AIM:MicroRNAs ( miRNAs) were recognized to play significant roles in cardiac hypertrophy .But, it remains unknown whether cyclin/Rb pathway is modulated by miRNAs during cardiac hypertrophy .This study investigates the potential roles of microRNA-1 (miR-1) and microRNA-16 (miR-16) in modulating cyclin/Rb pathway during cardiomyocyte hypertrophy .METHODS:An animal model of hypertrophy was established in a rat with abdominal aortic constriction (AAC).In addition, a cell model of hypertrophy was also achieved based on PE-promoted neonatal rat ventricular cardiomyocyte .RESULTS:miR-1 and-16 expression were markedly de-creased in hypertrophic myocardium and hypertrophic cardiomyocytes in rats .Overexpression of miR-1 and -16 suppressed rat cardiac hypertrophy and hypertrophic phenotype of cultured cardiomyocytes .Expression of cyclins D1, D2 and E1, CDK6 and phosphorylated pRb was increased in hypertrophic myocardium and hypertrophic cardiomyocytes , but could be reversed by enforced expression of miR-1 and -16.CDK6 was validated to be modulated post-transcriptionally by miR-1, and cyclins D1, D2 and E1 were further validated to be modulated post-transcriptionally by miR-16.CONCLUSION: Attenuations of miR-1 and -16 provoke cardiomyocyte hypertrophy via derepressing the cyclins D1, D2, E1 and CDK6, and activating cyclin/Rb pathway.

AIM:To investigate the effect of miR-214 on cardiomyocyte hypertrophy and the expression of the potential target genes . METHODS:A cell model of hypertrophy was established based on angiotensin-Ⅱ( Ang-Ⅱ)-induced neonatal mouse ventricular car-diomyocytes (NMVCs).Dual luciferase reporter assay was performed to verify the interaction between miR-214 and the 3’ UTR of MEF2C.The expression of MEF2C and hypertrophy-related genes at mRNA and protein levels was determined by RT-qPCR and Wes-tern blotting, respectively.RESULTS:The expression of ANP, ACTA1,β-MHC and miR-214 was markedly increased in Ang-Ⅱ-in-duced hypertrophic cardiomyocytes .Dual luciferase reporter assay revealed that miR-214 interacted with the 3’ UTR of MEF2C, and miR-214 was verified to inhibit MEF2C expression at the transcriptional level .The protein expression of MEF2C was markedly in-creased in the hypertrophic cardiomyocytes .Moreover, miR-214 mimic, in parallel to MEF2C siRNA, inhibited the expression of hy-pertrophy-related genes in Ang-Ⅱ-induced NMVCs.CONCLUSION:MEF2C is a target gene of miR-214, which mediates the effect of miR-214 on attenuating cardiomyocyte hypertrophy .

Objective To investigate the effects of intracellular magnetic labeling of stem cells with superparamagnetic iron oxide (SPIO) on the cell differentiation capability into hepatocyte-like cells.Methods Adiposederived stem cells (ADSCs) were obtained from the inguinal fat tissue of Sprague-Dawley rats.ADSCs were labeled with co-incubation of poly-l-lysine (PLL) and SPIO (25 μg/mL).Intracellular iron uptake was analyzed qualitatively with light microscopy.The viability of ADSCs was evaluated with trypan blue staining.SPIO-labeled and unlabled ADSCs were subjected to differentiate into hepatocyte-like cells with hepatocyte growth factor (HGF).Liver marker gene such as albumin (ALB) was analyzed by RT-PCR.The cell viability between the labeled cell group and unlabeled cell group adopted two independent sample t-Test.Results Light microscopy results revealed intracytoplasmic iron uptake and nearly 100％ of cell labeling efficiency.SPIO-labeled ADSCs had an unaltered viability as compared with unlabeled ADSCs (P＞0.05).After induction,glycogen storage within cytoplasm can be found in the two group on 14 d and 21 d,and the cells with positive staining increased on day 21.The two groups both express the ALB on 14 d and 21 d,which expressed higher on 21 d.Conclusion Intracellular magnetic labeling with SPIO did not affect the viability and capability of ADSCs to differentiate into hepatocyte-like cells.

