2016年6月28日訊/生物谷BIOON/--發表於國際雜誌Experimental Physiology上的一項研究報告中,來自皇后大學等研究機構的科學家通過研究發現,鍛鍊和禁食或許並不會改變參與能量產生的關鍵酶類的位置;SIRT3是參與脂肪代謝和能量產生的一種重要酶類;其位於人類骨骼肌細胞的線粒體中,可以通過靶向作用特定蛋白以及改變特殊蛋白的活性來發揮作用;機體中幾乎每個細胞都含有線粒體,而線粒體作為細胞的能量工廠可以持續產生維持機體功能所需的能量;因此深入研究線粒體中SIRT3酶對於理解機體細胞功能的發揮如何影響健康非常關鍵。
為了確定肌肉細胞中的SIRT3是否會改變,研究者將健康年輕男性分為兩組,一組進行1小時的耐力運動,而另外一組則進行48小時的禁食,隨後研究者在運動和禁食後的多個時間點對參與者進行骨骼肌肌肉活組織檢查,並且分離細胞中的線粒體,結果發現,儘管細胞中的SIRT3 mRNA的水平降低了,但其位置並沒有發生改變,這就說明,骨骼肌細胞線粒體內的SIRT3豐度的改變或許並不會調節其活性。
研究者Brendon Gurd教授說道,骨骼肌細胞通過激活許多線粒體蛋白來對刺激產生反應,以此來滿足細胞的能量需求;而通過控制蛋白質進入到細胞中的特定區域就可以實現對蛋白質的調節,因此我們假設,SIRT3或許可以進入到線粒體中對鍛鍊和禁食產生反應。
研究者還補充道,SIRT3所屬於的長壽蛋白(Sirtuins)家族被認為可以調節機體長壽和代謝健康;然而大多數的支持性數據都來自對細胞和動物模型的研究,這些蛋白質是否在機體老化和健康過程中扮演著重要角色還需要後期研究證實,而且研究者還需要深入研究來理解人類機體中長壽蛋白的調節機制。
本文研究首次調查了人類機體中SIRT3被調節的機制,深入理解控制SIRT3活性的分子機制不僅在基礎科學層面上非常重要,而且對於靶向作用該蛋白從而開發多種治療代謝性疾病的新型療法也提供了新的希望。未來研究中研究者計劃調查SIRT3可以特異性靶向作用哪種蛋白,以及如何利用這種機制來調節蛋白的活性。(生物谷Bioon.com)
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SIRT3 gene expression but not subcellular localization is altered in response to fasting and exercise in human skeletal muscle
Brittany A. Edgett, Meghan C. Hughes, Jennifer B. L. Matusiak, Christopher G. R. Perry, Craig A. Simpson, Brendon J. Gurd
The present study examined SIRT3 expression and mitochondrial localization in response to acute exercise and short-term fasting in human skeletal muscle. Experiment 1 involved 8 healthy men (age, 21.4 ± 2.8 years; VO2peak, 47.1 ± 11.8 ml min−1 kg−1) who performed a single bout of exercise at ∼55% of peak aerobic work rate for 1 h. Muscle biopsies were obtained at rest (Rest), immediately after exercise (EX-0), and 3 h post-exercise (EX-3). Experiment 2 involved 10 healthy men (age, 22.0 ± 1.5 years; VO2peak, 47.2 ± 6.7 ml min−1 kg−1) who underwent a 48-hour fast, with muscle biopsies collected 1 h postprandial (Fed) and following 48 h of fasting (Fast). Mitochondrial respiration was measured using high-resolution respirometry in permeabilized muscle fibre bundles to assess substrate oxidation. Whole body fat oxidation increased after both exercise (Rest: 0.96 ± 0.32, Exercise: 5.66 ± 1.97, P < 0.001) and fasting (Fed: 0.87 ± 0.51, Fast: 1.30 ± 0.37 kcal min−1, P < 0.05). SIRT3 gene expression decreased (P < 0.05) following both exercise (−8%) and fasting (−19%); however SIRT3 whole muscle protein content was unaltered following fasting. No changes were observed in SIRT3 mitochondrial localization following either exercise or fasting. Fasting also decreased the Vmax of glutamate (80 ± 43 vs. 50 ± 21 pmol sec−1 mg−1 dry wt, P < 0.05). These findings suggest that SIRT3 does not appear to be regulated by changes in mitochondrial localization at the time points measured in the current study in response to cellular energy stress in human skeletal muscle.