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Gluconeogenesis, lipogenesis, and HBV replication are commonly regulated by PGC-1α-dependent pathway.

Jhuang HJ, Hsu WH, Lin KT, Hsu SL, Wang FS, Chou CK, Lee KH, Tsou AP, Lai JM, Yeh SF, Huang CY - Oncotarget (2015)

Bottom Line: We found that 8-Br-cAMP and glucocorticoids synergistically induce PGC-1α and its downstream targets, including PEPCK and G6Pase.HH-F3 also inhibited fatty acid synthase (FASN) expression and decreased lipid accumulation by down-regulating PGC-1α.HH-F3 may have potential use for the treatment of chronic hepatitis B patients with associated metabolic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan.

ABSTRACT
PGC-1α, a major metabolic regulator of gluconeogenesis and lipogenesis, is strongly induced to coactivate Hepatitis B virus (HBV) gene expression in the liver of fasting mice. We found that 8-Br-cAMP and glucocorticoids synergistically induce PGC-1α and its downstream targets, including PEPCK and G6Pase. Also, HBV core promoter activity was synergistically enhanced by 8-Br-cAMP and glucocorticoids. Graptopetalum paraguayense (GP), a herbal medicine, is commonly used in Taiwan to treat liver disorders. Partially purified fraction of GP (named HH-F3) suppressed 8-Br-cAMP/glucocorticoid-induced G6Pase, PEPCK and PGC-1α expression and suppressed HBV core promoter activity. HH-F3 blocked HBV core promoter activity via inhibition of PGC-1α expression. Ectopically expressed PGC-1α rescued HH-F3-inhibited HBV surface antigen expression, HBV mRNA production, core protein levels, and HBV replication. HH-F3 also inhibited fatty acid synthase (FASN) expression and decreased lipid accumulation by down-regulating PGC-1α. Thus, HH-F3 can inhibit HBV replication, gluconeogenesis and lipogenesis by down-regulating PGC-1α. Our study indicates that targeting PGC-1α may be a therapeutic strategy for treatment of HBV infections. HH-F3 may have potential use for the treatment of chronic hepatitis B patients with associated metabolic syndrome.

No MeSH data available.


Related in: MedlinePlus

HH-F3 suppresses 8-Br-cAMP/dexamethasone-induced coactivator transcription factor gene expression and HBV core promoter activityHep3B/T2 cells were pretreated with 8-Br-cAMP/Dex for 30 min. Different concentrations of HH-F3 were then added in serum-free DMEM for 24 h. (A)PGC-1α mRNA was measured by Q-RT PCR and normalized to β-actin. Insulin was used as a positive control. (B and C) Nuclear extracts were isolated, and the levels of PGC-1α and HNF-4α, FOXO1 proteins were determined by Western blotting. B23 was used as a nuclear protein loading control. (D and E) For the promoter activity assay, Hep3B/T2 cells were transfected with luciferase reporter plasmids driven by the HBV core promoter (CP) and HBV X promoter (XP). One day after 8-Br-cAMP/Dex treatment in the absence or presence of different concentrations of HH-F3 in serum-free DMEM, cell lysates were prepared for luciferase activity analysis as described previously. *P < 0.05 compared with the vehicle group. #P < 0.05, ##P < 0.01 compared with the 8-Br-cAMP/Dex-induced group (n = 3).
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Figure 3: HH-F3 suppresses 8-Br-cAMP/dexamethasone-induced coactivator transcription factor gene expression and HBV core promoter activityHep3B/T2 cells were pretreated with 8-Br-cAMP/Dex for 30 min. Different concentrations of HH-F3 were then added in serum-free DMEM for 24 h. (A)PGC-1α mRNA was measured by Q-RT PCR and normalized to β-actin. Insulin was used as a positive control. (B and C) Nuclear extracts were isolated, and the levels of PGC-1α and HNF-4α, FOXO1 proteins were determined by Western blotting. B23 was used as a nuclear protein loading control. (D and E) For the promoter activity assay, Hep3B/T2 cells were transfected with luciferase reporter plasmids driven by the HBV core promoter (CP) and HBV X promoter (XP). One day after 8-Br-cAMP/Dex treatment in the absence or presence of different concentrations of HH-F3 in serum-free DMEM, cell lysates were prepared for luciferase activity analysis as described previously. *P < 0.05 compared with the vehicle group. #P < 0.05, ##P < 0.01 compared with the 8-Br-cAMP/Dex-induced group (n = 3).

Mentions: The metabolic regulator PGC-1α robustly coactivates the transcription of gluconeogenic enzyme genes through HNF4α and FOXO1 [16, 32]. To determine whether HH-F3 might affect the coactivation of PGC-1α, HNF4α and FOXO1 to regulate gluconeogenic enzyme transcription, Hep3B/T2 cells were pretreated with 8-Br-cAMP/Dex for 30 min followed by treatment with HH-F3 for 24 h, and then the level of PGC-1α, HNF4α and FOXO1 were examined by Q-RT PCR or Western blot analysis. As shown in Figure 3A and 3B, 8-Br-cAMP/Dex synergistically activated the gene and protein expression of PGC-1α. Treatment with HH-F3 suppressed 8-Br-cAMP/Dex-induced PGC-1α gene expression (Figure 3A and 3C). HH-F3 also decreased the protein levels of FOXO1 and HNF4α, which were associated with gluconeogenic transcription factor expression in Hep3B/T2 cells (Figure 3C). These results suggest that HH-F3-suppressed gluconeogenic enzyme expression may occur via inhibition of PGC-1α gene expression.


