Heart Failure and MEF2 Transcriptome Dynamics in Response to β-Blockers

Transcriptional changes during isoproterenol-induced cardiac fibrosis in mice

Introduction: β-adrenergic stimulation using β-agonists such as isoproterenol has been routinely used to induce cardiac fibrosis in experimental animal models. Although transcriptome changes in surgical models of cardiac fibrosis such as transverse aortic constriction (TAC) and coronary artery ligation (CAL) are well-studied, transcriptional changes during isoproterenol-induced cardiac fibrosis are not well-explored. Methods: Cardiac fibrosis was induced in male C57BL6 mice by administration of isoproterenol for 4, 8, or 11 days at 50 mg/kg/day dose. Temporal changes in gene expression were studied by RNA sequencing. Results and discussion: We observed a significant alteration in the transcriptome profile across the different experimental groups compared to the saline group. Isoproterenol treatment caused upregulation of genes associated with ECM organization, cell-cell contact, three-dimensional structure, and cell growth, while genes associated with fatty acid oxidation, sarcoplasmic reticulum calcium ion transport, and cardiac muscle contraction are downregulated. A number of known long non-coding RNAs (lncRNAs) and putative novel lncRNAs exhibited differential regulation. In conclusion, our study shows that isoproterenol administration leads to the dysregulation of genes relevant to ECM deposition and cardiac contraction, and serves as an excellent alternate model to the surgical models of heart failure.

Atenolol Ameliorates Skeletal Muscle Atrophy and Oxidative Stress Induced by Cast Immobilization in Rats

(1) Background: Skeletal muscle atrophy is a common and debilitating condition associated with disease, bed rest, and inactivity. We aimed to investigate the effect of atenolol (ATN) on cast immobilization (IM)-induced skeletal muscle loss. (2) Methods: Eighteen male albino Wistar rats were divided into three groups: a control group, an IM group (14 days), and an IM+ATN group (10 mg/kg, orally for 14 days). After the last dose of atenolol, forced swimming test, rotarod test, and footprint analysis were performed, and skeletal muscle loss was determined. Animals were then sacrificed. Serum and gastrocnemius (GN) muscles were then collected, serum creatinine, GN muscle antioxidant, and oxidative stress levels were determined, and histopathology and ¹H NMR profiling of serum metabolites were performed. (3) Results: Atenolol significantly prevented immobilization-induced changes in creatinine, antioxidant, and oxidative stress levels. Furthermore, GN muscle histology results showed that atenolol significantly increased cross-sectional muscle area and Feret's diameter. Metabolomics profiling showed that glutamine-to-glucose ratio and pyruvate, succinate, valine, citrate, leucine, isoleucine, phenylalanine, acetone, serine, and 3-hydroxybutyrate levels were significantly higher, that alanine and proline levels were significantly lower in the IM group than in the control group, and that atenolol administration suppressed these metabolite changes. (4) Conclusions: Atenolol reduced immobilization-induced skeletal muscle wasting and might protect against the deleterious effects of prolonged bed rest.

The MEF2A transcription factor interactome in cardiomyocytes

Transcriptional regulators encoded by the Myocyte Enhancer Factor 2 (MEF2) gene family play a fundamental role in cardiac development, homeostasis and pathology. Previous studies indicate that MEF2A protein-protein interactions serve as a network hub in several cardiomyocyte cellular processes. Based on the idea that interactions with regulatory protein partners underly the diverse roles of MEF2A in cardiomyocyte gene expression, we undertook a systematic unbiased screen of the MEF2A protein interactome in primary cardiomyocytes using an affinity purification-based quantitative mass spectrometry approach. Bioinformatic processing of the MEF2A interactome revealed protein networks involved in the regulation of programmed cell death, inflammatory responses, actin dynamics and stress signaling in primary cardiomyocytes. Further biochemical and functional confirmation of specific protein-protein interactions documented a dynamic interaction between MEF2A and STAT3 proteins. Integration of transcriptome level data from MEF2A and STAT3-depleted cardiomyocytes reveals that the balance between MEF2A and STAT3 activity exerts a level of executive control over the inflammatory response and cardiomyocyte cell survival and experimentally ameliorates Phenylephrine induced cardiomyocyte hypertrophy. Lastly, we identified several MEF2A/STAT3 co-regulated genes, including the MMP9 gene. Herein, we document the cardiomyocyte MEF2A interactome, which furthers our understanding of protein networks involved in the hierarchical control of normal and pathophysiological cardiomyocyte gene expression in the mammalian heart.

