重生骨骼，需要先“置之死地而后生”！

The hormone irisin encourages bone remodeling, in part by first triggering another substance that encourages some bone breakdown.

激素——鸢尾素可以促进骨骼重塑，这一部分是因为它首先会激发出另一种导致骨质破坏的物质。

Exercise builds muscle. But it also strengthens bones. Exactly how exercise boosts bone strength is a matter of debate—and a subject of scientific scrutiny. Now, a new study in mice shows how a hormone secreted by active muscle cells triggers bone remodeling.

锻炼能塑造肌肉，但锻炼也强化了骨骼。运动如何提高骨骼强度一直是一个引起争议的话题，也是科学详细研究的主题。 现在，一项借助小白鼠实验的新研究显示出活跃肌肉细胞分泌的激素是如何引发骨骼重建的。

Physical activity stimulates the release of multiple molecules from skeletal muscle. Take irisin, for example. This hormone, named after the Greek messenger goddess Iris, is produced by running rodents—and by us humans when we do high-intensity aerobic training. Once it’s generated, irisin improves bone density and strength.

运动身体可以刺激骨骼肌中多个分子的释放。 以鸢尾素为例，这种以希腊信使女神伊里丝命名的激素是啮齿动物和人类在进行高强度有氧训练时产生的。一经产生，鸢尾素可以改善骨密度和强度。

To find out how, Bruce Spiegelman and his colleagues at the Dana Farber Cancer Institute and Harvard Medical School took cultured bone cells and located the receptor to which irisin binds. This receptor protein is particularly abundant on cells called osteocytes. These cells are the master regulator of bone remodeling and the most abundant cell type in bone.

为了弄清楚其背后的具体过程，Bruce Spiegelman和他的同事们在达纳法伯癌症研究所(Dana Farber Cancer Institute)和哈佛医学院研究了经过培养后的骨细胞，找到了与鸢尾素结合的受体。 这种受体蛋白在称为骨细胞的细胞上特别丰富。这些细胞是影响骨重建的主要调节因子，也是骨骼中最丰富的一种细胞类型。

“What we found interesting in this paper is the magnitude of the effects we get in terms of irisin acting to stimulate osteocytes and preventing their death in culture. Also, their ability to make a key protein, sclerostin, under the stimulation of irisin.”

“我们在论文中最有意思的发现是，鸢尾素在刺激骨细胞再生和防止其在培养中死亡方面所发挥的作用非常巨大。此外，鸢尾素刺激制造一种关键蛋白质——硬化蛋白(sclerostin)的能力也不容小觑。”

Sclerostin is a protein that actually stimulates the breakdown of bone. That irisin, which builds bone, would promote the production of sclerostin, which destroys it, may seem counterintuitive. But Spiegelman says that its this bit of bone breakdown that signals the body to engage in some skeletal renovation.

硬化蛋白是一种实际上导致骨骼破坏的蛋白质。构建骨骼的鸢尾素会促进硬化蛋白的产生，可硬化蛋白会破坏骨头，这可能看起来可能违反直觉常识。 但Spiegelman解释道，正是这一丁点的骨质破坏会向身体发出信号，让身体开始重建出更强壮的骨骼。

The results appear in the journal Cell. [Hyeonwoo Kim et al., Irisin Mediates Effects on Bone and Fat via αV Integrin Receptors]

这项研究结果发表在《细胞》杂志上。 [由Hyeonwoo Kim等人著，鸢尾素通过αV整合素受体介导对骨骼和脂肪的影响Irisin Mediates Effects on Bone and Fat via αV Integrin Receptors]

Boning up on the actions of irisin could help us work out how we can derive the most from our workouts. And possibly keep our bones dense enough to keep us dancing in our dotage. And:

通过刺激鸢尾素的活动，可以帮助我们制定最大收益的训练方法，并可能帮助我们制定出保持骨骼强度的方法，让我们在古稀之年仍能欢快起舞。而且：

“The new work identifying the receptor also allows us to really much more easily identify what are other target cell types for irisin. With particular reference to neural cell types. Where there is suggestive evidence by us and others that irisin may play a neuroprotective effect in disorders such as Alzheimer’s Disease, Parkinson’s Disease and ALS.”

“即将展开的新一轮鉴定受体工作还使我们能够更容易地确定鸢尾素的其他靶细胞类型。我们将特别关注神经细胞类型。因为我们和其他的研究人员都推断鸢尾素对阿尔茨海默病、帕金森病和肌萎缩性侧索硬化症(ALS)等疾病起到神经保护作用具有很大的可能性。”