Maternal high-protein diet modulates hepatic growth axis in weaning piglets by reprogramming the IGFBP-3 gene.

PURPOSE: The aim of this study was to investigate the effects of maternal high dietary protein intake on the hepatic growth axis in offspring. METHODS: Fourteen primiparous purebred Meishan sows were fed either a standard-protein (SP, n = 7) diet or a high-protein (HP, 150% of SP, n = 7) diet during pregnancy. Offspring (one male and one female per group, n = 14) on day 70 of the embryonic stage and on days 1, 35 and 180 after birth were selected, weighed and killed. Serum samples were analyzed for Tch, insulin and insulin-like growth factor-binding protein 3 (IGFBP-3) levels. Liver samples were analyzed for IGFBP-3 and IGF-I mRNA expression by qRT-PCR and for IGFBP-3, IGF1R and growth hormone receptor (GHR) protein expression by Western blotting. The underlying mechanism of IGFBP-3 regulation was determined by methylated DNA immunoprecipitation (MeDIP) and chromatin immunoprecipitation (ChIP). RESULTS: High-protein exposure resulted in significantly higher body and liver weights of piglets, and it increased their serum T3 and T4 levels at birth and/or at weaning. Furthermore, the IGFBP-3 protein content in the liver and serum was significantly reduced in the HP-exposed weaning piglets, whereas at the transcriptional level IGFBP-3 mRNA expression was downregulated in the livers of HP group piglets. Finally, DNA hypermethylation and higher enrichment of the histone repressive marks H3K27me3 and H3K9me3 were observed. CONCLUSIONS: Taken together, these results suggest that a maternal high-protein diet during gestation epigenetically reprograms IGFBP-3 gene expression to modulate the hepatic growth axis in weaning piglets.

[The effect of RhoA/Rho kinase signal pathway on TGF-beta1-induced phenotypic differentiation of human dermal fibroblasts].

OBJECTIVE: To examine the effect of RhoA/Rho kinase signal pathway on TGF-beta1-induced phenotypic differentiation of human dermal fibroblasts. METHODS: The 4th generation of primary cultured human dermal fibroblasts were stimulated with TGF-beta1, (10 ng/ml). The expression of alpha-SMA was detected after treatment with TGF-beta1, for 0, 3, 6, and 24 h. The expression of alpha-SMA was also detected after treatment with different concentration of TGF-beta1 (0, 2, 10, 50 ng/ml). Then the human dermal fibroblasts (4th generation) were stimulated with TGF-beta1, (10 ng/ml) after being treated with the RhoA/Rho kinase signaling pathway inhibitor Y-27632 (10 umol/ml). The fibroblasts were treated with nothing as sham control, or with Y-27632 (10 umol/L) only as negative control group, or with TGF-beta1 (10 ng/ml) only as positive control group. The expression of alpha-SMA was detected in all the groups. Protein expression was analyzed with ANOVA statistical method. RESULTS: alpha-SMA expression in fibroblasts with 10 ng/ml TGF-beta1 stimulation for 0, 3, 6, 24 h was 1.0, 1.9 0.2, 2.1 +/- 0. 1, 3. 1 +/- 0.1, respectively. Alpha-SMA expression in 24 h group was significantly higher than that in other three groups (n = 4, P < 0.05). alpha-SMA expression in human dermal fibroblasts after stimulation with different concentration of TGF-beta1 (0, 2, 10, 50 ng/ml) was 1.0, 1.4 +/- 0.2, 3.2 + 0.1, 3.1 +/- 0.2, respectively. alpha-SMA expression in 10 ng/ ml group was significantly higher than that in 2 ng/ml group and control group (n = 4, P < 0.05). There was no statistical difference in alpha-SMA expression between 10 ng/ml group and 50 ng/ml group (n = 4, P > 0.05). With both Y-27632 (10 micromol/L) and TGF-beta1 stimulation, the cell phenotype differentiation was inhibited. Alpha-SMA expression in experimental group (1.2 +/- 0.2) was significantly reduced, when compared with that in positive control group (2.9 +/- 0.1) (n = 5, P < 0.05). There was no significant difference (n = 5, P > 0.05) in alpha-SMA expression between control group (1.0) and negative control group (1.1 +/- 0.1). CONCLUSIONS: RhoA/Rho kinase signaling pathway should be involved in TGF-beta1-induced phenotypic differentiation of human dermal fibroblasts.