Vitamin C facilitates direct cardiac reprogramming by inhibiting reactive oxygen species.

BACKGROUND: After myocardial infarction, the lost myocardium is replaced by fibrotic tissue, eventually progressively leading to myocardial dysfunction. Direct reprogramming of fibroblasts into cardiomyocytes via the forced overexpression of cardiac transcription factors Gata4, Mef2c, and Tbx5 (GMT) offers a promising strategy for cardiac repair. The limited reprogramming efficiency of this approach, however, remains a significant challenge. METHODS: We screened seven factors capable of improving direct cardiac reprogramming of both mice and human fibroblasts by evaluating small molecules known to be involved in cardiomyocyte differentiation or promoting human-induced pluripotent stem cell reprogramming. RESULTS: We found that vitamin C (VitC) significantly increased cardiac reprogramming efficiency when added to GMT-overexpressing fibroblasts from human and mice in 2D and 3D model. We observed a significant increase in reactive oxygen species (ROS) generation in human and mice fibroblasts upon Doxy induction, and ROS generation was subsequently reduced upon VitC treatment, associated with increased reprogramming efficiency. However, upon treatment with dehydroascorbic acid, a structural analog of VitC but lacking antioxidant properties, no difference in reprogramming efficiency was observed, suggesting that the effect of VitC in enhancing cardiac reprogramming is partly dependent of its antioxidant properties. CONCLUSIONS: Our findings demonstrate that VitC supplementation significantly enhances the efficiency of cardiac reprogramming, partially by suppressing ROS production in the presence of GMT.

Cardiomyocyte precursors generated by direct reprogramming and molecular beacon selection attenuate ventricular remodeling after experimental myocardial infarction.

BACKGROUND: Direct cardiac reprogramming is currently being investigated for the generation of cells with a true cardiomyocyte (CM) phenotype. Based on the original approach of cardiac transcription factor-induced reprogramming of fibroblasts into CM-like cells, various modifications of that strategy have been developed. However, they uniformly suffer from poor reprogramming efficacy and a lack of translational tools for target cell expansion and purification. Therefore, our group has developed a unique approach to generate proliferative cells with a pre-CM phenotype that can be expanded in vitro to yield substantial cell doses. METHODS: Cardiac fibroblasts were reprogrammed toward CM fate using lentiviral transduction of cardiac transcriptions factors (GATA4, MEF2C, TBX5, and MYOCD). The resulting cellular phenotype was analyzed by RNA sequencing and immunocytology. Live target cells were purified based on intracellular CM marker expression using molecular beacon technology and fluorescence-activated cell sorting. CM commitment was assessed using 5-azacytidine-based differentiation assays and the therapeutic effect was evaluated in a mouse model of acute myocardial infarction using echocardiography and histology. The cellular secretome was analyzed using mass spectrometry. RESULTS: We found that proliferative CM precursor-like cells were part of the phenotype spectrum arising during direct reprogramming of fibroblasts toward CMs. These induced CM precursors (iCMPs) expressed CPC- and CM-specific proteins and were selectable via hairpin-shaped oligonucleotide hybridization probes targeting Myh6/7-mRNA-expressing cells. After purification, iCMPs were capable of extensive expansion, with preserved phenotype when under ascorbic acid supplementation, and gave rise to CM-like cells with organized sarcomeres in differentiation assays. When transplanted into infarcted mouse hearts, iCMPs prevented CM loss, attenuated fibrotic scarring, and preserved ventricular function, which can in part be attributed to their substantial secretion of factors with documented beneficial effect on cardiac repair. CONCLUSIONS: Fibroblast reprogramming combined with molecular beacon-based cell selection yields an iCMP-like cell population with cardioprotective potential. Further studies are needed to elucidate mechanism-of-action and translational potential.

Exosomal MEF2C's Association With the Progression of CRC in Regulating CD36 Transcription.

