Search for genes that bring dormant

-Odo the gene expression change that occurs in the muscles during dormant-

理化学研究所（理研）生命機能科学研究センター網膜再生医療研究開発プロジェクトの砂川玄志郎上級研究員、生命医科学研究センタートランスクリプトーム研究チームのオレグ・グセフ客員主管研究員らのInternational joint research groupは、過酷な環境に置かれた哺乳類が自ら代謝を下げて生存を図る「休眠^[1]」に関わる遺伝子を探索し、転写因子Atf3^[2]がマウスの「日内休眠^[1]」に重要な役割を果たすことを発見しました。

本研究成果から、休眠研究のモデル動物としてマウスが有用であることが示されました。今後さらに休眠メカニズムの解析を進めることで、日内休眠や長期の休眠現象である冬眠^[1]を人工的に誘導する技術への応用が期待できます。

In an environment such as cold and hunger, some mammals try to survive by lowering their metabolism to reduce energy consumption.This phenomenon is called dormant, and the dormant for several months is called "hibernation" and several hours of dormant dormant is called day dormant.

This time, the international joint research group focuses on muscles that do not decrease even during dormant immovable state, and have identified dormant gene from the gene working in the mouse skeletal muscles.Above all, the gene encoding the transcription factor ATF3 has been indicated that the expression of dormancy has risen early, and it may be controlling the expression of other dormant genes.Furthermore, when the ATF3 gene was destroyed, the expression type of dormant was changed, indicating that ATF3 was involved in dormant control.

This study was published in the scientific magazine "Communications Biology" (November 15).

The decrease in body temperature during dormancy, which is guided under two conditions, requires the function of the ATF3 gene.

background

Mammals, including humans, can keep their body temperature constant even if the environment changes.This is because the energy sources and oxygen obtained by eating and breathing can be turned into heat by metabolism.On the other hand, in a crisis environment such as cold and hunger, some mammals try to survive by lowering their metabolism to reduce energy consumption.This phenomenon is called "dormant", and the dormant for several months is called "hibernation" and several hours of dumb are called "day dormant".

Oxygen consumption decreases to about 1 to 30 % of normal dormant animals, as a result, to a degree of degree higher than environmental temperature.However, it does not cause low -temperature disorder or frostbite like humans, and there is no particular abnormality in organs such as internal organs.The principles of such low -generation and hypothermia and hypothermia are unknown, and it has been attempted to clarify using hibernation animals, but it is difficult to artificially hibernate for research and genetic methods.Many cannot be applied, so the results have not been achieved.

Mouse, which has been established as a mammal model animal, does not hibernate, but is known to perform dormant day in a starvation.Therefore, the international joint research group has been conducting research on skeletal muscles in order to examine the dormant gene expression specific to dormant using mouse.It is known that although the dormant animal is unique, it hardly moves for a long time for a long time, but the muscle decline (atrophy) rarely occurs.

Research methods and results

マウスは24時間絶食すると、日内休眠を誘導できます。特にC57BL/6J^[3]という系統の個体は、20℃の環境温度で再現よく休眠を誘導できます（図1）。

Fig. 1 Guidance of daily dormant dormant due to fasting of mouse

If the mouse fasts 24 hours from the start of the Meira period (12 hours under the lighting), the body temperature will be reduced in the second half of the dark (12 hours under the shock) and the body temperature will decrease (the arrow in the figure).This state is called a daytime dormant, and it has been established as a method that can lead to dormant dormant.

休眠特異的遺伝子を見つける手掛かりとして、まず、日内休眠の間にだけ発現が変化し、前後では発現量が変化しない「休眠可逆性遺伝子」を探索しました（図2）。探索の手法には、特定の細胞でどの遺伝子が発現しているかだけではなく、遺伝子のどの配列から転写が始まるか（転写開始点）まで正確に把握できるCAGE法^[4]を用いました。その結果、骨格筋の細胞で休眠中のみ遺伝子発現が上昇した遺伝子を589個、低下した遺伝子を277個検出しました。

Figure 2 Exploration of dormantic reverse gene

Dormitory daytime is guided by specific environmental temperature and fasting.Therefore, if each condition is removed, the temperature cannot be dormant due to high temperatures, and the feeding cannot be dormant.By comparing these dormant inhibition and the gene expression in the case of dormancy, the gene that responds only to fasting and low -temperature environments can be distinguished from the gene that responds only to low -metabolism.As a result of the comparison, 330 gene in which the expression rises specifically and 137 gene in which the expression declines is examined, and these are specific to the low -metabolism state of daytime dormant dormant.(Fig. 3).

Figure 3 Search for hypotome -related genes

Next, the gene that satisfies both the conditions of dormant reverse genes and low -metabolic genes has been defined as "dormant specific gene" (Fig. 4).In the dormant gene, 226 gene rising during dormant and 61 gene decreased was found.Furthermore, accurately examining the transfer starting point of each gene, it was found that the gene in which the expression declines during dormant was stronger than other genes.Genes generally have multiple transfer starts, and are known to use the transcription starting point depending on the condition of the cells.This indicated that in low -dedicated muscle cells, the transcription of the gene may have changed significantly.

