著者

古市 泰郎 井上 菜穂子 増田 和実

出版者

一般社団法人日本体力医学会

雑誌

体力科学 (ISSN:0039906X)

巻号頁・発行日

vol.67, no.4, pp.261-267, 2018-08-01 (Released:2018-07-18)

参考文献数

18

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Carnitine is well recognized for transporting fatty acids across the mitochondrial membrane; however, studies conducted in the last decade have highlighted another role of carnitine in buffering the excess of mitochondrial acetyl-CoA, an intermediate metabolite of beta-oxidation and glycolytic metabolism. Although acetyl-CoA is an essential metabolite, excess accumulation of acetyl-CoA inhibits pyruvate dehydrogenase, resulting in negative regulation of glucose uptake. In this situation, carnitine binds to acetyl-CoA and is converted to acetylcarnitine, resulting in a decrease in acetyl-CoA levels. It has been demonstrated that carnitine acetylation is essential for glucose homeostasis, and that its dysfunction, caused by aging and high-fat feeding, induces metabolic failure. To analyze carnitine dynamics in skeletal muscle, we have used imaging mass spectrometry to visualize the distribution of acetylcarnitine in rodent skeletal muscle and performed tracing experiments using isotopic labeled carnitine. It was shown that carnitine uptake and acetylation were elevated in oxidative muscles, and that they were dynamically controlled by muscle contraction. Recent studies using cell culture experiments demonstrated that acetylcarnitine is exported from skeletal muscle cells. It is hypothesized that muscle carnitine acetylation in skeletal muscle is not only beneficial for buffering the excess acetyl-CoA, but also plays in the endocrine system. In fact, previous work has shown that plasma acetylcarnitine concentration increases during exercise in humans, suggesting that the acetylcarnitine produced during muscle contraction may be released from muscle cells to serve different functions. In this article, we reviewed the novel roles of carnitine in skeletal muscle by analyzing carnitine dynamics.

著者

眞鍋 康子 井上 菜穂子 高木 麻由美 藤井 宣晴

出版者

日本比較生理生化学会

雑誌

比較生理生化学 (ISSN:09163786)

巻号頁・発行日

vol.29, no.2, pp.70-75, 2012-04-30 (Released:2012-05-25)

参考文献数

46

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AMPキナーゼは,真核生物において高度に保存されたセリン/スレオニンキナーゼである。キナーゼ活性が同定されたのは1970年代初期であるが,その生物学的重要性が認識され始めたのは最近になってからである。細胞内のエネルギー・レベルを感知して,低エネルギー環境に適応するための種々の調節を行う。生命活動のイベントの多くは,細胞レベルであっても個体レベルであっても,何らかの形でエネルギー代謝と関連している。そのため,AMPキナーゼが担う役割も単なるエネルギー・センサーに留まるものではなく,細胞の基本的活動(増殖・分化など)から疾患の生起にまでわたる。本稿では,AMPキナーゼの分子構造および機能を解説する。