[Influence of twin pregnancy by assisted reproductive technology on neonatal outcomes].

OBJECTIVE: To study the influence of twin pregnancy by assisted reproductive technology (ART) versus twin pregnancy by spontaneous conception (SC) on neonatal outcomes. METHODS: A retrospective analysis was performed for the clinical data of 3 356 live twins with a gestational age of ≥24 weeks who were born in Nanjing Maternal and Child Health Hospital from 2017 to 2019, with 2 006 twins (1 003 pairs) in the ART group and 1 350 (675 pairs) in the SC group. The two groups were compared in terms of the mother's general information and pregnancy comorbidities and the general information, diseases, and outcomes of neonates. RESULTS: Compared with the SC group, the ART group had a significantly higher maternal age (P < 0.05) and significantly higher rates of primiparity, cesarean section, and cervical cerclage (P < 0.05). Compared with the SC group, the ART group had significantly higher incidence rates of maternal pregnancy comorbidities including hypertension, gestational diabetes, and postpartum hemorrhage (P < 0.05). Compared with the SC group, the ART group had a significantly lower mean gestational age of neonates (P < 0.05) and a significantly higher proportion of very-low-birth-weight infants (6.8% vs 5.8%, P < 0.05), while ART did not increase the risks of preterm birth and low Apgar score. There were no significant differences between the two groups in the mortality rate of neonates and the incidence rates of neonatal diseases including respiratory distress syndrome, stage II/III necrotizing enterocolitis, bronchopulmonary dysplasia, and grade III-IV intracranial hemorrhage (P > 0.05). CONCLUSIONS: Compared with twin pregnancy by SC, twin pregnancy by ART does not increase the neonatal mortality rate and risk of adverse outcomes.

Profiles analysis reveals circular RNAs involving zebrafish physiological development.

Recent studies have found that known functions of circular RNAs (circRNAs) include sequestration of microRNAs (miRNAs) or proteins, modulation of transcription and interference with splicing, and even translation to produce polypeptides. The zebrafish model is also demonstrably similar to humans in many studies. To explore the changes in circRNAs during embryonic development and to further research the mechanism of action of circRNAs in development-related diseases, Zebrafish embryos at the blastula period, gastrula period, segmentation period, throat stage, and incubation period were collected. Illumina deep-sequencing technology and CircRNA Identifier (CIRI) algorithm were used to detect circRNAs. In total, we identified 1,028 circRNAs (junction reads ≥5 and p < 0.05). Considering that the function of circRNAs is related to host genes, a bioinformatics analysis revealed these differentially expressed host genes are involved in NOTCH signaling pathways, cardiovascular system development, retinal ganglion cell axon guidance, and so on. Moreover, circRNAs can participate in biological regulation through the function of miRNA sponges. TargetScan and miRanda were used to predict 73 miRNAs binding to circRNAs such as miR-19b, miR-124, and so on. Some miRNAs play important roles in embryogenesis. The peak expression of circRNAs is distributed at different time points, suggesting that it may be involved in embryogenesis at different stages. Our study provides a foundation for understanding the dynamic regulation of circRNA transcriptomes during embryogenesis and identifies novel key circRNAs that might control embryonic development in a zebrafish model.

PID1 in adipocytes modulates whole-body glucose homeostasis.

The novel obesity-associated protein Phosphotyrosine Interaction Domain containing 1 (PID1) inhibits insulin-PI3K/Akt signaling pathway and insulin-stimulated glucose uptake in vitro. In this study, we generated fat tissue-specific aP2-PID1 transgenic (aP2-PID1tg) mice and PID1 knockout (PID1-/-) mice to explore how PID1 affects glucose metabolism in vivo. We observed insulin resistance and impaired insulin-PI3K/Akt signaling in aP2-PID1tg mice. Consistent with these data, the PID1-/- mice displayed improved glucose tolerance and insulin sensitivity under chow diet, with increased Akt phosphorylation in white adipose tissue (WAT). We further demonstrated that PID1 could interact with low density lipoprotein receptor-related protein 1 (LRP1) but not the insulin receptor (IR) in adipocytes, and its overexpression could lead to decreased GLUT4 level. Our results thus indentify PID1 as a critical regulator of glucose metabolism in adipocytes.

Knockdown of LYRM1 rescues insulin resistance and mitochondrial dysfunction induced by FCCP in 3T3-L1 adipocytes.

