The phosphatidylethanolamine (PE)-binding proteins (PEBPs) are an evolutionarily conserved family of proteins with pivotal biological functions. Here we describe the cloning and functional characterization of a novel family member, human phosphatidylethanolaminebinding protein 4 (hPEBP4). hPEBP4 is expressed in most human tissues and highly expressed in tumor cells. Its expression in tumor cells is further enhanced upon tumor necrosis factor (TNF) α treatment, whereas hPEBP4 normally co-localizes with lysosomes, TNFαstimulation triggers its transfer to the cell membrane, where it binds to Raf-1 and MEK1. L929 cells overexpressing hPEBP4 are resistant to both TNFα-induced ERK1/2, MEK1, and JNK activation and TNFα-mediated apoptosis. Co-precipitation and in vitro protein binding assay demonstrated that hPEBP4 interacts with Raf-1 and MEK1. A truncated form of hPEBP4, lacking the PE-binding domain, maintains lysosomal co-localization but has no effect on cellular responses to TNFα. Given that MCF-7 breast cancer cells expressed hPEBP4 at a high level, small interfering RNA was used to silence the expression of hPEBP4. We demonstrated that down-regulation of hPEBP4 expression sensitizes MCF-7 breast cancer cells to TNFα-induced apoptosis. hPEBP4 appears to promote cellular resistance to TNF-induced apoptosis by inhibiting activation of the Raf-1/MEK/ERK pathway, JNK, and PE externalization, and the conserved region of PE-binding domain appears to play a vital role in this biological activity of hPEBP4.

Carbon nanotubes (CNTs) have been successfully produced from 10 typical Chinese caking-coals using an arc plasma technique. For comparison, one caking coal from New Zealand is also tested. The results show that all coals tested can be used to produce significant quantities of CNTs with fullerenes as by-products. The CNTs are examined using scanning electron microscope and high resolution transmission electron microscope. It has been found that the yields of CNTs are closely related to coal properties. The CNT yield increases as the fixed carbon content in coal increases or as the volatile matter content in coal decreases.

Notch signaling plays a critical role in maintaining the balance between cell proliferation, differentiation, and apoptosis; hence, perturbed Notch signaling may contribute to tumorigenesis. Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in Africa and Asia. The mechanisms that orchestrate the multiple oncogenic insults required for initiation and progression of HCC are not clear. We constitutively overexpressed active Notch1 in human HCC to explore the effects of Notch1 signaling on HCC cell growth and to investigate the underlying molecular mechanisms. We show here that overexpression of Notch1 was able to inhibit the growth of HCC cells in vitro and in vivo. Biochemical analysis revealed the involvement of cell cycle regulated proteins in Notch1-mediated G0/G1 arrest of HCC cells. Compared with green fluorescent protein (GFP) control, transient transfection of Notch1 ICN decreased expression of cyclin A (3.5-fold), cyclin D1 (2-fold), cyclin E (4.5-fold), CDK2 (2.8-fold), and the phosphorylated form of retinoblastoma protein (3-fold). Up-regulation of p21waf/cip1 protein expression was observed in SMMC7721-ICN cells stably expressing active Notch1 but not in SMMC7721-GFP cells, which only express GFP. Furthermore, a 12-fold increase in p53 expression and an increase (4.8-fold) in Jun-NH2-terminal kinase activation were induced in SMMC7721-ICN cells compared with SMMC7721-GFP cells. In contrast, expression of the antiapoptotic Bcl-2 protein could not be detected in SMMC7721-ICN cells. These findings suggest that Notch1 signaling may participate in the development of HCC cells, affecting multiple pathways that control both cell proliferation and apoptosis.

Anovel coronavirus, severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV), has been identified as the causal agent of SARS. Spike (S) protein is a major structural glycoprotein of the SARS virus and a potential target for SARS-specific cell-mediated immune responses. A panel of S protein-derived peptides was tested for their binding affinity to HLA-A*0201 molecules. Peptides with high affinity for HLA-A*0201 were then assessed for their capacity to elicit specific immune responses mediated by cytotoxic T lymphocytes (CTLs) both in vivo, in HLA-A2.1/Kb transgenic mice, and in vitro, from peripheral blood lymphocytes (PBLs) sourced from healthy HLAA2.1+donors. SARS-CoV protein-derived peptide-1 (SSp-1 RLNEVAKNL), induced peptide-specific CTLs both in vivo (transgenic mice) and in vitro (human PBLs), which specifically released interferon-γ (IFN-γ) upon stimulation with SSp-1-pulsed autologous dendritic cells (DCs) or T2 cells. SSp-1-specific CTLs also lysed major histocompatibility complex (MHC)-matched tumor cell lines engineered to express S proteins. HLA-A*0201-SSp-1 tetramer staining revealed the presence of significant populations of SSp-1-specific CTLs in SSp-1-induced CD8+T cells. We propose that the newly identified epitope SSp-1 will help in the characterization of virus control mechanisms and immunopathology in SARS-CoV infection, and may be relevant to the development of immunotherapeutic approaches for SARS.

The mechanisms that underpin the intriguing capacity of Fas ligation on dendritic cells (DCs) to induce maturation and activation, rather than apoptosis, remain unclear. In the present study we confirm that Fas signaling induces both phenotypic and functional maturation of murine DCs, and we demonstrate that phenotypic maturation is associated with phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, activation of caspase-1, and secretion of interleukin-β(IL-1β). Specific inhibition of ERK1/2 diminished Fas ligation-induced caspase-1 activation, IL-1β secretion, and ensuing up-regulation of developmental markers, whereas treatment with neutralizing anti-IL-1β antibody abrogated phenotypic and functional maturation, indicating that IL-1βmediates Fas ligation-induced DC maturation in an autocrine manner. NF-κB activation was responsible for maintaining DC viability after Fas ligation. Inhibiting NF-κB did not affect either IL-1β secretion or phenotypic maturation but rather sensitized DCs to Fas-mediated apoptosis. In conclusion, positive signals originating from Fas are transduced through at least 2 different intracellular pathways in DCs, promoting not only survival but also an increase in maturation that correlates with increased antigen-presentation capability.