Lercanidipine attenuates angiotensin II-induced cardiomyocyte hypertrophy by blocking calcineurin-NFAT3 and CaMKII-HDAC4 signaling

CaMK II in Cardiovascular Diseases, Especially CaMK II-δ: Friends or Enemies

Cardiovascular diseases (CVDs) tend to affect the young population and are associated with a significant economic burden and psychological distress to the society and families. The physiological and pathological processes underlying CVDs are complex. Ca2+/calmodulin-dependent kinase II (CaMK II), a protein kinase, has multiple biological functions. It participates in multiple pathological processes and plays a central role in the development of CVDs. Based on this, this paper analyzes the structural characteristics and distribution of CaMK II, the mechanism of action of CaMK II, and the relationship between CaMK II and CVDs, including ion channels, ischemia-reperfusion injury, arrhythmias, myocardial hypertrophy, cardiotoxicity, hypertension, and dilated cardiomyopathy. Given the different regulatory mechanisms of different isoforms of CaMK II, the clinical use of specific targeted inhibitors or novel compounds should be evaluated in future research to provide new directions.

Activation of CaMKII/HDAC4 by SDF1 contributes to pulmonary arterial hypertension via stabilization Runx2

Stromal derived factor 1 (SDF1) has been shown to be involved in the pathogenesis of pulmonary artery hypertension (PAH). However, the detailed molecular mechanisms remain unclear. To address this, we utilized primary cultured rat pulmonary artery smooth muscle cells (PASMCs) and monocrotaline (MCT)-induced PAH rat models to investigate the mechanisms of SDF1 driving PASMCs proliferation and pulmonary arterial remodeling. SDF1 increased runt-related transcription factor 2 (Runx2) acetylation by Calmodulin (CaM)-dependent protein kinase II (CaMKII)-dependent HDAC4 cytoplasmic translocation, elevation of Runx2 acetylation conferred its resistance to proteasome-mediated degradation. The accumulation of Runx2 further upregulated osteopontin (OPN) expression, finally leading to PASMCs proliferation. Blocking SDF1, suppression of CaMKII, inhibition the nuclear export of HDAC4 or silencing Runx2 attenuated pulmonary arterial remodeling and prevented PAH development in MCT-induced PAH rat models. Our study provides novel sights for SDF1 induction of PASMCs proliferation and suggests that targeting SDF1/CaMKII/HDAC4/Runx2 axis has potential value in the management of PAH.

Leu27 IGF-II-induced hypertrophy in H9c2 cardiomyoblasts is ameliorated by saffron by regulation of calcineurin/NFAT and CaMKIIδ signaling

The insulin-like growth factor II receptor (IGF-IIR) induces myocardial hypertrophy under various pathological conditions like diabetes and hypertension via G protein receptors like Gαq or Gαs. Increased expression of the ligand IGF II and IGF-IIR induces pathological hypertrophy through downstream signaling mediators such as calcineurin, nuclear factor of activated T cells 3 and calcium-calmodulin (CaM)-dependent kinase II (CaMKII)-histone deacetylase 4 (HDAC4). The dried stigma of Crocus sativus L. (saffron) has a long repute as a traditional medicine against various disorders. In the present study, we have investigated whether C. sativus extract (CSE) canameliorate Leu²⁷ IGF-II triggered hypertrophy and have elucidated the underlying mechanism of protection. Additionally, the effects of oleic acid (OA), an activator of calcineurin and CaMKII was investigated thereof. The results demonstrate that CSE can ameliorate Leu²⁷ IGF-II-induced hypertrophy seemingly through regulation of calcineurin-NFAT3 and CaMKII-HDAC4 signaling cascade.

Small Molecule Compound Nerolidol attenuates Hypertension induced hypertrophy in spontaneously hypertensive rats through modulation of Mel-18-IGF-IIR signalling

BACKGROUND

Cardiovascular diseases are caused by multitudes of stress factors like hypertension and their outcomes are associated with high mortality and morbidity worldwide. Nerolidol, a naturally occurring sesquiterpene found in several plant species, embodies various pharmacological benefits against numerous health disorders. However, their effects on hypertension induced cardiac complications are not completely understood.

PURPOSE

The present study is to elucidate the efficacy of nerolidol against hypertension related cardiac hypertrophy in spontaneously hypertensive rats (SHRs).