LYR motif-containing 1 (LYRM1) was recently discovered to be involved in adipose tissue homeostasis and obesity-associated insulin resistance. We previously demonstrated that LYRM1 overexpression might contribute to insulin resistance and mitochondrial dysfunction. Additionally, knockdown of LYRM1 enhanced insulin sensitivity and mitochondrial function in 3T3-L1 adipocytes. We investigated whether knockdown of LYRM1 in 3T3-L1 adipocytes could rescue insulin resistance and mitochondrial dysfunction induced by the cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP), a mitochondrion uncoupler, to further ascertain the mechanism by which LYRM1 is involved in obesity-associated insulin resistance. Incubation of 3T3-L1 adipocytes with 1 µM FCCP for 12 h decreased insulin-stimulated glucose uptake, reduced intracellular ATP synthesis, increased intracellular reactive oxygen species (ROS) production, impaired insulin-stimulated Glucose transporter type 4 (GLUT4) translocation, and diminished insulin-stimulated tyrosine phosphorylation of Insulin receptor substrate-1 (IRS-1) and serine phosphorylation of Protein Kinase B (Akt). Knockdown of LYRM1 restored insulin-stimulated glucose uptake, rescued intracellular ATP synthesis, reduced intracellular ROS production, restored insulin-stimulated GLUT4 translocation, and rescued insulin-stimulated tyrosine phosphorylation of IRS-1 and serine phosphorylation of Akt in FCCP-treated 3T3-L1 adipocytes. This study indicates that FCCP-induced mitochondrial dysfunction and insulin resistance are ameliorated by knockdown of LYRM1.

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.

Differential expression profile of MicroRNAs during differentiation of cardiomyocytes exposed to polychlorinated biphenyls.

Exposure to persistent environmental pollutants, such as polychlorinated biphenyls (PCBs), is a risk factor for the development of congenital heart defects. MicroRNAs (miRNAs) have been shown to be involved in cardiac development. The objective of this study was to investigate changes in miRNA expression profiles during the differentiation of cardiomyocytes exposed to PCBs. For that purpose, PCBs (Aroclor 1254) at a concentration of 2.5 µmol/L were added on day 0 of differentiation of P19 mouse embryonal carcinoma cells into cardiac myocytes. The relative expression of miRNA genes was determined by miRNA microarray and real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR) analyses. The microarray results revealed that 45 miRNAs, of which 14 were upregulated and 31 were downregulated, were differentially expressed in P19 cells treated with PCBs compared with control cells. The miRNA expression data was validated with real-time RT-PCR. The expression of certain potential target genes (Wnt1) was found to be reduced in P19 cells treated with PCBs, whereas the expression of other potential predicted target genes (GSK3ß) was increased. Our results demonstrate a critical role of miRNAs in mediating the effect of PCBs during the differentiation of P19 cells into cardiac myocytes.

Monoclonal antibody to six transmembrane epithelial antigen of prostate-4 influences insulin sensitivity by attenuating phosphorylation of P13K (P85) and Akt: possible mitochondrial mechanism.

We examined the effects of anti-six-transmembrane epithelial antigen of the prostate-4 (STEAP4) antibodies on glucose transport in mature adipocytes and determined the mechanism of insulin resistance in obesity. Western blotting was performed to determine STEAP4 expression, to assess translocation of insulin-sensitive glucose transporter 4 (GLUT4), and to measure phosphorylation and total protein content of insulin-signaling proteins. Confocal laser microscopy and flow cytometry were used to detect intracellular reactive oxygen species (ROS) and fluctuations in mitochondrial membrane potential (ΔΨ). ATP production was measured by using a luciferase-based luminescence assay kit. After the application of anti-STEAP4 antibodies at 0.002 mg/mL, adipocytes exhibited reduced insulin-stimulated glucose transport by attenuating the phosphorylation of IRS-1, PI3K (p85), and Akt. The antibodies also potentially increase the level of ROS and decrease cellular ATP production and ΔΨ. In conclusion, (i) STEAP4 regulates the function of IRS-1, PI3K, and Akt and decreases insulin-induced GLUT4 translocation and glucose uptake; (ii) ROS-related mitochondrial dysfunction may be related to a reduced IRS-1 correlation with the PI3K signaling pathway, leading to insulin resistance. These observations highlight the potential role of STEAP4 in glucose homeostasis and possibly in the pathophysiology of type 2 diabetes related to obesity and may provide new insights into the mechanisms of insulin resistance in obesity.

