RESUMO
BACKGROUND: Long noncoding RNAs (lncRNAs) are emerging as important mediators of cardiac pathophysiology. The aim of the present study is to investigate the effects of lncR-30245, an lncRNA, on cardiac fibrogenesis and the underlying mechanism. METHODS: Myocardial infarction (MI) and transforming growth factor (TGF)-ß1 were used to induce fibrotic phenotypes. Cardiac fibrosis was detected by Masson's trichrome staining. Cardiac function was evaluated by echocardiography. Western blot, quantitative reverse transcription-polymerase chain reaction, and pharmacological approaches were used to investigate the role of lncR-30245 in cardiac fibrogenesis. RESULTS: Expression of lncR-30245 was significantly increased in MI hearts and TGF-ß1-treated cardiac fibroblasts (CFs). LncR-30245 was mainly located in the cytoplasm. Overexpression of lncR-30245 promoted collagen production and CF proliferation. Knockdown of lncR-30245 significantly inhibited TGF-ß1-induced collagen production and CF proliferation. LncR-30245 overexpression inhibited the antifibrotic role of peroxisome proliferator-activated receptor (PPAR)-γ and increased connective tissue growth factor (CTGF) expression, whereas lncR-30245 knockdown exerted the opposite effects. Rosiglitazone, a PPAR-γ agonist, significantly inhibited lncR-30245-induced CTGF upregulation and collagen production in CFs. In contrast, T0070907, a PPAR-γ antagonist, attenuated the inhibitory effects of lncR-30245 small interfering RNA (siRNA) on TGF-ß1-induced CTGF expression and collagen production. LncR-30245 knockdown significantly enhanced ejection fraction and fractional shortening and attenuated cardiac fibrosis in MI mice. CONCLUSION: Our study indicates that the lncR-30245/PPAR-γ/CTGF pathway mediates MI-induced cardiac fibrosis and might be a therapeutic target for various cardiac diseases associated with fibrosis.
Assuntos
Fator de Crescimento do Tecido Conjuntivo/metabolismo , Cardiopatias/metabolismo , PPAR gama/metabolismo , RNA Longo não Codificante , Animais , Benzamidas/farmacologia , Proliferação de Células , Colágeno/efeitos dos fármacos , Colágeno/metabolismo , Fibroblastos/metabolismo , Fibrose , Camundongos Endogâmicos C57BL , Modelos Animais , Infarto do Miocárdio/metabolismo , Piridinas/farmacologia , Rosiglitazona/farmacologia , Volume Sistólico , Fator de Crescimento Transformador beta1/farmacologia , Regulação para Cima/efeitos dos fármacosRESUMO
Background: MicroRNAs (miRNAs) have been emerged as important regulator in a multiple of cardiovascular disease, including arrhythmia, cardiac hypertrophy and fibrosis, and myocardial infarction. The aim of this study was to investigate whether miRNA let-7a has antihypertrophic effects in angiotensin II (AngII)-induced cardiac hypertrophy. Methods: Neonatal rat ventricular myocytes (NRVMs) were exposed to AngII for 36 h as a cellular model of hypertrophy; subcutaneous injection of AngII for 2 weeks was used to establish a mouse model of cardiac hypertrophy in vivo study. Cell surface area (CSA) was measured by immunofluorescence cytochemistry; expression of hypertrophy-related genes ANP, BNP, ß-MHC was detected by Real-time PCR; luciferase activity assay was performed to confirm the miRNA's binding site in the calmodulin (CaM) gene; CaM protein was detected by Western blot; the hypertrophy parameters were measured by echocardiographic assessment. Results: The expression of let-7a was decreased in AngII-induced cardiac hypertrophy in vitro and in vivo. Overexpression of let-7a attenuated AngII-induced increase of cell surface area and repressed the increased mRNA levels of ANP, BNP and ß-MHC. Dual-luciferase reporter assay showed that let-7a could bind to the 3'UTR of CaM 1 gene. Let-7a downregulated the expression of CaM protein. In vivo, let-7a produced inhibitory effects on cardiac hypertrophy, including the downregulation of cross-sectional area of cardiomyocytes in mouse heart, the reduction of IVSD and LVPWD, the suppression of hypertrophy marker genes ANP, BNP, ß-MHC mRNA level, and the downregulation of CaM protein level. Conclusions: let-7a possesses a prominent anti-hypertrophic property by targeting CaM genes. The findings provide new insight into molecular mechanism of cardiac hypertrophy.
Assuntos
Calmodulina/metabolismo , Cardiomegalia/genética , Cardiomegalia/metabolismo , MicroRNAs/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Regiões 3' não Traduzidas/genética , Angiotensina II/farmacologia , Animais , Fator Natriurético Atrial/genética , Calmodulina/genética , Cardiomegalia/induzido quimicamente , Células Cultivadas , MicroRNAs/genética , Peptídeo Natriurético Encefálico/genética , RNA Mensageiro/genética , Ratos , Reação em Cadeia da Polimerase em Tempo RealRESUMO
In the present study, we demonstrated that bone marrow mesenchymal stem cells (BMSCs) of the 3rd passage displayed the senescence-associated phenotypes characterized with increased activity of SA-ß-gal, altered autophagy, and increased G1 cell cycle arrest, ROS production, and expression of p53 and p21Cip1/Waf1 compared with BMSCs of the 1st passage. Cholesterol (CH) reduced the number of SA-ß-gal positive cells in a dose-dependent manner in aging BMSCs induced by H2O2 and the 3rd passage BMSCs. Moreover, CH inhibited the production of ROS and expression of p53 and p21Cip1/Waf1 in both cellular senescence models and decreased the percentage of BMSCs in G1 cell cycle in the 3rd passage BMSCs. CH prevented the increase in SA-ß-gal positive cells induced by RITA (reactivation of p53 and induction of tumor cell apoptosis, a p53 activator) or 3-MA (3-methyladenine, an autophagy inhibitor). Our results indicate that CH not only is a structural component of cell membrane but also functionally contributes to regulating cellular senescence by modulating cell cycle, autophagy, and the ROS/p53/p21Cip1/Waf1 signaling pathway.
