High Glucose-induced Cardiomyocyte Hypertrophy Research Articles

Rosmarinic acid inhibits high glucose-induced cardiomyocyte hypertrophy by activating Parkin-mediated mitophagy

To evaluate the effect of rosmarinic acid (RA) on mitophagy and hypertrophy of cardiomyocytes exposed to high glucose (HG). Rat cardiomyocytes (H9c2) exposed to HG (25 mmol/L) were treated with 50 μmol/L RA or with both RA treatment and Parkin siRNA transfection, with the cells cultured in normal glucose (5.5 mmol/L) and HG as the controls. The expressions of PINK1, Parkin and LC3II/LC3I in the cells were detected by Western blotting. The formation of mitochondrial autophagosomes was observed by transmission electron microscope. Flow cytometry was employed to detect the level of reactive oxygen species (ROS) and apoptotic rate of the cells. The activities of respiratory chain complex enzymes were measured by spectrophotometry. Fluorescence enzyme labeling and 3H-leucine labeling were used for determining the level of membrane potential and protein synthesis rate, respectively. The cell surface area was observed by light microscopy. RA treatment significantly increased the expression levels of PINK1, Parkin and LC3-II/I (P < 0.05), promoted the formation of mitochondrail autophagosome, inhibited the production of reactive oxygen species (P < 0.05), restored the activities of mitochondrial respiratory chain complex enzymes and mitochondrial membrane potential (P < 0.05), inhibited apoptosis (P < 0.05), and reduced the cell surface area and protein synthesis rate of H9c2 cells induced by HG exposure (P < 0.05). The protective effects of RA against HG-induced oxidative stress and cardiomyocyte hypertrophy was obviously blocked by inhibition of mitophagy mediated by transfection with Parkin siRNA (P < 0.05). RA can protect rat cardiomyocytes against oxidative stress injury and cardiomyocyte hypertrophy induced by HG by activating Parkin-mediated mitophagy.

EETs/PPARs activation together mediates the preventive effect of naringenin in high glucose-induced cardiomyocyte hypertrophy

BackgroundCardiac hypertrophy is a key pathological process in the context of diabetic cardiomyopathy. Naringenin exhibits multiple pharmacological activities, but the effect of naringenin on cardiomyocyte hypertrophy under diabetic conditions is still far from clear. MethodsCardiomyocyte hypertrophy was induced by high glucose (HG, glucose at 25.5 mmol/L) in H9c2 cells, which was determined by cell surface area, protein content and atrial natriuretic factor (ANF) mRNA expression. The effect of naringenin on cardiomyocyte hypertrophy was observed and its mechanisms were investigated by administration with various inhibitors on epoxyeicosatrienoic acids (EETs)/peroxisome proliferator-activated receptors (PPARs). The level of 14,15-EET was measured by ELISA. The mRNA and protein expressions were detected by qRT-PCR or Western blot, respectively. ResultsNaringenin (0.1, 1, 10 μmol/L) inhibited cardiomyocyte hypertrophy in a concentration-dependent manner (P < 0.05), up-regulated the expressions of PPARα, PPARβ, PPARγ and CYP2J3 (P < 0.05), and increased the level of 14,15-EET (P < 0.05). PPOH, a CYP2J3 inhibitor, blocked the naringenin-mediated improvement of myocardial hypertrophy (P < 0.01), and abolished the up-regulation of PPARs expressions (P < 0.01). Meanwhile, MK886, a PPARα antagonist, GSK0660, a PPARβ antagonist, and GW9662, a PPARγ antagonist, reversed the protection of naringenin on cardiomyocytes (P < 0.05), and abrogated the up-regulation of CYP2J3-EET produced by naringenin (P < 0.05). ConclusionsActivation of EETs and PPARs function together may be contributed to the anti-hypertrophic effect of naringenin in H9c2 cells under high glucose condition.

Berberine Ameliorates High Glucose-Induced Cardiomyocyte Injury via AMPK Signaling Activation to Stimulate Mitochondrial Biogenesis and Restore Autophagic Flux.

