Jingai Zhu

Pre-Pregnancy Body Mass Index in Relation to Infant Birth Weight and Offspring Overweight/Obesity: A Systematic Review and Meta-Analysis

Background Overweight/obesity in women of childbearing age is a serious public-health problem. In China, the incidence of maternal overweight/obesity has been increasing. However, there is not a meta-analysis to determine if pre-pregnancy body mass index (BMI) is related to infant birth weight (BW) and offspring overweight/obesity. Methods Three electronic bibliographic databases (MEDLINE, EMBASE and CINAHL) were searched systematically from January 1970 to November 2012. The dichotomous data on pre-pregnancy overweight/obesity and BW or offspring overweight/obesity were extracted. Summary statistics (odds ratios, ORs) were used by Review Manager, version 5.1.7. Results After screening 665 citations from three electronic databases, we included 45 studies (most of high or medium quality). Compared with normal-weight mothers, pre-pregnancy underweight increased the risk of small for gestational age (SGA) (odds ratios [OR], 1.81; 95% confidence interval [CI], 1.76–1.87); low BW (OR, 1.47; 95% CI, 1.27–1.71). Pre-pregnancy overweight/obesity increased the risk of being large for gestational age (LGA) (OR, 1.53; 95% CI, 1.44–1.63; and OR, 2.08; 95% CI; 1.95–2.23), high BW (OR, 1.53; 95% CI, 1.44–1.63; and OR, 2.00; 95% CI; 1.84–2.18), macrosomia (OR, 1.67; 95% CI, 1.42–1.97; and OR, 3.23; 95% CI, 2.39–4.37), and subsequent offspring overweight/obesity (OR, 1.95; 95% CI, 1.77–2.13; and OR, 3.06; 95% CI, 2.68–3.49), respectively. Sensitivity analyses revealed that sample size, study method, quality grade of study, source of pre-pregnancy BMI or BW had a strong impact on the association between pre-pregnancy obesity and LGA. No significant evidence of publication bias was observed. Conclusions Pre-pregnancy underweight increases the risk of SGA and LBW; pre-pregnancy overweight/obesity increases the risk of LGA, HBW, macrosomia, and subsequent offspring overweight/obesity. A potential effect modification by maternal age, ethnicity, gestational weight gain, as well as the role of gestational diseases should be addressed in future studies.

Mitochondrial dysfunction is induced by high levels of glucose and free fatty acids in 3T3-L1 adipocytes.

Hyperglycemia and high free fatty acids (FFAs) are two well-known characteristics of type 2 diabetes, and are also implicated in the etiology of insulin resistance. However, their roles in mitochondrial dysfunction of white adipocytes are not well-studied. In this study, we investigated the effects of high glucose (25 mM), high free fatty acids (FFAs, 1mM), or a combination of both high glucose+high FFAs on mitochondrial function in differentiated 3T3-L1 adipocytes after 48 h of treatment. We found that high glucose, high FFAs, or high glucose+high FFAs reduced insulin-stimulated glucose uptake in differentiated 3T3-L1 adipocytes. In addition, the mitochondria became smaller and more compact. Levels of the mitofusion protein mfn1 decreased and levels of the mitofission protein Drp1 increased as compared to controls. NRF1 was downregulated, and PGC-1 beta levels were diminished in the high glucose and high glucose+high FFAs conditions. Levels of PGC-1 alpha and mtTFA mRNA were greatly downregulated. No difference was found in the mitochondrial DNA (mtDNA) and intracellular ATP levels of treated cells compared to control cells. Cells treated with high glucose or high FFAs accumulated significant amounts of reactive oxygen species (ROS) and displayed a loss of the mitochondrial membrane potential. High glucose and high glucose+high FFAs led to similar decreases in intramitochondrial calcium concentration, although high FFAs had no effect. Therefore, high glucose and high FFAs can regulate insulin sensitivity, and mitochondrial dysfunction may occur in this process.

TNF-α induces mitochondrial dysfunction in 3T3-L1 adipocytes

TNF-alpha was the first proinflammatory cytokine identified linking obesity, insulin resistance and chronic inflammation. However, the mechanism of TNF-alpha in the etiology of insulin resistance is still far from clear. Because the mitochondria play an important role in energy metabolism, we investigated whether mitochondrial dysfunction is involved in pathogenesis of TNF-alpha-mediated insulin resistance. First, a fully differentiated insulin-resistant 3T3-L1 adipocyte model was established by incubating with 4 ng/ml TNF-alpha for 4 d, and then the mitochondrial morphology and functions were observed. TNF-alpha treatment induced pronounced morphological changes in the mitochondria, which became smaller and condensed, and some appeared hollow and absent of cristae. Mitochondrial dynamics changes were observed as increased mitofusion protein mfn1 and mitofission protein Drp1 levels compared with controls. No obvious effects on mitochondrial biogenesis were found. PGC-1alpha levels decreased, but no significant changes were found in mtTFA mRNA expression, NRF1mRNA expression and mitochondrial DNA (mtDNA). TNFalpha treatment also led to decreased mitochondrial membrane potential and reduced production of intracellular ATP, as well as accumulation of significant amounts of reactive oxygen species (ROS). Further research is required to determine if mitochondrial dysfunction is involved in the inflammatory mechanism of insulin resistance and may be a potential target for the treatment of insulin resistance.

