miR-145 is differentially regulated by TGF-β1 and ischaemia and targets Disabled-2 expression and wnt/β-catenin activity

lncRNA TUG1 as potential novel biomarker for prognosis of cardiovascular diseases

Globally, cardiovascular diseases (CVDs) are among the leading causes of death. In light of the high prevalence and mortality of CVDs, it is imperative to understand the molecules involved in CVD pathogenesis and the signaling pathways that they initiate. This may facilitate the development of more precise and expedient diagnostic techniques, the identification of more effective prognostic molecules and the identification of potential therapeutic targets. Numerous studies have examined the role of lncRNAs, such as TUG1, in CVD pathogenesis in recent years. According to this review article, TUG1 can be considered a biomarker for predicting the prognosis of CVD.

MicroRNA-4732-3p Is Dysregulated in Breast Cancer Patients with Cardiotoxicity, and Its Therapeutic Delivery Protects the Heart from Doxorubicin-Induced Oxidative Stress in Rats

Anthracycline-induced cardiotoxicity is the most severe collateral effect of chemotherapy originated by an excess of oxidative stress in cardiomyocytes that leads to cardiac dysfunction. We assessed clinical data from patients with breast cancer receiving anthracyclines and searched for discriminating microRNAs between patients that developed cardiotoxicity (cases) and those that did not (controls), using RNA sequencing and regression analysis. Serum levels of 25 microRNAs were differentially expressed in cases versus controls within the first year after anthracycline treatment, as assessed by three different regression models (elastic net, Robinson and Smyth exact negative binomial test and random forest). MiR-4732-3p was the only microRNA identified in all regression models and was downregulated in patients that experienced cardiotoxicity. MiR-4732-3p was also present in neonatal rat cardiomyocytes and cardiac fibroblasts and was modulated by anthracycline treatment. A miR-4732-3p mimic was cardioprotective in cardiac and fibroblast cultures, following doxorubicin challenge, in terms of cell viability and ROS levels. Notably, administration of the miR-4732-3p mimic in doxorubicin-treated rats preserved cardiac function, normalized weight loss, induced angiogenesis, and decreased apoptosis, interstitial fibrosis and cardiac myofibroblasts. At the molecular level, miR-4732-3p regulated genes of TGFβ and Hippo signaling pathways. Overall, the results indicate that miR-4732-3p is a novel biomarker of cardiotoxicity that has therapeutic potential against anthracycline-induced heart damage.

The effect of eight weeks of moderate and high intensity aerobic training on the gene expression of Mir-145, Wnt3a and Dab2 in the heart tissue of type 2 diabetic rats

Purpose

Pathological hypertrophy of heart tissue has been attributed to changes in some microRNAs and their target genes in heart tissue. This study intended to study the effects of eight weeks of moderate and high intensity aerobic training (MIT&HIT) on the mRNA of Mir-145, Wnt3a, and Dab2 in heart tissue of type 2 diabetic rats.

Methods

To implement this experimental research, 60 male Wistar rats were randomly divided into 6 groups, including Healthy-control (HC), Diabetic-control (DC), Moderate intensity training (MIT), Diabetes-MIT (DMIT), high intensity training (HIT) and Diabetes-HIT (DHIT). The aerobic training was conducted with moderate (50-60% VO2max) and high (85-90% VO2max) intensity, 5 days a week, for 8 weeks. The Mir-145, Wnt3a and Dab2 gene expression in the heart tissue samples was measured by Real Time PCR. Data were analyzed by one-way ANOVA and Tukey post hoc test at the P < 0.05.

Results

Moderate and high intensity aerobic training was associated with non-significant increase in Mir-145 mRNA of Heart tissue in type 2 diabetic rats than the diabetic control group(P < 0.05). Moderate and high intensity aerobic training was associated with significant increase in Wnt3a mRNA (P = 0.001) and significant decrease in Dab-2 mRNA (P = 0.001) of Heart tissue in type 2 diabetic rats than the diabetic control group. The Dab-2 mRNA was significantly lower of heart tissue in the diabetes- high intensity training group than the diabetes- moderate intensity training group (P = 0.001).

Conclusion

It seems that moderate and high intensity aerobic exercise can help regulate the genes of the physiological hypertrophy pathway of the heart tissue in diabetes.

Mir-1, miR-122, miR-132, and miR-133 Are Related to Subclinical Aortic Atherosclerosis Associated with Metabolic Syndrome

Previously, miR-1, miR-122, miR-126, miR-132, miR-133, and miR-370 were found to be related to coronary artery disease (CAD) progression. However, their relationship with subclinical atherosclerosis, especially in subjects with metabolic syndrome, is unknown. Therefore, our aim was to determine their relationship with arterial markers of subclinical atherosclerosis. Metabolic syndrome subjects (n = 182) with high cardiovascular risk but without overt cardiovascular disease (CVD) were recruited from the Lithuanian High Cardiovascular Risk (LitHiR) primary prevention program. The ardio-ankle vascular index (CAVI), augmentation index normalized to a heart rate of 75 bpm (AIxHR75), aortic pulse wave velocity (AoPWV), and carotid artery stiffness were assessed. MicroRNAs (miRs) were analyzed in serum. Pearson correlation and a univariate linear regression t-test showed that miR-1, miR-133b, and miR-133a were negatively associated with CAVI mean, whereas miR-122 was positively associated. MiR-1, miR-133b and miR-133a, and miR-145 were negatively associated with AIxHR75. MiR-122 correlated negatively with AoPWV. In multivariate linear regression models, miR-133b and miR-122 predicted CAVImean, miR-133 predicted AIxHR75, and miR-122 predicted AoPWV. MiR-132 predicted right carotid artery stiffness, and miR-1 predicted left carotid artery stiffness. The addition of smoking to miR-133b and miR-122 enhanced the prediction of CAVI. Age and triglycerides enhanced the prediction of AoPWV by miR-122. A cluster of four miRs are related to subclinical atherosclerosis in subjects with metabolic syndrome. Combined, they may have a more substantial diagnostic or prognostic value than any single miR. Future follow-up studies are needed to establish their clinical relevance.

MicroRNA-145, Wnt3a, and Dab2 Genes Expression Changes of the Cardiomyocytes in Hypercholesterolemic Rats Exposed to the Aerobic Training

The current study aimed to investigate the effect of a 12-week endurance training (ET) on microRNA-145 (miR-145) changes and Wnt3a and Dab2 cardiomyocytes genes expression of hypercholesterolemic Wistar male rats. Thirty-two male Wistar rats (191.2±19 g, 6-8 weeks age) were randomly assigned into the aerobic exercise-normal nutrition (ANN; n=8), hypercholesterolemic (HCL; n=8), aerobic exercise- hypercholesterolemic (ACL; n=8), and normal nutrition (NN; n=8). Hypercholesterolemia was created by adding 1% cholesterol to the food of the HCL and ACL rats. ET was done five sessions per week on nonconsecutive days for 12 weeks. Twenty-four hours after the last training session, the rats were killed, and the cardiomyocytes were removed. The expression of miR-145, Wnt3a, and Dab2 genes in cardiomyocytes was assessed by real time PCR method. The expression of miR-145 significantly increased in the ANN group in comparison with other groups (P = 0.001). Also, Dab2 gene expression significantly decreased in the ANN group in comparison with ACL (P = 0.001) and HCL (P = 0.001) groups. The results also showed that the Wnt3a in the ANN group was significantly different from NN (p=0.001), ACL, and HCL (p=0.001) groups. It can be concluded that aerobic training and cholesterol-rich foods play an essential regulatory role in the expression of miR-145, Dab2, and Wnt3a genes. However, cholesterol-rich foods appear to play a more significant regulatory role than aerobic exercise training.

