title: HBx co-localizes with COXIII in HL-7702 cells to upregulate mitochondrial function and ROS generation.
abstract: Hepatocellular carcinoma (HCC) is one of the most common malignant diseases, and HBx leads to the development of HBV-associated HCC. Mitochondria are key organelles that regulate apoptosis, cellular energetics and signal transduction pathways, and are the source of HBx-induced reactive oxygen species (ROS). Recent findings have shown that HBx interacts with the inner mitochondrial membrane protein, COXIII, via the yeast two-hybrid system, mating experiment and coimmunoprecipitation. The aim of the present study was to examine the co-localizaiton of HBx and COXIII in HL-7702 cells and to investigate ensuing alterations of mitochondrial function. An HL-7702 cell line stably expressing the HBx gene by lentivirus vectors was constructed. Confocal microscopy was utilized to assess the interaction between HBx protein and COXIII. Expression of COXIII, activities of cytochrome c oxidase (COX) and the mitochondrial membrane potential, which were functionally relevant to the HBx protein-COXIII interaction, were investigated in cell cultures. Moreover, the intracellular ROS levels were detected by flow cytometry. The results demonstrated that HBx co-localized with the inner mitochondrial protein, COXIII, in HL-7702 cells, causing the upregulation of COXIII protein expression as well as COX activity. However, HBx did not alter the mitochondrial membrane potential and mitochondria exhibited only slight swelling in HL-7702-HBx cells. Moreover, HBx elevated the generation of mitochondrial ROS in HL-7702-HBx cells. The main finding of the present study was that the co-localization of HBx and COXIII leads to upregulation of the mitochondrial function and ROS generation, which are associated with the oncogenesis of HBV-associated HCC.
authors.affiliation: Department of Infection, Union Hospital of Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Lai-Yu
authors.initials: LY
authors.lastname: Zou
authors.affiliation: Department of Gastroenterology, Union Hospital of Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Bi-Yun
authors.initials: BY
authors.lastname: Zheng
authors.affiliation: Department of Gastroenterology, Union Hospital of Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Xue-Fen
authors.initials: XF
authors.lastname: Fang
authors.affiliation: Department of Gastroenterology, Union Hospital of Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Gastroenterology, Union Hospital of Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Yue-Hong
authors.initials: YH
authors.lastname: Huang
authors.affiliation: Department of Gastroenterology, Union Hospital of Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Zhi-Xin
authors.initials: ZX
authors.lastname: Chen
authors.affiliation: Laboratory of Electron Microscopy, Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Lin-Ying
authors.initials: LY
authors.lastname: Zhou
authors.affiliation: Department of Gastroenterology, Union Hospital of Fujian Medical University, Gulou, Fuzhou, Fujian 350001, P.R. China.
authors.forename: Xiao-Zhong
authors.initials: XZ
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000821:virology; D002460:Cell Line; D004272:DNA, Mitochondrial / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006515:Hepatitis B virus / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000821:virology; D053078:Membrane Potential, Mitochondrial / Q000235:genetics; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004272:DNA, Mitochondrial; D017382:Reactive Oxygen Species; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein