Xiaoshan Hu

Identification of maternal serum microRNAs as novel non-invasive biomarkers for prenatal detection of fetal congenital heart defects.

BACKGROUND Congenital heart defects (CHD) are the most common form of malformation during embryonic development. Circulating miRNAs have recently been shown to serve as diagnostic/prognostic biomarkers in patients with cancers. Our current study focused on the altered expression of maternal serum miRNAs and their correlation with fetal CHD. METHODOLOGY/PRINCIPLE FINDINGS We systematically performed SOLiD sequencing followed by individual quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assays to identify and validate the expression of maternal serum miRNAs at 18-22 weeks of gestation. Four miRNAs (miR-19b, miR-22, miR-29c and miR-375) were found to be significantly up-regulated in pregnant women with fetal CHD, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.79, 0.671, 0.767 and 0.693, respectively. Furthermore, the combination of the four miRNAs using multiple logistic regression analysis showed a larger AUC (0.813) that was more efficient for the early detection of fetal CHD. CONCLUSIONS/SIGNIFICANCE We identified and validated a class of four maternal serum miRNAs which could act as novel non-invasive biomarkers for the prenatal detection of fetal CHD.

Effects of miR - 19b Overexpression on Proliferation, Differentiation, Apoptosis and Wnt/β-Catenin Signaling Pathway in P19 Cell Model of Cardiac Differentiation In Vitro

MicroRNA (miR)-19b is part of the miR-17–92 cluster associated with cardiac development. Here, we investigated the effects of overexpressing miR-19b on proliferation, differentiation, apoptosis, and regulation of the Wnt/β-catenin signaling pathway in the multipotent murine P19 cell line that can be induced to undergo cardiogenesis. P19 cells were transfected with the miR-19b plasmid or empty vector, and miR-19b overexpression was verified by Quantitative Real-Time PCR (qPCR). The miR-19b or vector control stable cell lines were selected using Blasticidin S HCl, and their proliferation, cell cycle, and apoptosis levels were analyzed using the Cell Counting Kit-8 and flow cytometry. P19 cell differentiation markers, apoptosis-related genes (bax, bcl-2), and Wnt/β-catenin signaling pathway-related genes were detected by qPCR, the corresponding proteins by Western blot. Expression of the Wnt pathway and differentiation marker proteins was also verified by immunofluorescence. Morphological changes associated with apoptosis were observed by electron microscopy and Hoechst staining. On the basis of these results, we demonstrated that miR-19b overexpression promoted proliferation and differentiation but inhibited apoptosis in P19 cells; Wnt and β-catenin expressions were decreased, while that of GSK3β was increased with miR-19b overexpression. Overexpression of miR-19b inhibited activation of the Wnt/β-catenin signaling pathway in P19 cells, which may regulate cardiomyocyte differentiation. Our findings may bring new insights into the mechanisms underlying cardiac diseases and suggest that miR-19b is a potential new therapeutic target for cardiovascular diseases.

microRNA expression profiling of the developing mouse heart

microRNAs (miRNAs) play an important role in regulating normal organ physiology and development. Many miRNAs show spatially and temporally restricted expression patterns during embryogenesis and organogenesis. This study aimed to characterize the miRNA profile of the fetal mouse heart at 4 key time-points [embryonic day (E)12.5, E14.5, E16.5 and E18.5] in its development, by performing a sequencing by oligonucleotide ligation and detection (SOLiD) miRNA screen. The 4 time-points were designated as groups M1 (E18.5), M2 (E16.5), M3 (E14.5) and M4 (E12.5). miRNAs found to have consistent fold-changes of >2.0) between the 4 time-points were selected for further analysis. Ten miRNAs (mmu-miR-23b, mmu-miR-24, mmu-miR-23a, mmu-miR-375, mmu-miR-29a, mmu-miR-93, mmu-miR-21, mmu-miR-25, mmu-let-7b and mmu-miR-27b) that were the most highly expressed in the 4 groups, including the percentage >1% of total read counts, were identified. No miRNA was consistently downregulated or upregulated. There were 16 differentially expressed miRNAs between the later development group (M1+M2) and the early development group (M3+M4), which were validated by quantitative real-time PCR. Several members of the let-7 miRNA cluster (mmu-let-7a/7d/7e/7f) were upregulated in the later development group compared with the early development group. A network analysis of the predicted targets of mmu-let-7a/7d/7e/7f identified 5 target genes (FOXP1, TBX5, HAND1, AKT2 and PPARGC1A), known to be involved in cardiac development. Therefore, this study identified several miRNAs that are abundantly expressed in the developing heart, several of which are differentially expressed in the 4 time-points studied. Findings of this analysis may thus clarify the mechanisms of normal heart development and provide a physiological basis for future studies on congenital heart disease.

Overexpression of miR-19b impairs cardiac development in zebrafish by targeting ctnnb1.

