The hepatitis B virus pre-core protein p22 activates Wnt sgnaling

An emerging theme for Wnt-addicted cancers is that the pathway is regulated at multiple steps via various mechanisms. Infection with hepatitis B virus (HBV) is a major risk factor for liver cancer, as is deregulated Wnt signaling, however, the interaction between these two causes is poorly understood. To investigate this interaction, we screened the effect of the various HBV proteins for their effect on Wnt/β-catenin signaling and identified the pre-core protein p22 as a novel and potent activator of TCF/β-catenin transcription. The effect of p22 on TCF/β-catenin transcription was dose dependent and inhibited by dominant-negative TCF4. HBV p22 activated synthetic and native Wnt target gene promoter reporters, and TCF/β-catenin target gene expression in vivo. Importantly, HBV p22 activated Wnt signaling on its own and in addition to Wnt or β-catenin induced Wnt signaling. Furthermore, HBV p22 elevated TCF/β-catenin transcription above constitutive activation in colon cancer cells due to mutations in downstream genes of the Wnt pathway, namely APC and CTNNB1. Collectively, our data identifies a previously unappreciated role for the HBV pre-core protein p22 in elevating Wnt signaling. Understanding the molecular mechanisms of p22 activity will provide insight into how Wnt signaling is fine-tuned in cancer

EIT enhanced self-Kerr nonlinearity in the three-level lambda system under Doppler broadening

Using density-matrix theory, an analytical expression of the self-Kerr nonlinear coefficient of a three-level lambda EIT medium for a weak probe light is derived. Influences of the coupling light and Doppler broadening on the self-Kerr coefficient are investigated and compared to experimental observation with a good agreement. The self-Kerr nonlinearity is basically modified and greatly enhanced in the spectral region corresponding to EIT transparent window. Furthermore, sign, slope, and magnitude of the self-Kerr coefficient can be controlled with frequency and intensity of the coupling light and temperature. Such controllable Kerr nonlinearity can find interesting applications in optoelectronic devices working with low-light intensity

Assessment of pre-clinical liver models based on their ability to predict the liver-tropism of AAV vectors

The liver is a prime target for in vivo gene therapies using recombinant adeno-associated viral vectors (rAAV). Multiple clinical trials have been undertaken for this target in the past 15 years, however we are still to see market approval of the first liver-targeted AAV-based gene therapy. Inefficient expression of the therapeutic transgene, vector-induced liver toxicity and capsid, and/or transgene-mediated immune responses reported at high vector doses are the main challenges to date. One of the contributing factors to the insufficient clinical outcomes, despite highly encouraging preclinical data, is the lack of robust, biologically- and clinically-predictive preclinical models. To this end, this study reports findings of a functional evaluation of six AAV vectors in twelve preclinical models of the human liver, with the aim to uncover which combination of models is the most relevant for the identification of AAV capsid variant for safe and efficient transgene delivery to primary human hepatocytes. The results, generated by studies in models ranging from immortalized cells, iPSC-derived and primary hepatocytes, and primary human hepatic organoids to in vivo models, increased our understanding of the strengths and weaknesses of each system. This should allow the development of novel gene therapies targeting the human liver

The Hepatitis B Virus Pre-Core Protein p22 Activates Wnt Signaling

An emerging theme for Wnt-addicted cancers is that the pathway is regulated at multiple steps via various mechanisms. Infection with hepatitis B virus (HBV) is a major risk factor for liver cancer, as is deregulated Wnt signaling, however, the interaction between these two causes is poorly understood. To investigate this interaction, we screened the effect of the various HBV proteins for their effect on Wnt/β-catenin signaling and identified the pre-core protein p22 as a novel and potent activator of TCF/β-catenin transcription. The effect of p22 on TCF/β-catenin transcription was dose dependent and inhibited by dominant-negative TCF4. HBV p22 activated synthetic and native Wnt target gene promoter reporters, and TCF/β-catenin target gene expression in vivo. Importantly, HBV p22 activated Wnt signaling on its own and in addition to Wnt or β-catenin induced Wnt signaling. Furthermore, HBV p22 elevated TCF/β-catenin transcription above constitutive activation in colon cancer cells due to mutations in downstream genes of the Wnt pathway, namely APC and CTNNB1. Collectively, our data identifies a previously unappreciated role for the HBV pre-core protein p22 in elevating Wnt signaling. Understanding the molecular mechanisms of p22 activity will provide insight into how Wnt signaling is fine-tuned in cancer

