老化と軸索内輸送

Age-related changes in the slow axonal transport of cytoskeletal proteins.

膜顆粒を運ぶ速い軸索内輸送は，神経細胞の種類や状態によらずほぼ一定の速度を示すが，細胞骨格蛋白を運ぶ遅い軸索内輸送の速度は，成長期に約1/2に減速し，加齢の進行に伴ってさらに減速する。これは遅い輸送速度がモーター分子の速度ではなく，運ばれる細胞骨格の重合状態に依存するためである。本稿では，輸送変化と細胞骨格の変化との対応を中心に現在の知見をまとめ，老化神経にしばしばみられる輸送障害の原因について考える一助としたい。

Technical advancements in video-assisted microscopy has enabled the direct visualization of fast axonal transport as the movement of membranous organelles along microtubules, at rates corresponding to the fast transport rate analyzed in vivo using the metabolic labeling technique. Slow axonal transport of cytoskeletal proteins, on the other hand, is much more difficult to observe directly probably for the following reasons; 1) they are not moving in the form of the polymerized cytoskeleton, 2) only a small fraction of cytoskeletal proteins is mobile at one time, and 3) the distance of each translocation event is short.