Background: Type II diabetes (T2D)-induced cardiomyocyte hypertrophy is closely linked to the impairment of mitochondrial function. Berberine has been shown to be a promising effect for hypoglycemia in T2D models. High glucose-induced cardiomyocyte hypertrophy in vitro has been reported. The present study investigated the protective effect and the underlying mechanism of berberine on high glucose-induced H9C2 cell line.Methods: High glucose-induced H9C2 cell line was used to mimic the hyperglycemia resulting in cardiomyocyte hypertrophy. Berberine was used to rescue in this model and explore the mechanism in it. Confocal microscopy, immunofluorescence, RT-PCR, and western blot analysis were performed to evaluate the protective effects of berberine in high glucose-induced H9C2 cell line.Results: Berberine dramatically alleviated hypertrophy of H9C2 cell line and significantly ameliorated mitochondrial function by rectifying the imbalance of fusion and fission in mitochondrial dynamics. Furthermore, berberine further promoted mitogenesis and cleared the damaged mitochondria via mitophagy. In addition, berberine also restored autophagic flux in high glucose-induced cardiomyocyte injury via AMPK signaling pathway activation.Conclusion: Berberine ameliorates high glucose-induced cardiomyocyte injury via AMPK signaling pathway activation to stimulate mitochondrial biogenesis and restore autophagicflux in H9C2 cell line.

GW29-e0743 CTRP9 inhibit high glucose-induced cardiomyocyte hypertrophy by autophagy

This study aimed to investigate the effect of CTRP9 on high glucose-induced cardiomyocyte hypertrophy and the related mechanism. A model of high glucose-induced cardiomyocyte hypertrophy was made in vitro. Rat cardiomyocyte were randomly divided into 5 groups: the control group, CTRP9 group, high

Relaxin ameliorates high glucose-induced cardiomyocyte hypertrophy and apoptosis via the Notch1 pathway.

The present study aimed to investigate the role of relaxin (RLX) on high glucose (HG)-induced cardiomyocyte hypertrophy and apoptosis, as well as the possible molecular mechanism. H9c2 cells were exposed to 33 mmol/l HG with or without RLX (100 nmol/ml). Cell viability, apoptosis, oxidative stress, cell hypertrophy and the levels of Notch1, hairy and enhancer of split 1 (hes1), atrial natriuretic polypeptide (ANP), brain natriuretic peptide (BNP), manganese superoxide dismutase (MnSOD), cytochrome C and caspase-3 were assessed in cardiomyocytes. Compared with the HG group, the viability of H9c2 cells was increased by RLX in a time- and dose-dependent manner, and was accompanied with a significant reduction in apoptosis. Furthermore, RLX significantly suppressed the formation of reactive oxygen species and malondialdehyde, and enhanced the activity of SOD. In addition, the levels of ANP, BNP, cytochrome C and caspase-3 were increased and Notch1, hes1 and MnSOD were inhibited in the HG group compared with those in the normal group. However, the Notch inhibitor DAPT almost abolished the protective effects of RLX. These results suggested that RLX protected cardiomyocytes from HG-induced hypertrophy and apoptosis partly through a Notch1-dependent pathway, which may be associated with reducing oxidative stress.

Effects of fibroblast growth factor inducible 14(Fn14)on high glucose induced-cardiomyocyte hypertrophy

Objective To investigate the effect and mechanisms of factor fibroblast growth factor inducible 14(Fn14)in the high glucose induced-cardiomyocyte hypertrophy. Method To observe the expression of collagen Ⅰ, connective tissue growth factor(CTGF), transforming growth factor-β1(TGF-β1), and Fn14 in high glucose induced-cardiomyocyte hypertrophy. Fn14 expressions was down-regulated by siRNA interference technique, and then the expressions of collagen Ⅰ, CTGF, and TGF-β1 were observed, and the mechanism was also explored. Results The expression of collagen I, CTGF and TGF-β1 was significantly up-regulated after high glucose induced-cardiomyocyte hypertrophy for 72 h. At the same time, the expression of Fn14 was increased after 72 h-treatment, and reached the peak at concentration of 30 mmol/L high glucose. High glucose could not up-regulated the expression of collagen Ⅰ, CTGF, and TGF-β1 after siFn14 interference, while the same result was observed in the expression of p-JNK. Conclusion The expressions of collagen Ⅰ, CTGF, TGF-β1, and Fn14 in cardiomyocyte of neonatal rats were induced by high glucose. While Fn14 expression was inhibited, the expressions of collagen Ⅰ, CTGF, and TGF-β1 were down-regulated, which seems to be involved with p-JNK signaling pathway. (Chin J Endocrinol Metab, 2016, 32: 411-414) Key words: Fn14; Cardiomyocyte hypertrophy; JNK signaling pathway

