流体动力学基因转染技术构建乙肝病毒HBx蛋白瞬时表达小鼠模型

目的：构建乙肝病毒HBx蛋白瞬时表达小鼠模型,为研究HBx在HBV感染相关原发性肝细胞癌发生中的分子机制奠定基础。方法：8只6~8周龄雄性CD-1小鼠,尾静脉注射真核表达质粒pcDNA-HBx及空载体pcDNA3.0,6~8 h处死小鼠并收集肝组织,抽提RNA及蛋白。RT-PCR和Western blot检测HBx表达情况;实时荧光定量PCR检测FXR靶基因SHP和Cyp7a1的mRNA表达。结果：核酸和蛋白水平上,pcDNA-HBx注射组小鼠肝脏内均可检测到HBx的表达;空载体对照组肝组织中未检测到HBx的表达;肝组织中瞬时过表达的HBx可以有效调控FXR通路下游靶基因SHP和Cyp7a1的mRNA表达。结论：成功实现了HBx在小鼠肝脏中的瞬时高表达,为今后整体水平上研究HBx提供了有效的动物模型。     

Occult hepatitis B virus and hepatocellular carcinoma

Occult hepatitis B virus (HBV) infection (OBI) is a challenging pathobiological and clinical issue that has been widely debated for several decades. By definition, OBI is characterized by the persistence of HBV DNA in the liver tissue (and in some cases also in the serum) in the absence of circulating HBV surface antigen (HBsAg). Many epidemiological and molecular studies have indicated that OBI is an important risk factor for hepatocellular carcinoma (HCC) development. OBI may exert direct pro-oncogenic effects through the activation of the same oncogenic mechanisms that are activated in the course of an HBsAg-positive infection. Indeed, in OBI as in HBV-positive infection, HBV DNA can persist in the hepatocytes both integrated into the host genome as well as free episome, and may maintain the capacity to produce proteins-mainly X protein and truncated preS-S protein - provided with potential transforming properties. Furthermore, OBI may indirectly favor HCC development. It has been shown that the persistence of very low viral replicative activity during OBI may induce mild liver necro-inflammation continuing for life, and substantial clinical evidence indicates that OBI can accelerate the progression of liver disease towards cirrhosis that is considered the most important risk factor for HCC development.     

HBx基因重组逆转录病毒载体的构建及表达

目的:构建携带HBx基因的重组逆转录病毒载体,为进一步研究HBx基因在HBV相关性HCC(原发性肝癌)发病机制中的作用以及建立肝癌动物模型奠定基础.方法:根据基因库中已公布的HBx序列设计引物,采用PCR技术从HBx腺病毒质粒中扩增出HBx基因.将HBx基因克隆到逆转录病毒载体pSEB-HUS质粒中.酶切、PCR及测序鉴定后经脂质体介导转染L02细胞,Western Blotting检测HBx蛋白的表达.结果:PCR、酶切及测序鉴定证实目的基因正确克隆至逆转录病毒质粒pSEB-HUS中,目的基因序列与GENE BANK报道一致,转染L02细胞后荧光显微镜可观察到GFP的表达.Western Blotting检测可见HBx蛋白的表达.结论:成功构建HBx重组逆转录病毒载体.     

乙型肝炎病毒X蛋白对DNA甲基转移酶3A/3B表达的影响

目的观察乙型肝炎病毒X蛋白（HBx）对QSG7701细胞中DNA甲基转移酶（DNMT）3A/3B表达的影响。方法本研究室前期构建好的重组表达质粒pcDNA-X及空载体pcDNA3.0分别转染QSG7701细胞,经含G418的选择性培养基筛选获得稳定转染HBV-X基因的细胞克隆（pcDNA-X/QSG7701）及稳定转染空载体pcDNA3.0的细胞克隆（pcDNA3.0/QSG7701）。采用RT-PCR、Westernblot分别检测转染细胞中HBxmRNA和HBx蛋白的表达。Real-timePCR检测3种细胞DNMT3A/3BmRNA的表达情况。免疫组织化学法检测3种细胞DNMT3A/3B蛋白的表达情况。结果RT-PCR、Westernblot检测结果显示pcDNA-X/QSG7701细胞中有HBxmRNA及HBx蛋白的表达。Real-timePCR结果显示pcDNA-X/QSG7701中DNMT3A/3BmRNA表达水平显著高于pcDNA3.0/QSG7701及未转染的细胞QSG7701（P〈0.05）。免疫组织化学检测结果显示pcDNA-X/QSG7701细胞中DNMT3A/3B蛋白表达水平显著高于pcDNA3.0/QSG7701及QSG7701细胞（P〈0.05）。结论稳定转染HBV-X基因的人源性永生化非瘤性肝细胞QSG7701中DNMT3A/3BmRNA和蛋白的表达水平均显著升高,提示HBV-X基因在mRNA及蛋白水平能上调转染细胞中DNMT3A/3B的表达,而细胞中DNMT3A/3B表达的增加是否能进一步影响癌基因、抑癌基因的表达水平,从而导致细胞癌变,尚有待进一步研究。     