Context: Exosomes are biologically active, extracellular vesicles that are involved in tumor-related processes, including activating tumors, facilitating tumor growth, and promoting inflammation. Objective: The study intended to investigate microRNAs (miRNAs) in exosomes that are associated with colorectal cancer (CRC). Design: The research team performed bioinformatics analysis, extracting RNA-sequencing (RNA-seq) datasets from the Cancer Genome Atlas (TCGA); ExoRBase, a database of different types of RNA information that scientists have extracted from human exosomes; and the Gene Expression Omnibus (GEO) databases, and analyzed the data. Setting: The study took place at the Department of Colorectal Surgery at the Chinese Academy of Medical Sciences and Peking Union Medical College in Beijing, China. Participants: From October 2020 to March 2021, a total of 28 CRC patients who underwent curative resection at the National Cancer Center were enrolled. Tumor samples and tumor-adjacent normal sample were obtained from these CRC patients. Postoperative pathological characteristics all shown adenocarcinoma. The research team recruited participants from the hospitals connected with CAMS and PUMC and obtained written informed consent from them for publication of a case report and any accompanying images. The Ethics Committee of the Cancer Institute (Hospital), CAMS & PUMC has officially recognized the study (NCC 2017-YZ-026). Outcome Measures: The research team: (1) extracted RNA-seq datasets from the TCGA, exoRBase and GEO and analyzed the differentially expressed genes (DEGs); (2) performed a cluster analysis of variant genes using weighted gene co-expression network analysis (WGCNA);(3) verified expression of myocyte enhancer factor 2C-genecards (MEF2C) and cluster of differentiation 36 (CD36) in CRC tissues; (4) explored the biological function of the MEF2C by performing proliferation, migration, and invasion assays; and (5) used a chromatin immunoprecipitation (ChIP) experiment to analyze mechanisms to reveal CD36 transcription regulated by exosomal MEF2C. Results: A significant mean difference in exosomal MEF2C existed between normal and tumor tissues. By performing a correlation analysis, the research team found 609 potential target points of exosomal MEF2C (r > 0.5, P < .05). Weighted correlation network analysis (WGCNA) and protein-protein interaction (PPI) network analysis indicated that CD36 may be the target of exosomal MEF2C. Univariate, multivariate, and Kaplan-Meier analyses showed that CD36 was closely related to the overall survival (OS) of CRC patients. Obvious differences existed in the expression levels of MEF2C and CD36 in CRC and normal tissues according to qPCR and immunohistochemical assays. Functional-experiments analysis in vitro showed that exosomal-MEF2C could be considered as an antioncogene. Mechanistically, ChIP assays showed that MEF2C regulated the transcriptional level of CD 36; thus, the expression of CD36 increased significantly. Conclusion: MEF2C is a potential biomarker of a favorable prognosis in CRC and is related to the progression of CRC. Moreover, the MEF2C-CD36 pathway may reveal the tumor regulation mechanism in CRC. The exosomal MEF2C was the hub gene in exosomes, with CD36 was identified as the potential target. Exosomal MEF2C may be a promising molecular biomarker for predicting a good prognosis and may have potential as a medical target for CRC.

Effects of long-term taurine supplementation on age-related changes in skeletal muscle function of Sprague-Dawley rats.