Conjugated linoleic acid prevents high glucose–induced hypertrophy and contractile dysfunction in adult rat cardiomyocytes

Diabetes mellitus is associated with increased risk and incidence of cardiovascular morbidity and mortality, independently of other risk factors typically associated with diabetes such as coronary artery disease and hypertension. This promotes the development of a distinct condition of the heart muscle known as diabetic cardiomyopathy. We have previously shown that conjugated linoleic acid (CLA) prevents endothelin-1–induced cardiomyocyte hypertrophy. However, the effects of CLA in preventing alterations in cardiomyocyte structure and function due to high glucose are unknown. We therefore hypothesized that CLA will have protective effects in an in vitro model of diabetic cardiomyopathy using adult rat cardiomyocytes exposed to high glucose. Our results demonstrate that subjecting adult rat cardiomyocytes to high glucose (25 mmol/L) for 24 hours significantly impaired the contractile function as evidenced by decreases in maximal velocity of shortening, peak shortening, and maximal velocity of relengthening. High glucose–induced contractile dysfunction was inhibited by pretreatment with CLA (30 μmol/L; 1 hour). In addition to contractile aberrations, exposing adult rat cardiomyocytes to high glucose for 48 hours induced cardiomyocyte hypertrophy. High glucose–induced cardiomyocyte hypertrophy was likewise prevented by CLA. The antihypertrophic effects of CLA were abolished when cardiomyocytes were pretreated with the pharmacologic inhibitor of peroxisome proliferator–activated receptor γ, GW9662 (1 μmol/L). In conclusion, our findings show that exposing cardiomyocytes to high glucose results in cardiomyocyte functional and structural abnormalities, and these abnormalities are prevented by pretreatment with CLA and mediated, in part, by peroxisome proliferator–activated receptor γ activation.

Study on the mechanism of HIF1a-SOX9 in glucose-induced cardiomyocyte hypertrophy.

A major cause of morbidity and mortality in cardiovascular disease is pathological cardiac hypertrophy. With an increase in the cellular surface area and upregulation of the atrial natriuretic peptide (ANP) gene, cardiac hypertrophy is a prominent feature of diabetic cardiomyopathy. ANP is a hypertrophic marker. Many works have been done to explore how the glucose induces the cardiac hypertrophy. However, it is not enough for us to figure it out. In this study, the influences of different glucose concentrations on cardiomyocytes were examined in vitro. The results showed that cardiomyocytes cultured with 25mM glucose tended to show a hypertrophic phenotype, while cardiomyocytes cultured with 35mM glucose tended to undergo apoptosis. An increased expression of SOX9 was observed when cardiomyocytes were cultured with 25mM glucose, but when the concentration of glucose was increased to 35mM, the expression of SOX9 decreased. We used the RNAi approach to knockdown SOX9 expression, to assess its effects on cardiomyocyte hypertrophy. The results showed that knockdown of the SOX9 gene suppressed the 25mM glucose-induced cardiomyocyte hypertrophy. The upregulation of the ANP gene was associated with overexpression of SOX9. Additionally, the results showed that high glucose (HG, 25mM) treatment increased the expression of hypoxia-inducible factor (HIF)1a. Further study showed that HIF1a participated in regulating SOX9 expression in response to HG. This study revealed a novel regulatory mechanism of HIF1a-SOX9 in high glucose-induced cardiomyocyte hypertrophy, as well as the related molecular mechanisms.

MicroRNA-182 modulates high glucose-induced cardiomyocyte hypertrophy via targeting Rac1