Identification of hub genes and transcription factor regulatory network for heart failure using RNA-seq data and robust rank aggregation analysis

Background

Heart failure (HF) is the end stage of various cardiovascular diseases with a high mortality rate. Novel diagnostic and therapeutic biomarkers for HF are urgently required. Our research aims to identify HF-related hub genes and regulatory networks using bioinformatics and validation assays.

Methods

Using four RNA-seq datasets in the Gene Expression Omnibus (GEO) database, we screened differentially expressed genes (DEGs) of HF using Removal of Unwanted Variation from RNA-seq data (RUVSeq) and the robust rank aggregation (RRA) method. Then, hub genes were recognized using the STRING database and Cytoscape software with cytoHubba plug-in. Furthermore, reliable hub genes were validated by the GEO microarray datasets and quantitative reverse transcription polymerase chain reaction (qRT-PCR) using heart tissues from patients with HF and non-failing donors (NFDs). In addition, R packages “clusterProfiler” and “GSVA” were utilized for enrichment analysis. Moreover, the transcription factor (TF)–DEG regulatory network was constructed by Cytoscape and verified in a microarray dataset.

Results

A total of 201 robust DEGs were identified in patients with HF and NFDs. STRING and Cytoscape analysis recognized six hub genes, among which ASPN, COL1A1, and FMOD were confirmed as reliable hub genes through microarray datasets and qRT-PCR validation. Functional analysis showed that the DEGs and hub genes were enriched in T-cell-mediated immune response and myocardial glucose metabolism, which were closely associated with myocardial fibrosis. In addition, the TF–DEG regulatory network was constructed, and 13 significant TF–DEG pairs were finally identified.

Conclusion

Our study integrated different RNA-seq datasets using RUVSeq and the RRA method and identified ASPN, COL1A1, and FMOD as potential diagnostic biomarkers for HF. The results provide new insights into the underlying mechanisms and effective treatments of HF.

Mapping the cardiac vascular niche in heart failure

The cardiac vascular and perivascular niche are of major importance in homeostasis and during disease, but we lack a complete understanding of its cellular heterogeneity and alteration in response to injury as a major driver of heart failure. Using combined genetic fate tracing with confocal imaging and single-cell RNA sequencing of this niche in homeostasis and during heart failure, we unravel cell type specific transcriptomic changes in fibroblast, endothelial, pericyte and vascular smooth muscle cell subtypes. We characterize a specific fibroblast subpopulation that exists during homeostasis, acquires Thbs4 expression and expands after injury driving cardiac fibrosis, and identify the transcription factor TEAD1 as a regulator of fibroblast activation. Endothelial cells display a proliferative response after injury, which is not sustained in later remodeling, together with transcriptional changes related to hypoxia, angiogenesis, and migration. Collectively, our data provides an extensive resource of transcriptomic changes in the vascular niche in hypertrophic cardiac remodeling.

The cardiac vascular niche is of major importance in homeostasis and disease, but knowledge of its complexity in response to injury remains limited. Here we combine lineage tracing with single cell RNA sequencing to show alterations in fibroblasts, endothelial and mural cells in hypertrophic remodeling.

Transcriptomic and genomic studies classify NKL54 as a histone deacetylase inhibitor with indirect influence on MEF2-dependent transcription

In leiomyosarcoma class IIa HDACs (histone deacetylases) bind MEF2 and convert these transcription factors into repressors to sustain proliferation. Disruption of this complex with small molecules should antagonize cancer growth. NKL54, a PAOA (pimeloylanilide o-aminoanilide) derivative, binds a hydrophobic groove of MEF2, which is used as a docking site by class IIa HDACs. However, NKL54 could also act as HDAC inhibitor (HDACI). Therefore, it is unclear which activity is predominant. Here, we show that NKL54 and similar derivatives are unable to release MEF2 from binding to class IIa HDACs. Comparative transcriptomic analysis classifies these molecules as HDACIs strongly related to SAHA/vorinostat. Low expressed genes are upregulated by HDACIs, while abundant genes are repressed. This transcriptional resetting correlates with a reorganization of H3K27 acetylation around the transcription start site (TSS). Among the upregulated genes there are several BH3-only family members, thus explaining the induction of apoptosis. Moreover, NKL54 triggers the upregulation of MEF2 and the downregulation of class IIa HDACs. NKL54 also increases the binding of MEF2D to promoters of genes that are upregulated after treatment. In summary, although NKL54 cannot outcompete MEF2 from binding to class IIa HDACs, it supports MEF2-dependent transcription through several actions, including potentiation of chromatin binding.

