HBx expression activates RhoA GTPase: impact on cell migration.

HBV (hepatitis B virus) remains a global health concern, especially in developing countries. It has been associated with the development of HCC (hepatocellular carcinoma). One of the four viral proteins, HBx, interacts with cellular proteins, which are involved in a series of cellular processes including cell migration. The Rho GTPases (guanine nucleotide triphosphatases) family of proteins is involved in the regulation of the reorganization of actin and cell migration. We have reported that HBV replication activates Rac1 through SH3 binding. Here, we reported that RhoA was activated by HBx in vitro. The cell motility was enhanced in HepG2 cells co-transfected with HBx and RhoA, compared with those transfected with RhoA alone. Our results were consistent with the recently reported role of RhoA in promoting cell motility and may provide new insights on the mechanism of HBV-associated HCC.

Proteomics profile of cellular response to chiral drugs: prospects for pharmaceutical applications.

Chiral drugs account for a large proportion of drugs available in the market. There is increasing awareness of the importance of drug chirality and the role it plays in explaining the oftentimes dramatic differences in biological activities in the current drug development portfolio. Using recently developed chiral drugs-cell interaction system, several examples of protein profiles induced by chiral drugs were illustrated in detail on the platform of 2-D LC interfaced with MS/MS system. In addition, the background of chiral drug investigation from which contemporary drug chirality research has emerged, the techniques involved in proteomics technology, the application of proteomics in this exciting area, and the perspectives in future applications are also discussed.

A comparative proteomic analysis of HepG2 cells incubated by S(-) and R(+) enantiomers of anti-coagulating drug warfarin.

Warfarin is a commonly prescribed oral anti-coagulant with narrow therapeutic index. It interferes with vitamin K cycle to achieve anti-coagulating effects. Warfarin has two enantiomers, S(-) and R(+) and undergoes stereoselective metabolism, with the S(-) enantiomer being more effective. We reported that the intracellular protein profile in HepG2 cells incubated with S(-) and R(+) warfarin, using iTRAQ-coupled 2-D LC-MS/MS. In samples incubated with S(-) and R(+) warfarin alone, the multi-task protein Protein SET showed significant elevation in cells incubated with S(-) warfarin but not in those incubated with R(+) warfarin. In cells incubated with individual enantiomers of warfarin in the presence of vitamin K, protein disulfide isomerase A3 which is known as a glucose-regulated protein, in cells incubated with S(-) warfarin was found to be down-regulated compared to those incubated with R(+) warfarin. In addition, Protein DJ-1 and 14-3-3 Proteinsigma were down-regulated in cells incubated with either S(-) or R(+) warfarin regardless of the presence of vitamin K. Our results indicated that Protein DJ-1 may act as an enzyme for expression of essential enzymes in vitamin K cycle. Taken together, our findings provided molecular evidence on a comprehensive protein profile on warfarin-cell interaction, which may shed new lights on future improvement of warfarin therapy.

Novel short antibacterial and antifungal peptides with low cytotoxicity: Efficacy and action mechanisms.

Short antimicrobial peptides with nine and eleven residues were developed against several clinically important bacterial and fungal pathogens (specifically Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Fusarium solani). Twelve analogues of previously reported peptides BP76 (KKLFKKILKFL) and Pac-525 (KWRRWVRWI) were designed, synthesized, and tested for their antimicrobial activities. Two of our eleven amino acid peptides, P11-5 (GKLFKKILKIL) and P11-6 (KKLIKKILKIL), have very low MICs of 3.1-12.5microg ml(-1) against all five pathogens. The MICs of these two peptides against S. aureus, C. albicans and F. solani are four to ten times lower than the corresponding MICs of the reference peptide BP76. P9-4 (KWRRWIRWL), our newly designed nine-amino acid analogue, also has particularly low MICs of 3.1-6.2microg ml(-1) against four of the tested pathogens; these MICs are two to eight times lower than those reported for Pac-525 (6.2-50microg ml(-1)).These new peptides (P11-5, P11-6 and P9-4) also exhibit improved stability in the presence of salts, and have low cytotoxicity as shown by the hemolysis and MTT assays. From the results of field-emission scanning electron microscopy, membrane depolarization and dye-leakage assays, we propose that these peptides exert their action by disrupting membrane lipids. Molecular dynamics simulation studies confirm that P11-6 peptide maintains relatively stable helical structure and exerts more perturbation action on the order of acyl tail of lipid bilayer.