The role of disabled-2 (Dab2) in diseases

Disabled-2 (Dab2/DOC-2) is a mitogen-responsive adaptor protein required for multiple cellular functions. It is involved in many signaling pathways and plays an integral role in vesicular uptake and trafficking, modulating immune function, protein-protein interactions, cellular homeostasis and differentiation, oncogenesis, and inflammatory processes in organ systems. It contains domains for binding to NPXY motif-containing and SH3 domain-containing adapter proteins, phosphoinositides, glycoprotein 100 (gp100, or megalin), integrins, clathrin, and myosin VI. However, the molecular mechanism(s) of Dab2's biological function still remain to be elucidated. In this review, we provide an extensive up-to-date understanding of the function of Dab2 and its regulation in cardiovascular diseases, immune disorders, tumorigenesis, and central nervous system disorders.

Nanoparticle Delivery of Anti-inflammatory LNA Oligonucleotides Prevents Airway Inflammation in a HDM Model of Asthma

To address the problem of poor asthma control due to drug resistance, an antisense oligonucleotide complementary to mmu-miR-145a-5p (antimiR-145) was tested in a house dust mite mouse model of mild/moderate asthma. miR-145 was targeted to reduce inflammation, regulate epithelial-mesenchymal transitions, and promote differentiation of structural cells. In addition, several chemical variations of a nontargeting oligonucleotide were tested to define sequence-dependent effects of the miRNA antagonist. After intravenous administration, oligonucleotides complexed with a pegylated cationic lipid nanoparticle distributed to most cells in the lung parenchyma but were not present in smooth muscle or the mucosal epithelium of the upper airways. Treatment with antimiR-145 and a nontargeting oligonucleotide both reduced eosinophilia, reduced obstructive airway remodeling, reduced mucosal metaplasia, and reduced CD68 immunoreactivity. Poly(A) RNA-seq verified that antimiR-145 increased levels of many miR-145 target transcripts. Genes upregulated in human asthma and the mouse model of asthma were downregulated by oligonucleotide treatments. However, both oligonucleotides significantly upregulated many genes of interferon signaling pathways. These results establish effective lung delivery and efficacy of locked nucleic acid/DNA oligonucleotides administered intravenously, and suggest that some of the beneficial effects of oligonucleotide therapy of lung inflammation may be due to normalization of interferon response pathways.

(-)-Epigallocatechin Gallate Promotes MicroRNA 145 Expression against Myocardial Hypoxic Injury through Dab2/Wnt3a/β-catenin

MicroRNA 145 (miR-145) is a critical modulator of cardiovascular diseases. The downregulation of myocardial miR-145 is followed by an increase in disabled-2 (Dab2) expression in cardiomyocytes. (-)-epigallocatechin gallate (EGCG) is a flavonoid that has been evaluated extensively due to its diverse pharmacological properties including anti-inflammatory effects. The aim of this study was to investigate the cardioprotective effects of EGCG under hypoxia-induced stress in vitro and in vivo. The hypoxic insult led to the suppression of miR-145 expression in cultured rat cardiomyocytes in a concentration-dependent manner. Western blotting and real-time PCR were performed. In rat myocardial infarction study, in situ hybridization, and immunofluorescent analyses were adopted. The western blot and real-time PCR data revealed that hypoxic stress with 2.5% O2 suppressed the expression of miR-145 and Wnt3a/[Formula: see text]-catenin in cultured rat cardiomyocytes but augmented Dab2. Treatment with EGCG attenuated Dab2 expression, but increased Wnt3a and [Formula: see text]-catenin in hypoxic cultured cardiomyocytes. Following in vivo myocardial infarction (MI) study, the data revealed the myocardial infarct area reduced by 48.5%, 44.6%, and 48.5% in EGCG (50[Formula: see text]mg/kg) or miR-145 dominant or Dab2 siRNA groups after myocardial infarction for 28 days, respectively. This study demonstrated that EGCG increased miR-145, Wnt3a, and [Formula: see text]-catenin expression but attenuated Dab2 expression. Moreover, EGCG ameliorated myocardial ischemia in vivo. The novel suppressive effect was mediated through the miR-145 and Dab2/Wnt3a/[Formula: see text]-catenin pathways.

Transforming Growth Factor-β1 Selectively Recruits microRNAs to the RNA-Induced Silencing Complex and Degrades CFTR mRNA under Permissive Conditions in Human Bronchial Epithelial Cells

Mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene lead to cystic fibrosis (CF). The most common mutation F508del inhibits folding and processing of CFTR protein. FDA-approved correctors rescue the biosynthetic processing of F508del-CFTR protein, while potentiators improve the rescued CFTR channel function. Transforming growth factor (TGF-β1), overexpressed in many CF patients, blocks corrector/potentiator rescue by inhibiting CFTR mRNA in vitro. Increased TGF-β1 signaling and acquired CFTR dysfunction are present in other lung diseases. To study the mechanism of TGF-β1 repression of CFTR, we used molecular, biochemical, and functional approaches in primary human bronchial epithelial cells from over 50 donors. TGF-β1 destabilized CFTR mRNA in cells from lungs with chronic disease, including CF, and impaired F508del-CFTR rescue by new-generation correctors. TGF-β1 increased the active pool of selected micro(mi)RNAs validated as CFTR inhibitors, recruiting them to the RNA-induced silencing complex (RISC). Expression of F508del-CFTR globally modulated TGF-β1-induced changes in the miRNA landscape, creating a permissive environment required for degradation of F508del-CFTR mRNA. In conclusion, TGF-β1 may impede the full benefit of corrector/potentiator therapy in CF patients. Studying miRNA recruitment to RISC under disease-specific conditions may help to better characterize the miRNAs utilized by TGF-β1 to destabilize CFTR mRNA.

LncRNA LINC01116 Promotes Cancer Cell Proliferation, Migration And Invasion In Gastric Cancer By Positively Interacting With lncRNA CASC11

Purpose

The oncogenic roles of lncRNA LINC01116 have been reported in several types of cancer, while its involvement in gastric cancer is unknown. This study aimed to investigate the involvement of LINC01116 in gastric cancer.

Methods

Gene expression was detected by qPCR. Correlations were analyzed by linear regression. Overexpression and siRNA silencing techniques were used to analyze gene functions. Cell invasion and migration were analyzed by Transwell assays.

Results

LINC01116 and lncRNA CASC11 were both upregulated in cancer tissues compared to cancer-adjacent tissues. Expression levels of LINC01116 and CASC11 were increased with the increase in clinical stages. Expression levels of LINC01116 and CASC11 were positively correlated. Overexpression of LINC01116 mediated the upregulated CASC11 in gastric cancer cells, and CASC11 overexpression also led to overexpressed LINC01116. Overexpression of LINC01116 and CASC11 led to promoted invasion and migration of gastric cancer cells. Rescue experiments showed that CASC11 knockdown attenuated the effects of LINC01116 overexpression. Overexpression of LINC01116 failed to significantly affect cancer cell proliferation.

