2012年1月20日,德州大学西南医学中心的研究人员在Nature杂志发表文章"Exercise-induced BCL2-regulated autophagy is required for muscle glucose homeostasis"指出,运动对于血糖代谢的益处可能源于身体“吞食自身“的能力。
自体吞噬,是细胞在饥饿和其他压力情况下,通过降解自身损伤或者不需要的部分来产生能量的过程,有时被称作细胞的“管家途径”。
众所周知,运动在很多方面对健康有好处,但是机理并不清楚。同样自体吞噬也有很多好处,这些好处与运动的作用有紧密的联系。我们假设运动的某些益处可以通过自体吞噬来解释。文章通讯作者Dr. Beth Levine说道,他是内科学和微生物学的教授,同时负责德州大学西南医学的自体吞噬研究中心。
Levine博士,是医学中心受到霍华德·休斯医学研究所资助的研究员,决定关注研究在高脂饮食的情况下,运动可以预防血糖异常的能力。她在小鼠方面的研究首先提供了运动能够激活自体吞噬的作用的证据。研究人员发现,遗传上不能提高自体吞噬的小鼠,在短期运动时,忍耐力下降,而且也不能防止血糖异常。
这个发现指导团队进行研究,在糖尿病中,自体吞噬对于慢性运动所起到的保护作用是否很重要。实验分为对照组和实验组,实验组为遗传上不能提高自体吞噬的小鼠,进行高脂饮食,两组都表现出糖尿病样的血糖代谢改变。但是,研究人员发现,运动逆转了对照组中的血糖异常,但对实验组无效。
在自体吞噬缺失的小鼠中,运动不能提高糖代谢水平,这个发现强烈的暗示自体吞噬是一个重要的机理,运动通过它能够防止糖尿病。Dr. Levine认为这个发现也提供了其他的可能,自体吞噬的激活可能对运动的其他好处,包括防止癌症,神经退化疾病和老化也有帮助。
Dr. Levine作出了很多基础发现,大部分归功于扩展自体吞噬领域。1999年,她找到了第一个哺乳动物自体吞噬基因beclin 1,该基因与乳腺癌的抑制因子相关联,这也标志着第一次发现了人类疾病和自体吞噬基因有关。
doi:10.1038/nature10758
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Exercise-induced BCL2-regulated autophagy is required for muscle glucose homeostasis
Congcong He, Michael C. Bassik, Viviana Moresi, Kai Sun, Yongjie Wei, Zhongju Zou, Zhenyi An, Joy Loh, Jill Fisher, Qihua Sun, Stanley Korsmeyer, Milton Packer, Herman I. May, Joseph A. Hill, Herbert W. Virgin, Christopher Gilpin, Guanghua Xiao, Rhonda Bassel-Duby, Philipp E. Scherer & Beth Levine
Exercise has beneficial effects on human health, including protection against metabolic disorders such as diabetes1. However, the cellular mechanisms underlying these effects are incompletely understood. The lysosomal degradation pathway, autophagy, is an intracellular recycling system that functions during basal conditions in organelle and protein quality control2. During stress, increased levels of autophagy permit cells to adapt to changing nutritional and energy demands through protein catabolism3. Moreover, in animal models, autophagy protects against diseases such as cancer, neurodegenerative disorders, infections, inflammatory diseases, ageing and insulin resistance4, 5, 6. Here we show that acute exercise induces autophagy in skeletal and cardiac muscle of fed mice. To investigate the role of exercise-mediated autophagy in vivo, we generated mutant mice that show normal levels of basal autophagy but are deficient in stimulus (exercise- or starvation)-induced autophagy. These mice (termed BCL2 AAA mice) contain knock-in mutations in BCL2 phosphorylation sites (Thr69Ala, Ser70Ala and Ser84Ala) that prevent stimulus-induced disruption of the BCL2–beclin-1 complex and autophagy activation. BCL2 AAA mice show decreased endurance and altered glucose metabolism during acute exercise, as well as impaired chronic exercise-mediated protection against high-fat-diet-induced glucose intolerance. Thus, exercise induces autophagy, BCL2 is a crucial regulator of exercise- (and starvation)-induced autophagy in vivo, and autophagy induction may contribute to the beneficial metabolic effects of exercise.