Application of bone suppression imaging in the diagnosis of occupational pneumoconiosis / 中国职业医学

@#Objective （ ） To explore the application value of bone suppression imaging BSI in the diagnosis of occupational （ pneumoconiosis） Methods - pneumoconiosis hereinafter referred to as " " . A total of 330 chest films of high kV digital （ ） radiograph DR of patients with suspected pneumoconiosis were selected by convenient sampling method. BSI is applied to the ， ， ， ， chest films and the differences of small opacity shape small opacity aggregation the number of large opacity lung areas small （ ）， opacity profusion and diagnostic stage of pneumoconiosis were analyzed by simple DR reading DR group simple BSI reading （ ） （ ） Results BSI group and DR and BSI combined reading combined group . There was no significant difference in the distribution of small shadows and the detection rate of small shadows aggregation and large shadows in pneumoconiosis among （ P ） ， the three film reading methods all >0.05 . For the concentration distribution of each lung area there was statistically （P< ）， significant difference between the DR group and the BSI group 0.05 but there was no statistically significant difference ， （ P ） between the DR group and the combined group and between the BSI group and the combined group all >0.05 . The results of ， consistency analysis showed that the DR group and the BSI group and the DR group and the combined group had high （ ， P< consistency in the judgment of small shadow intensity in the lung region both weighted Kappa coefficient were 0.75 all ） 0.01 . There was a high consistency between BSI group and DR group and combined group and DR group in the diagnosis of （ ， ， P< ） ， pneumoconiosis stage weighted Kappa coefficient were 0.77 0.79 all 0.01 . Compared with the DR group the diagnostic ， rate of pneumoconiosis stage Ⅰwas significantly reduced and the diagnostic rate of pneumoconiosis stage Ⅱ was significantly （ P< ） ， increased in the BSI group and the combined group all 0.01 . However there was no significant difference in the diagnosticrate of pneumoconiosis stage Ⅲ >0.05 . Both the BSI reading and DR and BSI combined reading can improve ， the display of pneumoconiosis lesions to varying degrees and therefore can improve the diagnosis of pneumoconiosis. In ， addition the identification and diagnosis of pneumoconiosis lesions in the BSI reading is comparable to that in the combined ， group which has a good application value in the diagnosis of pneumoconiosis.

The influence of GFP-actin expression on the adhesion dynamics of HepG2 cells on a model extracellular matrix.

Integrins belong to a family of important cell surface receptors which mediate the adhesion of most anchorage-dependent cells to nature extracellular matrix (ECM) and biomaterials. It is known that the binding of integrin with ECM proteins triggers mechanochemical responses of cytoskeleton. To date, the intricate interplay between integrin-ECM interaction and cytoskeleton dynamics leading to the regulation of cell morphogenesis on biomaterials remains largely unknown. In this study, green fluorescence protein (GFP)-actins were expressed in HepG2 cells for the temporal visualization of cytoskeletal structure of adherent cells on naturally derived materials. By combining confocal reflectance contrast microscopy and fluorescence microscopy, the adhesion contact dynamics, cytoskeleton remodeling and two-dimensional spreading of intact and GFP-actin expressing HepG2 cells on collagen and fibronectin-coated substrates are simultaneously probed during the initial cell seeding. First of all, our results show that the evolution of adhesion contact of HepG2 cells upon integrin-collagen or integrin-fibronectin interaction is impaired by GFP-actin expression. Also, the initial rate of cell deformation is reduced by 70% and 43% on fibronectin and collagen, respectively, upon GFP-actin expression. Interestingly, the steady-state adhesion energy of HepG2 cells remains unchanged and increases on fibronectin- and collagen-coated substrate, respectively, upon GFP-actin expression. Our highly integrated biophysical approach demonstrates that GFP-actins diffusively concentrate in the cytoplasmic cortex during initial cell seeding while adhesion contact evolves and cell spreads. Kinetics analysis on the adhesion contact formation demonstrates the intricate interplay between cytoskeleton property and ECM proteins in cell adhesion.

Comparative proteomics profile of lipid-cumulating oleaginous yeast: an iTRAQ-coupled 2-D LC-MS/MS analysis.

Accumulation of intracellular lipid in oleaginous yeast cells has been studied for providing an alternative supply for energy, biofuel. Numerous studies have been conducted on increasing lipid content in oleaginous yeasts. However, few explore the mechanism of the high lipid accumulation ability of oleaginous yeast strains at the proteomics level. In this study, a time-course comparative proteomics analysis was introduced to compare the non-oleaginous yeast Saccharomyces cerevisiae, with two oleaginous yeast strains, Cryptococcus albidus and Rhodosporidium toruloides at different lipid accumulation stages. Two dimensional LC-MS/MS approach has been applied for protein profiling together with isobaric tag for relative and absolute quantitation (iTRAQ) labelling method. 132 proteins were identified when three yeast strains were all at early lipid accumulation stage; 122 and 116 proteins were found respectively within cells of three strains collected at middle and late lipid accumulation stages. Significantly up-regulation or down-regulation of proteins were experienced among comparison. Essential proteins correlated to lipid synthesis and regulation were detected. Our approach provides valuable indication and better understanding for lipid accumulation mechanism from proteomics level and would further contribute to genetic engineering of oleaginous yeasts.