Conclusion

LINC01116 promoted cancer cell invasion and migration in gastric cancer by positively interacting with CASC11.

miR-145 supports cancer cell survival and shows association with DDR genes, methylation pattern, and epithelial to mesenchymal transition

Background

Despite several reports describing the dual role of miR-145 as an oncogene and a tumor suppressor in cancer, not much has been resolved and understood.

Method

In this study, the potential targets of miR-145 were identified bio-informatically using different target prediction tools. The identified target genes were validated in vitro by dual luciferase assay. Wound healing and soft agar colony assay assessed cell proliferation and migration. miR-145 expression level was measured quantitatively by RT-PCR at different stages of breast tumor. Western blot was used to verify the role of miR-145 in EMT transition using key marker proteins.

Result

Wound healing and soft agar colony assays, using miR-145 over-expressing stably transfected MCF7 cells, unraveled its role as a pro-proliferation candidate in cancerous cells. The association between miR-145 over-expression and differential methylation patterns in representative target genes (DR5, BCL2, TP53, RNF8, TIP60, CHK2, and DCR2) supported the inference drawn. These in vitro observations were validated in a representative set of nodal positive tumors of stage 3 and 4 depicting higher miR-145 expression as compared to early stages. Further, the role of miR-145 in epithelial-mesenchymal (EMT) transition found support through the observation of two key markers, Vimentin and ALDL, where a positive correlation with Vimentin protein and a negative correlation with ALDL mRNA expression were observed.

Conclusion

Our results demonstrate miR-145 as a pro-cancerous candidate, evident from the phenotypes of aggressive cellular proliferation, epithelial to mesenchymal transition, hypermethylation of CpG sites in DDR and apoptotic genes and upregulation of miR-145 in later stages of tumor tissues.

Targeting newly identified ERβ/TGF-β1/SMAD3 signals with the FDA-approved anti-estrogen Faslodex or an ERβ selective antagonist in renal cell carcinoma

Renal cell carcinoma (RCC) has the third highest mortality rate among urological tumors, and 20–30% of RCC patients present with metastatic RCC at the time of diagnosis. Although recent studies have indicated that estrogen receptor β (ERβ) could play promoting roles in RCC progression, the detailed mechanisms remain to be clarified. In the present study, we found that expression of ERβ, but not ERα, increases with tumor stage and grade, and also observed that modification of ERβ signals using estrogens/anti‐estrogens, shRNA knockdown of ERβ and overexpression of ERβ using ectopic cDNA affects RCC cell proliferation, migration and invasion. Mechanism analysis revealed that ERβ can promote RCC cell invasion via an increase in transforming growth factor β1 (TGF‐β1)/SMAD3 signals, and interrupting TGF‐β1/SMAD3 signals with a TGFβR1 inhibitor can reverse/block ERβ‐increased RCC cell migration. Importantly, preclinical analyses using in vivo mouse models of RCC revealed that targeting of this newly identified ERβ/TGF‐β1/SMAD3 pathway with either the FDA‐approved anti‐estrogen ICI182,780 (Faslodex) or a selective ERβ antagonist 4‐[2‐phenyl‐5,7 bis(trifluoromethyl)pyrazolo[1,5‐a]pyrimidin‐3‐yl]phenol can significantly reduce RCC tumor growth and invasion, which may be suitable as the basis for novel therapies to more effectively suppress metastatic RCC.

Aberrant miR-145-5p/β-catenin signal impairs osteocyte function in adolescent idiopathic scoliosis

Recently, noncoding RNAs have been thought to play important roles in the sporadic occurrence of spinal deformity of adolescent idiopathic scoliosis (AIS). As a prognostic factor for curve progression, low bone mass has been hypothesized to crosstalk with AIS pathogenesis. Abnormal osteoblasts activities are reported in AIS without a clear mechanism. In this study, bone biopsies from patients with AIS and control subjects and the primary osteoblasts derived from those samples were used to identify the potential microRNA (miRNA) candidates that interfere with osteoblasts and osteocytes function. Microarray analysis identified miRNA-145-5p (miR-145) as a potential upstream regulator. miR-145 and β-catenin mRNA ( CTNNB1) were overexpressed in AIS bone tissues and primary osteoblasts, and their expression correlated positively in AIS. Knockdown of miR-145 restored impaired osteocyte activity through the down-regulation of active β-catenin expression and its transcriptional activity. Significant negative correlations between circulating miR-145 and serum sclerostin, osteopontin, and osteoprotegerin were noted in patients with AIS, which was in line with our cellular findings. This is the first study to demonstrate the effect of aberrant miRNA expression and its effect on osteocyte function in AIS, which may contribute to the low bone mass. Our findings also provide insight into the development of circulating microRNAs as a bone quality biomarker or even a prognostic biomarker for AIS.-Zhang, J., Chen, H., Leung, R. K. K., Choy, K. W., Lam, T. P., Ng, B. K. W., Qiu,Y., Feng, J. Q., Cheng, J. C. Y., Lee, W. Y. W. Aberrant miR-145-5p/β-catenin signal impairs osteocyte function in adolescent idiopathic scoliosis.

MicroRNA-140-5p elevates cerebral protection of dexmedetomidine against hypoxic-ischaemic brain damage via the Wnt/β-catenin signalling pathway

Hypoxia–ischaemia (HI) remains a major cause of foetal brain damage presented a scarcity of effective therapeutic approaches. Dexmedetomidine (DEX) and microRNA‐140‐5p (miR‐140‐5p) have been highlighted due to its potentially significant role in the treatment of cerebral ischaemia. This study was to investigate the role by which miR‐140‐5p provides cerebral protection using DEX to treat hypoxic–ischaemic brain damage (HIBD) in neonatal rats via the Wnt/β‐catenin signalling pathway. The HIBD rat models were established and allocated into various groups with different treatment plans, and eight SD rats into sham group. The learning and memory ability of the rats was assessed. Apoptosis and pathological changes in the hippocampus CA1 region and expressions of the related genes of the Wnt/β‐catenin signalling pathway as well as the genes responsible of apoptosis were detected. Compared with the sham group, the parameters of weight, length growth, weight ratio between hemispheres, the rate of reaching standard, as well as Bcl‐2 expressions, were all increased. Furthermore, observations of increased levels of cerebral infarction volume, total mortality rate, response times, total response duration, expressions of Wnt1, β‐catenin, TCF‐4, E‐cadherin, apoptosis rate of neurons, and Bax expression were elevated. Following DEX treatment, the symptoms exhibited by HIBD rats were ameliorated. miR‐140‐5p and si‐Wnt1 were noted to attenuate the progression of HIBD. Our study demonstrates that miR‐140‐5p promotes the cerebral protective effects of DEX against HIBD in neonatal rats by targeting the Wnt1 gene through via the negative regulation of the Wnt/β‐catenin signalling pathway.

MicroRNA-145 Antagonism Reverses TGF-β Inhibition of F508del CFTR Correction in Airway Epithelia

RATIONALE

MicroRNAs (miRNAs) destabilize mRNA transcripts and inhibit protein translation. miR-145 is of particular interest in cystic fibrosis (CF) as it has a direct binding site in the 3'-untranslated region of CFTR (cystic fibrosis transmembrane conductance regulator) and is upregulated by the CF genetic modifier TGF (transforming growth factor)-β.

