JP
Labs and Faculty
Core Laboratories
Laboratory of Molecular Recognition

KATAOKA Hiroshi Prof. Ph.D.

Other Affiliations: Department of Biotechnology, Faculty of Agriculture, The University of Tokyo
Theme

Insect endocrinology, Insect physiology

Keyword

Molting & Metamorphosis, Diapause, Peptide hormone, Steroids

Message

Since my graduate school days, I have studied various insect-specific biological and physiological phenomena such as molting and metamorphosis, especially regulatory hormones that control growth and development. Through this research, I would like to clarify the mechanisms by which the developmental timing of living organisms is precisely controlled. In the field of life sciences, new technologies and methods have been updated every day. Thanks to that, research projects that would have taken several years 10 years ago can now be done just in a few weeks. On the other hand, the research currently being discussed may be forgotten as past research. Also, only a handful of students can continue graduate studies for the rest of their lives. At graduate school, I would like you to understand how to proceed scientific research, what to do now, and what is important for developing historical research. I would like you not only to compete for the speed of producing results, but also to recognize that you are the leading player in your research area and do your best.

Introduction

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.
References:
doi: 10.1016/j.jchromb.2012.12.014,
doi: 10.1074/jbc.M111.244384,
doi: 10.1242/dev.02428
doi: 10.1016/j.bbrc.2005.09.043,
doi: 10.1111/j.1365-2583.2005.00587.x.,
doi: 10.1074/jbc.M404514200

(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).
References:
doi: 10.1371/journal.pone.0103239,
doi: 10.1002/cne.22517,
doi: 10.1073/pnas.0907471107,
doi: 10.1371/journal.pone.0003048,
doi: 10.1271/bbb.70420,
doi: 10.1016/j.mce.2007.05.008,
doi: 10.1073/pnas.0511196103,
doi: 10.1074/jbc.M500308200

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.
References:
doi: 10.1016/j.ibmb.2020.103491,
doi: 10.1111/imb.12291,
doi: 10.1038/srep41651,
doi: 10.1371/journal.pone.0146619,
doi: 10.1371/journal.pone.0060824

  • LC-MS / MS used for ecdysone-related steroid analysis

  • Immunohistochemistry of myosuppressin-producing cells (green): the cover of PNAS

Biography

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