Background: MicroRNAs are broadly accepted as crucial regulators of cardiovascular development, and dysregulation of their expression has been linked to cardiac disease. MicroRNA cluster miR-17-92 has been implicated in cardiac development and function, yet its defined mechanisms of action in this context are uncertain. Here, we focused on miR-19b, a key component of the miR-17-92 cluster proven to induce cardiomyocyte proliferation in vitro. We aimed to identify the biological significance of miR-19b in cardiac development and its underlying molecular mechanism of action in vivo. Methods: We micro-injected zebrafish embryos with different concentrations (0, 2, 4 and 8 μm) of miR-19b mimics or a negative control, and assessed the embryo malformation rate, mortality rate, hatching rate and heart abnormalities at 72 hours post-fertilization (72 hpf). Results: We found that overexpression of miR-19b impacted left-right symmetry and cardiac development of zebrafish embryos, characterized by pericardial edema, slower heart rate and cardiac looping defects in a dose-dependent manner. Moreover, several important signaling molecules in the Wnt signaling pathway were abnormally expressed, suggesting that overexpression of miR-19b induces the inhibition of the Wnt signaling pathway by directly targeting ctnnb1. Interestingly, the deformed cardiac phenotype was partially rescued by treatment with the GSK3β inhibitor lithium chloride. Conclusion: Our findings suggest that miR-19b regulates laterality development and heart looping in zebrafish embryos by targeting ctnnb1.

Compared analysis of LncRNA expression profiling in pdk1 gene knockout mice at two time points.

Background/Aims: Previous studies have indicated that long non-coding RNAs (lncRNA) are related to the occurrence and development of many human diseases, such as cancer and the HELLP and the brachydactyly syndromes. However, studies of LncRNA in heart failure have not yet been reported. Here, we investigated cardiac lncRNA expression profiles in the myocardial-specific knockout pdk1 gene (KO) mouse model of heart failure. Methods: Cardiac samples were obtained from PDK1 KO and WT mice on postnatal (P) day 8 (P8) and day 40 (P40), and lncRNA expression profiles were analyzed by sequencing and screening using the Arraystar mouse lncRNA microarray. Quantitative real-time PCR analysis of these lncRNAs confirmed the identity of some genes. Results: Comparisons of the KO and control groups showed fold changes of >1.5 in the expression levels of 2,024 lncRNAs at P8, while fold changes of >2 in the expression levels of 4,095 lncRNAs were detected at P40. Nineteen lncRNAs were validated by RT-PCR. Bioinformatic and pathway analyses indicated that mkk7, a sense overlap lncRNA, may be involved in the pathological processes of heart failure through the MAPK signaling pathway. Conclusion: These data reveal differentially expressed lncRNA in mice with a myocardial-specific deletion of the pdk1 gene, which may provide new insights into the mechanism of heart failure in PDK1 knockout mice.

miR-30c regulates proliferation, apoptosis and differentiation via the Shh signaling pathway in P19 cells

MicroRNAs (miRNAs) are small, non-coding single-stranded RNAs that suppress protein expression by binding to the 3′ untranslated regions of their target genes. Many studies have shown that miRNAs have important roles in congenital heart diseases (CHDs) by regulating gene expression and signaling pathways. We previously found that miR-30c was highly expressed in the heart tissues of aborted embryos with ventricular septal defects. Therefore, this study aimed to explore the effects of miR-30c in CHDs. miR-30c was overexpressed or knocked down in P19 cells, a myocardial cell model that is widely used to study cardiogenesis. We found that miR-30c overexpression not only increased cell proliferation by promoting cell entry into S phase but also suppressed cell apoptosis. In addition, we found that miR-30c inhibited dimethyl sulfoxide-induced differentiation of P19 cells. miR-30c knockdown, in contrast, inhibited cell proliferation and increased apoptosis and differentiation. The Sonic hedgehog (Shh) signaling pathway is essential for normal embryonic development. Western blotting and luciferase assays revealed that Gli2, a transcriptional factor that has essential roles in the Shh signaling pathway, was a potential target gene of miR-30c. Ptch1, another important player in the Shh signaling pathway and a transcriptional target of Gli2, was downregulated by miR-30c overexpression and upregulated by miR-30c knockdown. Collectively, our study revealed that miR-30c suppressed P19 cell differentiation by inhibiting the Shh signaling pathway and altered the balance between cell proliferation and apoptosis, which may result in embryonic cardiac malfunctions.

Circulating LncRNAs as Novel, Non-Invasive Biomarkers for Prenatal Detection of Fetal Congenital Heart Defects

Objectives: To explore the clinical value of circulating long non-coding RNAs (lncRNAs) as biomarkers to predict fetal congenital heart defects (CHD) in pregnant women. Methods: Differential expression of lncRNAs isolated from the plasma of pregnant women with typical fetal CHD or healthy controls was analyzed by microarray. Gene ontology (GO), pathway and network analysis were performed to study the function of the lncRNAs. Differentially expressed lncRNAs were validated in plasma samples from 62 pregnant women with typical CHD and 62 matched controls by RT-PCR. The sensitivity and specificity of each lncRNA in the diagnosis of fetal CHD was determined by ROC curve analysis. Results: Microarray analysis identified 3694 up-regulated and 3919 down-regulated (fold change ≥2.0) lncRNAs. The top ten significantly differentially expressed, CHD-associated lncRNAs were validated by RT-PCR. Five significantly up-regulated or down-regulated lncRNAs were identified: ENST00000436681, ENST00000422826, AA584040, AA709223 and BX478947 with the AUC of ROC curves calculated as 0.892, 0.817, 0.755, 0.882 and 0.886, respectively. Conclusions: Specific lncRNAs aberrantly expressed in the plasma of pregnant women with typical fetal CHD may play a key role in the development of CHD and may be used as novel biomarkers for prenatal diagnosis of fetal CHD.