OBJECTIVES

To demonstrate that miR-145 mediates TGF-β inhibition of CFTR synthesis and function in airway epithelia.

METHODS

Primary human CF (F508del homozygous) and non-CF airway epithelial cells were grown to terminal differentiation at the air-liquid interface on permeable supports. TGF-β (5 ng/ml), a miR-145 mimic (20 nM), and a miR-145 antagonist (20 nM) were used to manipulate CFTR function. In CF cells, lumacaftor (3 μM) and ivacaftor (10 μM) corrected mutant F508del CFTR. Quantification of CFTR mRNA, protein, and function was done by standard techniques.

MEASUREMENTS AND MAIN RESULTS

miR-145 is increased fourfold in CF BAL fluid compared with non-CF (P < 0.01) and increased 10-fold in CF primary airway epithelial cells (P < 0.01). Exogenous TGF-β doubles miR-145 expression (P < 0.05), halves wild-type CFTR mRNA and protein levels (P < 0.01), and nullifies lumacaftor/ivacaftor F508del CFTR correction. miR-145 overexpression similarly decreases wild-type CFTR protein synthesis (P < 0.01) and function (P < 0.05), and eliminates F508del corrector benefit. miR-145 antagonism blocks TGF-β suppression of CFTR and enhances lumacaftor correction of F508del CFTR.

CONCLUSIONS

miR-145 mediates TGF-β inhibition of CFTR synthesis and function in airway epithelia. Specific antagonists to miR-145 interrupt TGF-β signaling to restore F508del CFTR modulation. miR-145 antagonism may offer a novel therapeutic opportunity to enhance therapeutic benefit of F508del CFTR correction in CF epithelia.

MicroRNA-145 regulates disabled-2 and Wnt3a expression in cardiomyocytes under hyperglycaemia

AIMS

MicroRNA-145 (miR-145) could protect cardiomyocyte apoptosis against oxidative stress and repair infarcted myocardium. Angiotensin II (Ang II), a pro-inflammatory cytokine could modulate myocardial remodelling. However, the role of hyperglycaemia on miR-145 expression in cardiomyocyte or diabetes is not known. The effect of Ang II on miR-145 expression under hyperglycaemia in cardiomyocytes remains unknown. We sought to investigate the effect of hyperglycaemia and Ang II on miR-145 expression in cardiomyocytes.

METHODS

Rat cardiomyocytes were cultured under high glucose concentration (25 mmol/L), and streptozotocin-induced diabetic rats were established. TaqMan^® MicroRNA real-time quantitative assay was used to quantitate miR-145.

RESULTS

Sustained high glucose concentration (hyperglycaemia) significantly decreased miR-145 expression in cardiomyocytes. Hyperglycaemia significantly increased Ang II mRNA expression and secretion from rat cardiomyocytes. Ang II suppressed miR-145 expression in cardiomyocytes. Hyperglycaemia increased Dab2 and decreased Wnt3a/ß-catenin expression in cardiomyocytes. Repression of miR-145 expression by Ang II resulted in increased Dab2 and decreased Wnt3a and ß-catenin expression under hyperglycaemia. In contrast, overexpression of miR-145 significantly decreased Dab2 mRNA and protein expression, whereas the mRNA and protein levels for Wnt3a and ß-catenin were significantly reduced in left ventricular myocardium from 5 days to 28 days in diabetic rats. The protein expression patterns of Dab2 and Wnt3a/ß-catenin in left ventricular myocardium of diabetic rats could be reversed upon treatment with valsartan.

CONCLUSIONS

Ang II downregulates miR-145 to regulate Dab2 and Wnt3a/ß-catenin expression in cardiomyocytes under high glucose concentration. Ang II plays a critical role in the regulation of miR-145 in cardiomyocytes under hyperglycaemic conditions.

A Novel Role for CAMKK1 in the Regulation of the Mesenchymal Stem Cell Secretome

Transplantation of adult stem cells into myocardial tissue after acute myocardial infarction (AMI), has been shown to improve tissue recovery and prevent progression to ischemic cardiomyopathy. Studies suggest that the effects of mesenchymal stem cells (MSC) are due to paracrine factors released by MSC, as the benefits of MSC can be achieved through delivery of conditioned media (CM) alone. We previously demonstrated that downregulation of Dab2 enhances MSC cardiac protein expression and improves cardiac function after AMI following MSC engraftment. In order to define the molecular mechanisms that regulate MSC secretome, we analyzed gene arrays in MSC following downregulation of Dab2 via TGFβ1 pretreatment or transfection with Dab2:siRNA or miR‐145. We identified 23 genes whose expressions were significantly changed in all three conditions. Among these genes, we have initially focused our validation and functional work on calcium/calmodulin‐dependent protein kinase kinase‐1 (CAMKK1). We quantified the effects of CAMKK1 overexpression in MSC following injection of CM after AMI. Injections of CM from MSC with CAMKK1 over‐expression correlated with an increase in vascular density (CAMKK1 CM: 2,794.95 ± 44.2 versus Control: 1,290.69 ± 2.8 vessels/mm²) and decreased scar formation (CAMKK1 CM 50% ± 3.2% versus Control: 28% ± 1.4%), as well as improved cardiac function. Direct overexpression of CAMKK1 in infarcted tissue using a CAMKK1‐encoding plasmid significantly improved ejection fraction (CAMKK1: 83.2% ± 5.4% versus saline: 51.7% ± 5.8%. Baseline: 91.3% ± 4.3%) and decreased infarct size after AMI. Our data identify a novel role for CAMKK1 as regulator of the MSC secretome and demonstrate that direct overexpression of CAMKK1 in infarcted cardiac tissue, results in therapeutic beneficial effects. Stem Cells Translational Medicine2017;6:1759–1766

Tumor-associated myoepithelial cells promote the invasive progression of ductal carcinoma in situ through activation of TGFβ signaling

The normal myoepithelium has a tumor-suppressing nature and inhibits the progression of ductal carcinoma in situ (DCIS) into invasive ductal carcinoma (IDC). Conversely, a growing number of studies have shown that tumor-associated myoepithelial cells have a tumor-promoting effect. Moreover, the exact role of tumor-associated myoepithelial cells in the DCIS-to-IDC development remains undefined. To address this, we explored the role of tumor-associated myoepithelial cells in the DCIS-to-IDC progression. We developed a direct coculture system to study the cell-cell interactions between DCIS cells and tumor-associated myoepithelial cells. Coculture studies indicated that tumor-associated myoepithelial cells promoted the invasive progression of a DCIS cell model in vitro, and mechanistic studies revealed that the interaction with DCIS cells stimulated tumor-associated myoepithelial cells to secrete TGFβ1, which subsequently contributed to activating the TGFβ/Smads pathway in DCIS cells. We noted that activation of the TGFβ signaling pathway promoted the epithelial-mesenchymal transition, basal-like phenotypes, stemness, and invasiveness of DCIS cells. Importantly, xenograft studies further demonstrated that tumor-associated myoepithelial cells enhanced the DCIS-to-IDC progression in vivo Furthermore, we found that TGFβ-mediated induction of oncogenic miR-10b-5p expression and down-regulation of RB1CC1, a miR-10b-5p-targeted tumor-suppressor gene, contributed to the invasive progression of DCIS. Our findings provide the first experimental evidence to directly support the paradigm that altered DCIS-associated myoepithelial cells promote the invasive progression of DCIS into IDC via TGFβ signaling activation.