Gluconeogenesis, lipogenesis, and HBV replication are commonly regulated by PGC-1α-dependent pathway.

Jhuang HJ, Hsu WH, Lin KT, Hsu SL, Wang FS, Chou CK, Lee KH, Tsou AP, Lai JM, Yeh SF, Huang CY - Oncotarget (2015)

HH-F3 suppresses 8-Br-cAMP/dexamethasone-induced coactivator transcription factor gene expression and HBV core promoter activityHep3B/T2 cells were pretreated with 8-Br-cAMP/Dex for 30 min. Different concentrations of HH-F3 were then added in serum-free DMEM for 24 h. (A)PGC-1α mRNA was measured by Q-RT PCR and normalized to β-actin. Insulin was used as a positive control. (B and C) Nuclear extracts were isolated, and the levels of PGC-1α and HNF-4α, FOXO1 proteins were determined by Western blotting. B23 was used as a nuclear protein loading control. (D and E) For the promoter activity assay, Hep3B/T2 cells were transfected with luciferase reporter plasmids driven by the HBV core promoter (CP) and HBV X promoter (XP). One day after 8-Br-cAMP/Dex treatment in the absence or presence of different concentrations of HH-F3 in serum-free DMEM, cell lysates were prepared for luciferase activity analysis as described previously. *P < 0.05 compared with the vehicle group. #P < 0.05, ##P < 0.01 compared with the 8-Br-cAMP/Dex-induced group (n = 3).
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Figure 3: HH-F3 suppresses 8-Br-cAMP/dexamethasone-induced coactivator transcription factor gene expression and HBV core promoter activityHep3B/T2 cells were pretreated with 8-Br-cAMP/Dex for 30 min. Different concentrations of HH-F3 were then added in serum-free DMEM for 24 h. (A)PGC-1α mRNA was measured by Q-RT PCR and normalized to β-actin. Insulin was used as a positive control. (B and C) Nuclear extracts were isolated, and the levels of PGC-1α and HNF-4α, FOXO1 proteins were determined by Western blotting. B23 was used as a nuclear protein loading control. (D and E) For the promoter activity assay, Hep3B/T2 cells were transfected with luciferase reporter plasmids driven by the HBV core promoter (CP) and HBV X promoter (XP). One day after 8-Br-cAMP/Dex treatment in the absence or presence of different concentrations of HH-F3 in serum-free DMEM, cell lysates were prepared for luciferase activity analysis as described previously. *P < 0.05 compared with the vehicle group. #P < 0.05, ##P < 0.01 compared with the 8-Br-cAMP/Dex-induced group (n = 3).
Mentions: The metabolic regulator PGC-1α robustly coactivates the transcription of gluconeogenic enzyme genes through HNF4α and FOXO1 [16, 32]. To determine whether HH-F3 might affect the coactivation of PGC-1α, HNF4α and FOXO1 to regulate gluconeogenic enzyme transcription, Hep3B/T2 cells were pretreated with 8-Br-cAMP/Dex for 30 min followed by treatment with HH-F3 for 24 h, and then the level of PGC-1α, HNF4α and FOXO1 were examined by Q-RT PCR or Western blot analysis. As shown in Figure 3A and 3B, 8-Br-cAMP/Dex synergistically activated the gene and protein expression of PGC-1α. Treatment with HH-F3 suppressed 8-Br-cAMP/Dex-induced PGC-1α gene expression (Figure 3A and 3C). HH-F3 also decreased the protein levels of FOXO1 and HNF4α, which were associated with gluconeogenic transcription factor expression in Hep3B/T2 cells (Figure 3C). These results suggest that HH-F3-suppressed gluconeogenic enzyme expression may occur via inhibition of PGC-1α gene expression.

Bottom Line: We found that 8-Br-cAMP and glucocorticoids synergistically induce PGC-1α and its downstream targets, including PEPCK and G6Pase.HH-F3 also inhibited fatty acid synthase (FASN) expression and decreased lipid accumulation by down-regulating PGC-1α.HH-F3 may have potential use for the treatment of chronic hepatitis B patients with associated metabolic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan.

ABSTRACT
PGC-1α, a major metabolic regulator of gluconeogenesis and lipogenesis, is strongly induced to coactivate Hepatitis B virus (HBV) gene expression in the liver of fasting mice. We found that 8-Br-cAMP and glucocorticoids synergistically induce PGC-1α and its downstream targets, including PEPCK and G6Pase. Also, HBV core promoter activity was synergistically enhanced by 8-Br-cAMP and glucocorticoids. Graptopetalum paraguayense (GP), a herbal medicine, is commonly used in Taiwan to treat liver disorders. Partially purified fraction of GP (named HH-F3) suppressed 8-Br-cAMP/glucocorticoid-induced G6Pase, PEPCK and PGC-1α expression and suppressed HBV core promoter activity. HH-F3 blocked HBV core promoter activity via inhibition of PGC-1α expression. Ectopically expressed PGC-1α rescued HH-F3-inhibited HBV surface antigen expression, HBV mRNA production, core protein levels, and HBV replication. HH-F3 also inhibited fatty acid synthase (FASN) expression and decreased lipid accumulation by down-regulating PGC-1α. Thus, HH-F3 can inhibit HBV replication, gluconeogenesis and lipogenesis by down-regulating PGC-1α. Our study indicates that targeting PGC-1α may be a therapeutic strategy for treatment of HBV infections. HH-F3 may have potential use for the treatment of chronic hepatitis B patients with associated metabolic syndrome.

No MeSH data available.


Related in: MedlinePlus