MEF2 in cardiac hypertrophy in response to hypertension

Hypertension is a globally prevalent pathological condition and an underlying risk factor for the development of cardiac hypertrophy leading to heart failure. Myocyte enhancer factor 2 (Mef2) has been identified as one of the primary effectors of morphological changes in the hypertensive heart, as part of a complex network of molecular signaling controlling cardiac gene expression. Experimental chronic pressure-overload models that mimic hypertension in the mammalian heart lead to the activation of various pathological mechanisms that result in structural changes leading to debilitating cardiac hypertrophy and ultimately heart failure. The purpose here is to survey the literature implicating Mef2 in hypertension induced cardiac hypertrophy, towards illuminating points of interest for understanding and potentially treating heart failure.

Myocyte Enhancer Factor 2A Plays a Central Role in the Regulatory Networks of Cellular Physiopathology

Cell regulatory networks are the determinants of cellular homeostasis. Any alteration to these networks results in the disturbance of cellular homeostasis and induces cells towards different fates. Myocyte enhancer factor 2A (MEF2A) is one of four members of the MEF2 family of transcription factors (MEF2A-D). MEF2A is highly expressed in all tissues and is involved in many cell regulatory networks including growth, differentiation, survival and death. It is also necessary for heart development, myogenesis, neuronal development and differentiation. In addition, many other important functions of MEF2A have been reported. Recent studies have shown that MEF2A can regulate different, and sometimes even mutually exclusive cellular events. How MEF2A regulates opposing cellular life processes is an interesting topic and worthy of further exploration. Here, we reviewed almost all MEF2A research papers published in English and summarized them into three main sections: 1) the association of genetic variants in MEF2A with cardiovascular disease, 2) the physiopathological functions of MEF2A, and 3) the regulation of MEF2A activity and its regulatory targets. In summary, multiple regulatory patterns for MEF2A activity and a variety of co-factors cause its transcriptional activity to switch to different target genes, thereby regulating opposing cell life processes. The association of MEF2A with numerous signaling molecules establishes a central role for MEF2A in the regulatory network of cellular physiopathology.

JNK signaling-dependent regulation of histone acetylation are involved in anacardic acid alleviates cardiomyocyte hypertrophy induced by phenylephrine

Cardiac hypertrophy is a complex process induced by the activation of multiple signaling pathways. We previously reported that anacardic acid (AA), a histone acetyltransferase (HAT) inhibitor, attenuates phenylephrine (PE)-induced cardiac hypertrophy by downregulating histone H3 acetylation at lysine 9 (H3K9ac). Unfortunately, the related upstream signaling events remained unknown. The mitogen-activated protein kinase (MAPK) pathway is an important regulator of cardiac hypertrophy. In this study, we explored the role of JNK/MAPK signaling pathway in cardiac hypertrophy induced by PE. The mice cardiomyocyte hypertrophy model was successfully established by treating cells with PE in vitro. This study showed that p-JNK directly interacts with HATs (P300 and P300/CBP-associated factor, PCAF) and alters H3K9ac. In addition, both the JNK inhibitor SP600125 and the HAT inhibitor AA attenuated p-JNK overexpression and H3K9ac hyperacetylation by inhibiting P300 and PCAF during PE-induced cardiomyocyte hypertrophy. Moreover, we demonstrated that both SP600125 and AA attenuate the overexpression of cardiac hypertrophy-related genes (MEF2A, ANP, BNP, and β-MHC), preventing cardiomyocyte hypertrophy and dysfunction. These results revealed a novel mechanism through which AA might protect mice from PE-induced cardiomyocyte hypertrophy. In particular, AA inhibits the effects of JNK signaling on HATs-mediated histone acetylation, and could therefore be used to prevent and treat pathological cardiac hypertrophy.

