心臓のK+チャネル遺伝子発現の日々の変動
Takeshi Yamashita1, Akiko Sekiguchi, Yu-ki Iwasaki
1The Cardiovascular Institute, Roppongi 7-3-10, Minato-ku, Tokyo 106-0032, Japan. yamt-tky@umin.ac.jp
Circulation
|April 2, 2003
まとめ
心臓のカリウムチャネル遺伝子の発現は日々のリズムを示し,暗闇でKv1.5がピークに達し,明るい時にはKv4.2に達する. イオンチャネルにおけるこれらの昼夜変動は,心臓の電気的活動と不律症のリスクに影響を与えます.
科学分野:
- 心臓病学 心臓病学
- 分子生物学は分子生物学である.
- クロノバイオロジーはクロノバイオロジーを用います.
背景:
- 心律不整は,しばしば昼夜変動を示します.
- 時計遺伝子を含む遺伝子発現は,毎日調整されています.
- 心臓のイオンチャネル遺伝子発現における日々の変動は,電気生理学と心律変異に影響を与える可能性があります.
研究 の 目的:
- 心臓のカリウム (K+) チャンネル遺伝子発現における昼夜リズムを調査する.
- 特定のK+チャネルトランスクリプトが日々の変動を示すかどうかを判断する.
- 遺伝子発現パターンを心臓の電気生理学的性質と相関させる.
主な方法:
- ネズミの心臓における8KVと6KRチャネルのmRNAレベルを24時間以上分析した.
- 孤立したミオサイトで測定されたタンパク質レベルとイオンチャネル電流密度.
- 異なる時間帯で,隔離され,貫通された心臓で,心房および心房の屈折性を評価した.
主要な成果:
- Kv1.5とKv4.2のmRNAレベルは,重要な昼夜変動を示した.
- Kv1.5はZeitgeber time (ZT) 18 (暗黒期) でピークに達し,Kv4.2はZT6 (光期) でピークに達した.
- タンパク質発現,イオン電流,心房屈折率の相応の変化が観察され,リズムが逆光サイクルによって逆転した.
結論:
- Kv1.5とKv4.2のチャネルは,心の中で独特の昼夜表現パターンを表しています.
- 暗闇中のKv1.5発現は,β-アドレナジック活性によって部分的に影響を受けます.
- 光中のKv4.2発現は,自律神経系の機能とは独立している.
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