Figure 4 Exploration of dormant specific gene

Dormant gene is a group of genes whose expression changes with skeletal muscles during dormant.This contains genes in various positions from upstream to downstream of muscle cell gene expression networks, such as the role of receiving dormant signals and the role of changing the nature of the muscles.The gene that causes dormant muscles is located upstream of this network, and its expression changes should appear earlier than the downstream genes.In order to identify such an upstream gene, it is important to find a gene that is already expressed high just before entering a complete dormant.

このような状況を作り出すため、休眠に入りそうになったときに優しく触れることでマウスの体に刺激を与え、休眠したくてもできない「断休眠状態」を作り出し、骨格筋の遺伝子発現を調べました（図5）。その結果、完全な休眠状態にある骨格筋と比較して、45個の遺伝子が上昇し、27個の遺伝子が低下していることが分かりました。この遺伝子の中から、転写因子Atf3をコードするAtf3遺伝子に着目しました。Atf3遺伝子は休眠特異的遺伝子にも属しており、さらに、多くの休眠特異的遺伝子のプロモーター^[5]領域には、転写因子Atf3の結合配列が含まれていることが分かりました。これは、休眠に入る際にまずAtf3遺伝子の発現が上昇し、多量に作られた転写因子Atf3が標的遺伝子のプロモーターに結合してそれらの発現を活性化、もしくは抑制することを意味しています。

Figure 5 Exploring gene expressions with high dormant pressure due to dormant dormant

By directly touching the mouse's body, it hindered dormant, creating a state that could not be dormant.This is a comparison of this dormant state and the expression of the skeletal muscles when dormant.It shows a gene (green point) that has a strong expression during dormant dormant and a weak gene (red point).

Therefore, in order to examine the functions of the ATF3 gene, a mouse (ATF3-knockout mouse) that destroyed the ATF3 gene was created, and analyzed the expression type of daytime dormancy.As a result, the ATF3-knockout mouse was dormant, but it was confirmed that the low metabolism condition at that time was a milder change compared to the normal mouse.This indicated that ATF3 is a transcription factor that involves not only muscles, but also in individual level control of dormant phenomena.

Fig. 6 ATF3 Mouse expression type of fasting dormant dormant due to gene destruction

Evaluating the expression type of fast-eating dormant dormant mouse (ATF3-ko), which destroyed the ATF3 gene, the ATF3-ko had a weaker metabolism during the dormant compared to wild mice.The light -colored line represents the actual measurement data, and the dark line represents the median at the time of each group.▲ Canceled feed, △ feed resumed.

Future expectations

This study revealed that the day's dormant dormant of mice, which can be experimentally guided, is an extremely powerful experimental system in research on dormant mechanisms.In the future, it is important to take the same approach to various organs other than muscles and explore more universal dormant control gene.

さらに、絶食性休眠よりも冬眠に近い冬眠様状態のマウスを調べることも重要です。International joint research groupの砂川上級研究員らは2020年に、脳の特定の神経細胞を刺激することで、環境温度や絶食条件なしでもマウスやラットを24時間位以上の休眠状態（冬眠様状態）にできることを報告しています^注1）。これらの知見に基づいて、将来はヒトの細胞や組織を休眠状態にするための分子メカニズムを探求します。ヒトで人工的な休眠誘導が実現すれば、組織や臓器を対外で長期保存する技術や、外傷や疾患により障害を受けた部位の症状の悪化を遅らせる治療法への応用など、医療分野への応用も期待できます。

supplementary explanation

International joint research group

Research on Life Functional Research Center for Life Functional Research Center for Research, Research and Development Project Senior Researcher Genjiro Sanagawa Technical staff Kiyomi Ishikawa visiting researcher Masayo Takahashi Biobiography Masayo TakahashiTeam Team Leader Hiroshi Kiyonari (Kiyari Hiroshi) Technology Takaya Abe Takaya Abe Research Center for Life Medical Sciences Center Lan Scrype Research Team Captained by Visiting Bureau (Oleg Gusev) Oleg Gusev (Kazan University Control Genomics Research Center Director Director)

Researcher Laslan Deviatiiarov Researcher Gusel Gazizova (GUZEL GAZIZOVA) Researcher Laslan DeviatiiArov.

Research support

This study was conducted at the RIKEN Management Expenses (Life Function Science Research), and partially, a special researcher system (Genjiro Sunagawa), the Japan Academic Promotion Association (JSPS) Scientific Research Auxiliary Funds.Area research (research area proposal type) "Understanding hypothermia mechanism using a near -shelter mouse (research representative: Genjiro Sunagawa)", the foundation (A) "Innovative organization that applies the low -metabolism mechanism of mammalsIt was provided with the development of the Conservation Law (research representative: Masayo Takahashi).

Original Society Information

Presenter

Research on Life Functional Research, Research, Research, Research, Research and Development Project, Visit Researcher Genshiro Sunagawa, Life Medical Science Research Center Transcriptomed Tome Research Team Visitors Inspector Oleg Gusev.

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