1, 8-cineole protects against ISO-induced heart failure by inhibiting oxidative stress and ER stress in vitro and in vivo

Sugemule-3 is widely adopted in clinical practice to manage cardio-cerebral diseases. 1, 8-cineole is the main ingredient of Sugemule-3, however, the underlying cellular mechanisms for its protective effect are poorly understood. 1, 8-cineole improved the survival of H9C2 cardiomyocytes during isoproterenol (ISO) injury and reduced ISO-induced apoptosis. Compared to the ISO group, 1, 8-cineole highly attenuated the generation of ISO-induced reactive oxygen species (ROS), the depolarization of △ψm, suppression of the Bax/Bcl-2 ratio, and p-caspase 3 expression, in vitro. Furthermore, 1, 8-cineole treatment in H9C2 cardiomyocytes lowered the expressions of 78-kDa glucose-regulated protein (GRP78), p-protein kinase-like ER kinase (PERK), activation of transcription factor (ATF) 4, and ER stress effector protein C/EBP and homologous protein (CHOP). These findings implied that 1, 8-cineole contribute to cardioprotection via the GRP78/CHOP pathways. Using animal models, 1, 8-cineole was revealed to markedly alleviate ISO-induced heart injury, and reduce cardiac hypertrophy, formation of the cytoplasmic vacuole, loss of myofiber, and fibrosis by inhibiting oxidative stress and ER stress. 1, 8-cineole reduces apoptosis by inhibiting signaling pathways related to oxidative stress and ER stress. These findings implicate 1, 8-cineole as a potential therapeutic target for cardiac hypertrophy-related heart diseases, including heart failure.

The Degree of Cardiac Remodelling before Overload Relief Triggers Different Transcriptome and miRome Signatures during Reverse Remodelling (RR)-Molecular Signature Differ with the Extent of RR

This study aims to provide new insights into transcriptome and miRome modifications occurring in cardiac reverse remodelling (RR) upon left ventricle pressure-overload relief in mice. Pressure-overload was established in seven-week-old C57BL/6J-mice by ascending aortic constriction. A debanding (DEB) surgery was performed seven weeks later in half of the banding group (BA). Two weeks later, cardiac function was evaluated through hemodynamics and echocardiography, and the hearts were collected for histology and small/bulk-RNA-sequencing. Pressure-overload relief was confirmed by the normalization of left-ventricle-end-systolic-pressure. DEB animals were separated into two subgroups according to the extent of cardiac remodelling at seven weeks and RR: DEB1 showed an incomplete RR phenotype confirmed by diastolic dysfunction persistence (E/e' ≥ 16 ms) and increased myocardial fibrosis. At the same time, DEB2 exhibited normal diastolic function and fibrosis, presenting a phenotype closer to myocardial recovery. Nevertheless, both subgroups showed the persistence of cardiomyocytes hypertrophy. Notably, the DEB1 subgroup presented a more severe diastolic dysfunction at the moment of debanding than the DEB2, suggesting a different degree of cardiac remodelling. Transcriptomic and miRomic data, as well as their integrated analysis, revealed significant downregulation in metabolic and hypertrophic related pathways in DEB1 when compared to DEB2 group, including fatty acid β-oxidation, mitochondria L-carnitine shuttle, and nuclear factor of activated T-cells pathways. Moreover, extracellular matrix remodelling, glycan metabolism and inflammation-related pathways were up-regulated in DEB1. The presence of a more severe diastolic dysfunction at the moment of pressure overload-relief on top of cardiac hypertrophy was associated with an incomplete RR. Our transcriptomic approach suggests that a cardiac inflammation, fibrosis, and metabolic-related gene expression dysregulation underlies diastolic dysfunction persistence after pressure-overload relief, despite left ventricular mass regression, as echocardiographically confirmed.

Hematopoietic Stem Cell Transcription Factors in Cardiovascular Pathology

Transcription factors as multifaceted modulators of gene expression that play a central role in cell proliferation, differentiation, lineage commitment, and disease progression. They interact among themselves and create complex spatiotemporal gene regulatory networks that modulate hematopoiesis, cardiogenesis, and conditional differentiation of hematopoietic stem cells into cells of cardiovascular lineage. Additionally, bone marrow-derived stem cells potentially contribute to the cardiovascular cell population and have shown potential as a therapeutic approach to treat cardiovascular diseases. However, the underlying regulatory mechanisms are currently debatable. This review focuses on some key transcription factors and associated epigenetic modifications that modulate the maintenance and differentiation of hematopoietic stem cells and cardiac progenitor cells. In addition to this, we aim to summarize different potential clinical therapeutic approaches in cardiac regeneration therapy and recent discoveries in stem cell-based transplantation.

