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MiR-19a regulates PTEN expression to mediate glycogen synthesis in hepatocytes.

Dou L, Meng X, Sui X, Wang S, Shen T, Huang X, Guo J, Fang W, Man Y, Xi J, Li J - Sci Rep (2015)

Bottom Line: Here, we define the impact of miR-19a on glycogen synthesis and IL-6-induced reduced glycogenesis in hepatocytes and its underlying mechanisms.We found that over-expression of miR-19a in NCTC 1469 cells and HEP 1-6 cells led to increased activation of the AKT/GSK pathway and synthesis of glycogen, whereas down-regulation of miR-19a impaired AKT/GSK phosphorylation and glycogenesis.Over-expression of miR-19a ameliorated IL-6-induced reduced glycogen synthesis in hepatocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China.

ABSTRACT
MiR-19a, a member of mir-17-92 microRNA clusters, has been demonstrated to promote cell proliferation and angiogenesis via regulating the PI3K/AKT pathway, the major insulin signaling pathway. However, whether miR-19a plays an important role in glycogen synthesis in hepatocytes remains unknown. Here, we define the impact of miR-19a on glycogen synthesis and IL-6-induced reduced glycogenesis in hepatocytes and its underlying mechanisms. Our studies indicate that miR-19a was down-regulated in the livers of db/db mice and mice injected with IL-6, as well as mouse NCTC 1469 hepatocytes and HEP 1-6 hepatocytes treated by IL-6. We found that over-expression of miR-19a in NCTC 1469 cells and HEP 1-6 cells led to increased activation of the AKT/GSK pathway and synthesis of glycogen, whereas down-regulation of miR-19a impaired AKT/GSK phosphorylation and glycogenesis. Over-expression of miR-19a ameliorated IL-6-induced reduced glycogen synthesis in hepatocytes. Moreover, we identified PTEN as the target of miR-19a by a luciferase assay. Down-regulation of PTEN rescued the effects of miR-19a suppression on the activation of the AKT/GSK pathway and improved glycogenesis in NTC 1469 cells. These findings show for the first time that miR-19a might activate the AKT/GSK pathway and glycogenesis via down-regulation of PTEN expression.

No MeSH data available.


Related in: MedlinePlus

MiR-19a is down-regulated in the livers of db/db mice and mice injected with IL-6 as well as mouse NCTC 1469 hepatocytes and HEP 1-6 hepatocytes treated with IL-6.(a) Reduced miR-19a expression in the livers of db/db mice, as verified by real-time PCR. (b–g) MiR-19a expression in the mouse NCTC 1469 hepatocytes and HEP 1–6 hepatocytes treated with 33.3 mM glucose for 48 h (b and c), 10 ng/ml hIL-6 for 24 h (d and e) and 10 ng/ml TNF-α for 24 h (f and g). (h) Expression of miR-19a in the livers of 12-week-old male C57BL/6J mice injected with 16 μg/ml IL-6 by pumps for 7 days. Data represent the mean ± S.D. N = 3 independent experiments or N = 5 mice.*p < 0.05; **p < 0.01 by ANOVAtest (vs. control).
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f1: MiR-19a is down-regulated in the livers of db/db mice and mice injected with IL-6 as well as mouse NCTC 1469 hepatocytes and HEP 1-6 hepatocytes treated with IL-6.(a) Reduced miR-19a expression in the livers of db/db mice, as verified by real-time PCR. (b–g) MiR-19a expression in the mouse NCTC 1469 hepatocytes and HEP 1–6 hepatocytes treated with 33.3 mM glucose for 48 h (b and c), 10 ng/ml hIL-6 for 24 h (d and e) and 10 ng/ml TNF-α for 24 h (f and g). (h) Expression of miR-19a in the livers of 12-week-old male C57BL/6J mice injected with 16 μg/ml IL-6 by pumps for 7 days. Data represent the mean ± S.D. N = 3 independent experiments or N = 5 mice.*p < 0.05; **p < 0.01 by ANOVAtest (vs. control).

Mentions: To profile the changes of the microRNA expression in hepatic insulin resistance, miRNA microarrays were used to analyze miRNAs in the livers of db/db mice (n = 5) and control mice (n = 5). Supplemental Table1 shows that the level of miR-19a was decreased in the livers of db/db mice. Consistently, real-time PCR verified reduced miR-19a expression in the livers of db/db mice (Fig. 1a). Several factors can lead to insulin resistance, such as high glucose and inflammatory factors, such as TNF-α and IL-6. According to our previous study, decreased glycogenesis and impaired activation of the PI3K/AKT pathway in liver cells can be induced by glucose, TNF-α and IL-6 (Supplemental Fig S1). Therefore, mouse NCTC 1469 cells and Hep 1–6 cells were treated with 33.3 mM glucose for 48 h, 10 ng/ml hIL-6 for 24 h and 10 ng/ml TNF-α for 24 h to induce insulin resistance. As shown in Fig. 1b–g, treatment with IL-6 but not glucose and TNF-α led to down-regulated miR-19a expression. To confirm the effect of IL-6 on the expression of miR-19a in vivo, 12-week-old male C57BL/6J mice were injected with 16 μg/ml IL-6 by pumps for 7 days. Expression of miR-19a was also reduced in the livers of mice injected with IL-6 (Fig. 1h). Our data demonstrate the possibility that down-regulation of miR-19a is involved in the pathogenesis of hepatic insulin resistance.


