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Hepatic SATB1 induces paracrine activation of hepatic stellate cells and is upregulated by HBx

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ABSTRACT

Chronic hepatitis B virus (HBV) infection is a major cause of chronic liver diseases, but its involvement in hepatic fibrogenesis remains unclear. Special AT-rich binding protein 1 (SATB1) has been implicated in reprogramming chromatin organization and transcription profiles in many cancers and non-cancer-related conditions. We found that hepatic SATB1 expression was significantly up-regulated in fibrotic tissues from chronic hepatitis B virus (HBV)-infected patients and HBV transgenic (HBV-Tg) mouse model. Knockdown of SATB1 in the liver significantly alleviated CCl4-induced fibrosis in HBV-Tg mouse model. Moreover, we suggested HBV encoded x protein (HBx) induced SATB1 expression through activation of JNK and ERK pathways. Enforced expression of SATB1 in hepatocytes promoted the activation and proliferation of hepatic stellate cells (HSCs) by secretion of connective tissue growth factor (CTGF), Interleukin-6 (IL-6) and platelet derived growth factor-A (PDGF-AA). Our findings demonstrated that HBx upregulated hepatic SATB1 which exerted pro-fibrotic effects by paracrine activation of stellate cells in HBV-related fibrosis.

No MeSH data available.


HBx upregulates SATB1 expression through the JNK and ERK pathway and the activation of c-Jun.(a) L02-HBx, CHL-HBx cells and corresponding control groups L02-Vector, L02-WT, CHL-Vector, CHL-WT were respectively treated with specific JNK inhibitor SP600125 (25 uM), ERK1/2 inhibitor U0126 (25 uM), PI3K inhibitor Ly294002 (25 uM), p38 inhibitor SB203580 (25 uM) for 48 hours. Protein levels of SATB1, c-Jun, phosphorylated and total JNK, ERK1/2, p38 and Akt were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (b) Real-time PCR analysis of SATB1 expression in L02-HBx, CHL-HBx cells and corresponding control groups after transfection with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 for 48 hours, respectively. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC. (c) Protein levels of SATB1, c-Jun, Sp1, NFKB1 were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (d) SATB1 promoter reporter vectors were contransfected with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 into L02-HBx and CHL-HBx cells, respectively. The SATB1 promoter activity was measured at 72 h posttranscfection. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC.
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f4: HBx upregulates SATB1 expression through the JNK and ERK pathway and the activation of c-Jun.(a) L02-HBx, CHL-HBx cells and corresponding control groups L02-Vector, L02-WT, CHL-Vector, CHL-WT were respectively treated with specific JNK inhibitor SP600125 (25 uM), ERK1/2 inhibitor U0126 (25 uM), PI3K inhibitor Ly294002 (25 uM), p38 inhibitor SB203580 (25 uM) for 48 hours. Protein levels of SATB1, c-Jun, phosphorylated and total JNK, ERK1/2, p38 and Akt were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (b) Real-time PCR analysis of SATB1 expression in L02-HBx, CHL-HBx cells and corresponding control groups after transfection with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 for 48 hours, respectively. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC. (c) Protein levels of SATB1, c-Jun, Sp1, NFKB1 were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (d) SATB1 promoter reporter vectors were contransfected with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 into L02-HBx and CHL-HBx cells, respectively. The SATB1 promoter activity was measured at 72 h posttranscfection. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC.

Mentions: It is known that HBx can induce the phosphorylation of ERK1/2, JNK and p38 MAPKs14. To elucidate the molecule mechanism of HBx-mediated SATB1 expression, U0126, SP600125, SB203580 and LY294002 were used to specifically render inactivate of ERK1/2, JNK,p38 MAPK and PI3k-Akt pathway, respectively. Pretreatment with the ERK1/2 inhibitor (U0126) and JNK inhibitor (SP600125) significantly suppressed HBx-induced SATB1 expression, while pretreatment with p38 or Akt inhibitors had no effect on the SATB1 expression (Fig. 4a and Supplementary Fig. S4a), indicating that ERK1/2 and JNK pathways contributed to HBx-induced SATB1 production. Besides, prominent changes in the levels of c-Jun were noted in HBx-induced SATB1 expression, which suggested that HBx promoted the expression of SATB1 probably in a c-Jun-dependent manner (Fig. 4a). Collectively, our results suggest that HBx may upregulate SATB1 expression via ERK1/2/c-Jun and JNK/c-Jun signal pathways in L02 cell line.