Wnt/β-catenin pathway in arrhythmogenic cardiomyopathy

Wnt/β-catenin signaling pathway plays essential roles in heart development as well as cardiac tissue homoeostasis in adults. Abnormal regulation of this signaling pathway is linked to a variety of cardiac disease conditions, including hypertrophy, fibrosis, arrhythmias, and infarction. Recent studies on genetically modified cellular and animal models document a crucial role of Wnt/β-catenin signaling in the molecular pathogenesis of arrhythmogenic cardiomyopathy (AC), an inherited disease of intercalated discs, typically characterized by ventricular arrhythmias and progressive substitution of the myocardium with fibrofatty tissue. In this review, we summarize the conflicting published data regarding the Wnt/β-catenin signaling contribution to AC pathogenesis and we report the identification of a new potential therapeutic molecule that prevents myocyte injury and cardiac dysfunction due to desmosome mutations in vitro and in vivo by interfering in this signaling pathway. Finally, we underline the potential function of microRNAs, epigenetic regulatory RNA factors reported to participate in several pathological responses in heart tissue and in the Wnt signaling network, as important modulators of Wnt/β-catenin signaling transduction in AC.

Elucidation of the precise regulatory mechanism of Wnt/β-catenin signaling in AC molecular pathogenesis could provide fundamental insights for new mechanism-based therapeutic strategy to delay the onset or progression of this cardiac disease.

MiR-145-5p regulates hypoxia-induced inflammatory response and apoptosis in cardiomyocytes by targeting CD40

An increasing body of evidence indicates that inflammation and apoptosis are involved in the development of acute myocardial infarction (AMI). In this study, we sought to investigate the specific role and the underlying regulatory mechanism of miR-145-5p in myocardial ischemic injury. H9c2 cardiac cells were exposed to hypoxia to establish a model of myocardial hypoxic/ischemic injury. We found that miR-145-5p was notably down-regulated, while CD40 expression was highly elevated in H9c2 cells following exposure to acute hypoxia. Additionally, hypoxia markedly enhanced the inflammatory response, as reflected by an increase in the secretion of the cytokines IL-1β, TNF-α, and IL-6, whereas the introduction of miR-145-5p effectively suppressed inflammatory factor production triggered by hypoxia. Furthermore, we observed hypoxia stimulation significantly augmented apoptosis accompanied by a decrease in the expression of Bcl-2 and an increase in the expression of Bax, Caspase-3, and Caspase-9. However, augmentation of miR-145-5p led to a dramatic prevention of hypoxia-induced apoptosis. Importantly, we identified CD40 as a direct target of miR-145-5p. Interestingly, the depletion of CD40 with small interfering RNAs (siRNAs) apparently repressed the production of inflammatory cytokines and apoptosis in the setting of acute hypoxic treated. Taken together, these data demonstrated that miR-145-5p may function as a cardiac-protective molecule in myocardial ischemic injury by ameliorating inflammation and apoptosis via negative regulation of CD40. The study gives evidence that miR-145-5p provides an interesting strategy for protecting cardiomyocytes from hypoxia-induced inflammatory response and apoptosis.

Analysis of microRNA Microarrays in Cardiogenesis

microRNAs are a subclass of noncoding RNAs which have been demonstrated to play pivotal roles in multiple cellular mechanisms. microRNAs are small RNA molecules of 22-24 nt in length capable of modulating protein translation and/or RNA stability by base-priming with complementary sequences of the mRNAs, normally at the 3'untranslated region. To date, over 2,000 microRNAs have been already identified in humans, and orthologous microRNAs have been also identified in distinct animals and plants ranging a wide vast of species. High-throughput analyses by microarrays have become a gold standard to analyze the changes on microRNA expression in normal and pathological cellular or tissue conditions. In this chapter, we provide insights into the usage of this uprising technology in the context of cardiac development and disease.

An epigenetic auto-feedback loop regulates TGF-β type II receptor expression and function in NSCLC

The downregulation of transforming growth factor-β (TGF-β) type II receptor (TβRII) expression and function plays a pivotal role in the loss of the TGF-β-induced tumor suppressor function that contributes to lung cancer progression. The aberrant expression of miRNAs has been shown to be involved in the regulation of oncogenes and tumor suppressor genes. Our current study involving miRNA microarray, northern blot and QRT-PCR analysis shows an inverse correlation between miR-20a and TβRII expression in non-small cell lung cancer (NSCLC) tissues and cell lines. Stable expression of miR-20a downregulates TβRII in lung epithelial cells which results in an inhibition of TGF-β signaling and attenuation of TGF-β-induced cell growth suppression and apoptosis. Stable knock down of miR-20a increases TβRII expression and inhibits tumorigenicity of lung cancer cells in vivo. Oncogene c-Myc promotes miR-20a expression by activating its promoter leading to downregulation of TβRII expression and TGF-Δ signaling. MiR-145, which is upregulated by TGF-β, inhibits miR-20a expression by targeting c-Myc and upregulates TβRII expression. These correlations among miRNAs and cellular proteins are supported by TCGA public database using NSCLC specimens. These results suggest a novel mechanism for the loss of TβRII expression and TGF-β-induced tumor suppressor functions in lung cancer through a complex auto-feedback loop TGF-β/miR-145/c-Myc/miR-20a/TβRII.

Ossotide promotes cell differentiation of human osteoblasts from osteogenesis imperfecta patients by up-regulating miR-145

Ossotide as an effective bone formation compound preparation has been proved to promote osteoblasts differentiation. MiR-145 is significantly decreased in osteogenesis imperfecta (OI) patients, but it is still unknown whether ossotide performed its effect by regulating miR-145. In this study, we investigated the effect of ossotide on regulating miR-145 expression and osteoblasts differentiation. The primary osteoblasts cells were isolated from OI patients and then cultured with different concentrations (0, 25, 50, 100, 200μg/l) of ossotide. The cell proliferation was detected with CCK-8 Elisa kit after ossotide treatment. The level of miR-145 expression was determined using qRT-PCR. In order to study whether ossotide up regulated miR-145, miR-145 mimic and miR-145 inhibitor were used to up regulate and down regulate the miR-145 levels in osteoblasts. The expressions of Runx2, Osx, β-catenin, TCF-1 were detected using Western blot and qRT-PCR. We observed that miR-145 was up regulated by ossotide treatment in miR-145 mimic or miR-145 inhibitor treated osteoblasts. What's more, up regulated miR-145 increased the expression of osteoblasts differentiation regulated protein Runx2 and Osx. In addition, Wnt signaling related β-catenin, TCF-1 were activated by up-regulated miR-145 which was induced by ossotide treatment. In summary, ossotide induced cell differentiation and Wnt signaling activation in osteoblasts by up regulating miR-145.

