No abstract

No abstract

Background and Aims One major obstacle of hepatitis B virus (HBV) research is the lack of efficient cell culture system permissive for viral infection and replication. The aim of our study was to establish a robust HBV infection model by using hepatocyte-like cells (HLCs) derived from human pluripotent stem cells. Methods HLCs were differentiated from human embryonic stem cells and induced pluripotent stem cells. Maturation of hepatocyte functions was determined. After HBV infection, viral total DNA, cccDNA, total RNA, pgRNA, HBeAg, HBsAg were measured. Results More than 90% of the HLCs expressed strong signals of human hepatocyte markers like albumin as well as known host factors required for HBV infection, suggesting that these cells present key features of mature hepatocytes. Notably, HLCs expressed the viral receptor sodium-taurocholate cotransporting polypeptide more stably than primary human hepatocytes (PHHs). HLCs supported robust infection and some spreading of HBV. Finally, by using this model, we identified two host-targeting agents, Genistin and PA452, as novel antivirals. Conclusions Stem cells-derived HLCs fully support HBV infection. This novel HBV infection HLCs model offers a unique opportunity to advance our understanding of the molecular details of the HBV life cycle, to further characterize virus-host interactions and to define new targets for HBV curative treatment.

No abstract

Well-aligned indium oxide pyramids were synthesized on a Ni-coated silicon (100) substrate by a chemical vapor deposition. Scanning electron microscopy and x-ray diffraction investigations show that these pyramids present a tetragonal morphology and single-crystalline cubic bixbyite structure. The size control of the pyramids was achieved by varying the growth temperature. Field-emission characteristics of the as-grown indium oxide pyramids were measured. The field-emission current density of the nanopyramids (average size: ∼180 nm) reached about 1 mA/cm2 at a threshold field of about 6.0 V/μm, which is comparable to that of carbon nanotubes, and can guarantee sufficient luminescence brightness in a flat panel display.

Hepatitis B virus (HBV) has a unique fourth openreading frame coding for a 16.5-kDa protein known as hepatitis B virus X protein (HBX). The importance of HBX in the life cycle of HBV has been well established, but the underlying molecular function of HBX remains controversial. We previously identified a proteasome subunit PSMA7 that interacts specifically with HBX in the Saccharomyces cerevisiae two-hybrid system. Here we demonstrate that PSMC1, an ATPase-like subunit of the 19 S proteasome component, also interacts with HBX and PSMA7. Analysis of the interacting domains among PSMA7, PSMC1, and HBX by deletion and site-directed mutagenesis suggested a mutually competitive structural relationship among these polypeptides. The competitive nature of these interactions is further demonstrated using a modified yeast two-hybrid dissociator system. The crucial HBX sequences involved in interaction with PSMA7 and PSMC1 are important for its function as a transcriptional coactivator. HBX, while functioning as a coactivator of AP-1 and acidic activator VP-16 in mammalian cells, had no effect on the transactivation function of their functional orthologs GCN4 and Gal4 in yeast. Overexpression of PSMC1 seemed to suppress the expression of various reporters in mammalian cells; this effect, however, was overcome by coexpression of HBX. In addition, HBX expression inhibited the cellular turnover of c-Jun and ubiquitin-Arg-␤-galactosidase, two well known substrates of the ubiquitin-proteasome pathway. Thus, interaction of HBX with the proteasome complex in metazoan cells may underlie the functional basis of proteasome as a cellular target of HBX.Human hepatitis B virus (HBV) 1 belongs to a group of hepadnaviruses that includes the hepatitis viruses of the woodchuck, ground squirrel, tree squirrel, Pekin duck, and heron. HBV has a unique fourth open reading frame, termed the hepatitis B virus X (HBX) gene. HBX gene is well conserved among the mammalian hepadnaviruses and codes for a 16.5-kDa protein (1, 2). The protein can activate the transcription of a variety of viral and cellular genes (3-5) and induce liver cancer in certain transgenic mouse model (6). Since HBX does not bind to DNA directly, its activity is thought to be mediated via protein-protein interactions. HBX has been shown to enhance transcription through AP-1 and AP-2 (7-9) and to activate various signal transduction pathways (10, 11). Several recent studies have also identified possible cellular targets of HBX, including members of the CREB/ATF family (12, 13), the TATA-binding protein (14), RNA polymerase subunit RPB5 (15, 16), the UV-damaged DNA-binding protein (17), and the replicative senescence p55 sen (18). HBX has also been shown to interact with p53 and inhibit its function (19,20). Furthermore, HBX possesses amino acid sequence homology to the functionally essential domains of Kunitz-type serine proteases inhibitors and mutation of this putative motif inactivates the transactivation function of HBX (21).Using the Saccharomyces cerevisiae two-hybrid syste...

No abstract

Hexagonal Se nanowires were synthesized using a simple vapor-phase growth with the assistance of the silicon powder as a source material, which turned out to be very important in the growth of the Se nanowires. The morphology, microstructure, and chemical compositions of the nanowires were characterized using various means (XRD, SEM, TEM, XPS, and Raman spectroscopy). The possible growth mechanism of the Se nanowires was explained. The as-grown Se nanowires may find wide applications in biology and optoelectronics.