Laboratory of Molecular Recognition
KATAOKA Hiroshi Prof. Ph.D.
Other Affiliations: Department of Biotechnology, Faculty of Agriculture, The University of Tokyo
Insect endocrinology, Insect physiology
Molting & Metamorphosis, Diapause, Peptide hormone, Steroids
We are conducting the following research projects.
Endocrine control mechanism of insect molting and metamorphosis
（1）Elucidation of ecdysone biosynthetic pathway
Insect molting and metamorphosis are strictly regulated by hormones, and it is regulated by ecdysone, a steroid hormone synthesized in the prothoracic gland. Ecdysone regulates the transcriptional levels of various genes through nuclear receptors similar to vertebrate estrogen receptor. Harmonization of appropriate cell proliferation, programmed cell death, nervous system maturation and cuticle formation, would result in ultimately the precisely timed molting and metamorphosis. However, some essential ecdysone biosynthetic enzymes and biosynthetic pathway (black box) are still unknown, although our group has identified several ecdysone biosynthetic enzymes so far.
（2）Elucidation of signal pathways that control ecdysone biosynthesis
Mammalian steroid hormone synthesis and secretion are regulated by a feedback mechanism on the hypothalamic-pituitary axis. Even in insects, ecdysone biosynthesis is extensively regulated by multiple peptide hormones synthesized in the central nervous system accordingly to environmental information exogenously and the body endogenously. Ecdysone biosynthesis is regulated by a group of peptidyl neurohormones such as prothoracicotropic hormone, prothoracicostatic peptide, myosuppressin, and pigment-dispersing factor (PDF).
Regulatory mechanisms of insect diapause
Insects have acquired a system called "diapause" to survive under the unsuitable situations such as winter. Diapause in winter is not a passive growth arrest due to low temperature, but an active adaptative strategy by the feedforward predictions of the arrival of winter due to environmental cues such as light changes in day length and activates programs consequently to stop growth in advance. Interestingly, this diapause is controlled by ecdysone, as well as molting and metamorphosis. In addition, diapause is also regulated by the peptidyl neurohormones from the central nervous system. Egg diapause is also known to be caused by inactivation through the ecdysone phosphorylation. However, it is not well understood how environmental information is perceived and how it leads to suppression of ecdysone secretion and inactivation of ecdysone. Also, the signals needed to break diapause are unclear. We are working on how insects sense environmental information and reflect it via the endocrine signals to control the timing of development.
|1999-||Present Professor, Laboratory of Molecular Recognition, Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo|
|1994 - 1999||Associate professor, Department of Biotechnology, The University of Tokyo|
|1988 - 1994||Assistant professor, Department of Agricultural Chemistry, The University of Tokyo|
|1988 – 1988||Post doctoral fellow, JSPS, The University of Tokyo|
|1986 - 1988||Post doctoral fellow, Sandoz Crop Protection, Zoecon Research Institute, USA|
|1986||Ph. D. Department of Agricultural Chemistry, The University of Tokyo|
|1983||M. Sc. Department of Agricultural Chemistry, The University of Tokyo|
|1981||B. Sc. Department of Agricultural Chemistry, The University of Tokyo|