Monoclonal antibody to the six-transmembrane epithelial antigen of prostate 4 promotes apoptosis and inhibits proliferation and glucose uptake in human adipocytes.

We previously identified the six-transmembrane epithelial antigen of prostate (STEAP) 4 as a novel plasma membrane protein that is up-regulated in obese patients and may play a significant role in the development of human obesity. In this study, a STEAP4-specific antibody was used to characterize the biological functions of the STEAP4 protein in human adipocytes. Cell viability assays (Trypan Blue exclusion), CCK-8 assays and cell cycle analysis showed that the STEAP4 antibody inhibited pre-adipocyte proliferation. Morphological observations by electron microscopy and confocal laser microscopy, annexin V-FITC labeling, caspase-3 and caspase-8 activity assays as well as data from quantitative real-time RT-PCR (qPCR) further determined that the STEAP4 antibody could promote apoptosis in pre-adipocytes. Based on quantitative Oil Red O staining and the expression profiles of specific markers, we demonstrated that the STEAP4 antibody did not affect adipogenesis, but the 2-deoxy-d-[3H]-glucose uptake tests showed that it induced the insulin-stimulated glucose uptake in mature human adipocytes. In conclusion, our results demonstrated that the STEAP4 antibody does not influence human adipocyte differentiation, but it is likely that the STEAP4 protein regulates proliferation and apoptosis and plays an important role in modulating the insulin sensitivity of human adipocytes.

TNF-alpha 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.

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.

Mitochondrial dysfunction is induced by the overexpression of UCP4 in 3T3-L1 adipocytes.

Uncoupling proteins (UCPs) belong to a superfamily of mitochondrial transporters that uncouple ATP synthesis from electron transport. We have previously shown that uncoupling protein 4 (UCP4) is differentially expressed in omental adipose tissue in diet-induced obese and normal rats. Overexpression of UCP4 promotes proliferation and inhibits apoptosis and differentiation of preadipocytes. In this work, we further characterized the effect of UCP4 on mitochondrial function in mature 3T3-L1 adipocytes. Transmission electron microscopy (TEM) showed that adipocytes overexpressing UCP4 displayed condensed mitochondria with twisted, condensed, and unclear cristae. Moreover, the loss of the mitochondrial membrane potential and intramitochondrial calcium was found. The adipocytes overexpressing UCP4 also showed decreased mitochondrial copy number (mtDNA) and lower mRNA expression of key factors in mitochondrial biogenesis, including PGC-1alpha and mtTFA. NRF-1 and ERRbeta levels were down-regulated, while NRF-2 levels were upregulated. In addition, UCP4 overexpression impaired mitochondrial fusion and fission, as indicated by decreased mitofusin mfn1, mfn2, and mitofission DRP1. When it came to total adipocytes, the UCP4 overexpressing adipocytes showed higher production reactive oxygen species and diminished levels of intracellular ATP. Furthermore, overexpression of UCP4 brought about impaired insulin sensitivity in adipocytes. UCP4 plays an important role in mitochondrial function and adipocyte insulin resistance. Its function deserves further attention.

[Regulative role of TNFalpha on STEAP4 gene in matured human adipocytes].

OBJECTIVE: Human STEAP4, a novel obesity-related gene, is associated with insulin sensitivity regulation in human adipocytes. This study aimed to explore the regulative role of TNFalpha on STEAP4 gene in matured human adipocytes. METHODS: Human preadipocytes were cultured and differentiated into matured adipocytes in vitro. Fully differentiated adipocytes (Day 17) were treated with different concentrations of TNFalpha (0, 5, 10, 25 and 50 ng/mL) for 24 hrs. Total RNA and protein were extracted from the adipocytes. Levels of STEAP4 mRNA and protein expression were determined by real-time quantitative RT-PCR and Western blot respectively. RESULTS: Different concentrations (5, 10, 25 and 50 ng/mL) of TNFalpha treatment for 24 hrs resulted in a significant increase in the STEAP4 mRNA expression of human matured adipocytes.The maximal effect was seen in the 50 ng/mL of TNFalpha treatment group. In parallel, STEAP4 protein synthesis in matured adipocytes increased in response to TNFalpha treatment of different concentrations (5, 10, 25 and 50 ng/mL) for 24 hrs. The maximal up-regulated effect was seen in the 25 ng/mL of TNFalpha treatment group. CONCLUSIONS: TNFalpha can up-regulate STEAP4 mRNA expression in human matured adipocytes.