Kyoko Tsukiyama-Kohara

Adipose tissue reduction in mice lacking the translational inhibitor 4E-BP1.

All nuclear-encoded mRNAs contain a 5′ cap structure (m7GpppN, where N is any nucleotide), which is recognized by the eukaryotic translation initiation factor 4E (eIF4E) subunit of the eIF4F complex. The eIF4E-binding proteins constitute a family of three polypeptides that reversibly repress cap-dependent translation by binding to eIF4E, thus preventing the formation of the eIF4F complex. We investigated the biological function of 4E-BP1 by disrupting its gene (Eif4ebp1) in the mouse. Eif4ebp1−/− mice manifest markedly smaller white fat pads than wild-type animals, and knockout males display an increase in metabolic rate. The males white adipose tissue contains cells that exhibit the distinctive multilocular appearance of brown adipocytes, and expresses the uncoupling protein 1 (UCP1), a specific marker of brown fat. Consistent with these observations, translation of the peroxisome proliferator-activated receptor-γ co-activator 1 (PGC1), a transcriptional co-activator implicated in mitochondrial biogenesis and adaptive thermogenesis, is increased in white adipose tissue of Eif4ebp1−/− mice. These findings demonstrate that 4E-BP1 is a novel regulator of adipogenesis and metabolism in mammals.

Heparin-like glycosaminoglycans prevent the infection of measles virus in SLAM-negative cell lines

The wide tissue tropism of the measles virus (MV) suggests that it involves ubiquitously expressed molecules. We have constructed a recombinant MV expressing the enhanced green fluorescent protein (EGFP) (rMV-EGFP) and demonstrated that the rMV-EGFP infected several cell types (HEK-293, HepG2, Hep3B, Huh7, and WRL68 cells) that do not express the human signalling lymphocyte activation molecule (SLAM), which is known as a cellular receptor for morbilliviruses. MV infection of HEK-293 and HepG2 cells was not inhibited in an infectivity-inhibition assay using an anti-SLAM monoclonal antibody, indicating that MV could infect cells without using SLAM. Soluble heparin (HP) inhibited the rMV-EGFP infectivity in SLAM-negative cell lines in a dose-dependent manner. Direct interaction between purified virions and HP was detected in a surface plasmon resonance assay. We also demonstrated that the hemagglutinin (H) protein, but not the fusion (F) protein is responsible for the interaction between the virions and HP. Taken together, our results suggest that HP-like glycosaminoglycans bind to the H protein of MV and play a key role in the infection of SLAM-negative cells.

Imaging living mice using a 1‐T compact MRI system

To determine the feasibility of imaging living mice with a 1‐T compact MRI system and investigate appropriate imaging techniques for use in routine animal experiments.

Expression in baculovirus vector system of the nucleocapsid protein gene of rinderpest virus.

The rinderpest (RV) nucleocapsid (NP) gene segment was inserted into the genome of Autographa californica nuclear polyhedrosis virus (AcNPV) adjacent to the polyhedrin promoter. The expression of NP protein in Sf9 cells was confirmed by indirect immunofluorescence and by Western blotting analysis with monoclonal antibodies. Recombinant RV-NP protein was purified by ultracentrifugation on a sucrose density gradient, and used as an antigen for an enzyme linked immunosorbent assay to detect anti RV-NP antibody. Both IgM and IgG antibodies against RV-NP were detected in the sera of rabbits infected with the L strain of RV. The pattern of development of IgG anti RV-NP antibody closely correlated with that of virus neutralizing antibody. In rabbits inoculated with recombinant vaccinia virus expressing RV-H gene (RRV-H), anti RV-NP was not detected. The results indicated that the baculovirus vector system can be used for the preparation of the diagnostic antigen of rinderpest as well as to distinguish between natural infection and vaccination with RRV-H.