HBx inhibits proliferation and induces apoptosis via Fas/FasL upregulation in rat renal tubular epithelial cells

He, Ping; Zhou, Guangyu; Qu, Dan; Zhang, Beiru; Wang, Yanqiu

doi:10.5301/jn.5000304

Cited by 13 publications

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“…Our previous studies of the pathology of renal tissues of patients with HBV-GN indicated that apoptosis occurs mainly at the proximal and distal ends of the tubular epithelial cells, and only rarely in the glomeruli [12]. We also found that transfection of the HBx eukaryotic expression vector into in vitro cultured renal tubular epithelial cells induced renal epithelial apoptosis via Fas/FasL up-regulation [13]. However, the upstream signal pathway responsible for Fas/ FasL activation in tubular epithelial cells is still unknown.…”

Section: Introductionmentioning

confidence: 79%

“…Similarly, an in vitro study of liver cells indicated that HBx induces apoptosis due to activation of the MLK3-MKK7-JNKs signaling module, which up-regulates FasL expression. Our previous research [13] showed that HBx inhibits proliferation and induces apoptosis via Fas/FasL up-regulation in rat renal tubular epithelial cells. Therefore, it is important to determine if HBx also activates the MLK3-MKK7-JNKs signaling module and induces apoptosis in renal tubular epithelial cells.…”

Section: Introductionmentioning

confidence: 99%

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Hepatitis B Virus X Protein Modulates Apoptosis in NRK-52E Cells and Activates Fas/FasL Through the MLK3-MKK7-JNK3 Signaling Pathway

Zhang

Liu

et al. 2016

Cell Physiol Biochem

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Background/Aims: The hepatitis B virus X protein (HBx) contributes to HBV-induced injury of renal tubular cells and induces apoptosis via Fas/FasL up-regulation. However, the mechanism of Fas/FasL activation is unknown. Recent studies indicated that HBx induction of apoptosis in hepatic cells depends on activating the MLK3-MKK7-JNKs signaling module, which then up-regulates FasL expression. In this study, we used NRK-52E cells transfected an HBx expression vector to examine the role of the MLK3-MKK7-JNKs signaling pathway on HBx-induced renal tubular cell injury. Methods: NRK-52E cells were transfected with pc-DNA3.1(+)-HBx to establish an HBx over-expression model, and with pc-DNA3.1(+)-HBx and pSilencer3.1-shHBx to establish an HBx low expression model. One control group was not transfected and another control group was transfected with an empty plasmid. Cell proliferation was determined by the formazan dye method (Cell Counting Kit-8) and apoptosis was measured by flow cytometry and fluorescence microscopy. Western blotting was used to measure the expression of Fas, FasL, and MLK3-MKK7-JNKs signaling pathway-related proteins. The activity of caspase-8 was measured by spectrophotometry. Results: Transfection of NRK-52E cells with pc-DNA3.1(+)-HBx inhibited cell proliferation and increased apoptosis and caspase-8 activity. The expression of Fas, FasL, and MLK3-MKK7-JNKs signaling pathway-related proteins were also greater in the pc-DNA3.1(+)-HBx group, but lower in RNAi group. Furthermore, the activity of MLK3-MKK7-JNKs signaling pathway, expression of Fas/FasL, and apoptosis were significantly lower in the pc-DNA3.1(+)-HBx group when treated with K252a, a known inhibitor of MLK3. Conclusions: Our results show that HBx induces apoptosis in NRK-52E cells and activates Fas/FasL via the MLK3-MKK7-JNK3-c-Jun signaling pathway.

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Hepatitis B Virus X Protein Modulates Apoptosis in NRK-52E Cells and Activates Fas/FasL Through the MLK3-MKK7-JNK3 Signaling Pathway

Zhang

Liu

et al. 2016

Cell Physiol Biochem

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“…The membrane attack complex (C5b-9) leads to podocyte injury, including calcium influx, oxidative injury, production of arachidonic acid metabolites, cell cycle dysregulation, and endoplasmic reticulum stress [21, 22], These lead to podocyte apoptosis, reduced podocyte adhesion, and detachment of podocytes from GBM, which may result in proteinuria and renal failure [19, 22]. However, some recent reports that identified HBV-DNA, HBV-RNA, and cccDNA in the kidneys suggested that direct virally induced renal damage may also play an important role in the disease process [3, 12, 23]. The focus of the present paper is to examine the direct effect of HBV on podocyte injury and to find the reason for the reduced podocyte numbers in HBV-GN.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have shown that the absolute number and relative density of podocytes are reduced in HBV-GN [4], although the precise mechanism of this effect is unknown. In our previous study of tubular epithelial cells [2, 12], we found that HBx inhibited cell proliferation and induced apoptosis. Thus, in the present study, we investigated the effects of HBx on the apoptosis and adhesion of podocytes and the mechanism of this response.…”