Taurine (2-aminoethanesulfonic acid) is a free amino acid found abundantly in mammalian tissues. Increasing evidence suggests that taurine plays a role in the maintenance of skeletal muscle function and increase of exercise capacity. Most energy drinks contain this amino acid; however, there is insufficient research on the effects of long-term, low-dose supplementation of taurine. In this study, we investigated the effects of long-term administration of taurine at low doses on aging in rodents. In Experiment 1, we examined age-related changes in aging Sprague-Dawley (SD) rats (32-92 weeks old) that O2 consumption and spontaneous activity decreased significantly with aging. In Experiment 2, we examined the effects of long-term (21-week) administration of taurine on healthy aging SD rats. SD rats were stabilized for 32-34 weeks and divided into three groups, administrated water (control), 0.5% taurine (25 mg/kg  body weight (BW)/day), or 1% taurine (50 mg/kg  BW/day) from age 34 to 56 weeks (5 days/week, 5 mL/kg BW). Our findings suggest that long-term administration of taurine at relatively low dose could attenuate the age-related decline in O2 consumption and spontaneous locomotor activity. Upon intestinal absorption, taurine might modulate age-related changes in respiratory metabolism and skeletal muscle function via peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), succinate dehydrogenase (SDH), cytochrome c (Cycs), myocyte enhancer factor 2A (MEF2A), glucose transporter 4 (GLUT4), and myoglobin, which are regulated by the activation of AMP-activated protein kinase (AMPK). This article examines the mechanism underlying the effects of taurine on age-related changes, which may have potential clinical implications.

Silencing of MEF2D by siRNA Loaded Selenium Nanoparticles for Ovarian Cancer Therapy.

BACKGROUND: Delivery of therapeutic small interfering RNA (siRNA) via functionalized nanoparticles holds great promise for cancer therapy. However, developing a safe and efficient delivery carrier of siRNA is a challenging issue. METHODS: RGDfC peptide was used to modify the surface of selenium nanoparticles (SeNPs) to synthesize a biocompatible siRNA delivery vehicle (R-SeNPs), and MEF2D-siRNA was loaded onto R-SeNPs to prepare a functionalized selenium nanoparticle R-Se@MEF2D-siRNA. The chemical properties of R-SeNPs were characterized, and the anticancer efficacy as well as related mechanisms of R-Se@MEF2D-siRNA were further explored. RESULTS: R-Se@MEF2D-siRNA was significantly taken up by SKOV3 cells and could enter SKOV3 cells mainly in the clathrin-associated endocytosis way. The result of in vitro siRNA release demonstrated that R-Se@MEF2D-siRNA could release MEF2D-siRNA quicker in a microenvironment simulating a lysosomal environment in tumor cells compared to a normal physiological environment. The results of qRT-PCR assay proved that R-Se@MEF2D-siRNA could effectively silence the expression of the MEF2D gene in SKOV3 cells. R-Se@MEF2D-siRNA remarkably suppressed the proliferation of SKOV3 cells and further triggered its apoptosis. In addition, R-Se@MEF2D-siRNA had the capability to disrupt mitochondrial membrane potential (MMP) in SKOV3 cells and resulted in the overproduction of reactive oxygen species (ROS), indicating that mitochondrial dysfunction and ROS generation played an important role in the apoptosis of SKOV3 cells induced by R-Se@MEF2D-siRNA. In vivo, R-Se@MEF2D-siRNA also exhibited excellent antitumor activity mainly through decreasing tumor cells proliferation and triggering their apoptosis in tumor-bearing nude mice. CONCLUSION: R-Se@MEF2D-siRNA provides an alternative strategy for ovarian cancer treatment in the clinic.

Research into the intervention effect of folic acid on arsenic-induced heart abnormalities in fetal rats during the periconception period.