The oncogenic interplay between Hepatitis B virus proteins and Wnt signalling

© 2018 Dr. Bang Manh TranLiver cancer is the sixth most common cancer worldwide, and is ranked fourth for the number of cancer-related mortality. The vast majority of liver cancer cases are hepatocellular carcinoma (HCC) where viral hepatitis infection is the main cause. Alarmingly, the World Health Organisation (WHO) estimates that nearly one third of the global population has been infected by the hepatitis B virus (HBV), and 240 million people become chronic carriers of the virus. These patients carry a high risk of developing cirrhosis, liver failure and HCC. While treatments can help ameliorate the disease burden, no cure is currently available for HBV chronic infection. Cumulative risk factor for HCC development in these patients can be as high as 15%. However, the oncogenic mechanisms of HBV-related liver cancer are not well understood. Originally discovered by its link to cancer, the Wnt signalling pathway, detailed in Chapter 1, was found to be active in over 60% of HCC cases. As such, the Wnt pathway could serve as an oncogenic conduit that HBV infection utilises to drive hepatic tumourigenesis. However, HBV is highly human hepatocyte-tropic and the lack of a model system that closely resembles human primary hepatocytes has been a barrier for the scientific community to further advance our understanding. Thus, this thesis attempts to expand our knowledge on the oncogenic interplay between HBV proteins and Wnt signalling. Another aim of this thesis is to develop a novel model system that can serve as a platform that closely mimics the human liver context for future studies of early events in HBV infection and its impact on Wnt signalling. In Chapter 1, I provide an overview of the literature on HBV biology, Wnt signalling and roles of HBV on the pathogenesis of HCC. In Chapter 2, I detail all the materials, methods and techniques that I utilised to carry out the investigation in this thesis. In Chapter 3, various structural proteins of HBV are screened for their effect on the Wnt pathway in the hepatoma cell line Huh7. I identify a HBV precore protein named p22 as a novel activator of Wnt signalling. Its stimulatory role is conserved among several different genotypes and is unique to p22 as activation of Wnt signalling was not observed with other HBV precore species. In Chapter 4, I determine the Wnt-activating role of HBV p22 in the contexts of cell lines other than Huh7 and in a classical model of Wnt signalling, namely the Xenopus axis duplication assay. Upregulation of Wnt signalling by p22 was consistently observed in each non-hepatic continuous cell line examined. Interestingly, this stimulatory effect of p22 is dampened by co-transfection with a dominant-negative (dn) isoform of T-cell factor 4 (TCF4), a transcriptional activator of Wnt signalling, suggesting that p22 can activate the Wnt pathway via TCF4. In Chapter 5, I investigate the stimulatory effect of HBV p22 in vivo using the hydrodynamic tail-vein injection mouse model. The livers of mice injected with HBV p22 show a significant upregulation of Wnt target genes Fzd7 and Glul, compared to control mice. In addition, I establish the ex vivo model system of liver organoids from mouse and human, and characterise them thoroughly. I demonstrate that these liver organoids can be isolated, expanded and effectively differentiated into hepatocytes. Furthermore, they closely mimic their liver tissues of origin, thus providing a promising tool for future HBV studies. Finally, in Chapter 6, I bring all the results in this thesis together for the final discussion/overview. Collectively, the findings from this thesis demonstrate and highlight the role of HBV precore p22 as a novel potent activator of the Wnt pathway. Moreover, the ex vivo model of liver organoids can serve as a powerful tool for further investigation of the oncogenic effects of natural HBV infection as well as by HBV precore p22 in isolation. In ongoing research in the Vincan laboratory, the effect of natural HBV infection on cellular signalling pathways and processes will be defined. This might provide novel avenues for drug discovery and therapy

Frizzled7 activates β-catenin-dependent and β-catenin-independent Wnt signalling pathways during developmental morphogenesis: implications for therapeutic targeting in colorectal cancer

Frizzled7 activates β-catenin-dependent and β-catenin-independent Wnt signalling pathways, is highly conserved through evolution from the ancient phylum hydra to man, plays essential roles in stem cells, tissue homeostasis and regeneration in the adult, and is upregulated in diverse cancers. Much of what is known about the core components of the Wnt signalling pathways was derived from studying the function of Frizzled7 orthologues in the development of lower organism. As we interrogate Frizzled7 signalling and function for therapeutic targeting in cancer, it is timely to revisit lower organisms to gain insight into the context dependent and dynamic nature of Wnt signalling for effective drug design

Cu2O/Fe3O4/UiO-66 nanocomposite as an efficient fenton-like catalyst: Performance in organic pollutant degradation and influencing factors based machinelearning