Manipulation of beta-adrenergic receptor in pressure-overloaded murine hearts mimics adverse and reverse cardiac remodeling

Transverse aortic constriction (TAC) has been widely used to create pressure overload induced heart failure in mice. However, this conventional model has some limitations such as low reproducibility and long creation period of cardiac failure. In order to establish a highly reproducible cardiac failure model that mimics adverse cardiac remodeling (ACR) we combined pressure overload and beta-adrenergic receptor stimuli using isoproterenol (ISO) and explored the optimal TAC model by changing the durations of TAC and the doses of ISO. Thus we constructed a suitable model for ACR with an effective combination of 3-week TAC and subsequent one-week ISO (3 mg/kg/day) infusion. Using RNA-Seq analyses, we identified that the up-regulated genes were mainly related to fibrosis including Fbn1, C1qtnf6 and Loxl2; and that the down-regulated genes were associated with mitochondrial function including Uqcrc1, Ndufs3, and Idh2 in failing hearts of our ACR model. Next, we followed the changes in cardiac function after ceasing ISO infusion. Left ventricular function gradually recovered after cessation of ISO, suggesting cardiac reverse remodeling (CRR). Gene expression signatures of hearts, which exhibited CRR, were almost identical to that of TAC hearts without ISO. In conclusion, our new model exhibits a transition to ACR and subsequent CRR with high reproducibility. This murine model might add new insights into the experiments of heart failure technically as well as scientifically.

Different class IIa HDACs repressive complexes regulate specific epigenetic responses related to cell survival in leiomyosarcoma cells

Transcriptional networks supervising class IIa HDAC expression are poorly defined. Here we demonstrate that MEF2D is the key factor controlling HDAC9 transcription. This control, which is part of a negative feed-back loop during muscle differentiation, is hijacked in cancer. In leiomyosarcomas the MEF2D/HDAC9 vicious circuit sustains proliferation and cell survival, through the repression of the death receptor FAS. Comprehensive genome-wide studies demonstrate that HDAC4 and HDAC9 control different genetic programs and show both specific and common genomic binding sites. Although the number of MEF2-target genes commonly regulated is similar, only HDAC4 represses many additional genes that are not MEF2D targets. As expected, HDAC4-/- and HDAC9-/- cells increase H3K27ac levels around the TSS of the respective repressed genes. However, these genes rarely show binding of the HDACs at their promoters. Frequently HDAC4 and HDAC9 bind intergenic regions. We demonstrate that these regions, recognized by MEF2D/HDAC4/HDAC9 repressive complexes, show the features of active enhancers. In these regions HDAC4 and HDAC9 can differentially influence H3K27 acetylation. Our studies describe new layers of class IIa HDACs regulation, including a dominant positional effect, and can contribute to explain the pleiotropic actions of MEF2 TFs.

CaM kinase II regulates cardiac hemoglobin expression through histone phosphorylation upon sympathetic activation

Sympathetic activation of β-adrenoreceptors (β-AR) represents a hallmark in the development of heart failure (HF). However, little is known about the underlying mechanisms of gene regulation. In human ventricular myocardium from patients with end-stage HF, we found high levels of phosphorylated histone 3 at serine-28 (H3S28p). H3S28p was increased by inhibition of the catecholamine-sensitive protein phosphatase 1 and decreased by β-blocker pretreatment. By a series of in vitro and in vivo experiments, we show that the β-AR downstream protein kinase CaM kinase II (CaMKII) directly binds and phosphorylates H3S28. Whereas, in CaMKII-deficient myocytes, acute catecholaminergic stimulation resulted in some degree of H3S28p, sustained catecholaminergic stimulation almost entirely failed to induce H3S28p. Genome-wide analysis of CaMKII-mediated H3S28p in response to chronic β-AR stress by chromatin immunoprecipitation followed by massive genomic sequencing led to the identification of CaMKII-dependent H3S28p target genes. Forty percent of differentially H3S28p-enriched genomic regions were associated with differential, mostly increased expression of the nearest genes, pointing to CaMKII-dependent H3S28p as an activating histone mark. Remarkably, the adult hemoglobin genes showed an H3S28p enrichment close to their transcriptional start or end sites, which was associated with increased messenger RNA and protein expression. In summary, we demonstrate that chronic β-AR activation leads to CaMKII-mediated H3S28p in cardiomyocytes. Thus, H3S28p-dependent changes may play an unexpected role for cardiac hemoglobin regulation in the context of sympathetic activation. These data also imply that CaMKII may be a yet unrecognized stress-responsive regulator of hematopoesis.

