InaRIS Fellow (2021-2030)

Yoshifumi Yamaguchi

Professor,Institute of Low Temperature Science, Hokkaido University*Profile is at the time of the award.

2021InaRISBiology & Life sciences

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Research topics: Identification and functional analysis of factors that enable mammalian hibernation

Keyword

Summary: Hibernation is an adaptive strategy to survive a harsh season by suppressing energy consumption and maintaining a low body temperature, but only a limited number of mammals can hibernate. Although it is known that hibernation is accompanied by significant changes in body temperature and energy metabolism, little is known about the molecular mechanisms of hibernation. In this study, we aim to uncover three major mysteries of hibernation, namely "cold tolerance," "seasonal body changes," and "hibernation triggers," using the Syrian hamster, which is an animal model relatively easy to induce hibernation in a laboratory.

Citation

Hibernation is a phenomenon that achieves the "flexibility" and "robustness" of life. Hibernation in mammals is a outlive strategy to survive severe conditions such as low temperature and starvation through inducing systemic suppression of metabolism and hypothermia. Most mammals, including humans, are unable to hibernate, but some mammals, such as bears and squirrels, are able to. Unlike non-hibernators, hibernators are resistant to tissue damages caused by prolonged hypothermia and those during the recovery process from the low body temperature. Hibernators are also known to be resistant to disuse muscle atrophy caused by immobility associated with hibernation. Furthermore, hibernators have many fascinating characteristics associated with hibernation, such as seasonal fluctuations in appetite and body weight, efficient burning of stored fat, endogenous seasonal timers.

However, mechanisms for the regulation of these physiological changes and for the characteristics associated with hibernation are still largely unknown, possibly due to a number of technical limitations. Hibernation is the remaining frontier of life science in the 21st century. This study not only deepens our knowledge and understanding of this interesting life phenomena, but is also expected for medical and pharmaceutical applications, such as artificial hibernation and surgery under hypothermia.

Dr. Yamaguchi's research proposal addresses these issues head-on. Over the past decade, he has performed experiments using the Syrian hamster, which is relatively easy to induce hibernation in the laboratory. With introducing recently developed technologies, he has identified genes involved in hibernation and verified their functions in animals. To date, he has found a drastic changes in white adipose tissues precedes the onset of hibernation in Syrian hamsters acclimated to winter-like condition, and suggested production of endogenous ligands that enhance the ability of lipid catabolism and anabolism simultaneously in the winter-like body of the animals. He has also discovered dietary nutritional factors which confer cold tolerance. He is now identifying candidate genes that affect cycles of the deep torpor bout and periodic arousal.

Based on the above results obtained by his on-going research, this study aims to elucidate the molecular mechanisms of the three major mysteries of hibernation: cold tolerance, seasonal body changes, and hibernation triggers. Thus, his research proposal is full of original ideas and will open up the unexplored new world of life science, hibernation. Dr. Yamaguchi is a promising scientist for a new era of hibernation research. With the support of the InaRIS Fellowship, he is expected to realize his novel ideas and to unravel the mysteries of hibernation during the next 10 years.

Message from fellow

I am happy to have the long-term support of InaRIS for 10 years, which will allow me to stably conduct research on hibernation, a phenomenon that occurs on a yearly basis, and to have time to deeply consider unexpected experimental results. It will also be of great help that I can have the support both for and from the researchers and technicians who work with me. I will challenge myself to uncover the mysteries of hibernation.