携HBx基因逆转录病毒载体的构建

【目的】构建携HBx基因的逆转录病毒载体 ,为研究HBx基因与肝癌生物学行为间的关系提供基础。【方法】采用PCR技术从HBV全基因组中扩增HBx基因 ;将HBx基因亚克隆至质粒pLNSX ,构建质粒 pLNSHBx ,磷酸钙 DNA共沉淀法将重组体导入包装细胞系PA317,检测培养上清病毒滴度。【结果】应用PCR技术成功地从HBV基因组中克隆出全长HBx基因 ,并经序列分析证实 ;建立了产病毒细胞株PA317/HBx ,检测其培养上清病毒滴度为 8.9× 10 4 CFU ,PCR证实重组病毒中含有HBx基因。【结论】成功构建了携HBx基因的较高滴度逆转录病毒载体。     

Hepatitis B x antigen (HBx) is an important therapeutic target in the pathogenesis of hepatocellular carcinoma

Hepatitis B virus (HBV) is a human pathogen that has infected an estimated two billion people worldwide. Despite the availability of highly efficacious vaccines, universal screening of the blood supply for virus, and potent direct acting anti-viral drugs, there are more than 250 million carriers of HBV who are at risk for the sequential development of hepatitis, fibrosis, cirrhosis and hepatocellular carcinoma (HCC). More than 800,000 deaths per year are attributed to chronic hepatitis B. Many different therapeutic approaches have been developed to block virus replication, and although effective, none are curative. These treatments have little or no impact upon the portions of integrated HBV DNA, which often encode the virus regulatory protein, HBx. Although given little attention, HBx is an important therapeutic target because it contributes importantly to (a) HBV replication, (b) in protecting infected cells from immune mediated destruction during chronic infection, and (c) in the development of HCC. Thus, the development of therapies targeting HBx, combined with other established therapies, will provide a functional cure that will target virus replication and further reduce or eliminate both the morbidity and mortality associated with chronic liver disease and HCC. Simultaneous targeting of all these characteristics underscores the importance of developing therapies against HBx.     

miRNA-7/21/107 contribute to HBx-induced hepatocellular carcinoma progression through suppression of maspin

Maspin suppresses tumor progression by promoting cell adhesion and apoptosis and by inhibiting cell motility. However, its role in tumorigenesis of hepatocellular carcinoma (HCC) remains unclear. The gene regulation of maspin and its relationship with HCC patient prognosis were investigated in this study. Maspin expression was specifically reduced in HBV-associated patients and correlated with their poor prognosis. Maspin downregulation in HCC cells was induced by HBx to promote their motility and resistance to anoikis and chemotherapy. HBx-dependent induction of microRNA-7, -107, and -21 was further demonstrated to directly target maspin mRNA, leading to its protein downregulation. Higher expressions of these microRNAs also correlated with maspin downregulation in HBV-associated patients, and were associated with their poor overall survival. These data not only provided new insights into the molecular mechanisms of maspin deficiency by HBx, but also indicated that downregulation of maspin by microRNAs confers HBx-mediated aggressiveness and chemoresistance in HCC.     

Hepatitis B Virus HBx Protein Interactions with the Ubiquitin Proteasome System

The hepatitis B virus (HBV) causes acute and chronic hepatitis, and the latter is a major risk factor for the development of hepatocellular carcinoma (HCC). HBV encodes a 17-kDa regulatory protein, HBx, which is required for virus replication. Although the precise contribution(s) of HBx to virus replication is unknown, many viruses target cellular pathways to create an environment favorable for virus replication. The ubiquitin proteasome system (UPS) is a major conserved cellular pathway that controls several critical processes in the cell by regulating the levels of proteins involved in cell cycle, DNA repair, innate immunity, and other processes. We summarize here the interactions of HBx with components of the UPS, including the CUL4 adaptor DDB1, the cullin regulatory complex CSN, and the 26S proteasome. Understanding how these protein interactions benefit virus replication remains a challenge due to limited models in which to study HBV replication. However, studies from other viral systems that similarly target the UPS provide insight into possible strategies used by HBV.