Loss of Glycine N-Methyltransferase Associates with Angiopoietin-Like Protein 8 Expression in High Fat-Diet-Fed Mice

Figures

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  Figure 1. Characterization of the mice fed with HFD and ND. (A) The representative pictures showing HFD-fed and ND-fed mice. (B) The body weight of the mice was measured weekly; * p < 0.05, compared to the ND control group. (C–F) The fasting triglyceride (C), total cholesterol (D), glucose (E), and insulin (F) in the blood of the mice were analyzed; * p < 0.05, compared to the relative ND control groups. (G) The hepatic Angptl8 expression was examined by Western blot. (H) The mRNA levels of hepatic Angptl8 was analyzed by qPCR; * p < 0.05, compared to the ND control group. (I) The plasma Angptl8 was analyzed by ELISA; * p < 0.05, compared to the ND control group.

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  Figure 2. Insulin induces Akt phosphorylation and Angptl8 expression. (A) The primary hepatocytes were treated with insulin at different concentrations for 1 h. The expression of indicated proteins was examined by Western blot. (B) The primary hepatocytes were treated with insulin (1 μM) for different time periods. The expression of the indicated proteins was examined by Western blot. (C–D) The hepatic Angptl8 mRNA levels in the primary hepatocytes treated with or without insulin at different concentrations (C) and time periods (D) were analyzed by qPCR; * p < 0.05, compared to the control group.

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  Figure 3. Insulin-induced Angptl8 is mediated by the PI3K/Akt signaling pathway. (A–B) The primary hepatocytes were incubated in the culture medium with or without insulin (1 μM) and LY294002 (10 μM) for 1 h. The expression of indicated proteins (A) and Angptl8 mRNA (B) was examined by Western blot and qPCR respectively. (C–D) The primary hepatocytes were incubated in the culture medium with or without insulin (1 μM) and MK2206 (10 μM) for 1 h. The expression of indicated proteins (C) and Angptl8 mRNA (D) was examined by Western blot and qPCR, respectively. (E–F) The primary hepatocytes were transiently transfected with dominant-negative Akt plasmids, followed by an insulin treatment for 1 h. The expression of indicated proteins (E) and Angptl8 mRNA (F) was examined by Western blot and qPCR, respectively. (G–H) The primary hepatocytes were transiently transfected with constitutively activated myrAkt plasmids followed by a treatment of insulin for 1 h. The expression of indicated proteins (G) and Angptl8 mRNA (H) was examined by Western blot and qPCR, respectively.

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  Figure 4. The inverse correlation of GNMT and Angptl8 expression in the livers of HFD-fed mice. (A–B) The expression of hepatic GNMT protein (A) and mRNA (B) in the HFD-fed and ND-fed mice was revealed by Western blot and qPCR respectively. (C) The data of Angptl8 and GNMT mRNA expression was extracted from a microarray dataset, GSE39549; * p < 0.05, compared between the HFD and ND groups. (D) The data of Angptl8 and GNMT mRNA levels for each mouse were plotted. The inverse correlation of Angptl8 and GNMT was confirmed by Pearson’s correlation; * p < 0.01. (E) The liver tissues were obtained from wild type and GNMT-KO mice. The expression of indicated proteins were examined by Western blot. (F) The primary culture of hepatocytes was established from wild type and GNMT-KO mice. The primary hepatocytes were treated with LY294002 or MK2206, and the expression of indicated proteins was determined by Western blot.