siRNA group (0.072 ± 0.025) (P < 0.05) indicating mitochondrial membrane potential was significantly reduced in Pax-8 siRNA group. Above parameters were similar between NC siRNA group and BC siRNA group (P > 0.05). CONCLUSION: Inhibiting Pax-8 results in enhanced cardiomyocytes apoptosis through the mitochondrial pathway.

[MicroRNA-144 over-expression induced myocytes apoptosis].

OBJECTIVE: To investigate the effects of microRNA-144 (miR-144) expression on H9C2 (2-1) myocytes. METHODS: MiR-144 was up-regulated in primary cultured H9C2 (2-1) myocytes through transfection. Cells transfected with Lipofectamine(TM) 2000 and its mixture with miRNA synthesized randomly as blank control and negative control respectively. The up-regulation of miR-144 was confirmed by real-time PCR. Cell apoptosis was evaluated by means of CCK-8, Caspase-3 and flow cytometry. RESULTS: Real-time PCR results showed that the miR-144 expression was obviously increased in miR-144 up-regulation group (2178.84 ± 838.52) compared with negative (2.06 ± 0.73) and blank (1.00 ± 0.00) control group (all P < 0.01). The proliferation was lower, the activity of Caspase-3 was elevated and the apoptosis rates were significantly increased in miR-144 up-regulation group compared with negative and blank control group, while no significant difference was found between the latter 2 groups. CONCLUSION: MiR-144 mimics may selectively up-regulate the expression of miR-144 in myocardial cells and consequently promote apoptosis and inhibit proliferation in myocardial cells.

[Ryanodine downregulates the expression of p-eNOS (Thr495) and improves the functions of rapamycin treated endothelial outgrowth cells].

OBJECTIVE: To observe the effects of ryanodine on rapamycin treated endothelial outgrowth cells (EOCs). METHODS: The mononuclear cells were harvested from umbilical cord blood by Ficoll density gradient centrifugation, then induced into EOCs and expanded in vitro. The endothelial characteristics of EOCs were identified by immunostaining and fluorescent staining. The EOCs were pretreated with or without ryanodine (10 µmol/L) for 1 h, and then treated with or without rapamycin (10 nmol/L) for 24 h. Proliferation was evaluated by CCK8 and migration was measured by Transwell. The protein expression of EOCs was evaluated by immunobloting technique with total eNOS antibody and phospho-eNOS (Thr495) antibody. RESULTS: Compared with control group, the proliferation and migration capacities of EOCs were significantly reduced while the phosphorylation of eNOS (Thr495) protein was significantly upregulated in rapamycin group (P < 0.05), expression of total eNOS was not affected by rapamycin (P > 0.05). Compared with rapamycin group, the proliferation and migration capacities of EOCs were significantly increased and the phosphorylation of eNOS (Thr495) protein was significantly downregulated in ryanodine + rapamycin group (P < 0.05). The proliferation and migration capacities, the phosphorylation of eNOS (Thr495) protein and the expression of total eNOS were not affected by ryanodine alone (P > 0.05). CONCLUSIONS: Rapamycin reduced proliferation and migration capacities while upregulated the phosphorylation of eNOS (Thr495) protein of EOCs and these effects could be partly reversed by cotreatment with ryanodine.

[Experimental analysis of microRNAs related to cardiac development differential expression].

OBJECTIVE: To investigate the differential expression profiles of microRNAs in the knockout Pax-8 mice by miRNA microarray analysis and study the function of microRNA during cardiac development. METHODS: The knockout Pax-8 mice model was established and the total RNA derived from Pax-8 KO-/- and Pax-8 KO+/- mice heart. MicroRNA microarray containing 567 mammalian microRNA probes was used to investigate the microRNAs differential expression between Pax-8 KO-/- and Pax-8 KO+/- mice. The candidates of microRNAs were confirmed by real time RT-PCR assay. RESULTS: The heart of pax-8 KO-/- mice became spheroidal. Left ventricle enlargement, left ventricular wall and interventricular septum thickening and papillary muscles in left ventricle enlargement were found. Furthermore, many apoptotic cells were discovered in left ventricular wall and interventricular septum in pax-8 KO-/- mice. The MicroRNA microarray result displayed 10 microRNAs differential expressions, in which 2 microRNAs became down-regulated and 8 microRNAs up-regulated by more than two folds in pax-8 KO-/- mice. This was in accordance with the result of real-time RT-PCR. CONCLUSION: Some microRNAs may play important roles in cardiac development and ventricular septal defect pathogenesis.