BACKGROUND: The incidence of CHD is the highest among birth defects and is increasing year to year. CHD seriously harms the health of infants and young children and presents a large economic burden to families and society. The pathogenesis of CHD and preventive measures are the focus of current research. Our research aimed to explore the intervention effect of folic acid on heart abnormalities resulting from sodium arsenic (NaAsO2) exposure during the periconception period. METHODS: Sixty 35-day-old female SD rats were randomly divided into 5 groups with 12 rats in each group. Group A was the control group. The rats were given distilled water and ordinary chow. The rats in group B were given distilled water containing 75 mg/L NaAsO2 and ordinary chow. The rats in groups C, D, and E were given distilled water containing 75 mg/L NaAsO2 and chow containing 0.53 mg/kg, 5.3 mg/kg, and 10.6 mg/kg folic acid, respectively. The general condition of the embryos and the histopathology of the embryonic hearts were examined. The acetylation levels of histone H3K9 in heart tissues and the expression levels of Mef2C (which is related to heart development) were observed. RESULTS: The embryo weight and placental weight of groups B-E were significantly lower than those of group A (P < 0.05). The heart malformation rate of the fetal rats in groups B-E was significantly higher than that of the fetal rats in group A (P < 0.05). We found that the level of H3K9 acetylation in fetal rat cardiomyocytes in groups B-E was significantly higher than that in group A (P < 0.05) and that the level of H3K9 acetylation in groups C-E was lower than that in group B (P < 0.05). The mRNA level of Mef2C in fetal rat cardiomyocytes in group B-E was significantly higher than that in group A (P < 0.05), and the mRNA level of Mef2C in groups C-E was significantly lower than that in group B (P < 0.05). CONCLUSION: Supplementation with folic acid during the periconception period can interfere with the toxic effects of arsenic on the heart. The mechanism may be that lowering the acetylation levels of histone H3K9 in heart tissues leads to decreased expression levels of Mef2C, which may play a protective role in heart development in fetal rats.

[Effect of Xiaozhong Zhitong Ointment on MEF2 mRNA and protein expression in rats with gastrointestinal muscle injury].

OBJECTIVE: To investigate the effect of Xiaozhong Zhitong Ointment(XZZTO) on remodeling and repair of skeletal muscle injury in rats based on the expression mechanism of microRNA. METHODS: The rat gastrocnemius injury model was established by blunt contusion model. The expression of MEF2 gene and protein in gastrocnemius muscle was detected by quantitative PCR at 4, 7, 14 and 21 days after injury with XZZTO. The mechanism of the effect of XZZTO on the muscle remodeling and repair of rat gastrocnemius contusion model was discussed. RESULTS: The expression level of MEF2 in the treatment group was significantly higher than that of the control group and model group, which further confirmed the important role of MEF2 in inducing skeletal muscle remodeling and repair process in the topical drugs. The expression of MEF2 increased at 7 days after injury and remained at a high level until 21 days after injury. Compared with the model group, the peak expression period was about 14 days, and then returned to the general state. CONCLUSIONS: The expression level of MEF2 shows an upward trend. Even 21 days after injury, the expression of MEF2 dose not show a significant downward trend. It can be seen that XZZTO can promote the expression of MEF2. At the same time, XZZTO can regulate the regeneration and repair of skeletal muscle. Therefore, XZZTO can play a regeneration and repair role after skeletal muscle injury through gene regulation.

Anacardic acid attenuates pressure-overload cardiac hypertrophy through inhibiting histone acetylases.

Cardiac hypertrophy has become a major cardiovascular problem wordwide and is considered the early stage of heart failure. Treatment and prevention strategies are needed due to the suboptimal efficacy of current treatment methods. Recently, many studies have demonstrated the important role of histone acetylation in myocardium remodelling along with cardiac hypertrophy. A Chinese herbal extract containing anacardic acid (AA) is known to possess strong histone acetylation inhibitory effects. In previous studies, we demonstrated that AA could reverse alcohol-induced cardiac hypertrophy in an animal model at the foetal stage. Here, we investigated whether AA could attenuate cardiac hypertrophy through the modulation of histone acetylation and explored its potential mechanisms in the hearts of transverse aortic constriction (TAC) mice. This study showed that AA attenuated hyperacetylation of acetylated lysine 9 on histone H3 (H3K9ac) by inhibiting the expression of p300 and p300/CBP-associated factor (PCAF) in TAC mice. Moreover, AA normalized the transcriptional activity of the heart nuclear transcription factor MEF2A. The high expression of cardiac hypertrophy-linked genes (ANP, ß-MHC) was reversed through AA treatment in the hearts of TAC mice. Additionally, we found that AA improved cardiac function and survival rate in TAC mice. The current results further highlight the mechanism by which histone acetylation is controlled by AA treatment, which may help prevent and treat hypertrophic cardiomyopathy.

