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Biomolecular Networks Laboratories, Cell Biology and Metabolism Group
Nanobiology Laboratories
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Biomolecular Networks Laboratories
Research Group of Lipid Biosignals
Biomolecular Dynamics Group
Developmental Biology Group
Chromosome Replication Group

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Laboratory of Genetics
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Laboratory of Developmental Immunology
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Synaptic Plasticity Group

Biophysical Dynamics Laboratories
Physiological Laboratory
Nonequilibrium Physics Group
Functional Proteomics Group
Nano-Biophotonics Group

Biomedical Engineering Laboratories
Systems Neuroscience Group
Department of Molecular Genetics
Laboratory of Intercellular Communications
Laboratory of Stem Cell Research
Laboratory of Protein Informatics
Laboratory of Biocatalysis Science

Collaborative institutes
Laboratory of Immune Regulation Chugai Pharmaceutical CO.,LTD.
Optical Nano Device Group
OMRON Corporation

Professor Kazuhiro IWAI image1 +81-6-6879-3420
Associate Prof. Hiromasa TOJO +81-6-6879-3427

FAX +81-6-6879-3429
Postal Mail Address 1-3Yamada-oka, Suita, Osaka 565-0871, Department of Biophysics and Biochemistry, Graduate School of Medicine, Osaka University
For more information http://www.cellbio.med.osaka-u.ac.jp

Our laboratory works on 3 topics. Since we introduce them in details in our own homepage, we describe outline of our work here.

1 Roles of the ubiquitin conjugation system in the regulation of a broad array of cellular function

The ubiquitin system conjugates a small globular protein, ubiquitin, to proteins post-translationally and regulates their function. Although it was discovered as a part of energy-dependent protein degradation system, the ubiquitin system is now recognized as a reversible post-translational protein conjugation system to regulate protein function via multiple ways. We are dissecting the roles of the ubiquitin system from the following points of view.

a) Mechanism underlying timely and selective substrate recognition by the ubiquitin system.

b) Involvement of the ubiquitin conjugation system in cancer, allergy, and neurodegenerative disorders.

c) Physiological roles of a novel polyubiquitin chain; the linear polyubiquitin.

2 Regulatory mechanism of iron metabolism and its involvement in diseases

Although it might be difficult to realize that roles of iron in our body, it is well-established that iron is essential nutrient for us to play inevitable roles in many biological processes including oxygen transport and energy metabolism. Also, wed like to note that we cannot generate deoxynucleic acids without iron. On the other hand, iron is highly toxic because of its high reactivity with oxygen to generate radicals. Therefore, iron metabolism must be regulated tightly because both iron deficiency and overload provoke deleterious effects on our health. Moreover, abnormality in iron metabolism is involved in the pathogenesis of several diseases including hepatitis C and neurodegenerative disorders. We are working on the following projects to understand the roles iron metabolism plays in our body.

a) Understanding the roles of iron in the pathogenesis of the diseases and development methods to manipulate iron metabolism for treatment of those diseases.

b) Involvement of mitochondria in the regulation of iron homeostasis in cells.

c) Elucidation of dynamism of iron and iron prosthetic groups such as heme or iron-sulfur cluster.

d) Regulation of iron metabolism in Saccharomyces cerevisiae.

3 Development of HPLC/mass spectrometry-based strategies for lipidomics and proteomics - application to disease and health analyses

 The recent sophistication of mass spectrometry (MS) allows us to comprehensively analyze proteins (proteomics) and metabolites (metabolomics) in tissue samples. Metabolites are diverse with a quite wide spectrum of polarity, and it is difficult to handle all metabolites at a time. We focus on lipids that are scaffolds of cellular membranes where lipidic signaling molecules are generated and interplay with membrane proteins to mediate various functions. We are currently developing HPLC/MS-based strategies for lipid metabolomics (lipidomics) and membrane proteomics, side by side, from a single tissue specimen. To facilitate the strategy development, we have already developed a highly efficient fluoropolymer-coated electrospray ionization tip (FortisTip) that makes hyphenation of HPLC with MS quite easy, leading to very stable MS measurements of peptides and lipids. Extensive use of these analytical technologies could greatly promote a research on lipid enzymology, membrane biochemistry, and disease and health analyses.

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