Common differentially expressed proteins were found in mouse cleft palate models induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin and retinoic acid.

Cleft palate(CP) is a widely studied congenital malformation. However, its etiology and pathogenesis still remain unclear. Proteins are fundamental molecules that participate in every biological process within cells. In this study, we established CP mouse models induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and retinoic acid (RA), using proteomics technology isobaric tags for relative and absolute quantitation (iTRAQ) to investigate the key proteins in the formation of CP. Pregnant mice were given a gavage of TCDD 28µg/kg or retinoic acid 80mg/kg of body weight or equivalent corn oil at gestational day 10.5(GD10.5) and sacrificed at GD 17.5. Foetal mice were recorded and collected for further detection. Western blot was performed to verify the iTRAQ results. Eventually, we obtained 18 common differentially expressed proteins in TCDD group and RA group compared with normal control, 17 up-regulated and 1 down-regulated. 14-3-3sigma and Annexin A1 were up-regulated in experimental groups at GD17.5, which was consistent with Western blot. We speculated that the common differentially expressed proteins might be one of the molecular mechanisms in the formation of cleft palate.

Preliminary research on DNA methylation changes during murine palatogenesis induced by TCDD.

2,3,7,8-Tetrachlrodibenzo-p-dioxin (TCDD) has been shown to induce cleft palate through growth factor and receptor expression changes during palatogenesis. DNA methylation is an important epigenetic modification that can regulate gene expressions and may be involved in TCDD-induced cleft palate. In this study, we investigated the effects of TCDD on the global and CpG DNA methylation status and the expression levels of DNA methyltransferases (Dnmts) in palate tissue of fetal mice. Pregnant C57BL/6J mice were administered with corn oil or TCDD 28 µg/kg at gestation day 10.5(GD10.5), and sacrificed at GD13.5, 14.5, 15.5. Fetal palates were collected for molecular analysis. Global DNA methylation status was detected by Methylamp™ Global DNA Methylation Quantification Ultra Kit. The expression of DNA methyltransferases were examined by quantitative real-time PCR(q-PCR). Methylation Specific PCR (MSP) was performed to analyze CpG methylation status of Dnmts. We found that the global DNA methylation level and the expression of Dnmt3a were higher at GD13.5 in the TCDD group. The methylation level of CpG site 2 in the promoter region of Dnmt3a in the control group was higher than that of the TCDD group at GD13.5. The low CpG methylation level of Dnmt3a at GD13.5 which causes the up-expression of Dnmt3a may induce global hypermethylation in fetal palate tissue. The aberrant global methylation status at GD13.5 may be the cause of palate malformation in fetal mice induced by TCDD.

[Global DNA methylation changes during palatal formation in fetal mice induced by 2,3,7,8-tetrachlrodibenzo-p-dioxin].

Objective: To investigate global DNA methylation and DNA methyhransferases participation in the mechanism of cleft palate induced by maternal exposure to 2,3,7,8-tetrachlrodibenzo-p-dioxin (TCDD)in mice. Methods: 40 pregnant C57BL/6J mice were randomly divided into 2 groups: the control group(n =20) and TCDD-exposure group(n =20).On gestation day 10.5 (GD10.5),the mice in TCDD-group were orally administrated with TCDD 28 µg/kg, while the mice in the control group received equivalent corn oil. The pregnant mice were sacrificed on GD13.5,GD14.5,GD15.5,GD16.5,GD17.5,fetal palates were collected for analysis. Global DNA methylation levels were detected by Methylamp TM Global DNA Methylation Quantification Ultra Kit through an ELISA-like reaction. The expression levels of DNA methyltransferases were examined by quantitative real-time PC R(q-PCR).IBM SPSS 20.0 software was applied for statistical analysis. Kolmogorov-Smirnov test was used for normal distribution check, and the distribution was normal. Independent t-test was carried out among two groups. P ＜ 0.05 was considered statistically significant. Results: The global DNA methylation level in TCDD-exposure group was significantly higher than that in control group on GD13.5 (49.52％ ±4.03％ vs 33.42％ ± 6.78％,P ＜ 0.01),while lower on GD14.5 (24.10％ ±2.29％ vs 30.12％ ±3.92％,P ＜0.05) and on GD16.5 (32.77％ ±0.98％ vs 36.45％ ± 3.27％,P ＜ 0.05).The expression level of Dnmt1 mRNA in TCDD-exposure group was higher than that in control group on GD13.5(1.28±0.11 vs 1.01 ±0.10,P＜0.05) and on GD16.5(1.04 ±0.05 vs 0.81 ±0.01,P ＜0.01).The expression level of Dnmt3a mRNA in TCDD-exposure group was higher than that in control group on GD13.5 (1.15 ±0.17 vs 0.81 ±0.02,P ＜0.05)and on GD16.5 (1.11 ± 0.06 vs 0.96 ± 0.06,P ＜ 0.05).The expression level of Dnmt3b mRNA in TCDD-exposure group was higher than that in control group on GD14.5(0.97 ±0.06 vs 0.72 ±0.06,P ＜0.01). Conclusions: It is supposed that complicated mechanisms are exist to regulate global DNA methylation levels in palatal tissue of fetal mice. The significant increased DNA methylation level on GD13.5 resulting from up-expression of Dnmt1 and Dnmt3a may be one of the epigenetic mechanisms which cause palate malformation in fetal mice induced by maternal exposure to TCDD.

Delivery of megsin siRNA plasmid reveals therapeutic potential against diabetic nephropathy by down-regulating p27(kip1) level.

BACKGROUND: Diabetic nephropathy is a complex disease with poor outcomes, and our current treatment measures are limited. It is urgent to search for novel therapeutic targets. Recently, a mesangium-predominant gene, megsin, has emerged as a participant in mesangial cell proliferation and/or mesangial matrix expansion. This study investigated the effect of megsin down-regulation on the progression of diabetic nephropathy. METHODS: Streptozotocin (STZ)-induced diabetic CD-1 mice after uninephrectomy received a pBAsi mU6 Neo megsin siRNA plasmid for 12 weeks and were compared with age-matched nondiabetic mice. In vitro mouse mesangial cells were transfected with pBAsi mU6 Neo megsin siRNA plasmid using Lipofectamine 2000 reagent and further cultured in DMEM containing high glucose for up to 48 hours. All of the cells were collected for protein extraction and the supernatant for type IV collagen measurement. The expression of megsin, matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteases-2 (TIMP-2) and p27(Kip1) was determined by Western blotting. RESULTS: The megsin siRNA plasmid alleviated proteinuria and glomerular type IV collagen accumulation 12 weeks after the STZ injection, down-regulated renal cell proliferation and normalized the imbalance between MMP-2 and TIMP-2. Also, in vitro experiments showed that the glomerular mesangial cellular proliferation and type IV collagen production induced by high glucose were relieved after the transfection of megsin siRNA plasmid. The level of p27(kip1) was down-regulated in transfected mesangial cells significantly. CONCLUSIONS: The study suggests that the down-regulation of megsin might exert beneficial effects on the diabetic kidney partly through down-regulation of p27(kip1) level and that megsin may serve as a novel therapeutic target in the management of diabetic nephropathy.