對成年哺乳動物幹細胞的功能來說至關重要的特性之一是,長時間保持靜止狀態的能力以及需要再生時做出反應的能力。骨骼肌數量及功能的損失是人類晚年衰老的共同特徵,與被稱為「衛星細胞」的骨骼肌幹細胞的再生能力的喪失有關。
Pura Mu?oz-Cánoves及同事發現,衰老中的「衛星細胞」發生從靜止狀態向衰老前狀態的不可逆轉變,這與已被發現是衰老的一個標誌的腫瘤抑制蛋白p16INK4a的表達水平增加有關。成年期間p16INK4a的抑制被發現能將「衛星細胞」保持在一個可逆的靜止狀態,使肌肉能夠再生;p16INK4a在老年人的「衛星細胞」中失調,肌肉再生潛力喪失。(生物谷Bioon.com)
生物谷推薦的英文摘要:
Nature doi:10.1038/nature13013
Geriatric muscle stem cells switch reversible quiescence into senescence
Pedro Sousa-Victor, Susana Gutarra, Laura García-Prat, Javier Rodriguez-Ubreva, Laura Ortet, Vanessa Ruiz-Bonilla, Mercè Jardí, Esteban Ballestar, Susana González, Antonio L. Serrano, Eusebio Perdiguero & Pura Mu?oz-Cánoves
Regeneration of skeletal muscle depends on a population of adult stem cells (satellite cells) that remain quiescent throughout life. Satellite cell regenerative functions decline with ageing. Here we report that geriatric satellite cells are incapable of maintaining their normal quiescent state in muscle homeostatic conditions, and that this irreversibly affects their intrinsic regenerative and self-renewal capacities. In geriatric mice, resting satellite cells lose reversible quiescence by switching to an irreversible pre-senescence state, caused by derepression of p16INK4a (also called Cdkn2a). On injury, these cells fail to activate and expand, undergoing accelerated entry into a full senescence state (geroconversion), even in a youthful environment. p16INK4a silencing in geriatric satellite cells restores quiescence and muscle regenerative functions. Our results demonstrate that maintenance of quiescence in adult life depends on the active repression of senescence pathways. As p16INK4a is dysregulated in human geriatric satellite cells, these findings provide the basis for stem-cell rejuvenation in sarcopenic muscles.