AIM:To determine circular RNA (circRNA) profiles in the diabetic mouse myocardium , and to investigate the effect of circRNA_000203 on fibrotic phenotypes in cardiac fibroblasts .METHODS:Masson trichrome stai-ning was performed on the myocardium of the diabetic db /db mice and the non diabetic db/m control mice .circRNA ex-pression profile in the diabetic myocardium was detected by circRNAs microarray .The expression of circRNA_000203 was determined by real time fluorescence quantitative PCR ( RT-qPCR ) .Recombinant circRNA_000203 adenovirus was pre-pared for enforced the expression of circRNA_000203 in mouse cardiac fibroblasts.The expression of Col1a2, Col3a1andα-SMA was determined in circRNA_000203-modified cardiac fibroblasts , respectively .RESULTS:Masson trichrome stai-ning showed that fibrosis was increased in the diabetic mouse myocardium .The results of circRNA array detection revealed that circRNAs were dysregulated in the diabetic myocardium .circRNA_000203 was up-regulated in the diabetic myocardi-um.Significant over-expression of circRNA_000203 was achieved in the cardiac fibroblasts after infection with the recombi-nant circRNA_000203 adenovirus.The mRNA and protein expression of Col1a2, Col3a1 and α-SMA was significantly in-creased in the cardiac fibroblasts with over-expression of circRNA_000203.CONCLUSION:circRNA_000203 is up-regu-lated in the diabetic mouse myocardium .It has pro-fibrotic effect on the cardiac fibroblasts .

AIM:To investigate the effect of caspase-8 small hairpin RNA ( shRNA) on attenuating apoptosis of human mesenchymal stem cells ( hMSCs ) .METHODS: Two recombinant plasmids for over-expression of caspase-8 shRNA, pAd-Cap8 shRNA1 and pAd-Cap8 shRNA2, were constructed.Caspase-8 mRNA was determined in pAd-Cap8 shRNA-transfected human HEK293 cells by Q-PCR.The screened pAd-Cap8 shRNA was used to construct the recombinant adenovirus plasmid , which was linearized and transfected into HEK 293 cells for packaging and amplification of the recombi-nant adenovirus rAd-Cap8 shRNA.The expression of caspase-8 at mRNA and protein levels was determined by Q-PCR and Western blotting .Annexin V/PI staining and determination of caspase-8 activity were performed to assess apoptosis of hM-SCs under the conditions of serum deprivation and hypoxia .The mRNA expression of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), insulin-like growth factor 1 (IGF-1), Bcl-2 and Bcl-xL was analyzed by Q-PCR.RESULTS:The pAd-Cap8 shRNA, which efficiently inhibited caspase-8 expression, was screened by Q-PCR.The recombinant adenovirus plasmid for caspase-8 shRNA was constructed and used to package and amplify the recombinant ad-enovirus ( rAd)-Cap8 shRNA successfully .rAd-Cap8 shRNA-mediated caspase-8 shRNA markedly inhibited caspase-8 ex-pression in hMSCs .Over-expression of caspase-8 shRNA by infection of rAd-Cap8 shRNA also efficiently decreased the ap-optotic rate and caspase-8 activity in hMSCs under the conditions of serum deprivation and hypoxia , with up-regulation of the mRNA expression of HGF, IGF-1 and Bcl-2.CONCLUSION:Caspase-8 shRNA attenuates hMSC apoptosis under the conditions of serum deprivation and hypoxia .

AIM:To investigate the effect of microRNA-214 ( miR-214) on cardiomyocyte hypertrophy and the expression of the potential target genes .METHODS:A cell model of hypertrophy was established based on angiotensin-Ⅱ( Ang-Ⅱ)-induced neonatal mouse ventricular cardiomyocytes ( NMVCs) .Dual luciferase reporter assay was performed to verify the interaction between miR-214 and the 3’ UTR of MEF2C.The expression of MEF2C and hypertrophy-related genes at mRNA and protein levels was determined by RT-qPCR and Western blot , respectively .RESULTS:The expression of ANP, ACTA1,β-MHC and miR-214 was markedly increased in Ang-Ⅱ-induced hypertrophic cardiomyocytes .Dual lu-ciferase reporter assay revealed that miR-214 interacted with the 3’ UTR of MEF2C, and miR-214 was verified to inhibit MEF2C expression at the transcriptional level .The protein expression of MEF2C was markedly increased in the hypertro-phic cardiomyocytes .Moreover, miR-214 mimic, in parallel to MEF2C siRNA, inhibited the expression of hypertrophy-re-lated genes in Ang-Ⅱ-induced NMVCs.CONCLUSION:MEF2C is a target gene of miR-214, which mediates the effect of miR-214 on attenuating cardiomyocyte hypertrophy .

AIM:Increasing evidence indicates that inflammation contributes to the initiation and perpetuation of atrial fibrillation ( AF) .Al-though tumor necrosis factor ( TNF)-αlevels are increased in patients with AF , the role of TNF-αin the pathogenesis of AF remains unclear.Recent research has revealed that T-type Ca2+currents ( ICa,T ) play an important role in the pathogenesis of AF .METH-ODS:In this study , we used the whole-cell voltage-clamp technique and biochemical assays to explore the role of TNF-αin the regula-tion of ICa,T in atrial myocytes.RESULTS:We found that compared with sinus rhythm (SR) controls, T-type calcium channel (TCC) subunit mRNA levels were decreased , while TNF-αexpression levels were increased , in human atrial tissue from patients with AF .In murine atrial myocyte HL-1 cells, after cultured for 24 h, 12.5, 25 and 50 μg/L TNF-αsignificantly reduced the protein expression levels of the TCC α1G subunit in a concentration-dependent manner .The peak current was reduced by the application of 12.5 or 25μg/L TNF-αin a concentration-dependent manner [from ( -15.08 ±1.11) pA/pF in controls to ( -11.89 ±0.83) pA/pF and (-8.54 ±1.55) pA/pF in 12.5 and 25 μg/L TNF-αgroups, respectively].TNF-αapplication also inhibited voltage-dependent inactivation of ICa,T shifted the inactivation curve to the left .CONCLUSION:These results suggest that TNF-αis involved in the path-ogenesis of AF, probably via decreasing ICa,T function in atrium-derived myocytes through impaired channel function and down -regula-tion of channel protein expression .This pathway thus represents a potential pathogenic mechanism in AF .

