Enhancement of the antigen-specific cytotoxic T lymphocyte-inducing ability in the PMDC11 leukemic plasmacytoid dendritic cell line via lentiviral vector-mediated transduction of the caTLR4 gene.

The aim of the present study was to enhance the efficiency of leukemia immunotherapy by increasing the antigen-specific cytotoxic T lymphocyte-inducing ability of leukemia cells. The leukemic plasmacytoid dendritic cell line PMDC05 containing the HLA-A02/24 antigen, which was previously established in our laboratory (Laboratory of Hematology and Oncology, Graduate School of Health Sciences, Niigata University, Niigata, Japan), was used in the present study. It exhibited higher expression levels of CD80 following transduction with lentiviruses encoding the CD80 gene. This CD80-expressing PMDC05 was named PMDC11. In order to establish a more potent antigen-presenting cell for cellular immunotherapy of tumors or severe infections, PMDC11 cells were transduced with a constitutively active (ca) toll-like receptor 4 (TLR4) gene using the Tet-On system (caTLR4-PMDC11). CD8(+) T cells from healthy donors with HLA-A02 were co-cultured with mutant WT1 peptide-pulsed PMDC11, lipopolysaccharide (LPS)-stimulated PMDC11 or caTLR4-PMDC11 cells. Interleukin (IL)-2 (50 IU/ml) and IL-7 (10 ng/ml) were added on day three of culture. Priming with mutant WT1 peptide-pulsed PMDC11, LPS-stimulated PMDC11 or caTLR4-PMDC11 cells was conducted once per week and two thirds of the IL-2/IL-7 containing medium was replenished every 3-4 days. Immediately prior to the priming with these various PMDC11 cells, the cultured cells were analyzed for the secretion of interferon (IFN)-γ in addition to the percentage and number of CD8(+)/WT1 tetramer(+) T cells using flow cytometry. caTLR4-PMDC11 cells were observed to possess greater antigen-presenting abilities compared with those of PMDC11 or LPS-stimulated PMDC11 cells in a mixed leukocyte culture. CD8 T cells positive for the WT1 tetramer were generated following 3-4 weeks of culture and CD8(+)/WT1 tetramer+ T cells were markedly increased in caTLR4-PMDC11-primed CD8(+) T cell culture compared with PMDC11 or LPS-stimulated PMDC11-primed CD8(+) T cell culture. These CD8(+) T cells co-cultured with caTLR4-PMDC11 cells were demonstrated to secrete IFN-γ and to be cytotoxic to WT1-expressing target cells. These data suggested that the antigen-specific cytotoxic T lymphocyte (CTL)-inducing ability of PMDC11 was potentiated via transduction of the caTLR4 gene. The present study also suggested that caTLR4-PMDC11 cells may be applied as potent antigen-presenting cells for generating antigen-specific CTLs in adoptive cellular immunotherapy against tumors and severe viral infections

Structures of SMG1-UPFs Complexes: SMG1 Contributes to Regulate UPF2-Dependent Activation of UPF1 in NMD

SummarySMG1, a PI3K-related kinase, plays a critical role in nonsense-mediated mRNA decay (NMD) in mammals. SMG1-mediated phosphorylation of the UPF1 helicase is an essential step during NMD initiation. Both SMG1 and UPF1 are presumably activated by UPF2, but this regulation is incompletely understood. Here we reveal that SMG1C (a complex containing SMG1, SMG8, and SMG9) contributes to regulate NMD by recruiting UPF1 and UPF2 to distinct sites in the vicinity of the kinase domain. UPF2 binds SMG1 in an UPF1-independent manner in vivo, and the SMG1C-UPF2 structure shows UPF2 recognizes the FRB domain, a region that regulates the related mTOR kinase. The molecular architectures of several SMG1C-UPFs complexes, obtained by combining electron microscopy with in vivo and in vitro interaction analyses, competition experiments, and mutations, suggest that UPF2 can be transferred to UPF1 within SMG1C, inducing UPF2-dependent conformational changes required to activate UPF1 within an SMG1C-UPF1-UPF2 complex

Immunologic Monitoring of Cellular Responses by Dendritic/Tumor Cell Fusion Vaccines

Although dendritic cell (DC)- based cancer vaccines induce effective antitumor activities in murine models, only limited therapeutic results have been obtained in clinical trials. As cancer vaccines induce antitumor activities by eliciting or modifying immune responses in patients with cancer, the Response Evaluation Criteria in Solid Tumors (RECIST) and WHO criteria, designed to detect early effects of cytotoxic chemotherapy in solid tumors, may not provide a complete assessment of cancer vaccines. The problem may, in part, be resolved by carrying out immunologic cellular monitoring, which is one prerequisite for rational development of cancer vaccines. In this review, we will discuss immunologic monitoring of cellular responses for the evaluation of cancer vaccines including fusions of DC and whole tumor cell

Impairment of starvation-induced and constitutive autophagy in Atg7-deficient mice

Autophagy is a membrane-trafficking mechanism that delivers cytoplasmic constituents into the lysosome/vacuole for bulk protein degradation. This mechanism is involved in the preservation of nutrients under starvation condition as well as the normal turnover of cytoplasmic component. Aberrant autophagy has been reported in several neurodegenerative disorders, hepatitis, and myopathies. Here, we generated conditional knockout mice of Atg7, an essential gene for autophagy in yeast. Atg7 was essential for ATG conjugation systems and autophagosome formation, amino acid supply in neonates, and starvation-induced bulk degradation of proteins and organelles in mice. Furthermore, Atg7 deficiency led to multiple cellular abnormalities, such as appearance of concentric membranous structure and deformed mitochondria, and accumulation of ubiquitin-positive aggregates. Our results indicate the important role of autophagy in starvation response and the quality control of proteins and organelles in quiescent cells