STUDY DESIGN

For preliminary in vitro studies, H9c2 cardiomyoblasts cells were challenged with 200 nM Angiotensin-II (AngII) for 12 h and were then treated with nerolidol for 24 h. The hypertrophic effect in H9c2 cells were analyzed by actin staining and the modulations in hypertrophic protein markers and mediators were determined by Western blotting analysis. For in vivo experiments, sixteen week-old male Wistar Kyoto (WKY) and SHRs were segregated into five groups (n = 9): Control WKY, hypertensive SHRs, SHRs with low dose (75 mg/kg b.w/day) nerolidol, SHRs with high dose (150 mg/kg b.w/day) nerolidol and SHR rats treated with an anti-hypertensive drug captopril (50 mg/kg b.w/day). Nerolidol treatment was given orally for 8 weeks and were analysed through Echocardiography. After euthanasia, hematoxylin and eosin staining, Immunohistochemical analysis and Western blotting was performed on left ventricle tissue.

RESULTS

Western blotting analysis revealed that nerolidol significantly attenuates AngII induced expression of hypertrophic markers ANP and BNP in H9c2 cardiomyoblasts. In addition, actin staining further ascertained the potential of nerolidol to ameliorate AngII induced cardiac hypertrophy. Moreover, nerolidol administration suppressed the hypertrophic signalling mediators like calcineurin, GATA4, Mel-18, HSF-2 and IGFIIR in a dose-dependent fashion. In silico studies also ascertained the role of Mel-18 in the ameliorative effects of nerolidol. Further, these intriguing in vitro results were further confirmed in in vivo SHR model. Oral neraolidol in SHRs efficiently reduced blood pressure and ameliorated hypertension induced cardiac hypertrophic effects by effectively reducing the levels of proteins involved in cardiac MeL-18-HSF2-IGF-IIR signalling.

CONCLUSION

Collectively, the data reveals that the cardioprotective effect of nerolidol against hypertension induced hypertrophy involves reduction in blood pressure and regulation of the cardiac Mel-18-IGFIIR signalling cascade.

Calcium inhibitor inhibits high glucose‑induced hypertrophy of H9C2 cells

The aim of the present study was to explore whether the hypertrophy of H9C2 cardiomyocytes was induced by high glucose, to investigate whether the calcium channel inhibitor (Norvasc) could inhibit this process and to clarify the possible signaling pathways. The morphology of H9C2 cells was observed under an optical microscope, and the cell surface area was measured by Image Pro Plus 6.1 software. Furthermore, fluorescence spectrophotometry was used to detect intracellular calcium concentration ([Ca²⁺]i). ELISA was performed to detect calcineurin (CaN) activity; reverse transcription-quantitative PCR and western blotting were performed to detect the mRNA and protein expression levels of CaN Aβ subunit (CnAβ), nuclear factor of activated T cells 3 (NFAT3) and β type myosin heavy chain (β-MHC). Cell size was increased with the increase in glucose concentration of culture medium at 48 and 72 h, respectively, and decreased with the addition of Norvasc compared with those without Norvasc (P<0.05). There was no significant difference in cell size with the addition of Norvasc compared with cells cultured with 5 mM glucose (P>0.05). The average [Ca²⁺]i activity of single cells in the 48- and 72-h culture groups treated with 50 mM glucose was significantly higher than cells treated with 5 mM glucose (P<0.05); and the fluorescent value of average [Ca²⁺]i activity of single cells was lower, following the addition of Norvasc than that without Norvasc (P<0.05). CaN activity in the 48- and 72-h culture group treated with 50 mM glucose was markedly higher than that treated with 5 mM glucose, and the activity of CaN notably decreased with the addition of Norvasc compared with those without Norvasc. The mRNA and protein expression levels of CnAβ, NFAT3 and β-MHC in the 48- and 72-h culture groups treated with 50 mM glucose were all significantly higher than those treated with 5 mM glucose (P<0.05). The mRNA and protein expression of CnAβ, NFAT3 and β-MHC cultured with 50 mM glucose were significantly decreased following the addition of Norvasc (P<0.05). Thus, the calcium channel inhibitor Norvasc may inhibit high glucose-induced hypertrophy of H9C2 cardiomyocytes by inhibiting the Ca²⁺-CaN-NFAT3 signaling pathway.

Distinct roles of calmodulin and Ca2+/calmodulin-dependent protein kinase II in isopreterenol-induced cardiac hypertrophy

Intracellular calcium is related to cardiac hypertrophy. The Ca_V1.2 channel and Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) and CaM regulate the intracellular calcium content. However, the differences in CaMKII and CaM in cardiac hypertrophy are still conflicting and are worthy of studying as drug targets. Therefore, in this study, we aim to investigate the roles and mechanism of CaM and CaMKII on Ca_V1.2 in pathological myocardial hypertrophy. The results showed that ISO stimulation caused SD rat heart and cardiomyocyte hypertrophy. In vivo, the HW/BW, LVW/BW, cross-sectional area, fibrosis ratio and ANP expression were all increased. There were no differences in Ca_V1.2 channel expression in the in vivo model or the in vitro model, but the ISO stimulation induced channel activity, and the [Ca²⁺]_i increased. The protein expression levels of CaMKII and p-CaMKII were all increased in the ISO group, but the CaM expression level decreased. AIP inhibited ANP, CaMKII and p-CaMKII expression, and ISO-induced [Ca²⁺]_i increased. AIP also reduced HDAC4, p-HDAC and MEF2C expression. However, CMZ did not play a cardiac hypertrophy reversal role in vitro. In conclusion, we considered that compared with CaM, CaMKII may be a much more important drug target in cardiac hypertrophy reversal.