Oxytocin alters the morphology of hypothalamic neurons via the transcription factor myocyte enhancer factor 2A (MEF-2A).

Oxytocin (OT) has gained attention not only as anxiolytic drug and as potential treatment option for autistic children; it also acts as a growth and differentiation factor in neuronal cells. While behavioral effects of OT have been studied in detail, knowledge about the cellular effects of OT is relatively sparse. In this study, we present evidence for three hypotheses: 1) OT leads to neurite retraction in hypothalamic neurons via the OT receptor (OTR) 2) The transcription factor MEF-2A is a central regulator of OT-induced neurite retraction, and 3) The MAPK pathway is critical for OT-induced MEF-2A activation. Incubation of rat hypothalamic H32 cells with 10 nM to 1 µM OT, vasopressin, and the specific OTR agonist TGOT, over the course of 12 h resulted in a time-dependent, significant retraction of neurites. In addition, the size of the nuclear compartment increased, whereas the overall cell size remained unchanged. OT treatment for 10 h increased the cellular viability significantly, and this effect could be blocked by a specific OTR antagonist, providing evidence for a specific and pro-active effect of OT on neurite retraction, and not as an unspecific side effect of apoptosis. The molecular mechanism that controls OT-induced neurite retraction includes a reduced phosphorylation of the transcription factor MEF-2A at Serine 408 (S408). This dephosphorylation is under the control of the OTR-coupled MAPK pathway, as blocking MEK1/2 by U0126 inhibited MEF-2A activation and subsequent neurite retraction. The siRNA-mediated knockdown of MEF-2A prevented the OT-induced neurite retraction, providing direct evidence for a role of MEF-2A in morphological alterations induced by OT treatment. In summary, the present study reveals a previously unknown OTR-coupled MAPK-MEF-2A pathway, which is responsible for OT-induced neurite retraction of hypothalamic neurons.

Shenfu Injection attenuates rat myocardial hypertrophy by up-regulating miR-19a-3p expression.

Shenfu Injection (SFI) is a classical Chinese medicine used to treat heart failure. Our previous study demonstrated that miRNAs underwent changes in rats with myocardial hypertrophy induced by abdominal aortic constriction. Interestingly, there was a significant change in miR-19a-3p, whose target gene is known to be associated with MEF2 signaling. However, whether and how SFI regulates miR-19a-3p in the treatment of myocardial hypertrophy has not been investigated. The purpose of the present study was to investigate the regulatory effect of SFI on miR-19a-3p in MEF2 signaling in the rat hypertrophic myocardium. We found that the miR-19a-3p expression level was significantly decreased in the hypertrophic myocardium, and MEF2A was the target gene of miR-19a-3p. The protein expressions of MEF2A, ß-MHC, BNP and TRPC1 were significantly increased in hypertrophic cardiomyocytes. MiR-19a-3p was up-regulated after SFI treatment, and the protein expressions of these genes were significantly decreased. In addition, miR-19a-3p over-expression in hypertrophic cardiomyocytes could decrease MEF2A mRNA and protein expressions, and anti-miR-19a-3p showed the opposite result. Our study provided substantial evidence that miR-19a-3p played a functional role in MEF2 signaling in myocardial hypertrophy. SFI attenuated cardiomyocyte hypertrophy probably through up-regulating or maintaining the miR-19a-3p levels and regulating the MEF2 signaling pathway.

An integrated approach to identify critical transcription factors in the protection against hydrogen peroxide-induced oxidative stress by Danhong injection.

