2013年7月18日

The epigenetics of fat

The epigenetics of fat
脂肪表观遗传学

Altered states
改变了的状态


Limbering up does not just help shed fat. It also changes how fatty tissue works
伸展运动不仅有助于减肥,也改变脂肪组织的工作方式


Jul 13th 2013 |From The Economist print edition: Science and technology


Don't worry. My epigenetic markers will take care of it
别担心。我的表观遗传学标志物会处理的


EXERCISE is the closest thing medicine has to a panacea. Though hitting the treadmill is more effort than swallowing a pill, the benefits are worth it. Even modest amounts of exercise protect against diseases ranging from diabetes and osteoporosis to heart attacks and senility.
运动是医学上最接近于万能药的一种东西。虽然在跑步机上运动要比吞下一枚药片费力许多,但是值得的。甚至是少量的运动也能抵御各种疾病,从糖尿病和骨质疏松症到心脏病和衰老。

Exercise works its magic in many ways. It improves the power and efficiency of the heart; it boosts the release of certain neurotransmitters (the chemicals nerve cells use to talk to each other); and it stimulates cells' garbage-disposal machinery. Now a group of researchers led by Charlotte Ling of Lund University, in Sweden, has discovered another effect of exercise. It alters the way genes work in the tissue that stores fat.
运动在多个方面发挥着它的神奇功效。它提升了心脏的能力和效率;促进某些神经传递素(神经细胞用来彼此交流的化学物质)的释放;和刺激细胞的垃圾处理机制。日前瑞典隆德(兰德)大学Charlotte Ling领导的一个研究小组已经发现了运动的另外一个效果。它改变了基因在存储脂肪的组织中的工作方式。

In a paper published in the Public Library of Science, Dr Ling and her colleagues report the effects of six months of moderate exercise on 23 male couch-potatoes who were in their 30s and 40s. The men were supposed to attend three workouts a week. In the event, they managed an average of 1.8. Nevertheless, besides finding the usual effects―reduced heart rate, lowered blood pressure and a drop in cholesterol levels―the researchers also observed changes in the men's adipose tissue, the place where fat is stored. Specifically, the way fat cells in this tissue expressed their genes had altered.
在一篇发表于《科学公共图书馆》的论文中,Ling博士和他的同僚们报告了6个月的少量运动在23名整天坐在沙发看电视的三四十岁男性身上产生的效果。这些男人们本来应该每周参加3次锻炼。最终,他们做到了平均每周1.8次。然而,除了发现通常的效果外―心率减慢、血压降低和胆固醇水平下降―研究人员还观察到了他们的脂肪组织中的变化,脂肪组织即是脂肪被储存的地方。特别的是,脂肪组织细胞中基因的表达方式已经发生了改变。

This is epigenetics, a rapidly developing branch of biology that focuses not on the genes themselves but rather on how particular genes behave in specific cells. Which genes are active in a cell can be changed by making chemical alterations (known as epigenetic markers) to their DNA. Such alterations let the body fine-tune its response to the environment, and modern gene-sequencing techniques can detect them without too much difficulty.
这就是表观遗传学,生物学中快速发展的一个分支,它并不关注基因本身,而是将焦点放于特定细胞中特定基因是如何表现的。细胞中哪些基因是活跃的,这是能够通过修改DNA的化学成分(表观遗传学标志物)而改变的。这些修改使得身体微调其对环境的反应,而现代的基因测序技术能够比较轻松地检测到。

Dr Ling, who is interested in adult-onset diabetes (often associated with too much body fat), knew that exercise stimulates epigenetic changes in muscle cells. These alter how muscle processes sugar. When she and her colleagues looked for similar alterations in their charges' adipose tissue, they found lots―18,000 markers distributed across 7,663 genes. This matters, because adipose tissue is not just a passive store of energy, it is also an organ in its own right, producing a range of biologically active chemicals that have all manner of effects on the rest of the body.
致力于研究成人发病型糖尿病(通常与过多的身体脂肪有关)的Ling博士已经知道,运动刺激了肌肉细胞的后天改变。这些改变着肌肉如何处理糖分。当她和她的同僚们在脂肪组织中寻找相似变化时,他们发现了很多―18000个标记物分布于7663个基因中。这个关系重大,因为脂肪组织并不只是被动地储存能量,它也是一个能自行产生一系列具有生物活性的化学物质的器官,这些化学物质对身体的其它部位有着各个方面的影响。

Genetic epicenter
基因之源


What all these epigenetic markers are doing remains obscure. But among the altered genes were 18 known to be associated with obesity and another 21 linked with adult-onset diabetes. When Dr Ling's colleagues picked two such altered genes and silenced them completely in laboratory-grown fat cells, the cells changed, becoming more efficient at processing and depositing fat. That leads, Dr Ling notes, to the hypothesis that one reason exercise is good for you is because it improves the ability of fatty tissue to do its job. Lipids thus get stored in the right place instead of settling elsewhere in the body, where they do harm. As she observes, if you do have surplus fat it is better to have it stored in fatty tissue than in the liver or the pancreas.
这些表观遗传学标志物到底都做了什么目前仍然不清楚。但是在这些被修改了的基因当中,18种已知与肥胖有关,而另外12种与成人发病型糖尿病有关。当Ling博士的团队从实验室生长的脂肪细胞中挑选了两个这种改变后的基因并将其完全关闭后,这些细胞反生了变化,它们在处理和储存脂肪上变得更加高效了。Ling博士写道,这引出了一种假设,运动对人有好处的一个原因在于它提升了脂肪组织的工作能力。因此,油脂就被储存在了正确的地方而不是驻留在身体的其它位置而产生危害。正如她所观察到的,如果你有多余的脂肪,那最好将其储存在脂肪组织中,而不要位于肝脏或胰腺。

This study is only a beginning. Working out which epigenetic changes wrought by exercise are important, and which incidental, will take time. But, given worries about how overweight people are becoming, and the incessant message from many governments that their citizens should take more exercise, studies like Dr Ling's should help by shining light on the way exercise actually works its magic.
此类研究仅仅是一个开端。找出哪些基因的后天改变是由运动造成的是至关重要的,以及哪些是偶发的,这些都需要时间。但是,鉴于人们对于是如何变得过重的忧虑,以及许多政府不断的要求其国民要多运动的信息,像Ling博士这样的研究应该有助于人们弄明白运动到底是如何起作用的