MiR-19a regulates PTEN expression to mediate glycogen synthesis in hepatocytes.

Dou L, Meng X, Sui X, Wang S, Shen T, Huang X, Guo J, Fang W, Man Y, Xi J, Li J - Sci Rep (2015)

MiR-19a is down-regulated in the livers of db/db mice and mice injected with IL-6 as well as mouse NCTC 1469 hepatocytes and HEP 1-6 hepatocytes treated with IL-6.(a) Reduced miR-19a expression in the livers of db/db mice, as verified by real-time PCR. (b–g) MiR-19a expression in the mouse NCTC 1469 hepatocytes and HEP 1–6 hepatocytes treated with 33.3 mM glucose for 48 h (b and c), 10 ng/ml hIL-6 for 24 h (d and e) and 10 ng/ml TNF-α for 24 h (f and g). (h) Expression of miR-19a in the livers of 12-week-old male C57BL/6J mice injected with 16 μg/ml IL-6 by pumps for 7 days. Data represent the mean ± S.D. N = 3 independent experiments or N = 5 mice.*p < 0.05; **p < 0.01 by ANOVAtest (vs. control).
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Related In: Results  -  Collection

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f1: MiR-19a is down-regulated in the livers of db/db mice and mice injected with IL-6 as well as mouse NCTC 1469 hepatocytes and HEP 1-6 hepatocytes treated with IL-6.(a) Reduced miR-19a expression in the livers of db/db mice, as verified by real-time PCR. (b–g) MiR-19a expression in the mouse NCTC 1469 hepatocytes and HEP 1–6 hepatocytes treated with 33.3 mM glucose for 48 h (b and c), 10 ng/ml hIL-6 for 24 h (d and e) and 10 ng/ml TNF-α for 24 h (f and g). (h) Expression of miR-19a in the livers of 12-week-old male C57BL/6J mice injected with 16 μg/ml IL-6 by pumps for 7 days. Data represent the mean ± S.D. N = 3 independent experiments or N = 5 mice.*p < 0.05; **p < 0.01 by ANOVAtest (vs. control).
Mentions: To profile the changes of the microRNA expression in hepatic insulin resistance, miRNA microarrays were used to analyze miRNAs in the livers of db/db mice (n = 5) and control mice (n = 5). Supplemental Table1 shows that the level of miR-19a was decreased in the livers of db/db mice. Consistently, real-time PCR verified reduced miR-19a expression in the livers of db/db mice (Fig. 1a). Several factors can lead to insulin resistance, such as high glucose and inflammatory factors, such as TNF-α and IL-6. According to our previous study, decreased glycogenesis and impaired activation of the PI3K/AKT pathway in liver cells can be induced by glucose, TNF-α and IL-6 (Supplemental Fig S1). Therefore, mouse NCTC 1469 cells and Hep 1–6 cells were treated with 33.3 mM glucose for 48 h, 10 ng/ml hIL-6 for 24 h and 10 ng/ml TNF-α for 24 h to induce insulin resistance. As shown in Fig. 1b–g, treatment with IL-6 but not glucose and TNF-α led to down-regulated miR-19a expression. To confirm the effect of IL-6 on the expression of miR-19a in vivo, 12-week-old male C57BL/6J mice were injected with 16 μg/ml IL-6 by pumps for 7 days. Expression of miR-19a was also reduced in the livers of mice injected with IL-6 (Fig. 1h). Our data demonstrate the possibility that down-regulation of miR-19a is involved in the pathogenesis of hepatic insulin resistance.

Bottom Line: Here, we define the impact of miR-19a on glycogen synthesis and IL-6-induced reduced glycogenesis in hepatocytes and its underlying mechanisms.We found that over-expression of miR-19a in NCTC 1469 cells and HEP 1-6 cells led to increased activation of the AKT/GSK pathway and synthesis of glycogen, whereas down-regulation of miR-19a impaired AKT/GSK phosphorylation and glycogenesis.Over-expression of miR-19a ameliorated IL-6-induced reduced glycogen synthesis in hepatocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China.

ABSTRACT
MiR-19a, a member of mir-17-92 microRNA clusters, has been demonstrated to promote cell proliferation and angiogenesis via regulating the PI3K/AKT pathway, the major insulin signaling pathway. However, whether miR-19a plays an important role in glycogen synthesis in hepatocytes remains unknown. Here, we define the impact of miR-19a on glycogen synthesis and IL-6-induced reduced glycogenesis in hepatocytes and its underlying mechanisms. Our studies indicate that miR-19a was down-regulated in the livers of db/db mice and mice injected with IL-6, as well as mouse NCTC 1469 hepatocytes and HEP 1-6 hepatocytes treated by IL-6. We found that over-expression of miR-19a in NCTC 1469 cells and HEP 1-6 cells led to increased activation of the AKT/GSK pathway and synthesis of glycogen, whereas down-regulation of miR-19a impaired AKT/GSK phosphorylation and glycogenesis. Over-expression of miR-19a ameliorated IL-6-induced reduced glycogen synthesis in hepatocytes. Moreover, we identified PTEN as the target of miR-19a by a luciferase assay. Down-regulation of PTEN rescued the effects of miR-19a suppression on the activation of the AKT/GSK pathway and improved glycogenesis in NTC 1469 cells. These findings show for the first time that miR-19a might activate the AKT/GSK pathway and glycogenesis via down-regulation of PTEN expression.

No MeSH data available.


Related in: MedlinePlus