C hronic hepatitis B virus (HBV) infection has been proven to be one of the most important risk factors for the development of hepatocellular carcinoma (HCC) (3, 9). However, the pathogenesis of cancer in HBV infection is still not fully understood, and it appears that multiple factors and cellular signaling pathways are involved in hepatocarcinogenesis (28). Integration of HBV genome into host DNA can lead to alterations in cellular gene function or generate chromosomal instability (1, 10, 43). Expression of some oncogenic HBV proteins such as HBx and truncated Pre-S2/S has been shown to have a direct effect on malignant transformation of the liver (42) and to promote metastasis of the malignant cells, and there is thus a very high mortality rate for HCC patients (18). Another HBV protein, encoded by a singly spliced 2.2-kb HBV DNA and referred to as the hepatitis B spliced protein (HBSP), is found to be expressed in liver biopsy tissues from four out of five chronic patients but not from two hepatitis C virus-infected patient samples and one normal liver sample (39). Our prior study also showed that a 2.2-kb splice variant was present in all tumor and peritumor samples from 12 HCC patients studied (20). Exogenous expression of HBSP in transfected Huh-7 cells can induce cell apoptosis (40). However, the cytopathic effect of the HBSP was unclear, and its role in progression, invasion, and metastasis of HBV-related HCC has not yet been elucidated.We previously showed that cathepsin B (CTSB) was one of the major intracellular interacting partners of HBSP, and it was identified using a yeast two-hybrid screening assay (8). This led us to investigate whether the HBSP could interact with CTSB in the context of hepatoma cells to affect cell migration, invasion, and metastasis, all of which can be modulated by CTSB acting directly and indirectly on extracellular matrix (ECM) component remodeling and degradation (26,47). CTSB is a lysosomal cysteine protease that plays an important role in physiological protein turnover and processing (19,41). In nonmalignant cells, CTSB is mainly stored in the lysosome, whereas in malignant cells, CTSB redistributes into exocytic vesicles at the cell periphery, leading to its secretion and association with binding partners on the tumor cell surface (22,33). CTSB can cleave and activate a wide variety of substrates in proteolytic pathways that increase neoplastic progression. It has been shown that activation of urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs) by CTSB not only enhances ECM degradation and cancer cell motility and invasion (14) but also induces in vitro angiogenesis (2). In addition to interacting with other proteases, CTSB may regulate the activity of kinase signaling networks, cell surface receptors, and signaling molecules such as chemokines, cytokines and growth factors (25). However, such interactions are usually bidirectional because kinases can also regulate many proteases through phosphorylation while proteases can control the actio...

Hepatitis B virus X protein (HBx protein) is a multifunctional regulatory protein. The transactivation of nuclear factor kappa B (NF-κB) by HBx protein has been shown to be of importance in the pathogenesis of HBV-related diseases. However, the mechanism involved remains largely unclear. In this study, a CytoTrap yeast two-hybrid system was employed to screen binding partners of the HBx protein; 29 cellular proteins, including valosin-containing protein (VCP), were identified. The interaction between HBx protein and VCP was further confirmed in vitro and in vivo using a glutathione S-transferase pull-down assay and co-immunoprecipitation, respectively. It was also shown that this interaction is mediated by amino acid residues 51-120 of the HBx protein. In Huh-7 hepatoma cells, HBx protein enhanced the VCP-mediated activation of NF-κB. Our findings provide new insights into the molecular mechanisms that lead to the activation of NF-κB by HBx protein.

BackgroundTo investigate mosquito larval habitats and resistance to common insecticides in areas with high incidence rates of mosquito-borne diseases in Jining, Shandong Province, and to provide a scientific basis for the future prevention and control of mosquito-borne diseases and the rational use of insecticides. Methods and resultsFrom June to September 2018, mosquito habitat characteristics and species compositions in Jintun town were studied through a cross-sectional survey. Larvae and pupae were collected in different habitats using the standard dipping technique. A total of 7,815 mosquitoes, comprising 7 species from 4 genera, were collected. Among them, Culex pipiens pallens (n = 5,336, 68.28%) was the local dominant species and found in all four habitats (rice paddies, irrigation channels, water containers, drainage ditches). There were 1,708 Cx. tritaeniorhynchus (21.85%), 399 Anopheles sinensis (5.11%), 213 Armigeres subalbatus (2.72%), 124 Aedes albopictus (1.59%), and 35 other (Cx. bitaeniorhynchus and Cx. halifaxii) (0.45%) mosquito samples collected. Spearman correlation analysis was employed to evaluate the relationship between larval density and the physicochemical characteristics of the breeding habitat. It was found that the larval density of Cx. tritaeniorhynchus correlated positively with water depth (r = 0.927 p = 0.003), the larval density of An. sinensis correlated positively with dissolved oxygen (DO) (r = 0.775 p = 0.041) and the larval density of Cx. p. pallens correlated positively with ammonia nitrogen (r = 0.527 p = 0.002). Resistance bioassays were carried out on the dominant populations of Cx. p. pallens: mosquitoes presented very high resistance to cypermethrin and deltamethrin, moderate PLOS ONE PLOS ONE | https://doi.org/10.

Hepatitis B spliced protein (HBSP) encoded by a 2.2 kb singly spliced hepatitis B virus (HBV) pre-genomic RNA (spliced between positions 2447 and 489 nt) is involved in the pathogenesis of HBV infection, whereas the exact mechanism is far from being fully elucidated. In this study, a yeast two-hybrid system using HBSP as bait was employed to screen binding partners for HBSP from a human liver cDNA library. The interaction between HBSP and fibrinogen γ chain (FGG) was further confirmed in vitro using a GST pull-down assay and confirmed in vivo using a mammalian two-hybrid assay and co-immunoprecipitation. It was identified that this interaction is mediated by the N terminal 47 amino acid residues of HBSP. HBSP could inhibit fibrin polymerization, factor XIIIa-mediated fibrin cross-linking, adhesion of platelets to fibrinogen and ADP-stimulated platelet aggregation. However, the interaction-mediating fragment 1-47 of HBSP is not sufficient for the inhibitory activity on fibrinogen function. The findings suggested that HBSP may participate in the hemostatic abnormality in patients with HBV-related liver diseases.

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