世界冠軍能在兩個(gè)多小時(shí)里跑完馬拉松全程,，而普通人繞操場(chǎng)跑幾圈就會(huì)吃不消,，為何會(huì)有這么大差異？美國(guó)研究人員發(fā)現(xiàn),，一個(gè)與肌肉耐力有關(guān)的基因可能是原因之一,。缺少這種基因的實(shí)驗(yàn)鼠，能不知疲倦地每天晚上在轉(zhuǎn)籠里跑好幾個(gè)小時(shí),。相關(guān)論文發(fā)表于7月18日的《臨床檢查期刊》（The Journal of Clinical Investigation,，JCI）。
美國(guó)賓夕法尼亞大學(xué)的一個(gè)研究小組報(bào)告說(shuō),，這個(gè)基因叫做IL-15Rα（白細(xì)胞介素-15受體阿爾法）,。它制造的蛋白質(zhì)曾被發(fā)現(xiàn)與肌肉收縮有關(guān)，但此前還沒(méi)有在活的動(dòng)物身上對(duì)這一基因進(jìn)行研究,。
研究人員對(duì)實(shí)驗(yàn)鼠進(jìn)行基因改造,，使其缺失這個(gè)基因，結(jié)果這些實(shí)驗(yàn)鼠每天晚上在轉(zhuǎn)籠里跑動(dòng)的路程是普通鼠的6倍多,。缺少這一基因的實(shí)驗(yàn)鼠的肌肉里有更多的線粒體和肌肉纖維,，比較不容易疲勞。
研究顯示,，缺少這一基因使得實(shí)驗(yàn)鼠腿部的快肌變得像慢肌,，包括收縮性能、對(duì)能量的利用方式等都有變化,。在動(dòng)物的肌肉中,，快肌收縮較快，負(fù)責(zé)需要速度的動(dòng)作,，容易疲勞,；慢肌收縮較慢，不能進(jìn)行快速精密的動(dòng)作,，但能運(yùn)載更多氧氣,，耐力較強(qiáng)。
這個(gè)基因?qū)θ祟惪赡芤灿型瑯佑绊?。研究小組與澳大利亞研究人員合作,，分析了一些世界級(jí)運(yùn)動(dòng)員的基因數(shù)據(jù)，結(jié)果發(fā)現(xiàn)某些特定的IL-15Rα基因突變版本在以耐力見(jiàn)長(zhǎng)的運(yùn)動(dòng)員中更多見(jiàn),。例如在長(zhǎng)距離鐵人三項(xiàng)運(yùn)動(dòng)員中,，超過(guò)四分之三的人擁有某個(gè)版本的突變。這意味著,，一些耐力超強(qiáng)的運(yùn)動(dòng)員可能在基因上有先天優(yōu)勢(shì),。
研究這一基因在肌肉疾病和代謝疾病中的作用,，可望幫助尋找新的療法。不過(guò),，該基因不僅在肌肉中發(fā)揮作用,，還影響到其他多種組織，目前還不知道抑制它的作用是否會(huì)有不良影響,。(生物谷 Bioon.com)
生物谷推薦原文出處：
J Clin Invest. doi:10.1172/JCI44945.
Loss of IL-15 receptor α alters the endurance, fatigability, and metabolic characteristics of mouse fast skeletal muscles
Emidio E. Pistilli, Sasha Bogdanovich, Fleur Garton, Nan Yang, Jason P. Gulbin, Jennifer D. Conner, Barbara G. Anderson, LeBris S. Quinn, Kathryn North, Rexford S. Ahima and Tejvir S. Khurana1
IL-15 receptor α (IL-15Rα) is a component of the heterotrimeric plasma membrane receptor for the pleiotropic cytokine IL-15. However, IL-15Rα is not merely an IL-15 receptor subunit, as mice lacking either IL-15 or IL-15Rα have unique phenotypes. IL-15 and IL-15Rα have been implicated in muscle phenotypes, but a role in muscle physiology has not been defined. Here, we have shown that loss of IL-15Rα induces a functional oxidative shift in fast muscles, substantially increasing fatigue resistance and exercise capacity. IL-15Rα–knockout (IL-15Rα–KO) mice ran greater distances and had greater ambulatory activity than controls. Fast muscles displayed fatigue resistance and a slower contractile phenotype. The molecular signature of these muscles included altered markers of mitochondrial biogenesis and calcium homeostasis. Morphologically, fast muscles had a greater number of muscle fibers, smaller fiber areas, and a greater ratio of nuclei to fiber area. The alterations of physiological properties and increased resistance to fatigue in fast muscles are consistent with a shift toward a slower, more oxidative phenotype. Consistent with a conserved functional role in humans, a genetic association was found between a SNP in the IL15RA gene and endurance in athletes stratified by sport. Therefore, we propose that IL-15Rα has a role in defining the phenotype of fast skeletal muscles in vivo.
