Medical Biochemistry

MT_ByotaiSeika_1 Kuniaki Saito, Ph.D. Professor

A human body consists of a number of cells called 60 trillion. These cells interact each other and response for environmental signal to form a precise human body system. We are trying to understand various biological phenomena involving this system with a molecular level, especially by focusing on immune-relating diseases. Furthermore, we currently are focusing to determine medically relevant new biomarker to develop a diagnosis at early stage of disease.

Research and Education

Graduate students in our laboratory are expected to learn a series of techniques of biochemistry, immunology, cell biology and molecular biology.
Our current research target molecule is indoleamine 2,3-dioxygenase (IDO) and pro-inflammatory cytokines.
IDO is the rate-limiting and first enzyme of the L-tryptophan (L-Trp)-kynurenine pathway that converts the essential amino acid L-Trp to N-formylkynurenine in mammalian extrahepatic tissues. IDO is induced by pro-inflammatory cytokines in the course of an inflammatory response in many human cell types, including macrophages, astrocytes, fibroblasts, and epithelial cells. Most recently, this enzyme has emerged as an important immunomodulator of T-cell function and inducer of immune tolerance. Therefore, role of IDO for immune-related diseases is one of the topic in this field. In our laboratory, especially the physiological roles of IDO and pro-inflammatory cytokine following immune-related diseases will be examined by using both experimental animal model and gene deficient mice.

Schematic overview of IDO and immune regulation

Schematic overview of IDO and immune regulation

Photo (laboratory member))

Photo (laboratory member)



1. Studies on tissue and cellular distribution of indoleamine 2,3-dioxygenase 2: the absence of IDO1 upregulates IDO2 expression in the epididymis.
Fukunaga M, Yamamoto Y, Kawasoe M, Arioka Y, Murakami Y, Hoshi M, Saito K.
J Histochem Cytochem. 2012 Nov;60(11):854-60. doi:10.1369/0022155412458926.
2. Inhibition of increased indoleamine 2,3-dioxygenase activity attenuates Toxoplasma gondii replication in the lung during acute infection.
Murakami Y, Hoshi M, Hara A, Takemura M, Arioka Y, Yamamoto Y, Matsunami H, Funato T, Seishima M, Saito K.
Cytokine. 2012 Aug;59(2):245-51. doi: 10.1016/j.cyto.2012.04.022.
3. Posttranslational modification of indoleamine 2,3-dioxygenase.
Fujigaki H, Seishima M, Saito K.
Anal Bioanal Chem. 2012 Jun;403(7):1777-82. doi: 10.1007/s00216-012-5946-2. Review.
4. L-tryptophan-kynurenine pathway metabolites regulate type I IFNs of acute viral myocarditis in mice.
Hoshi M, Matsumoto K, Ito H, Ohtaki H, Arioka Y, Osawa Y, Yamamoto Y, Matsunami H, Hara A, Seishima M, Saito K.
J Immunol. 2012 Apr 15;188(8):3980-7. doi: 10.4049/jimmunol.1100997.
5. Pre-administration of L-tryptophan improved ADR-induced early renal failure in mice.
Arioka Y, Yamamoto Y, Hoshi M, Matsumoto K, Takamatsu M, Hara A, Seishima M, Saito K.
Life Sci. 2012 Aug 21;91(3-4):100-6. doi: 10.1016/j.lfs.2012.06.018.


Professor: Kuniaki Saito
Assistant professor: Yasuko Yamamoto