AIM:To investigate whether the association of connexin 43 ( Cx43 ) and L-type calcium channel involved in the pathogenesis of atrial fibrillation ( AF) .METHODS:The biochemical assays and whole-cell patch-clamp technique were used to study the expression of Cx43 in human atrial tissue.The co-localization of Cx43 and L-type calcium channel, and the regulation of L-type calcium current in atrial myocytes were investigated.RESULTS:The expression of Cx43 at mRNA and protein levels was decreased in human atrial tissues of AF patients.In cultured atrium-derived myocytes ( HL-1 cells) , knockdown of Cx43 significantly inhibited the mRNA expression of L-type calcium channelα1c subunit, as well as L-type calcium current.Co-localization of Cx43 with L-type calcium channel α1c subunit in mouse atrial myocytes was observed.CONCLUSION:The decrease in Cx43 is involved in the pathogenesis of AF, probably through reducing the L-type calcium current in atrial myoctyes by co-localization with L-type calcium channel, thus representing the potential pathogenesis in atrial fibrillation.

OBJECTIVETo investigate the association of desmoplakin with the distribution and function of Nav1.5 by RNA silencing technology in HL-1 cells.

METHODSHL-1 cells with desmoplakin expression suppression by RNA silencing were examined for desmoplakin and Nav1.5 protein expressions by Western blotting, and the distribution and co-location of desmoplakin and Nav1.5 protein were detected by immunofluorescence staining. Patch-clamp recording was applied to analyze the changes in whole-cell sodium current after desmoplakin silencing.

RESULTSCompared with the untreated group and negative control group, the cells with desmoplakin silencing showed obviously reduced expressions of desmoplakin and Nav1.5 proteins. Co-localization of desmoplakin and Nav1.5 was detected at cell-cell contact in untreated and control conditions, and desmoplakin expression silencing induced a drastic redistribution of Nav1.5 with decreased peak current density (156.3∓6.2 vs 41.8∓3.1, n=6, P<0.05), a shift in voltage dependence of steady-state inactivation (-42 mV vs -61 mV, n=5, P<0.05), and prolonged time of recovery from inactivation.

CONCLUSIONDesmoplakin silencing caused redistribution of Nav1.5 protein and also changes in its electrophysiological properties in HL-1 cells.

Animals ; Cell Line ; Desmoplakins ; genetics ; metabolism ; Gene Silencing ; Mice ; Mutation ; Myocytes, Cardiac ; metabolism ; NAV1.5 Voltage-Gated Sodium Channel ; metabolism

OBJECTIVETo investigate the role of miR-199a-3p in cardiac fibrosis and the potential target of miR-199a-3p.

METHODSCardiac fibroblasts were isolated from C57BL/6 mice and cultured. The miR-199a-3p mimic and Smad1 siRNA were transiently transfected into the cardiac fibroblasts via liposome. Dual luciferase reporter assay was performed to confirm the interaction between miR-199a-3p and the 3'-UTR of Smad1. The expressions of Smad1 and fibrosis-related genes at the mRNA and protein levels in the cells after miR-199a-3p mimic transfection were determined using RT-qPCR and Western blotting, respectively. The expressions of Smad1, Smad3 and fibrosis-related genes at the protein level in cells transfected with miR-199a-3p mimic and Smad1 siRNA were detected using Western blotting.

RESULTSOver-expression of miR-199a-3p significantly increased the expression of cardiac fibrosis-related genes in cultured mouse cardiac fibroblasts. Dual luciferase reporter assay revealed the interaction of miR-199a-3p with the 3'-UTR of Smad1. The results of RT-qPCR and Western blotting confirmed that miR-199a-3p inhibited Smad1 expression at the post- transcriptional level. Transfection with miR-199a-3p mimic and siRNA-mediated Smad1 silencing consistently activated the Smad3 signaling pathway and enhanced the expressions of cardiac fibrosis-related genes in the cardiac fibroblasts.

CONCLUSIONSAs the target gene of miR-199a-3p, Smad1 mediates the pro-fibrotic effect of miR-199a-3p by activating the Smad3 signaling in cultured mouse cardiac fibroblasts.