Expression Profile of microRNAs in Hypertrophic Cardiomyopathy and Effects of microRNA-20 in Inducing Cardiomyocyte Hypertrophy Through Regulating Gene MFN2

Myocardial hypertrophy is an important cause of heart failure and sudden death. Studies have shown that Mitofusin-2 (MFN2) is downregulated in myocardial hypertrophy, but the upstream regulation mechanism underlying its downexpression in cardiomyocytes is still unclear. This study aims to identify the expression profile of microRNAs (miRNAs) in hypertrophic cardiomyopathy (HCM) and explore the function of miRNA-20 in inducing cardiomyocyte hypertrophy through regulating MFN2. Through miRNA + mRNA microarray analysis, 1451 miRNAs were identified, 367 miRNAs expressed differently between groups. Meanwhile, a number of 24,718 mRNAs were identified, among which 5850 mRNAs were upregulated and 3005 mRNAs were downregulated in HCM group compared with the control group. Expression of hsa-miRNA-20a-5p was 2.26 times higher in the HCM group compared with the control group and 7 target gene prediction programs predicted MFN2 as a target of miRNA-20. In vitro model of hypertrophic cardiomyocytes displayed high expression level of miRNA-20, atrial natriuretic peptide (ANP) mRNA, and protein, accompanying low expression level of Mfn2 mRNA and protein, which meant miRNA-20 played a role in cardiomyocyte hypertrophy and might interact with MFN2 to function. Thereafter, overexpression of miRNA-20 led to cell hypertrophy accompanied with lowly expressed Mfn2 mRNA and protein. When transfected with miRNA-20 inhibitors, the expression of miRNA-20 and ANP gene was attenuated and MFN2 was the other way around. The cell surface area of Ang II group and mimic group was significantly larger compared with the control group, and in the inhibitor+Ang II group, the area was significantly decreased compared with the Ang II group. Dual-luciferase assays showed that miRNA-20 bound to 3' untranslated region of MFN2 and inhibited its expression. In conclusion, hypertrophic myocardium and normal myocardium have different miRNA expression profiles and the effect of miRNA-20 reducing the expression of MFN2 plays a role in promoting cardiomyocyte hypertrophy.

Effect of atorvastatin on cardiomyocyte hypertrophy through suppressing MURC induced by volume overload and cyclic stretch

MURC (muscle‐restricted coiled‐coil protein) is a hypertrophy‐related gene. Hypertrophy can be induced by mechanical stress. The purpose of this research was to investigate the hypothesis that MURC mediates hypertrophy in cardiomyocytes under mechanical stress. We used the in vivo model of an aortocaval shunt (AV shunt) in adult Wistar rats to induce myocardial hypertrophy. We also used the in vitro model of cyclic stretch in rat neonatal cardiomyocytes to clarify MURC expression and the molecular regulation mechanism. The flexible membrane culture plate seeding with cardiomyocytes Cardiomyocytes seeded on a flexible membrane culture plate were stretched by vacuum pressure to 20% of maximum elongation at 60 cycles/min. AV shunt induction enhanced MURC protein expression in the left ventricular myocardium. Treatment with atorvastatin inhibited the hypertrophy induced by the AV shunt. Cyclic stretch markedly enhanced MURC protein and mRNA expression in cardiomyocytes. Addition of extracellular‐signal‐regulated kinase (ERK) inhibitor PD98059, ERK small interfering RNA (siRNA), angiotensin II (Ang II) antibody and atorvastatin before stretch, abolished the induction of MURC protein. An electrophoretic mobility shift assay showed that stretch enhanced the DNA binding activity of serum response factor. Stretch increased but MURC mutant plasmid, ERK siRNA, Ang II antibody and atorvastatin reversed the transcriptional activity of MURC induced by stretch. Adding Ang II to the cardiomyocytes also induced MURC protein expression. MURC siRNA and atorvastatin inhibited the hypertrophic marker and protein synthesis induced by stretch. Treatment with atorvastatin reversed MURC expression and hypertrophy under volume overload and cyclic stretch.