SGK1 inhibitor reverses hyperglycemia partly through decreasing glucose absorption

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   Figure 1

   Effects of an SGK1 inhibitor on hyperglycemia in db/db mice. Db/db mice were fed chow containing either no compound (db/db group, db/db) or EMD638683 at 4.46 mg/g of chow (db/db+EMD group, db/db+EMD) from 10 weeks of age. Db/m mice served as the control (db/m group, db/m). The body weight was obtained every week from 10 to 18 weeks of age. The food intake, fasting blood glucose, and systolic blood pressure were measured every 2 weeks. The HbA1c level was checked at 4 and 8 weeks after intervention. Glucose and insulin tolerance tests were performed at 17 and 18 weeks of age respectively. (A) Body weight. (B) Food intake. (C) Fasting blood glucose. (D) HbA1c. (E) Plasma glucose curves under the glucose tolerance tests. (F) Plasma glucose curves under the insulin tolerance tests. The data are presented as the mean ± s.d., n = 8 mice per group. ^###P<0.001 vs control group of db/m mice. ^*P<0.05; ^**P<0.01 vs control group in db/db mice.
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   Figure 2

   Effects of an SGK1 inhibitor on intestinal SGLT1 expression in db/db mice. Mice were fed chow containing either no compound (db/m group, db/m; db/db group, db/db) or EMD638683 at 4.46 mg/g of chow (db/db+EMD group, db/db+EMD) from 10 weeks of age, and intestinal tissue was excised at 18 weeks of age and analyzed. (A and B) SGK1 mRNA (A) and protein (B) levels in intestinal tissue from db/db and control db/m mice. (C and D) SGLT1 mRNA (C) and protein (D) levels in intestinal tissue from db/m, db/db, and db/db+EMD mice. The total RNA was isolated from intestinal tissue, and first-strand cDNA was synthesized as described in the Methods section. Real-time quantitative PCR was performed, and the values were normalized to the level of β-actin mRNA. Protein was extracted from the intestinal tissue and subjected to western blot analysis. The relative protein levels were normalized to the GAPDH or β-actin protein level. The bands were quantified through densitometry using the Quantity One system. The results (means ± s.d.) are expressed as the fold change relative to the levels of the db/m group (Con, 100% or 1). ^#P<0.05 vs control group of db/m mice. *P<0.05; **P<0.01 vs control group in db/db mice.
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   Figure 3

   Effects of an SGK1 inhibitor on SGLT1 expression in IEC-6 cells. IEC-6 cells were serum deprived overnight before dexamethasone and/or the SGK1 inhibitor (EMD638683, EMD) was added. (A and B) SGK1 mRNA (A) and protein (B) expression in dexamethasone (Dex)-treated IEC-6 cells. (C and D) Sglt1 mRNA (C) and protein (D) expression in Dex-treated IEC-6 cells. (E and F) Sglt1 mRNA (E) and protein (F) expression in Dex- and EMD-treated IEC-6 cells. The total RNA was extracted, and real-time quantitative PCR was performed. The relative mRNA levels were normalized to β-actin mRNA expression. The protein was extracted from IEC-6 cells and subjected to western blot analysis. The bands were quantified by densitometry using the Quantity One system. The results (means ± s.d.) are expressed as the fold change relative to the levels of the control group (Con, 100% or 1). ^#P<0.05; ^##P<0.01; ^###P<0.001 vs untreated control cells; *P<0.05 vs Dex-treated cells.
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   Figure 4

   Effects of an SGK1 inhibitor on glucose absorption in IEC-6 cells. IEC-6 cells were serum deprived overnight before dexamethasone and/or the SGK1 inhibitor (EMD638683, EMD) was added. (A) Representative data and quantification of the glucose absorption by flow cytometry in Dex-treated IEC-6 cells. (B) Representative data and quantification of the glucose absorption by flow cytometry in Dex- and EMD-treated IEC-6 cells. A glucose uptake assay using the 2-NBDG screening system was performed as described in the Materials and Methods section. The fluorescence intensities in the absence of 2-NBDG were measured and considered as the background. The relative fluorescence intensities minus the background levels were used for the data analysis. Values are means ± s.d. of three replicates in four separate experiments. ^#P<0.05; ^###P<0.001 vs untreated control cells; *P<0.05 vs Dex-treated cells. A full color version of this figure is available at http://dx.doi.org/10.1530/JME-15-0285.

• © 2016 Society for Endocrinology