Hepatic SATB1 induces paracrine activation of hepatic stellate cells and is upregulated by HBx
HBx upregulates SATB1 expression through the JNK and ERK pathway and the activation of c-Jun.(a) L02-HBx, CHL-HBx cells and corresponding control groups L02-Vector, L02-WT, CHL-Vector, CHL-WT were respectively treated with specific JNK inhibitor SP600125 (25 uM), ERK1/2 inhibitor U0126 (25 uM), PI3K inhibitor Ly294002 (25 uM), p38 inhibitor SB203580 (25 uM) for 48 hours. Protein levels of SATB1, c-Jun, phosphorylated and total JNK, ERK1/2, p38 and Akt were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (b) Real-time PCR analysis of SATB1 expression in L02-HBx, CHL-HBx cells and corresponding control groups after transfection with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 for 48 hours, respectively. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC. (c) Protein levels of SATB1, c-Jun, Sp1, NFKB1 were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (d) SATB1 promoter reporter vectors were contransfected with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 into L02-HBx and CHL-HBx cells, respectively. The SATB1 promoter activity was measured at 72 h posttranscfection. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC.
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f4: HBx upregulates SATB1 expression through the JNK and ERK pathway and the activation of c-Jun.(a) L02-HBx, CHL-HBx cells and corresponding control groups L02-Vector, L02-WT, CHL-Vector, CHL-WT were respectively treated with specific JNK inhibitor SP600125 (25 uM), ERK1/2 inhibitor U0126 (25 uM), PI3K inhibitor Ly294002 (25 uM), p38 inhibitor SB203580 (25 uM) for 48 hours. Protein levels of SATB1, c-Jun, phosphorylated and total JNK, ERK1/2, p38 and Akt were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (b) Real-time PCR analysis of SATB1 expression in L02-HBx, CHL-HBx cells and corresponding control groups after transfection with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 for 48 hours, respectively. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC. (c) Protein levels of SATB1, c-Jun, Sp1, NFKB1 were analyzed by western blot. Full-length blots are included in the Supplementary Fig. S8. (d) SATB1 promoter reporter vectors were contransfected with siRNA targeting various transcription factors c-Jun, Sp1, NFKB1 into L02-HBx and CHL-HBx cells, respectively. The SATB1 promoter activity was measured at 72 h posttranscfection. (n = 3). *P < 0.05, **P < 0.01 vs. L02-HBx NC or CHL-HBx NC.
Mentions: It is known that HBx can induce the phosphorylation of ERK1/2, JNK and p38 MAPKs14. To elucidate the molecule mechanism of HBx-mediated SATB1 expression, U0126, SP600125, SB203580 and LY294002 were used to specifically render inactivate of ERK1/2, JNK,p38 MAPK and PI3k-Akt pathway, respectively. Pretreatment with the ERK1/2 inhibitor (U0126) and JNK inhibitor (SP600125) significantly suppressed HBx-induced SATB1 expression, while pretreatment with p38 or Akt inhibitors had no effect on the SATB1 expression (Fig. 4a and Supplementary Fig. S4a), indicating that ERK1/2 and JNK pathways contributed to HBx-induced SATB1 production. Besides, prominent changes in the levels of c-Jun were noted in HBx-induced SATB1 expression, which suggested that HBx promoted the expression of SATB1 probably in a c-Jun-dependent manner (Fig. 4a). Collectively, our results suggest that HBx may upregulate SATB1 expression via ERK1/2/c-Jun and JNK/c-Jun signal pathways in L02 cell line.

View Article: PubMed Central - PubMed

ABSTRACT

Chronic hepatitis B virus (HBV) infection is a major cause of chronic liver diseases, but its involvement in hepatic fibrogenesis remains unclear. Special AT-rich binding protein 1 (SATB1) has been implicated in reprogramming chromatin organization and transcription profiles in many cancers and non-cancer-related conditions. We found that hepatic SATB1 expression was significantly up-regulated in fibrotic tissues from chronic hepatitis B virus (HBV)-infected patients and HBV transgenic (HBV-Tg) mouse model. Knockdown of SATB1 in the liver significantly alleviated CCl4-induced fibrosis in HBV-Tg mouse model. Moreover, we suggested HBV encoded x protein (HBx) induced SATB1 expression through activation of JNK and ERK pathways. Enforced expression of SATB1 in hepatocytes promoted the activation and proliferation of hepatic stellate cells (HSCs) by secretion of connective tissue growth factor (CTGF), Interleukin-6 (IL-6) and platelet derived growth factor-A (PDGF-AA). Our findings demonstrated that HBx upregulated hepatic SATB1 which exerted pro-fibrotic effects by paracrine activation of stellate cells in HBV-related fibrosis.

No MeSH data available.