[Effects of endothelial progenitor cells and endothelial outgrowth cells in repair of injured carotid vessel: a comparative study with rabbits].

OBJECTIVE: To compare the effects of endothelial progenitor cells (EPCs) and endothelial outgrowth cells (EOCs) on the repair of injured vessels. METHODS: Mononuclear cells (MNCs) were isolated from rabbit peripheral blood by density-gradient centrifugation. EPCs and EOCs were obtained from the culture of MNCs and labeled with the cell dye CM-DiI for cells tracking. Eighteen rabbits were made into models of balloon-injured common carotid artery and then divided into 2 equal groups to undergo injection of the suspensions of EPCs or EOCs. Nine rabbits underwent injection of normal saline as control group. Four weeks after transplantation, the rabbits underwent venous injection of Evans blue, and then were killed with the injured vessels taken out. Fluorescence-labeled both types of cells, endothelial regeneration rate and IA/MA ratio were detected. RESULTS: Four weeks after transplantation, fluorescence-labeled EPCs and EOCs were detected within the tunica intima, mostly in the neointima and on the luminal surface of injured vessel. The endothelialization area of denuded vessel of the EPC and EOC groups were 91.6% +/- 3.6% and 89.1% +/- 6.3% respectively, both significantly larger than that of the control group (62.1% +/- 7.5%, both P < 0.01), however, without significant difference between the 2 former groups (P = 0.50). The intima area/media area ratio of the EPC and EOC groups were 0.48 +/- 0.11 and 0.44 +/- 0.06, both significantly lower than that of the control group (0.88 +/- 0.14, both P < 0.01), however, without significant difference between the 2 former groups (P = 0.59). CONCLUSION: Transplantation of both EPCs and EPCs accelerate the reendothelialization and reduce the neointimal formation with similar effects.

[Effects of compound Salvia injection on number and activity of endothelial progenitor cells].

OBJECTIVE: To investigate the effects of Compound Salvia injection (CSI) on the number and activity of endothelial progenitor cells (EPCs). METHOD: Mononuclear fraction of human umbilical cord blood was obtained by density gradient centrifugation and plated on fibronectin coated culture dishes. Cells were divided in to five groups: group control, group VEGF, group CSI 50, group CSI 10 and group CSI 2 (supplemented with none cytokine, VEGF 10 ng x mL(-1), CSI 50, 10, 2 microg x mL(-1), respectively). After six days in culture, cell clusters were viewed with an inverted microscope, fluorescence-activated cell sorting (FACS) analysis of PE-CD34 and FITC-VE-Cadherin was performed to detect number of EPCs, adhesion assay was performed by replating cells on fibronectin coated dishes, and then counting adherent cells. RESULT: Numbers of EPCs of group VEGF, group CSI 10 and group CSI 2 were significantly increased as compared with those of group control ( P < 0.01, P < 0.05, P < 0.01, respectively), and numbers of EPCs of group CSI 2 were more than those of group CSI 10 and group V (P < 0.01). Compared with group control, number of EPCs of group CSI 50 was significantly decreased (P < 0.01). Compared with group control, numbers of clusters and adhesive EPCs of group CSI 10 and group CSI 2 were significantly increased, while those of group CSI 50 were significantly decreased. CONCLUSION: Low concentration CSI can significantly promote EPCs augmentation and enhance its functional activity, while high concentration CSI significantly restrains it.

[Isolation, culture and identification of two types of endothelial progenitor cells from peripheral blood in rabbits].