The persistent presence of organic pollutants like dyes in water environment necessitates innovative approaches for efficient degradation. In this research, we developed an advanced hybrid catalyst by combining metal oxides (Cu2O, Fe3O4) with UiO-66, serving as a heterogeneous Fenton catalyst for for efficient RB19 breakdown in water with H2O2. The control factors to the catalytic behavior were also quantified by machine learning. Experimental results show that the catalytic performance was much better than its individual components (P < 0.05 &amp; non-zero 95% C.I). The improved catalytic efficiency was linked to the occurrence of active metal centers (Fe, Cu, and Zr), with Cu(I) from Cu2O playing a crucial role in promoting increased production of HO•. Also, UiO-66 served as a catalyst support, attracting pollutants to the reaction center, while magnetic Fe3O4 aids catalyst recovery. The optimal experimental parameters for best performance were pH at 7, catalyst loading of 1.6 g/L, H2O2 strength of 0.16 M, and reaction temperature of 25 °C. The catalyst can be magnetically separated and regenerated after five recycling times without significantly reducing catalytic activity. The reaction time and pH were ranked as the most influencing factors on catalytic efficiency via Random Forest and SHapley Additive exPlanations models. The findings show that developed catalyst is a suitable candidate to remove dyes in water by Fenton heterogeneous reaction

Organophosphate esters in indoor dust from 12 countries: Concentrations, composition profiles, and human exposure

A total of 20 organophosphate triesters (OPEs), including seven alkyl-OPEs, three chlorinated (Cl)-OPEs, seven aryl-OPEs, and three oligomeric-OPEs were measured in 341 house dust samples collected from 12 countries during the period 2010–2014. OPEs were ubiquitous in indoor dust, and the total concentrations of OPEs (∑OPEs; sum of 20 OPEs) ranged from 49.4 to 249,000 ng/g dry weight (dw). Generally, Cl-OPEs were the predominant compounds (51% of total) in indoor dust samples, with a median concentration of 800 ng/g, followed by alkyl-OPEs (31%), aryl-OPEs (17%), and oligomeric-OPEs (1%), with median concentrations of 480, 270, and 21.9 ng/g, respectively. ∑OPE concentrations in indoor dust from more industrialized countries (South Korea: median, 31,300; Japan: 29,800; and the United States: 26,500 ng/g dw) were one or two orders of magnitude higher than those from less industrialized countries (Greece: 7140, Saudi Arabia: 5310, Kuwait: 4420, Romania: 4110, Vietnam: 1190, China: 1120, Colombia: 374, India: 276, and Pakistan: 138 ng/g dw). Statistically significant positive correlations (0.114 < r < 0.748, p < 0.05) were found among the concentrations of 16 OPEs in dust samples, indicating similar sources of these compounds. The median estimated daily intakes of ΣOPEs via dust ingestion for children and adults were in the ranges of 0.29–64.8 and 0.07–14.9 ng/kg bw/day, respectively

Organophosphate esters in indoor dust from 12 countries : concentrations, composition profiles, and human exposure

A total of 20 organophosphate triesters (OPEs), including seven alkyl-OPEs, three chlorinated (Cl)-OPEs, seven aryl-OPEs, and three oligomeric-OPEs were measured in 341 house dust samples collected from 12 countries during the period 2010–2014. OPEs were ubiquitous in indoor dust, and the total concentrations of OPEs (∑OPEs; sum of 20 OPEs) ranged from 49.4 to 249,000 ng/g dry weight (dw). Generally, Cl-OPEs were the predominant compounds (51% of total) in indoor dust samples, with a median concentration of 800 ng/g, followed by alkyl-OPEs (31%), aryl-OPEs (17%), and oligomeric-OPEs (1%), with median concentrations of 480, 270, and 21.9 ng/g, respectively. ∑OPE concentrations in indoor dust from more industrialized countries (South Korea: median, 31,300; Japan: 29,800; and the United States: 26,500 ng/g dw) were one or two orders of magnitude higher than those from less industrialized countries (Greece: 7140, Saudi Arabia: 5310, Kuwait: 4420, Romania: 4110, Vietnam: 1190, China: 1120, Colombia: 374, India: 276, and Pakistan: 138 ng/g dw). Statistically significant positive correlations (0.114 < r < 0.748, p < 0.05) were found among the concentrations of 16 OPEs in dust samples, indicating similar sources of these compounds. The median estimated daily intakes of ΣOPEs via dust ingestion for children and adults were in the ranges of 0.29–64.8 and 0.07–14.9 ng/kg bw/day, respectively