Research press release


Nature Neuroscience

Seasonal tracking via DNA methylation



Steven Brownたちは、短い昼間(通常の1日12時間ではなく1日11時間という実験条件)を数週間経験したマウスは、自発練習(踏み車走行)を行う総量が減少し、こうした行動の変化にはSCNニューロンでのゲノム全体にわたるDNAメチル化の変化が伴っていることを発見した。DNAメチル化を損なう薬理的阻害物質は、正常な24時間の光周期においたマウスの踏み車走行動作を同じく変化させた。Brownたちは、マウスでのこれらの発見は、哺乳類脳におけるエピジェネティックな変化が、日光への曝露が変化した際の応答行動を調整するのに重要である可能性を示唆していると確信している。

Shortening or lengthening the 24-hour circadian light cycle can cause epigenetic changes in the mouse brain, and these changes can in turn affect circadian behavior such as physical activity, reports a study published online this week in Nature Neuroscience. Understanding these epigenetic regulations may be important in suppressing the negative consequences faced by people in certain occupations (such as night-shift workers) who are exposed to shortened day cycles for an extended period of time.

During the short days of autumn and winter, the neuroendocrine system alters its responsiveness to circadian cues such as shortened daylight and late dawn. These changes in exposure to daylight are also known to affect the fluctuation of molecular clock genes in the mammalian suprachiasmatic nuclei (SCN), a brain area responsible for controlling circadian behavior.

Steven Brown and colleagues find that mice exposed to short days (11 hours of light a day versus the normal 12 hours in a laboratory setting) for several weeks decrease the amount of voluntary exercise (wheel running) they do, and that this change in behavior is correlated with genome-wide changes in DNA methylation of SNC neurons. A pharmacological inhibitor that impairs DNA methylation also altered wheel-running behavior in mice exposed to normal 24-hour light cycle. The authors believe that these findings in mice suggest that epigenetic changes in mammalian brains may be critical to modulate behavior in response to change in exposure to daylight.

doi: 10.1038/nn.3651

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