Selective Heart Irradiation Induces Cardiac Overexpression of the Pro-hypertrophic miR-212

Background: A deleterious, late-onset side effect of thoracic radiotherapy is the development of radiation-induced heart disease (RIHD). It covers a spectrum of cardiac pathology including also heart failure with preserved ejection fraction (HFpEF) characterized by left ventricular hypertrophy (LVH) and diastolic dysfunction. MicroRNA-212 (miR-212) is a crucial regulator of pathologic LVH via FOXO3-mediated pathways in pressure-overload-induced heart failure. We aimed to investigate whether miR-212 and its selected hypertrophy-associated targets play a role in the development of RIHD. Methods: RIHD was induced by selective heart irradiation (50 Gy) in a clinically relevant rat model. One, three, and nineteen weeks after selective heart irradiation, transthoracic echocardiography was performed to monitor cardiac morphology and function. Cardiomyocyte hypertrophy and fibrosis were assessed by histology at week 19. qRT-PCR was performed to measure the gene expression changes of miR-212 and forkhead box O3 (FOXO3) in all follow-up time points. The cardiac transcript level of other selected hypertrophy-associated targets of miR-212 including extracellular signal-regulated kinase 2 (ERK2), myocyte enhancer factor 2a (MEF2a), AMP-activated protein kinase, (AMPK), heat shock protein 40 (HSP40), sirtuin 1, (SIRT1), calcineurin A-alpha and phosphatase and tensin homolog (PTEN) were also measured at week 19. Cardiac expression of FOXO3 and phospho-FOXO3 were investigated at the protein level by Western blot at week 19. Results: In RIHD, diastolic dysfunction was present at every time point. Septal hypertrophy developed at week 3 and a marked LVH with interstitial fibrosis developed at week 19 in the irradiated hearts. In RIHD, cardiac miR-212 was overexpressed at week 3 and 19, and FOXO3 was repressed at the mRNA level only at week 19. In contrast, the total FOXO3 protein level failed to decrease in response to heart irradiation at week 19. Other selected hypertrophy-associated target genes failed to change at the mRNA level in RIHD at week 19. Conclusions: LVH in RIHD was associated with cardiac overexpression of miR-212. However, miR-212 seems to play a role in the development of LVH via FOXO3-independent mechanisms in RIHD. As a central regulator of pathologic remodeling, miR-212 might become a novel target for RIHD-induced LVH and heart failure.

Chronic kidney disease induces left ventricular overexpression of the pro-hypertrophic microRNA-212

Chronic kidney disease (CKD) is a public health problem that increases the risk of cardiovascular morbidity and mortality. Heart failure with preserved ejection fraction (HFpEF) characterized by left ventricular hypertrophy (LVH) and diastolic dysfunction is a common cardiovascular complication of CKD. MicroRNA-212 (miR-212) has been demonstrated previously to be a crucial regulator of pathologic LVH in pressure-overload-induced heart failure via regulating the forkhead box O3 (FOXO3)/calcineurin/nuclear factor of activated T-cells (NFAT) pathway. Here we aimed to investigate whether miR-212 and its hypertrophy-associated targets including FOXO3, extracellular signal-regulated kinase 2 (ERK2), and AMP-activated protein kinase (AMPK) play a role in the development of HFpEF in CKD. CKD was induced by 5/6 nephrectomy in male Wistar rats. Echocardiography and histology revealed LVH, fibrosis, preserved systolic function, and diastolic dysfunction in the CKD group as compared to sham-operated animals eight and/or nine weeks later. Left ventricular miR-212 was significantly overexpressed in CKD. However, expressions of FOXO3, AMPK, and ERK2 failed to change significantly at the mRNA or protein level. The protein kinase B (AKT)/FOXO3 and AKT/mammalian target of rapamycin (mTOR) pathways are also proposed regulators of LVH induced by pressure-overload. Interestingly, phospho-AKT/total-AKT ratio was increased in CKD without significantly affecting phosphorylation of FOXO3 or mTOR. In summary, cardiac overexpression of miR-212 in CKD failed to affect its previously implicated hypertrophy-associated downstream targets. Thus, the molecular mechanism of the development of LVH in CKD seems to be independent of the FOXO3, ERK1/2, AMPK, and AKT/mTOR-mediated pathways indicating unique features in this form of LVH.