Section: Discussionmentioning

confidence: 99%

“…The plasmid pcDNA3.1(+)-HBx was constructed as previously reported [12]. Some experiments had three treatment groups: (i) control (no transfection); (ii) transfection with empty pc-DNA3.1(+) plasmid; and (iii) transfection with pc-DNA3.1(+)-HBx and evaluated after 48 h. Lipofectamine TM LTX and PLUS TM transfection reagents (Invitrogen, USA) were used to conduct the transfection according to the steps described in the instructions.…”

Section: Methodsmentioning

confidence: 99%

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Hepatitis B Virus X Protein Reduces Podocyte Adhesion via Downregulation of α3β1 Integrin

Liu

Zhang

et al. 2017

Cell Physiol Biochem

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Background/Aims: Hepatitis B virus (HBV)-associated glomerulonephritis (HBV-GN) is characterized by a reduced number of podocytes due to apoptosis and shedding from the basement membrane. However, the pathological mechanism of HBV-GN is unclear. We previously showed that hepatitis B virus X protein (HBx) promotes apoptosis in tubular epithelial cells. In this study, we transfected podocytes with HBx and examined the effects on adhesion and apoptosis of these cells. Methods: Podocytes were transfected with pc-DNA3.1 (+)-HBx. One control group was not transfected and another control group was transfected with empty plasmids. Podocyte adhesion was assessed by a fluorescence assay, apoptosis was measured by flow cytometry and fluorescence microscopy, and expression of α3β1 integrin was determined by western blotting and the reverse transcription polymerase chain reaction (RT-PCR). Activity of caspase-8 was measured by a spectrophotometric assay. Results: Relative to controls, podocytes with pc-DNA3.1(+)-HBx had reduced cell adhesion, increased apoptosis, reduced expression of α3β1 integrin, and increased caspase-8 activity. β1 integrin blockage reduced podocyte adhesion, but increased apoptosis and caspase-8 activity. Treatment of transfected podocytes with a caspase-8 inhibitor (Z-IETD-FMK) had no effect on the HBx-mediated integrin downregulation and reduced podocyte adhesion, suggesting that α3β1 integrin downregulaton is sufficient to alter cell adhesion. Conclusions: Our in vitro results indicate that HBx reduced podocyte adhesion and expression of α3β1 integrin, and increased apoptosis. Moreover, HBx-mediated downregulation of α3β1 integrin expression is sufficient to reduce podocyte adhesion. HBx-induced apoptosis of podocytes may contribute to HBV-GN.

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HBxAg suppresses apoptosis of human placental trophoblastic cell lines via activation of the PI3K/Akt pathway

Wang

Shi²,

Bai

et al. 2016

Cell Biology International

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The aim of this study is to investigate the effect of hepatitis B virus X (HBx) protein on the apoptosis of placental trophoblastic cells and its potential mechanism. A pcDNA3.1 expression vector of HBx gene was built and transfected into JEG-3 and HTR-8 human placental trophoblastic cell lines, respectively. After transfection for 48 h, RT-PCR and immunofluorescence analyses showed that HBx mRNA and protein expression was detected in JEG-3 and HTR-8 cells. Flow cytometry revealed that early apoptosis of JEG-3 and HTR-8 cells was reduced by pcDNA-HBx transfection. Immunofluorescence and Western blotting showed that PI3K and p-Akt were significantly upregulated in HTR-8 cells. HBx ectopic expression did not change the viability of JEG-3 and HTR-8 cells when the PI3K/Akt pathway was blocked by its specific inhibitor LY294002. Moreover, the pcDNA-PI3K expression vector and pcDNA-HBx were transfected individually or co-transfected into the cells. The results showed that pcDNA-PI3K/pcDNA-HBx co-transfection promoted the expression of PI3K protein compared with the pcDNA-PI3K transfection group but did not increase the expression of HBx protein compared with pcDNA-HBx transfection group. In conclusion, HBx gene can be transferred into JEG-3 and HTR-8 human placental trophoblastic cell lines and cause inhibition of cell apoptosis. Its effect of apoptosis inhibition is related to the activation of the PI3K/Akt signaling pathway.

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HBx inhibits proliferation and induces apoptosis via Fas/FasL upregulation in rat renal tubular epithelial cells

Abstract: Our results suggest that HBx induces apoptosis in NRK-52E cells, at least in part through activation of the Fas/FasL pathway. The activation of caspase-8 appears to mediate the induction of apoptosis.

Cited by 13 publications

References 0 publications

Hepatitis B Virus X Protein Modulates Apoptosis in NRK-52E Cells and Activates Fas/FasL Through the MLK3-MKK7-JNK3 Signaling Pathway

Hepatitis B Virus X Protein Modulates Apoptosis in NRK-52E Cells and Activates Fas/FasL Through the MLK3-MKK7-JNK3 Signaling Pathway

Hepatitis B Virus X Protein Reduces Podocyte Adhesion via Downregulation of α3β1 Integrin

HBxAg suppresses apoptosis of human placental trophoblastic cell lines via activation of the PI3K/Akt pathway

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