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——鳶尾素可以促進骨骼重塑，這一部分是因為它首先會激發(fā)出另一種導致骨質破壞的物質。

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.

鍛煉能塑造肌肉，但鍛煉也強化了骨骼。運動如何提高骨骼強度一直是一個引起爭議的話題，也是科學詳細研究的主題。 現在，一項借助小白鼠實驗的新研究顯示出活躍肌肉細胞分泌的激素是如何引發(fā)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.

運動身體可以刺激骨骼肌中多個分子的釋放。 以鳶尾素為例，這種以希臘信使女神伊里絲命名的激素是嚙齒動物和人類在進行高強度有氧訓練時產生的。一經產生，鳶尾素可以改善骨密度和強度。

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.

為了弄清楚其背后的具體過程，Bruce Spiegelman和他的同事們在達納法伯癌癥研究所(Dana Farber Cancer Institute)和哈佛醫(yī)學院研究了經過培養(yǎng)后的骨細胞，找到了與鳶尾素結合的受體。 這種受體蛋白在稱為骨細胞的細胞上特別豐富。這些細胞是影響骨重建的主要調節(jié)因子，也是骨骼中最豐富的一種細胞類型。

“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.”

“我們在論文中最有意思的發(fā)現是，鳶尾素在刺激骨細胞再生和防止其在培養(yǎng)中死亡方面所發(fā)揮的作用非常巨大。此外，鳶尾素刺激制造一種關鍵蛋白質——硬化蛋白(sclerostin)的能力也不容小覷。”

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.

硬化蛋白是一種實際上導致骨骼破壞的蛋白質。構建骨骼的鳶尾素會促進硬化蛋白的產生，可硬化蛋白會破壞骨頭，這可能看起來可能違反直覺常識。 但Spiegelman解釋道，正是這一丁點的骨質破壞會向身體發(fā)出信號，讓身體開始重建出更強壯的骨骼。

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

這項研究結果發(fā)表在《細胞》雜志上。 [由Hyeonwoo Kim等人著，鳶尾素通過αV整合素受體介導對骨骼和脂肪的影響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:

通過刺激鳶尾素的活動，可以幫助我們制定最大收益的訓練方法，并可能幫助我們制定出保持骨骼強度的方法，讓我們在古稀之年仍能歡快起舞。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.”

“即將展開的新一輪鑒定受體工作還使我們能夠更容易地確定鳶尾素的其他靶細胞類型。我們將特別關注神經細胞類型。因為我們和其他的研究人員都推斷鳶尾素對阿爾茨海默病、帕金森病和肌萎縮性側索硬化癥(ALS)等疾病起到神經保護作用具有很大的可能性。”