jun-BメッセンジャーRNAとAP-1の活性を,光と昼夜時計によって調節する
J M Kornhauser1, D E Nelson, K E Mayo
1Institute for Neuroscience, Northwestern University, Evanston, IL 60208.
まとめ
光は,上下神経核 (SCN) の哺乳類の昼夜時計を同期させます. このプロセスには,日中活動に不可欠なjun-Bのようなすぐ初期の遺伝子が含まれています.
科学分野:
- 神経科学は神経科学である.
- クロノバイオロジーはクロノバイオロジーを用います.
- 分子生物学は分子生物学である.
背景:
- 視床下部のスプラキアスマティック核 (SCN) は,哺乳類における主日経ペースメーカーとして機能する.
- シルカディアンリズムは,外部のシグナル,主に光によって同期 (誘導) されます.
- c-fosのようなすぐ初期の遺伝子は,光のような刺激に反応して急速に発現し,神経の可塑性や信号伝達における役割を示唆しています.
研究 の 目的:
- シルカディアン光の誘導中のSCNにおける即時早期の遺伝子発現の役割を調査する.
- SCNにおける光誘発遺伝子発現が相依存であり,行動リズムシフトと関連しているかどうかを判断する.
主な方法:
- 光曝露後の歯類と黄金のハムスターのSCNにおけるc-fos,c-jun,およびjun-BのメッセンジャーRNA (mRNA) レベルを測定する.
- SCNにおけるAP-1転写因子複合体の結合活動を評価する.
- 遺伝子の発現とAP-1結合活動と昼間の相と行動リズムシフトの発生を相関させる.
主要な成果:
- 光刺激はSCNにおけるc-fos遺伝子の発現を誘発し,Fosが昼間活動に関与することを示唆する.
- フォティック刺激は,SCNにおけるJun-B mRNAとAP-1 DNA結合活性を特に上調し,C-Junに最小限の影響を及ぼします.
- jun-B mRNAとAP-1結合の誘導は相依存であり,光刺激によって行動リズムが変化したときのみ発生する.
結論:
- 光とSCN循環器のペースメーカーは相互作用し,特定の直近早期の遺伝子を調節する.
- SCNにおけるjun-BとAP-1活動の光調節は,日中リズムの誘導に潜在的に関与する重要なメカニズムである.
- これらの発見は,内部生物学的時計を調整するために,SCN内で光情報が処理される分子経路を強調しています.
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