Oxidative stress plays a vital role in many pathological processes of the cardiovascular diseases. However, the underlying mechanism remains unclear, especially on a transcription factor (TF) level. In this study, a new method, concatenated tandem array of consensus transcription factor response elements (catTFREs), and an Illumina-based RNA-seq technology were integrated to systematically investigate the role of TFs in hydrogen peroxide (H2O2)-induced oxidative stress in cardiomyocytes; the damage was then rescued by Danhong injection (DHI), a Chinese standardized product approved for cardiovascular diseases treatment. The overall gene expression revealed cell apoptosis and DNA repair were vital for cardiomyocytes in resisting oxidative stress. By comprehensively integrating the transcription activity of TFs and their downstream target genes, an important TFs-target network were constructed and 13 TFs were identified as critical TFs in DHI-mediated protection in H2O2-induced oxidative stress. By using the integrated approach, seven TFs of these 13 TFs were also identified in melatonin-mediated protection in H2O2-induced damage. Furthermore, the transcription activity of DNA-(apurinic or apyrimidinic site) lyase (Apex1), Myocyte-specific enhancer factor 2D (Mef2d) and Pre B-cell leukemia transcription factor 3 (Pbx3) was further verified in pluripotent stem cell-derived cardiomyocytes. This research offers a new understanding of cardiomyocytes in response to H2O2-induced oxidative stress and reveals additional potential therapeutic targets. The combination of two parallel omics datasets (corresponding to the transcriptome and proteome) can reduce the noise in high-throughput data and reveal the fundamental changes of the biological process, making it suitable and reliable for investigation of critical targets in many other complicated pathological processes.

Phenylephrine-induced cardiac hypertrophy is attenuated by a histone acetylase inhibitor anacardic acid in mice.

Cardiac hypertrophy is a complex process involving highly coordinated but tight regulation of multiple elements, such as in epigenetics, which make an important contribution to myocardium remodeling and cardiac hypertrophy. Epigenetic regulations, particularly histone acetylation, have been implicated in cardiac hypertrophy, however, the exact mechanism is still largely unknown. In the present study, we explored the potential attenuating effects of Chinese herbal extract anacardic acid on phenylephrine-induced cardiac hypertrophy and the underlying mechanism. The mouse cardiac hypertrophy model was established and the hearts were collected from C57BL/6 mice for further analyses. The data showed that anacardic acid modulated the cardiac genes expression and attenuated the phenylephrine-induced cardiac hypertrophy via the suppression of histone acetylases activity and downstream cardiac genes. In addition, anacardic acid abrogated histone and MEF2A acetylation and DNA-binding activity by blocking p300-HAT and PCAF-HAT activities. In addition, anacardic acid normalized the cardiac hypertrophy-related genes expressions (ANP, BNP, cTnT, cTnI, ß-MHC, and Cx43) induced by phenylephrine at the level of transcription and translation. In addition, anacardic acid did not affect the blood routine index, hepatic function, renal function, and myocardial enzymes. Therefore, anacardic acid may prove to be a candidate drug to cure hypertrophic cardiomyopathy.

Myocyte Enhancer Factor-2A Gene Mutation and Coronary Artery Disease.

BACKGROUND: Premature ventricular contractions (PVCs) are common in the general population, and frequent PVCs may result in the poor quality of life or even the damage of cardiac function. We examined the efficacy and safety of a traditional Chinese medicine Wenxin Keli for the treatment of frequent PVCs among a relatively large Chinese cohort. METHODS: We performed a randomized, double-blind, placebo-controlled, parallel-group, multicenter trial. A total of 1200 eligible participants were randomly assigned in a ratio of 1:1 to receive Wenxin Keli or the placebo for 4 weeks. The primary and secondary endpoint was the change of PVC numbers and PVC-related symptoms after a 4-week treatment compared with baseline, respectively. In addition, vital signs, laboratory values, and electrocardiographic parameters were assessed in a safety analysis. RESULTS: At the initial evaluation, no significant differences in the baseline characteristics were observed between the Wenxin Keli group and the placebo group. A smaller number of PVCs was observed after the 4-week treatment than at baseline, in both the Wenxin Keli group (5686 ± 5940 vs. 15,138 ± 7597 beats/d, P < 0.001) and the placebo group (10,592 ± 8009 vs. 14,529 ± 5929 beats/d, P < 0.001); moreover, the Wenxin Keli group demonstrated a significantly greater reduction in the frequency of PVCs than the placebo group (P < 0.001). In a full analysis set, patients in the Wenxin Keli group exhibited significantly higher total effective responses in the reduction of PVCs compared to those in the placebo group (83.8% vs. 43.5%,P < 0.001). The per-protocol analysis yielded similar results (83.0% vs. 39.3%,P < 0.001). Treatment with Wenxin Keli also demonstrated superior performance compared to the placebo with respect to PVC-related symptoms. No severe adverse effects attributable to Wenxin Keli were reported. CONCLUSIONS: Wenxin Keli treatment effectively reduced the overall number of PVCs and alleviated PVC-related symptoms in patients without structural heart diseases and had no severe side effects.

