The role of dipeptidyl peptidase 4 (DPP4) in the preservation of renal function: DPP4 involvement in hemoglobin expression

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   Figure 1

   Changes in Hbb and Hba1 mRNA expression levels in WT and DPP4-deficient rats at 42 days after the i.p. injection of STZ (30 mg/kg) or the vehicle. The mRNA expression levels were measured by qPCR. All mRNA signals were normalized to the signal for Gapdh. Data are shown as the mean±s.d. Non-STZ-treated, WT (n=6); STZ-treated, WT (n=10); non-STZ-treated, DPP4-deficient (n=6); and STZ-treated, DPP4-deficient (n=10). *P<0.05 and ***P<0.001; one-way ANOVA followed by post hoc comparisons using Bonferroni's multiple comparison test.
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   Figure 2

   Changes in DPP4 (B), HBA1 (C), HBA2 (D), HBG1 (E), and HBG2 (F) mRNA expression levels in HEK293 cells from the DPP4 siRNA knockdown using DPP4 siRNA1 (DPP4 KD) and control siRNA (Control). The levels of mRNA expression were measured by qPCR and compared with those for the untreated cells. mRNA signals were normalized to the signal for GAPDH. The experiments were repeated three times, and the data are shown as the mean±s.d. (A) RT-PCR analysis of DPP4 mRNA expression by DPP4 knockdown using four pre-designed siRNAs and control siRNA. ***P<0.001; one-way ANOVA followed by post hoc comparisons using Bonferroni's multiple comparison test.
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   Figure 3

   Changes in DPP4 (B), HBA2 (C), and HBB (D) mRNA expression levels in Caki-1 cells from the DPP4 siRNA knockdown using DPP4 siRNA1 (DPP4 KD) and control siRNA (Control). The levels of mRNA expression were measured by qPCR and compared with those of the untreated cells. mRNA signals were normalized to the signal for GAPDH. The experiments were repeated three times, and the data are shown as the mean±s.d. (A) RT-PCR analysis of Dpp4 mRNA expression by DPP4 knockdown using four pre-designed siRNAs and control siRNA. ***P<0.001; one-way ANOVA followed by post hoc comparisons using Bonferroni's multiple comparison test.
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   Figure 4

   Changes in HBA1, HBA2, HBG1, and HBG2 mRNA expression levels at 12, 24, and 48 h after the addition of soluble human DPP4 (final concentration of 500 ng/ml) in HEK293 cells. The levels of mRNA expression were measured by qPCR and compared with those of the control group. mRNA signals were normalized to the signal for GAPDH. The experiments were repeated three times, and the data are shown as the mean±s.d. *P<0.05, **P<0.01, and ***P<0.001; Student's t-test.
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   Figure 5

   Changes in HBA2 and HBB mRNA expression levels at 12, 24, and 48 h after the addition of soluble human DPP4 (final concentration of 500 ng/ml) in Caki-1 cells. The levels of mRNA expression were measured by qPCR and compared with those for the control group. mRNA signals were normalized to the signal for Gapdh. The experiments were repeated three times, and the data are shown as the mean±s.d. *P<0.05 and ***P<0.001; Student's t-test.
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   Figure 6

   Changes in DPP4 activity (A), DPP4 mRNA expression level (B), western immunoblots of DPP4 (C), and HBA1 (D), HBA2 (E), HBG1 (F), and HBG2 (G) mRNA expression levels 48 h after the addition of the DPP4 inhibitor, sitagliptin (final concentration of 1000 μM), in HEK293 cells. The levels of mRNA expression were measured by qPCR and compared with those for the control group. mRNA signals were normalized to the signal for GAPDH. The experiments were repeated three times, and the data are shown as the mean±s.d. ***P<0.001; Student's t-test.
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   Figure 7

   Changes in DPP4 activity (A), DPP4 mRNA expression level (B), western immunoblots of DPP4 (C), and HBA2 (D), and HBB (E) mRNA expression levels 48 h after the addition of the DPP4 inhibitor, sitagliptin (final concentration of 1000 μM), in Caki-1 cells. The levels of mRNA expression were measured by qPCR and compared with those for the control group. mRNA signals were normalized to the signal for Gapdh. The experiments were repeated three times, and the data are shown as the mean±s.d. *P<0.05, **P<0.01, and ***P<0.001; Student's t-test.

• © 2014 Society for Endocrinology