HBx transfection limits proliferative capacity of podocytes through cell cycle regulation.
Our previous studies have shown that podocyte number is significantly decreased in glomeruli of children with hepatitis B virus (HBV)-associated glomerulonephritis. In this study, we aimed to explore whether exogenous expression of HBx protein could directly inhibit podocyte proliferation in vitro, and to investigate its role in cell cycle regulation. HBx gene was delivered into cultured mouse podocytes through an adenovirus-based vector. Cell morphology was evaluated with Wright-Giemsa staining. Cell growth and proliferation were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5,6-carboxyfluorescein diacetate, succinimidyl ester (CFSE)-based proliferation assays. Cell cycle phase was analyzed by flow cytometry, and the expression of cell cycle regulatory proteins was examined by western blot analysis. It was found that the aberrant nuclear changes like double and multiple micronuclei, which reflect mitotic catastrophe, accumulated in podocytes after 5 days post-infection. MTT assay showed that Ad.HBx-infected podocytes grew much more slowly than controls at day 4 post-infection and thereafter. Furthermore, CFSE-based proliferation assay also showed that the proliferation of HBx-expressing podocytes was significantly inhibited than that of controls at 3-day post-infection, and that the difference became much more obvious at day 5 post-infection. Cell cycle analysis showed that the transfection of HBx resulted in significant up-regulation of both cyclin B1 and CDK-inhibitor p21 expression and G2/M phase arrest, and slight down-regulation of cyclin A expression. These results demonstrated that exogenous expression of HBx might limit the proliferative capacity of podocytes through cell cycle regulation, thus suggesting that HBx may play a role in podocyte injuries in HBV-associated glomerulonephritis.
Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Yu
Y
Zhang
Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Yu
Y
Chen
Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Fengjie
F
Yang
Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China jhzhou999@163.com.
Jianhua
J
Zhou
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002453:Cell Cycle; D002461:Cell Line, Transformed; D056744:Cyclin B1 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D005434:Flow Cytometry; D051379:Mice; D050199:Podocytes / Q000166:cytology*; D015534:Trans-Activators / Q000235:genetics*; D014162:Transfection; D054334:Viral Regulatory and Accessory Proteins
C493957:Cdkn1a protein, mouse; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein
HBV-associated glomerulonephritis; cell cycle; hepatitis B virus X protein; podocyte