MicroRNA-145 inhibits hepatic stellate cell activation and proliferation by targeting ZEB2 through Wnt/β-catenin pathway

The activation of hepatic stellates cells (HSCs) is well believed to play a pivotal role in the development of liver fibrosis. MicroRNA-145 (miR-145) is known to suppress the progression of hepatocellular carcinoma, and is previously reported to be associated with Wnt/β-catenin pathway, but its role in the progression of hepatic fibrosis and activation of HSCs remains unknown and is warranted for investigation. In the present study, we found that the expression of miR-145 is significantly down-regulated in vivo in CCl4-induced mice liver fibrosis as well as in transforming growth factor-β1 (TGF-β1) induced HSC-T6 cell lines and human hepatic stellate cell line LX-2 in vitro. Furthermore, over-expression of miR-145 inhibited TGF-β1-induced the activation and proliferation of HSC-T6 cells in vitro. Mechanistically, we identified that zinc finger E-box-binding homeobox 2 (ZEB2), a key mediator of epithelial-to-mesenchymal transition, acted as a functional downstream target for miR-145. Interestingly, ZEB2 was shown to be involved in the TGF-β1-induced HSCs activation by regulating Wnt/β-catenin signaling pathway. Taken together, our results revealed the critical regulatory role of miR-145 in HSCs activation and implied miR-145 as a potential candidate for therapy of hepatic fibrosis by regulation of Wnt/β-catenin through targeting ZEB2.

The Role of miRNAs in Cartilage Homeostasis

Osteoarthritis (OA) is an age-related disease with poorly understood pathogenesis. Recent studies have demonstrated that miRNA might play a key role in OA initiation and development. We reviewed recent publications and elucidated the connection between miRNA and OA cartilage anabolic and catabolic signals, including four signaling pathways: TGF-β/Smads and BMPs signaling, associated with cartilage anabolism; and MAPK and NF-KB signaling, associated with cartilage catabolism. We also explored the relationships with MMP, ADAMTS and NOS (NitricOxide Synthases) families, as well as with the catabolic cytokines IL-1 and TNF-α. The potential role of miRNAs in biological processes such as cartilage degeneration, chondrocyte proliferation, and differentiation is discussed. Collective evidence indicates that miRNAs play a critical role in cartilage degeneration. These findings will aid in understanding the molecular network that governs articular cartilage homeostasis and in to elucidate the role of miRNA in the pathogenesis of OA.

MicroRNA-143 Activation Regulates Smooth Muscle and Endothelial Cell Crosstalk in Pulmonary Arterial Hypertension

RATIONALE

The pathogenesis of pulmonary arterial hypertension (PAH) remains unclear. The 4 microRNAs representing the miR-143 and miR-145 stem loops are genomically clustered.

OBJECTIVE

To elucidate the transcriptional regulation of the miR-143/145 cluster and the role of miR-143 in PAH.

METHODS AND RESULTS

We identified the promoter region that regulates miR-143/145 microRNA expression in pulmonary artery smooth muscle cells (PASMCs). We mapped PAH-related signaling pathways, including estrogen receptor, liver X factor/retinoic X receptor, transforming growth factor-β (Smads), and hypoxia (hypoxia response element), that regulated levels of all pri-miR stem loop transcription and resulting microRNA expression. We observed that miR-143-3p is selectively upregulated compared with miR-143-5p during PASMC migration. Modulation of miR-143 in PASMCs significantly altered cell migration and apoptosis. In addition, we found high abundance of miR-143-3p in PASMC-derived exosomes. Using assays with pulmonary arterial endothelial cells, we demonstrated a paracrine promigratory and proangiogenic effect of miR-143-3p-enriched exosomes from PASMC. Quantitative polymerase chain reaction and in situ hybridization showed elevated expression of miR-143 in calf models of PAH and in samples from PAH patients. Moreover, in contrast to our previous findings that had not supported a therapeutic role in vivo, we now demonstrate a protective role of miR-143 in experimental pulmonary hypertension in vivo in miR-143-/- and anti-miR-143-3p-treated mice exposed to chronic hypoxia in both preventative and reversal settings.

CONCLUSIONS

MiR-143-3p modulated both cellular and exosome-mediated responses in pulmonary vascular cells, whereas inhibition of miR-143-3p blocked experimental pulmonary hypertension. Taken together, these findings confirm an important role for the miR-143/145 cluster in PAH pathobiology.

Potential application of miRNAs as diagnostic and therapeutic tools in chronic pancreatitis

Chronic pancreatitis (CP) is a progressive inflammatory disease typified by end-stage fibrosis. This disease can also increase the risk of pancreatic cancer. The associated diagnosis, pain and other complications further add to the burden of disease management. In recent years, significant progress has been achieved in identifying miRNAs and their physiological functions, including mRNA repression and protein expression control. Given the extensive effort made on miRNA research, a close correlation has been discovered between certain types of miRNAs and disease progression, particularly for tissue fibrosis. Designing miRNA-related tools for disease diagnosis and therapeutic treatments presents a novel and potential research frontier. In the current review, we discuss various miRNAs closely interacting with CP, as well as the possible development of targeted miRNA therapies in managing this disease.

Liposarcoma miRNA signatures identified from genome-wide miRNA expression profiling

AIMS

To identify the miRNA expression profile of liposarcoma (LPS) that could facilitate detection of LPS, and provide the basis for further investigation of molecular-targeted therapeutic drugs.

MATERIALS & METHODS

A real-time quantitative PCR assay was performed to analyze the expression of 1888 miRNAs from 25 LPS tumor tissue samples, 16 samples of adipose tissue adjacent to the tumors and 18 normal adipose tissue samples from patients with LPS.

RESULTS

Ten dysregulated miRNAs were identified that effectively distinguished LPS tissue from adipose tissue and benign lipoma tissue, and LPS tumor tissues from normal adipose tissues in LPS patients. Furthermore, the expression profiles of miRNAs could also classify the subtype of LPS.

CONCLUSION

The identified miRNAs appear to be novel biomarkers for the detection of LPS, and may contribute to an understanding of the mechanisms of LPS tumorigenesis and its development, and further elucidate the characteristics of LPS subtypes.

Prognostic role of miR-200c in various malignancies: a systematic review and meta-analysis

MiR-200c expression is dysregulated in various malignancies and may predict the survival of patients with cancer, although the results of different studies conflict. Therefore, we conducted a meta-analysis to resolve this discrepancy. We queried the PubMed and Embase using multiple search strategies. Data were extracted from studies comparing overall survival and progression-free survival in patients with cancer with high and low levels of miR-200c expression. Fixed and random models were used where appropriate. A combined hazards ratio (HR) was calculated to estimate the association of high levels of miR-200c with survival. We selected 16 studies of 1485 participants for our final meta-analysis. Upregulated expression of miR-200c predicted significantly worse overall survival in patients with cancer (HR 1.51; 95% confidence interval [CI] 1.06-2.16, P = 0.023). Subgroup analysis indicated that high levels of miR-200c was associated with decreased survival of Caucasians and patients with gynecological tumors with pooled HR values of 1.82 (95% CI 1.27-2.26, P = 0.01) and 3.23 (95% CI 1.11-9.38, P = 0.032), respectively. Because of the absence of apparent heterogeneity, the combined HRs were 1.69 (95% CI 1.24-2.30, P = 0.001) for squamous cell carcinoma and 1.91 (95% CI 1.40-2.59, P < 0.001) for samples from peripheral blood. Increased expression of miR-200c significantly associated with shorter progression-free survival of patients with cancer (HR 2.37; 95% CI 1.47-3.81, P < 0.001). Our meta-analysis indicates that the level of miR-200c expression predicted survival of patients with cancer, particularly for Caucasians and patients with gynecological cancer. Increased expression of miR-200c predicted shorter survival of patients with squamous cell carcinomas. Our findings indicate that monitoring the levels of miR-200c in blood may be useful for following tumor progression as well as patients' prognosis.