AIM: To investigate how to isolate, culture and identify two types of endothelial progenitor cells from peripheral blood in rabbits. METHODS: Mononuclear cells(MNCs) were isolated from rabbit peripheral blood. Endothelial progenitor cells (EPCs) and endothelial outgrowth cells (EOCs) were obtained from MNCs through different ways of isolation and culture. Two types of cells were assessed by DiI-ac-LDL uptake and lectin binding, and then they were identified by immunofluorescence of flk-1, immunocytochemistry of CD34 and VIII factor related antigen and vasculogenesis activity in vitro. RESULTS: Two types of endothelial progenitor cells were obtained from rabbit peripheral blood through different ways of isolation and culture. EPCs on the seventh day and EOCs on the sixteenth day were positive for ac-LDL uptake and lectin binding, and both of them expressed CD34, flk-1 and VIII factor related antigen. EOCs were assembled into primitive vascular tube-like structures when plated in matrigel. CONCLUSION: EPCs and EOCs could be obtained from rabbit peripheral blood when different ways of isolation and culture were performed. The system of cell culture can be applied to subsequent experiments in cell transplantation.

[Preliminary study of ALK3 downstream genes related to ventricular septum defect].

To investigate the function of ALK3 gene, the gene regulation and the signaling pathway related to ventricular septum defect during heart development. The model mice with ALK3 gene knock-out via alpha-MHC-Cre/lox P system were bred. The mRNA expression level of control group was compared with that of experiment group and ALK3 downstream genes were screened using PCR-select cDNA subtraction microarray. The mRNA of control group was extracted from E11.5 normal mouse hearts, and that of experiment group, from E11.5 hearts of mice with alpha-MHC Cre(+/-) ALK3(F/+) genotype. It was found that the mice with ALK3 gene knock-out produced heart defects involving the interventricular septum. The platelet-activating factors acetylhydrolase and the transcription factor Pax-8 and so on, were down-regulated. However, the Protein Tyrosine Kinase (PTK) of Focal Adhesion Kinase (FAK) subfamily and beta subtype protein 14-3-3 were up-regulated in the alpha-MHC Cre(+/-) ALK3(F/-) mice. These data provide support that ALK3 gene played an important role during heart development. The platelet-activating factors acetylhydrolase and Pax-8 genes could be important ALK3 downstream genes in the BMP signaling pathway during interventricular septum development. PTK and beta subtype protein 14-3-3 might be regulatory factors in this pathway.

[A study on myocardial Pax-8 gene].

OBJECTIVE: Conventional deletion of ALK3, also termed as bone morphogenetic protein (BMP) receptor IA, in mice might result in early embryonic lethality. To investigate the function of ALK3 in cardiac development, the cardiac-specific deletion of ALK3 in mice was made by Dr. Schneider, using Cre recombinase driven by the alpha-MHC promoter that Dr. Fukushipe worked out. Such specific deletion of ALK3 caused death in mid-gestation with defects in the trabeculae, interventricular septum, and endocardial cushion. Since ALK3 is not a cardiac-specific gene, it is extremely important to identify ALK3 downstream genes. METHODS: Alpha-MHC Cre+/-, ALK3 F/- and alpha-MHC Cre+/-, ALK3 F/+ embryos were obtained after 20 alpha-MHC Cre+/-, ALK3 +/- mice and 20 ALK3 F/F mice were mating. The ALK3 downstream genes were screened using microarray made in Germany that could identify 25000 genes in mouse. Two populations of mRNA, one derived from the embryonic heart (11.5 days) of alpha-MHC Cre+/-, ALK3 F/- mice, and the other derived from the alpha-MHC Cre+/-, ALK3 F/+ mice, were compared. Cardiac-specific ALK3 downstream genes were identified using real time quantitative RT-PCR and in situ hybridization. RESULTS: The expression of 12 genes, such as Pax-8 and Hox-3.5 were down-regulated in alpha-MHC Cre+/-, ALK3 F/- mouse heart. The expression of 16 genes including Ras-related protein Rab-5b and EPS-8 protein was up-regulated in the group of alpha-MHC Cre+/-, ALK3 F/-. It was found that the Box protein Pax-8 gene was down-regulated by 7.1 fold (P < 0.001) in the alpha-MHC Cre+/-, ALK3 F/- mice by real time quantitative RT-PCR. It was also revealed that the Box protein Pax-8 gene was expressed stronger in alpha-MHC Cre+/-, ALK3 F/+ than alpha-MHC Cre+/-, ALK3 F/- E11.5 days mouse heart by means of in situ hybridization. CONCLUSION: The Box protein Pax-8 gene is an important and cardiac-specific ALK3 downstream gene in the BMP signaling pathway during inter-ventricular septum development.