Restoration of impaired endothelial myocyte enhancer factor 2 function rescues pulmonary arterial hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a progressive disease of the pulmonary arterioles, characterized by increased pulmonary arterial pressure and right ventricular failure. The cause of PAH is complex, but aberrant proliferation of the pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells is thought to play an important role in its pathogenesis. Understanding the mechanisms of transcriptional gene regulation involved in pulmonary vascular homeostasis can provide key insights into potential therapeutic strategies. METHODS AND RESULTS: We demonstrate that the activity of the transcription factor myocyte enhancer factor 2 (MEF2) is significantly impaired in the PAECs derived from subjects with PAH. We identified MEF2 as the key cis-acting factor that regulates expression of a number of transcriptional targets involved in pulmonary vascular homeostasis, including microRNAs 424 and 503, connexins 37, and 40, and Kruppel Like Factors 2 and 4, which were found to be significantly decreased in PAH PAECs. The impaired MEF2 activity in PAH PAECs was mediated by excess nuclear accumulation of 2 class IIa histone deacetylases (HDACs) that inhibit its function, namely HDAC4 and HDAC5. Selective, pharmacological inhibition of class IIa HDACs led to restoration of MEF2 activity in PAECs, as demonstrated by increased expression of its transcriptional targets, decreased cell migration and proliferation, and rescue of experimental pulmonary hypertension models. CONCLUSIONS: Our results demonstrate that strategies to augment MEF2 activity hold potential therapeutic value in PAH. Moreover, we identify selective HDAC IIa inhibition as a viable alternative approach to avoid the potential adverse effects of broad spectrum HDAC inhibition in PAH.

Yin Yang-1 suppresses invasion and metastasis of pancreatic ductal adenocarcinoma by downregulating MMP10 in a MUC4/ErbB2/p38/MEF2C-dependent mechanism.

BACKGROUND: Increasing evidence indicates an important role of transcription factor Yin Yang-1 (YY1) in human tumorigenesis. However, its function in cancer remains controversial and the relevance of YY1 to pancreatic ductal adenocarcinoma (PDAC) remains to be clarified. METHODS: In this study, we detected YY1 expression in clinical PDAC tissue samples and cell lines using quantitative RT-PCR, immunohistochemistry and western blotting. We also detected MUC4 and MMP10 mRNA levels in 108 PDAC samples using qRT-PCR and analyzed the correlations between YY1 and MUC4 or MMP10 expression. The role of YY1 in the proliferation, invasion and metastatic abilities of PDAC cells in vitro was studied by CCK-8 assay, cell migration and invasion assays. In vivo pancreatic tumor growth and metastasis was studied by a xenogenous subcutaneously implant model and a tail vein metastasis model. The potential mechanisms underlying YY1 mediated tumor progression in PDAC were explored by digital gene expression (DGE) sequencing, signal transduction pathways blockage experiments and luciferase assays. Statistical analysis was performed using the SPSS 15.0 software. RESULTS: We found that the expression of YY1 in PDACs was higher compared with their adjacent non-tumorous tissues and normal pancreas tissues. However, PDAC patients with high level overexpression of YY1 had better outcome than those with low level overexpression. YY1 expression levels were statistically negatively correlated with MMP10 expression levels, but not correlated with MUC4 expression levels. YY1 overexpression suppressed, whereas YY1 knockdown enhanced, the proliferation, invasion and metastatic properties of BXPC-3 cells, both in vitro and in vivo. YY1 suppresses invasion and metastasis of pancreatic cancer cells by downregulating MMP10 in a MUC4/ErbB2/p38/MEF2C-dependent mechanism. CONCLUSIONS: The present study suggested that YY1 plays a negative role, i.e. is a tumor suppressor, in PDAC, and may become a valuable diagnostic and prognostic marker of PDAC.