MicroRNAs in pulmonary arterial hypertension: pathogenesis, diagnosis and treatment

Pulmonary arterial hypertension (PAH) is a severe and increasingly prevalent disease, manifested by the maladaptation of pulmonary vasculature, which consequently leads to right heart failure and possibly even death. The development of PAH is characterized by specific functional as well as structural changes, primarily associated with the aberrant function of the pulmonary artery endothelial cells, smooth muscle cells, and vascular fibroblasts. MicroRNAs constitute a class of small ≈22-nucleotides-long non-coding RNAs that post-transcriptionally regulate gene expression and that may lead to significant cell proteome changes. While the involvement of miRNAs in the development of various diseases--especially cancer--has been reported, numerous miRNAs have also been associated with PAH onset, progression, or treatment responsiveness. This review focuses on the role of microRNAs in the development of PAH as well as on their potential use as biomarkers and therapeutic tools in both experimental PAH models and in humans. Special attention is given to the roles of miR-21, miR-27a, the miR-17-92 cluster, miR-124, miR-138, the miR-143/145 cluster, miR-150, miR-190, miR-204, miR-206, miR-210, miR-328, and the miR-424/503 cluster, specifically with the objective of providing greater insight into the pervasive roles of miRNAs in the pathogenesis of this deadly condition.

Prediction of long-term outcome after acute myocardial infarction using circulating miR-145

BACKGROUND

Recent reports have shown that miR-145 concentration correlates with infarct size. In this paper, we attempt to predict heart failure and cardiovascular death after acute myocardial infarction using circulating miR-145 concentration.

METHODS

We assessed 246 patients with first ST-segment-elevation myocardial infarction who underwent successful percutaneous coronary intervention. We measured circulating miR-145, N-terminal fragment of the precursor B-type natriuretic peptide, myocardial-band creatine kinase, and cardiac troponin-I concentrations on day 5 after primary percutaneous coronary intervention and assessed their correlations with long-term clinical outcome.

RESULTS

During the one-year follow-up period, 72 patients experienced primary composite cardiac events (cardiac death or hospitalization for worsening heart failure). Multivariable Cox proportional hazards analysis indicated that circulating miR-145 (hazard ratio 7.174, 95% confidence interval 4.208-12.229); p < 0.0001) was a significant independent predictor of cardiac events after adjustment for multiple confounders.

CONCLUSION

Circulating miR-145 may be a novel biomarker for predicting long-term outcome after acute myocardial infarction.

Micro-RNAs and next generation sequencing: new perspectives in heart failure

miRNAs are small non-coding RNAs that regulate gene expression. They have significant role in the regulation of cardiovascular function and conditions, such as Heart Failure (HF), as demonstrated by studies of miRNA expression profiling in myocardial tissue. The importance of the use of miRNAs as biomarkers in HF was enhanced when found that they exist extracellularly, with remarkable stability and there are indications that their expression levels reflect the cell response in cardiovascular conditions including Heart Failure. Advances in technology and bioinformatics broaden the field of applications of miRNAs in HF. The introduction of new platforms, such as Next Generation Sequencing, enabled the discovery of novel miRNAs that might be utilized as Heart Failure biomarkers for diagnostic and prognostic purposes and with potential applications in targeted therapeutics.

miR-93-directed downregulation of DAB2 defines a novel oncogenic pathway in lung cancer

The disabled homolog 2 (DAB2) gene was recently identified as a tumor suppressor gene with its expression down-regulated in multiple cancer types. The role of DAB2 in lung tumorigenesis, however, is not fully characterized, and the mechanisms of DAB2 dysregulation in lung cancer are not defined. Here we show that low DAB2 levels in lung tumor specimens are significantly correlated with poor patient survival, and that DAB2 over-expression significantly inhibits cell growth in cultured lung cancer cells, indicating its potent tumor suppressor function. We next identify that microRNA miR-93 functions as a potent repressor of DAB2 expression by directly targeting the 3′UTR of the DAB2 mRNA. Using in vitro and in vivo approaches, we demonstrate that miR-93 over-expression plays an important role in promoting lung cancer cell growth, and that its oncogenic function is primarily mediated by down-regulating DAB2 expression. Our clinical investigations further indicate that high tumor levels of miR-93 are correlated with poor survival of lung cancer patients. The correlations of both low DAB2 and high miR-93 expression with poor patient survival strongly support the critical role of the miR-93/DAB2 pathway in determining lung cancer progression.

HEF1 promotes epithelial mesenchymal transition and bone invasion in prostate cancer under the regulation of microRNA-145

The principal problem arising from prostate cancer (PCa) is its propensity to metastasize to bones, and it's crucial to understand the mechanism of tumor progression to metastasis in order to develop therapies that may reduce the morbidity and mortality of PCa patients. Although we had identified that microRNA(miR)-145 could repress bone metastasis of PCa via regulating epithelial-mesenchymal transition (EMT) in previous study, it is still unknown how miR-145 regulated EMT. In the present study, we constructed a luciferase reporter system and identified HEF1 as a direct target of miR-145. More importantly, HEF1 was shown to promote migration, invasion and EMT of PC-3 cells, a human PCa cell line originated from a bone metastatic PCa specimen. And HEF1 was also shown to partially mediate miR-145 suppression of EMT and invasion. Furthermore, inhibition of HEF1 repressed bone invasion of PC-3 cells in vivo. Expression of HEF1 was negatively correlated with miR-145 in primary PCa and bone metastatic specimens, but HEF1 was higher in samples which were more likely to commit to bone metastasis or those with higher free prostate-specific antigen (fPSA) levels and Gleason scores. Taken together, these findings indicate that HEF1 promotes EMT and bone invasion in prostate cancer by directly targeted by miR-145, and miR-145 suppresses EMT and invasion, at least in part, through repressing HEF1.

Comparative Analyses of MicroRNA Microarrays during Cardiogenesis: Functional Perspectives

Cardiovascular development is a complex process in which several transcriptional pathways are operative, providing instructions to the developing cardiomyocytes, while coping with contraction and morphogenetic movements to shape the mature heart. The discovery of microRNAs has added a new layer of complexity to the molecular mechanisms governing the formation of the heart. Discrete genetic ablation of the microRNAs processing enzymes, such as Dicer and Drosha, has highlighted the functional roles of microRNAs during heart development. Importantly, selective deletion of a single microRNA, miR-1-2, results in an embryonic lethal phenotype in which both morphogenetic, as well as impaired conduction, phenotypes can be observed. In an effort to grasp the variability of microRNA expression during cardiac morphogenesis, we recently reported the dynamic expression profile during ventricular development, highlighting the importance of miR-27 on the regulation of a key cardiac transcription factor, Mef2c. In this review, we compare the microRNA expression profile in distinct models of cardiogenesis, such as ventricular chamber development, induced pluripotent stem cell (iPS)-derived cardiomyocytes and the aging heart. Importantly, out of 486 microRNAs assessed in the developing heart, 11% (55) displayed increased expression, many of which are also differentially expressed in distinct cardiogenetic experimental models, including iPS-derived cardiomyocytes. A review on the functional analyses of these differentially expressed microRNAs will be provided in the context of cardiac development, highlighting the resolution and power of microarrays analyses on the quest to decipher the most relevant microRNAs in the developing, aging and diseased heart.