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.

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.

Integrated Analysis of Dysregulated lncRNA Expression in Fetal Cardiac Tissues with Ventricular Septal Defect

Ventricular septal defects (VSD) are the most common form of congenital heart disease, which is the leading non-infectious cause of death in children; nevertheless, the exact cause of VSD is not yet fully understood. Long non-coding RNAs (lncRNAs) have been shown to play key roles in various biological processes, such as imprinting control, circuitry controlling pluripotency and differentiation, immune responses and chromosome dynamics. Notably, a growing number of lncRNAs have been implicated in disease etiology, although an association with VSD has not been reported. In the present study, we conducted an integrated analysis of dysregulated lncRNAs, focusing specifically on the identification and characterization of lncRNAs potentially involving in initiation of VSD. Comparison of the transcriptome profiles of cardiac tissues from VSD-affected and normal hearts was performed using a second-generation lncRNA microarray, which covers the vast majority of expressed RefSeq transcripts (29,241 lncRNAs and 30,215 coding transcripts). In total, 880 lncRNAs were upregulated and 628 were downregulated in VSD. Furthermore, our established filtering pipeline indicated an association of two lncRNAs, ENST00000513542 and RP11-473L15.2, with VSD. This dysregulation of the lncRNA profile provides a novel insight into the etiology of VSD and furthermore, illustrates the intricate relationship between coding and ncRNA transcripts in cardiac development. These data may offer a background/reference resource for future functional studies of lncRNAs related to VSD.

Differential DNA Methylation Status Between Human Preadipocytes and Mature Adipocytes

Obesity is a multifactorial disease resulting from interactions between susceptibility genes, psychosocial, and environmental factors. However, it is becoming evident that interindividual differences in obesity susceptibility depend also on epigenetic factors, although the mechanisms have not been fully elucidated. We have undertaken a genome-wide analysis of DNA methylation of human preadipocytes and mature adipocytes to examine the differences in methylation between them. We found hypomethylation occurring in 2,701 genes and hypermethylation in 1,070 genes after differentiation. Meanwhile, Gene Ontology analysis and Ingenuity Pathway Analysis showed many significant gene functions and pathways with altered methylation status after adipocyte differentiation. In addition, Signal-Net analysis showed that tumor necrosis factor-α, mitogen-activated protein kinase, and interleukin-8 were important to the formation of this network. Our results suggest that DNA methylation mechanisms may be involved in regulating the differentiation process of human preadipocytes.

Overexpression of NYGGF4 (PID1) induces mitochondrial impairment in 3T3-L1 adipocytes

NYGGF4 is a recently discovered gene that is involved in obesity-associated insulin resistance. The exact mechanism by which NYGGF4 induces insulin resistance has not yet been fully elucidated. In this study, we demonstrated that the overexpression of NYGGF4 in 3T3-L1 adipocytes decreased mitochondrial mass, mitochondrial DNA, and intracellular ATP synthesis. In addition, NYGGF4 overexpression also led to an imbalance of the mitochondrial dynamics and excess intracellular ROS production. Collectively, our results indicated that the overexpression of NYGGF4 caused mitochondrial dysfunction in adipocytes, which might be responsible for the development of NYGGF4-induced insulin resistance.

MicroRNA-375 overexpression influences P19 cell proliferation, apoptosis and differentiation through the Notch signaling pathway

Our previous study reported that microRNA-375 (miR-375) is significantly upregulated in ventricular septal myocardial tissues from 22-week-old fetuses with ventricular septal defect as compared with normal controls. In the present study, the specific effects of miR-375 on P19 cell differentiation into cardiomyocyte-like cells were investigated. Stable P19 cell lines overexpressing miR-375 or containing empty vector were established, which could be efficiently induced into cardiomyocyte-like cells in the presence of dimethyl sulfoxide in vitro. miR-375 overexpression was verified using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was determined according to total cell counts; cell cycle distribution and apoptosis levels were examined using flow cytometry. Apoptosis-related morphological changes were observed using Hoechst staining and fluorescence microscopy. During P19 cell differentiation, the cardiomyogenesis-related mRNAs (cardiac troponin T, GATA binding protein 4, myocyte-specific enhancer factor 2C) and mRNAs involved in the Notch signaling pathway (Notch2, Delta-like 1 and hes family bHLH transcription factor 1) were detected at days 0, 4, 6 and 10. Their differential expression was examined using RT-qPCR; the apoptosis-related genes BAX and Bcl-2 were also detected using this method. The corresponding proteins were evaluated by western blotting. Compared with the control group, miR-375 overexpression inhibited proliferation but promoted apoptosis in P19 cells, and the associated mRNAs and proteins were decreased during differentiation. miR-375 has an important role in cardiomyocyte differentiation, and can disrupt this process via the Notch signaling pathway. The present findings contribute to the understanding of the mechanisms of congenital heart disease and facilitate the development of new gene therapies.

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.