Neuroendocrine phenotypes in a boy with 5q14 deletion syndrome implicate the regulatory roles of myocyte-specific enhancer factor 2C in the postnatal hypothalamus.

The 5q14.3 deletion syndrome is a rare chromosomal disorder characterized by moderate to severe intellectual disability, seizures and dysmorphic features. We report a 14-year-old boy with 5q14.3 deletion syndrome who carried a heterozygous deletion of the myocyte-specific enhancer factor 2c (MEF2C) gene. In addition to the typical neurodevelopmental features of 5q14.3 deletion syndrome, he showed recurrent hypoglycemia, appetite loss and hypothermia. Hormonal loading tests using insulin, arginine and growth hormone-releasing factor revealed that growth hormone was insufficiently released into serum in response to these stimuli, thus disclosing the hypothalamic dysfunction in the present case. To uncover the biological roles of MEF2C in the hypothalamus, we studied its expression in the postnatal mouse brain. Notably, neuropeptide Y (NPY)-positive interneurons in the hypothalamic arcuate nuclei highly expressed MEF2C. In contrast, the Rett syndrome-associated protein, Methyl-CpG binding Protein 2 (MECP2) was barely expressed in these neurons. MEF2C knockdown or overexpression experiments using Neuro2a cells revealed that MEF2C activated the endogenous transcription of NPY. Conversely, siRNA-mediated knockdown of MECP2 led to derepression of the Npy gene. These data support the concept that MEF2C and MECP2 share common molecular pathways regulating the homeostatic expression of NPY in the adult hypothalamus. We propose that individuals with 5q14.3 deletion syndrome may exhibit neuroendocrine phenotypes through the functional loss of MEF2C in the postnatal hypothalamus.

Meta-analysis of genome-wide studies identifies MEF2C SNPs associated with bone mineral density at forearm.

BACKGROUND: Forearm fractures affect 1.7 million individuals worldwide each year and most occur earlier in life than hip fractures. While the heritability of forearm bone mineral density (BMD) and fracture is high, their genetic determinants are largely unknown. AIM: To identify genetic variants associated with forearm BMD and forearm fractures. METHODS: BMD at distal radius, measured by dual-energy x-ray absorptiometry, was tested for association with common genetic variants. We conducted a meta-analysis of genome-wide association studies for BMD in 5866 subjects of European descent and then selected the variants for replication in 715 Mexican American samples. Gene-based association was carried out to supplement the single-nucleotide polymorphism (SNP) association test. We then tested the BMD-associated SNPs for association with forearm fracture in 2023 cases and 3740 controls. RESULTS: We found that five SNPs in the introns of MEF2C were associated with forearm BMD at a genome-wide significance level (p<5×10(-8)) in meta-analysis (lead SNP, rs11951031[T] -0.20 SDs per allele, p=9.01×10(-9)). The gene-based association test suggested an association between MEF2C and forearm BMD (p=0.003). The association between MEF2C variants and risk of fracture did not achieve statistical significance (SNP rs12521522[A]: OR=1.14 (95% CI 0.92 to 1.35), p=0.14). Meta-analysis also revealed two genome-wide suggestive loci at CTNNA2 and 6q23.2. CONCLUSIONS: These findings demonstrate that variants at MEF2C were associated with forearm BMD, implicating this gene in the determination of BMD at forearm.