In a phase 2a study, the all-oral, interferon-free, and ribavirin-free regimen of daclatasvir, asunaprevir, and BMS-791325 was well tolerated and achieved high rates of SVR12 in patients with HCV genotype 1 infection. Further studies of this regimen are warranted. ClinicalTrials.gov, number NCT01455090.

Epstein-Barr virus (EBV) nuclear antigen 3C (EBNA3C) is one of the essential latent antigens for primary B-cell transformation. Previous studies established that EBNA3C facilitates degradation of several vital cell cycle regulators, including the retinoblastoma (pRb) and p27KIP proteins, by recruitment of the SCF Skp2 E3 ubiquitin ligase complex. EBNA3C was also shown to be ubiquitinated at its N-terminal residues. Furthermore, EBNA3C can bind to and be degraded in vitro by purified 20S proteasomes. Surprisingly, in lymphoblastoid cell lines, EBNA3C is extremely stable, and the mechanism for this stability is unknown. In this report we show that EBNA3C can function as a deubiquitination enzyme capable of deubiquitinating itself in vitro as well as in vivo. Functional mapping using deletion and point mutational analysis showed that both the N-and C-terminal domains of EBNA3C contribute to the deubiquitination activity. We also show that EBNA3C efficiently deubiquitinates Mdm2, an important cellular proto-oncogene, which is known to be overexpressed in several human cancers. The data presented here further demonstrate that the N-terminal domain of EBNA3C can bind to the acidic domain of Mdm2. Additionally, the N-terminal domain of EBNA3C strongly stabilizes Mdm2. Importantly, EBNA3C simultaneously binds to both Mdm2 and p53 and can form a stable ternary complex; however, in the presence of p53 the binding affinity of Mdm2 toward EBNA3C was significantly reduced, suggesting that p53 and Mdm2 might share a common overlapping domain of EBNA3C. We also showed that EBNA3C enhances the intrinsic ubiquitin ligase activity of Mdm2 toward p53, which in turn facilitated p53 ubiquitination and degradation. Thus, manipulation of the oncoprotein Mdm2 by EBNA3C potentially provides a favorable environment for transformation and proliferation of EBV-infected cells.

Glutamate and aspartate are the primary excitatory neurotransmitters in the mammalian central nervous system and have also been implicated as mediators of excitotoxic neuronal injury and death. The precise control of extracellular glutamate and aspartate is crucial to the maintenance of normal synaptic transmission and the prevention of excitotoxicity following acute insults to the brain, such as stroke or head trauma, or during the progression of neurodegenerative diseases such as amyotrophic lateral sclerosis. The removal of excitatory amino acids (EAAs) from the extracellular space is primarily mediated by a family of sodium-dependent glutamate transporters. These transporters use the sodium electrochemical gradients of the cell to actively concentrate EAAs in both neurons and glia. Five members of this transporter family have been cloned recently and include both 'glial'-specific and 'neuron'-specific subtypes. Although these subtypes share many common functional properties, there are considerable differences in developmental expression, chronic and acute regulation by cellular signaling pathways, and contribution to disease processes among the subtypes. In this review recent studies of glutamate transporter expression, regulation, function, and pathological relevance are summarized, and some of the discrepancies and unexpected results common to any rapidly progressing field are discussed.

Na؉ -dependent glutamate transporters are the primary mechanism for removal of excitatory amino acids (EAAs) from the extracellular space of the central nervous system and influence both physiologic and pathologic effects of these compounds. Recent evidence suggests that the activity and cell surface expression of a neuronal subtype of glutamate transporter, EAAC1, are rapidly increased by direct activation of protein kinase C and are decreased by wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-K). We hypothesized that this regulation could be analogous to insulin-induced stimulation of the GLUT4 subtype of glucose transporter, which is dependent upon activation of PI3-K. Using C6 glioma, a cell line that endogenously and selectively expresses EAAC1, we report that platelet-derived growth factor (PDGF) increased Na3 H]-glutamate transport activity within 30 min. This effect of PDGF was not due to a change in total cellular EAAC1 immunoreactivity but was instead correlated with an increase cell surface expression of EAAC1, as measured using a membrane impermeant biotinylation reagent combined with Western blotting. A decrease in nonbiotinylated intracellular EAAC1 was also observed. These studies suggest that PDGF causes a redistribution of EAAC1 from an intracellular compartment to the cell surface. These effects of PDGF were accompanied by a 35-fold increase in PI3-K activity and were blocked by the PI3-K inhibitors, wortmannin and LY 294002, but not by an inhibitor of protein kinase C. Other growth factors, including insulin, nerve growth factor, and epidermal growth factor had no effect on glutamate transport nor did they increase PI3-K activity. These studies suggest that, as is observed for insulin-mediated translocation of GLUT4, EAAC1 cell surface expression can be rapidly increased by PDGF through activation of PI3-K. It is possible that this PDGF-mediated increase in EAAC1 activity may contribute to the previously demonstrated neuroprotective effects of PDGF.The rapid clearance of glutamate from the extracellular space of the central nervous system by Na ϩ -dependent high affinity glutamate transporters is critical to the maintenance of effective synaptic transmission and the prevention of excitotoxic injury. Increases in extracellular EAAs 1 after head trauma and ischemic events have been described (1-3) and are presumably related to both a failure of inward transport and increased reverse operation of the carriers (4, 5). A family of glutamate transporters mediates this high affinity uptake and includes five members, the glial transporters GLT-1 (human homologue EAAT2) and GLAST (EAAT1), the neuronal transporters EAAC1 (EAAT3) and EAAT4, and the retinal transporter EAAT5 (6 -10). The EAAC1 subtype of transporter is enriched in the pyramidal cells of hippocampus and cortex (11,12), two areas rich in glutamatergic transmission and exquisitely sensitive to excitotoxic insults (13). Animals treated with antisense oligonucleotides to "knock down" EAAC1 expression develop a seizure phenotype,...