Differential expression profile of long non-coding RNAs during differentiation of cardiomyocytes.

Many long non-coding RNAs (lncRNAs) are species specific and seem to be less conserved than protein-coding genes. Some of them are involved in the development of the lateral mesoderm in the heart and in the differentiation of cardiomyocytes. The purpose of the study was to investigate the expression profiles of lncRNAs during the differentiation of P19 cells into cardiomyocytes, with a view to studying the biological function of lncRNAs and their involvement in the mechanism of heart development. First, we observed the morphology of P19 cells during differentiation using an inverted microscope. Then, cardiac troponin T (cTnT) expression was detected to validate that the cells had successfully differentiated into cardiac myocytes by real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR) and western blotting. Lastly, the expression profile of lncRNA genes was obtained using an lncRNA microarray and real-time RT-PCR analyses. The microarray results showed that 40 lncRNAs were differentially expressed, of which 28 were upregulated and 12 were downregulated in differentiated cardiomyocytes. The differentially expressed lncRNAs were further validated. Our results illustrated a critical role of lncRNAs during the differentiation of P19 cells into cardiac myocytes, which will provide the foundation for further study of the biological functions of lncRNAs and the mechanism of heart development.

Effect of miR-20b on apoptosis, differentiation, the BMP signaling pathway and mitochondrial function in the P19 cell model of cardiac differentiation in vitro

Objective To explore the effect of miR-20b on apoptosis, differentiation, the BMP signaling pathway and mitochondrial function in the P19 cell model of cardiac differentiation in vitro. Methods A miR-20b over-expression vector, a miR-20b silencing vector and their corresponding empty vectors were constructed and transfected into P19 cells, separately. Stably miR-20b overexpressing and silenced P19 cell lines were successfully selected by blasticidin and puromycin, separately. The cells were induced to undergo apoptosis in FBS-free-α-MEM. The induced cells were examined by flow cytometry and measurement of their caspase-3 activities. Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) was used to evaluate the relative expression of marker genes of cardiomyocytes during differentiation, such as cTnT, GATA4 and ANP. QRT-PCR was also used to detect the mitochondrial DNA (mtDNA) copy number. We investigated the cellular ATP production using a luciferase-based luminescence assay. The reactive oxygen species (ROS) was determined by DCFDA (2’, 7’-Dichlorofluorescein diacetate) and the mitochondrial membrane potential (MMP) was elucidated by a JC-1 fluorescent probe, both using fluorescence microscopy and flow cytometer. The expression of BMP signaling pathway-related proteins were analyzed by Western blotting. Results Stably miR-20b overexpressing and silenced P19 cell lines were successfully obtained. MiR-20b overexpression increased apoptosis and promoted differentiation in P19 cells by promoting the activation of the BMP signaling pathway. In addition, miR-20b overexpression induced mitochondrial impairment in P19 cells during differentiation, which was characterized by lower MMP, raised ATP synthesis and increased ROS levels. The effects of miR-20b silencing were the exact opposite to those of overexpression. Conclusion Collectively, these results suggested that miR-20b was very important in apoptosis, differentiation and mitochondrial function of P19 cells. MiR-20b may represent a new therapeutic target for congenital heart diseases and provide new insights into the mechanisms of cardiac diseases.

ShRNA-mediated gene silencing of AHR promotes the differentiation of P19 mouse embryonic carcinoma cells into cardiomyocytes

The aryl hydrocarbon receptor (AHR) is a basic helix-loop-helix (bHLH) transcription factor that is activated by environmental contaminants including polychlorinated biphenyls (PCBs). The AHR affects a variety of processes that are involved in cell growth and differentiation. In this study, we constructed a P19 embryonic carcinoma cell line with AHR gene silencing using the vector-based approach of short hairpin (sh)RNA interference that allows cells to differentiate into cardiac myocytes when treated with dimethyl sulfoxide (DMSO). The expression levels of the cardiac development-specific GATA4 and Nkx2.5 genes were measured using real-time quantitative polymerase chain reaction (qPCR). Our data showed that the expression levels of the GATA4 and Nkx2.5 genes were increased in the AHR-silenced P19 cells compared with the control groups. Four critical genes (ARNT, CYP1A1, GSK3β and β-catenin) expressed in the AHR and in the Wnt signaling pathway were also measured by qPCR. We found that the expression levels of ARNT, CYP1A1 and β-catenin were suppressed, whereas GSK3β expression was elevated in the AHR-silenced P19 cells. Therefore, it is possible that the silencing of AHR promotes the differentiation of P19 cells through the AHR and Wnt signal transduction pathway.