To investigate the role and signalling of microRNA(miR)-182 on regulating high glucose-induced cardiomyocyte hypertrophy. The candidates of miR which might potentially be involved on targeting Rac1 were predicted by applying bioinformatics analysis. The expression of all related candidates miRs was verified by real-time reverse transcription-PCR (RT-PCR) in cardiac tissues of db/db mice and db/m mice. Then the relationship between candidates miR and Rac1 was investigated with Pearson relevant analysis. Neonatal mice cardiomyocytes were cultured and divided into 2 groups: normal glucose group and high glucose group. The level of selected miR and Rac1 in two groups was detected by RT-PCR. Neonatal mice cardiomyocytes were then randomly divided into 4 groups: normal glucose group, selected microRNA mimics control group, high glucose group, high glucose plus selected miR mimics control group. The morphology of cardiomyocyte in each group was detected under light microscope. Furthermore, Rac1, β-MHC and α-SMA expressions were detected in cultured cardiomyocyte treated by high glucose for 48 h after transfecting selected miR mimics by RT-PCR and Western blot. A total of 6 miR candidates potentially targeting Rac1 were screened by bioinformatics, which were miR-182, miR-142-3p, miR-140, miR-101a, miR-429 and miR-200b. Among these candidates, miR-182 and miR-142-3p expression was significantly downregulated in cardiac tissues of db/db mice compared with db/m controls (P < 0.05). MiR-182 was negatively correlated with Rac1 by person analysis (r = -0.891 02). Downregulation of miR-182 and upregulation of Rac1, β-MHC, α-SMA were found in high glucose-induced cardiomyocyte. After transfection of miR-182 mimics, hypertrophic changes were significantly reduced and Rac1 as well β-MHC expression was significantly downregulated in cardiomyocyte incubated with high glucose. MiR-182 might be involved in the regulation of high glucose-induced myocardial hypertrophy process via targeting Rac1.

O-GlcNAcylation involvement in high glucose-induced cardiac hypertrophy via ERK1/2 and cyclin D2

Continuous hyperglycemia is considered to be the most significant pathogenesis of diabetic cardiomyopathy, which manifests as cardiac hypertrophy and subsequent heart failure. O-GlcNAcylation has attracted attention as a post-translational protein modification in the past decade. The role of O-GlcNAcylation in high glucose-induced cardiomyocyte hypertrophy remains unclear. We studied the effect of O-GlcNAcylation on neonatal rat cardiomyocytes that were exposed to high glucose and myocardium in diabetic rats induced by streptozocin. High glucose (30mM) incubation induced a greater than twofold increase in cell size and increased hypertrophy marker gene expression accompanied by elevated O-GlcNAcylation protein levels. High glucose increased ERK1/2 but not p38 MAPK or JNK activity, and cyclin D2 expression was also increased. PUGNAc, an inhibitor of β-N-acetylglucosaminidase, enhanced O-GlcNAcylation and imitated the effects of high glucose. OGT siRNA and ERK1/2 inhibition with PD98059 treatment blunted the hypertrophic response and cyclin D2 upregulation. OGT inhibition also prevented ERK1/2 activation. We also observed concentric hypertrophy and similar changes of O-GlcNAcylation level, ERK1/2 activation and cyclin D2 expression in myocardium of diabetic rats induced by streptozocin. In conclusion, O-GlcNAcylation plays a role in high glucose-induced cardiac hypertrophy via ERK1/2 and cyclin D2.

MiR-150 regulates high glucose-induced cardiomyocyte hypertrophy by targeting the transcriptional co-activator p300

p300, a transcriptional co-activator with histone acetyl transferase (HAT) activity, plays an essential role in the pathogenesis of cardiomyocyte hypertrophy in response to multiple pro-hypertrophic stimuli including hyperglycemia. However, the precise mechanisms by which p300 expression is regulated remain unclear. The purpose of this study was to investigate the role of miR-150, a potential p300-targeting microRNA (miRNA), in the post-transcriptional control of p300 expression and cardiomyocyte hypertrophy induced by high glucose. We observed that the expression of miR-150 was significantly reduced, whereas the expression of p300 was strongly elevated, concomitant with cardiomyocyte hypertrophy, in the hearts of diabetic rats compared with normal controls. Similar alterations were observed in neonatal rat cardiomyocytes that had been exposed to high levels of glucose. miR-150 mimics inhibited p300 3′-UTR luciferase reporter activity, as well as endogenous p300 expression. In addition, miR-150 mimics prevented glucose-induced cardiomyocyte hypertrophy. Co-transfection with a p300 expression vector and miR-150 mimics reversed the protective effect of miR-150 on cardiomyocyte hypertrophy. We further showed that the high glucose-mediated activation of PKCβ2 in turn mediated the down-regulation of miR-150 expression. These data demonstrated a novel upstream role for miR-150 in p300-mediated cardiomyocyte hypertrophy and revealed a previously uncharacterized miRNAs and HATs cross-talk mechanism for the hypertrophic phenotype induced by high glucose.