A deep sequencing approach to uncover the miRNOME in the human heart

MicroRNAs (miRNAs) are a class of non-coding RNAs of ∼22 nucleotides in length, and constitute a novel class of gene regulators by imperfect base-pairing to the 3′UTR of protein encoding messenger RNAs. Growing evidence indicates that miRNAs are implicated in several pathological processes in myocardial disease. The past years, we have witnessed several profiling attempts using high-density oligonucleotide array-based approaches to identify the complete miRNA content (miRNOME) in the healthy and diseased mammalian heart. These efforts have demonstrated that the failing heart displays differential expression of several dozens of miRNAs. While the total number of experimentally validated human miRNAs is roughly two thousand, the number of expressed miRNAs in the human myocardium remains elusive. Our objective was to perform an unbiased assay to identify the miRNOME of the human heart, both under physiological and pathophysiological conditions. We used deep sequencing and bioinformatics to annotate and quantify microRNA expression in healthy and diseased human heart (heart failure secondary to hypertrophic or dilated cardiomyopathy). Our results indicate that the human heart expresses >800 miRNAs, the majority of which not being annotated nor described so far and some of which being unique to primate species. Furthermore, >250 miRNAs show differential and etiology-dependent expression in human dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM). The human cardiac miRNOME still possesses a large number of miRNAs that remain virtually unexplored. The current study provides a starting point for a more comprehensive understanding of the role of miRNAs in regulating human heart disease.

Role of the Wnt-Frizzled system in cardiac pathophysiology: a rapidly developing, poorly understood area with enormous potential

Abstract  The Wnt-Frizzled (Fzd) G-protein-coupled receptor system, involving 19 distinct Wnt ligands and 10 Fzd receptors, plays key roles in the development and functioning of many organ systems. There is increasing evidence that Wnt-Fzd signalling is important in regulating cardiac function. Wnt-Fzd signalling primarily involves a canonical pathway, with dishevelled-1-dependent nuclear translocation of β-catenin that derepresses Wnt-sensitive gene transcription, but can also include non-canonical pathways via phospholipase-C/Ca(2+) mobilization and dishevelled-protein activation of small GTPases. Wnt-Fzd effects vary with specific ligand/receptor interactions and associated downstream pathways. This paper reviews the biochemistry and physiology of the Wnt-Fzd complex, and presents current knowledge of Wnt signalling in cardiac remodelling processes such as hypertrophy and fibrosis, as well as disease states such as myocardial infarction (MI), heart failure and arrhythmias. Wnt signalling is activated during hypertrophy; inhibiting Wnt signalling by activating glycogen synthase kinase attenuates the hypertrophic response. Wnt signalling has complex and time-dependent actions post-MI, so that either beneficial or harmful effects might result from Wnt-directed interventions. Stem cell biology, a promising area for therapeutic intervention, is highly regulated by Wnt signalling. The Wnt system regulates fibroblast function, and is prominently altered in arrhythmogenic ventricular cardiomyopathy, a familial disease involving excess deposition of fibroadipose tissue. Wnt signalling controls connexin43 expression, thereby contributing to the regulation of cardiac electrical stability and arrhythmia generation. Although much has been learned about Wnt-Fzd signalling in hypertrophy and infarction, its role is poorly understood for a broad range of other heart disorders. Much more needs to be learned for its contributions to be fully appreciated, and to permit more effective exploitation of its enormous potential in therapeutic development.

SDF-1 in myocardial repair

Stem cell therapy for the prevention and treatment of cardiac dysfunction holds significant promise for patients with ischemic heart disease. Excitingly early clinical studies have demonstrated safety and some clinical feasibility, while at the same time studies in the laboratory have investigated mechanisms of action and strategies to optimize the effects of regenerative cardiac therapies. One of the key pathways that has been demonstrated critical in stem cell-based cardiac repair is (stromal cell-derived factor-1) SDF-1:CXCR4. SDF-1:CXCR4 has been shown to affect stem cell homing, cardiac myocyte survival and ventricular remodeling in animal studies of acute myocardial infarction and chronic heart failure. Recently released clinical data suggest that SDF-1 alone is sufficient to induce cardiac repair. Most importantly, studies like those on the SDF-1:CXCR4 axis have suggested mechanisms critical for cardiac regenerative therapies that if clinical investigators continue to ignore will result in poorly designed studies that will continue to yield negative results.

A role for miR-145 in pulmonary arterial hypertension: evidence from mouse models and patient samples

RATIONALE

Despite improved understanding of the underlying genetics, pulmonary arterial hypertension (PAH) remains a severe disease. Extensive remodeling of small pulmonary arteries, including proliferation of pulmonary artery smooth muscle cells (PASMCs), characterizes PAH. MicroRNAs (miRNAs) are noncoding RNAs that have been shown to play a role in vascular remodeling.

OBJECTIVE

We assessed the role of miR-145 in PAH.

METHODS AND RESULTS

We localized miR-145 in mouse lung to smooth muscle. Using quantitative PCR, we demonstrated increased expression of miR-145 in wild-type mice exposed to hypoxia. PAH was evaluated in miR-145 knockout and mice treated with anti-miRs via measurement of systolic right ventricular pressure, right ventricular hypertrophy, and percentage of remodeled pulmonary arteries. miR-145 deficiency and anti-miR-mediated reduction resulted in significant protection from the development of PAH. In contrast, miR-143 anti-miR had no effect. Furthermore, we observed upregulation of miR-145 in lung tissue of patients with idiopathic and heritable PAH compared with unaffected control subjects and demonstrated expression of miR-145 in SMC of remodeled vessels from such patients. Finally, we show elevated levels of miR-145 expression in primary PASMCs cultured from patients with BMPR2 mutations and also in the lungs of BMPR2-deficient mice.

CONCLUSIONS

miR-145 is dysregulated in mouse models of PAH. Downregulation of miR-145 protects against the development of PAH. In patient samples of heritable PAH and idiopathic PAH, miR-145 is expressed in remodeled vessels and mutations in BMPR2 lead to upregulation of miR-145 in mice and PAH patients. Manipulation of miR-145 may represent a novel strategy in PAH treatment.

The epicardium as a candidate for heart regeneration

The mammalian heart loses its regenerative capacity during early postnatal stages; consequently, individuals surviving myocardial infarction are at risk of heart failure due to excessive fibrosis and maladaptive remodeling. There is an urgent need, therefore, to develop novel therapies for myocardial and coronary vascular regeneration. The epicardium-derived cells present a tractable resident progenitor source with the potential to stimulate neovasculogenesis and contribute de novo cardiomyocytes. The ability to revive ordinarily dormant epicardium-derived cells lies in the identification of key stimulatory factors, such as Tβ4, and elucidation of the molecular cues used in the embryo to orchestrate cardiovascular development. myocardial infarction injury signaling reactivates the adult epicardium; understanding the timing and magnitude of these signals will enlighten strategies for myocardial repair.