Hepatitis C Virus Core Protein Down-Regulates Expression of Src-Homology 2 Domain Containing Protein Tyrosine Phosphatase by Modulating Promoter DNA Methylation

Hepatitis C virus (HCV) is the major causative pathogen associated with liver cirrhosis and hepatocellular carcinoma. The main virion component, the core (C) protein, has been implicated in several aspects of HCV pathology including oncogenesis and immune subversion. Here we show that expression of the C protein induced specific tyrosine phosphorylation of the TCR-related signaling proteins ZAP-70, LAT and PLC-γ in the T cells. Stable expression of the C protein specifically reduced Src homology domain 2-containing protein tyrosine phosphatase 1 (SHP-1) mRNA and protein accumulation. Quantitative CpG methylation analysis revealed a distinct CpG methylation pattern at the SHP-1 gene promoter in the C protein expressing cells that included specific hypermethylation of the binding site for Sp1 transcription factor. Collectively, our results suggest that HCV may suppress immune responses and facilitate its own persistence by deregulating phosphotyrosine signaling via repressive epigenetic CpG modification at the SHP-1 promoter in the T cells.

In vivo pair correlation microscopy reveals dengue virus capsid protein nucleocytoplasmic bidirectional movement in mammalian infected cells

Flaviviruses are major human disease-causing pathogens, including dengue virus (DENV), Zika virus, yellow fever virus and others. DENV infects hundreds of millions of people per year around the world, causing a tremendous social and economic burden. DENV capsid (C) protein plays an essential role during genome encapsidation and viral particle formation. It has been previously shown that DENV C enters the nucleus in infected cells. However, whether DENV C protein exhibits nuclear export remains unclear. By spatially cross-correlating different regions of the cell, we investigated DENV C movement across the nuclear envelope during the infection cycle. We observed that transport takes place in both directions and with similar translocation times (in the ms time scale) suggesting a bidirectional movement of both C protein import and export.Furthermore, from the pair cross-correlation functions in cytoplasmic or nuclear regions we found two populations of C molecules in each compartment with fast and slow mobilities. While in the cytoplasm the correlation times were in the 2–6 and 40–110 ms range for the fast and slow mobility populations respectively, in the cell nucleus they were 1–10 and 25–140 ms range, respectively. The fast mobility of DENV C in cytoplasmic and nuclear regions agreed with the diffusion coefficients from Brownian motion previously reported from correlation analysis. These studies provide the first evidence of DENV C shuttling from and to the nucleus in infected cells, opening new venues for antiviral interventions.

Cellular Localization of Exogenous Cry1Ab/c and its Interaction with Plasma Membrane Ca2+-ATPase in Transgenic Rice

The cellular localization of exogenous proteins expressed in transgenic crops not only determines their stability, but also their effects on crop growth and development, including under stressful conditions; however, the underlying molecular mechanisms remain unknown. Here, we determined the cellular distribution of exogenously expressed Cry1Ab/c protein in insect-resistant transgenic rice Huahui-1 (HH1) cells through subcellular localization, immunohistochemistry, immunofluorescence, and western blot analyses. Interaction between the Cry1Ab/c protein and the preliminarily screened endogenous plasma membrane protein Ca2+-ATPase was investigated through yeast two-hybrid, bimolecular fluorescence complementation (BIFC), and co-immunoprecipitation analyses. The potential interaction mechanism was analyzed by comparing the cellular localization and interaction sites between Cry1Ab/c and Ca2+-ATPase. Phenotypic indices and Ca2+-ATPase activity, which may be regulated by the Cry1Ab/c–Ca2+-ATPase interaction, were determined in transgenic HH1 and the parental line Minghui-63 under stress-free and salt-stress conditions. The results showed that Cry1Ab/c was not only distributed in the cytoplasm and nucleus but was also distributed on the plasma membrane, where it interacted with plasma membrane Ca2+-ATPase. This interaction partially retain plasma membrane protein Ca2+-ATPase in the nucleus by a BIFC experiment and thus may affect Ca2+-ATPase activity on the membrane by altering the cellular location of the protein. Consistently, our results confirmed that the presence of Cry1Ab/c in the transgenic HH1 resulted in a reduction in Ca2+-ATPase activity as well as causing detrimental effects on plant phenotype, including significantly reduced plant height and biomass, compared to parental MH63; and that these detrimental effects were more pronounced under salt stress conditions, impacting the salt resistance of the transgenic plants. We suggest that the Cry1Ab/c–Ca2+-ATPase interaction may explain the plasma membrane localization of Cry1Ab/c, which lacks a signal peptide and a transmembrane domain, and the adverse effects of Cry1Ab/c expression on the growth and development of transgenic HH1 plants under salt stress. This information may clarify the molecular mechanisms of these unintended effects and demonstrate the feasibility of evaluating the success and performance of genetic modification of commercially vital crops.

Impact of environmental temperature to the content of protein on fresh, cold and frozen meat

This study aims to determine the amount of protein content in Aceh cattle beef in the quadriceps muscle (chuck) and to find out the best storage between cold and frozen to protein levels of beef. This study used 10 samples of Aceh cattle beef parts of the quadriceps (chuck) which were divided into 3 treatment groups, group I meat was treated in fresh condition, Group II meat was treated in cold at 8 °C and Group III meat will be treated in frozen at -19 °C. Protein content in meat was analysed by the Independent Samples Test. The results showed that the amount of Aceh beef protein in the quadriceps (chuck) in fresh; 15, 47%, cold 10, 20% and frozen; 9, 97. It was concluded that storing meat in cold and frozen ways is affect the protein content. Frozen meat storage is better to keep protein content than Cold meat storage.