Genome-wide analysis of muscle gene expression in response to an intense cycling exercise. Effect of two protein-leucine enriched diets

Protein-leucine supplement ingestion following strenuous endurance exercise accentuates skeletal-muscle protein synthesis and adaptive molecular responses, but the underlying transcriptome is uncharacterized. In a randomized single-blind triple-crossover design, 12 trained men completed 100 min of high-intensity cycling then ingested either 70/15/180/30g protein/leucine/carbohydrate/fat (15LEU), 23/5/180/30g (5LEU) or 0/0/274/30g (CON) beverages during the first 90 min of a 240-min recovery period. Vastus lateralis muscle samples (30 and 240-min post-exercise) underwent transcriptome analysis by microarray followed by bioinformatic analysis. Gene expression was regulated by Protein-leucine in a dose-dependent manner impacting the inflammatory response, muscle growth and development. At 30 min, 15LEU and 5LEU vs. CON activated transcriptome networks with geneset functions involving cell-cycle arrest (Z-score 2.0-2.7; P<0.01), leukocyte maturation (1.7; P=0.007), cell viability (2.4; P=0.005), promyogenic networks encompassing myocyte differentiation and myogenin (MYOD1, MYOG), and a proteinaceous extracellular matrix, adhesion, and development programme correlated with plasma lysine, arginine, tyrosine, taurine, glutamic acid, and asparagine concentrations. High protein-leucine dose (15LEU-5LEU) activated an IL1b-centered proinflammatory network and leukocyte migration, differentiation, and survival functions (2.0-2.6; <0.001). By 240 min, the protein-leucine transcriptome was anti-inflammatory and promyogenic (IL-6, NF-kβ, SMAD, STAT3 network inhibition), with overrepresented functions including decreased leukocyte migration and connective tissue development (-1.8-2.4; P<0.01), increased apoptosis of myeloid and muscle cells (2.2-3.0; P<0.002) and cell metabolism (2.0-2.4; P<0.01). The analysis suggests protein-leucine ingestion modulates inflammatory-myogenic regenerative processes during skeletal muscle recovery from endurance exercise. Further cellular and translational research is warranted to validate amino acid-mediated myeloid and myocellular mechanisms within skeletal-muscle functional plasticity. Total RNA obtained from isolated skeletal muscles

剧烈耐力运动后摄入蛋白质-亮氨酸补充剂可增强骨骼肌蛋白质合成与适应性分子应答，但其背后的转录组特征尚未被阐明。本研究采用随机单盲三交叉设计，纳入12名受过训练的男性受试者，令其完成100分钟高强度骑行运动后，在240分钟的恢复周期内，于前90分钟分别饮用三种配方饮品：70/15/180/30g蛋白质/亮氨酸/碳水化合物/脂肪（15LEU组）、23/5/180/30g（5LEU组），以及0/0/274/30g的对照饮品（CON组）。分别于运动后30分钟与240分钟采集股外侧肌（vastus lateralis）样本，通过微阵列（microarray）开展转录组分析，随后进行生物信息学分析。研究发现，蛋白质-亮氨酸以剂量依赖性方式调控基因表达，进而影响炎症应答、肌肉生长与发育进程。运动后30分钟时，与CON组相比，15LEU与5LEU组激活的转录组网络所涉及的基因集功能包括：细胞周期阻滞（Z评分(Z-score) 2.0~2.7；P<0.01）、白细胞成熟（Z评分1.7；P=0.007）、细胞存活（Z评分2.4；P=0.005），涵盖肌细胞分化与肌生成素（MYOD1、MYOG）的促肌生成网络，以及与血浆赖氨酸、精氨酸、酪氨酸、牛磺酸、谷氨酸、天冬酰胺浓度相关的蛋白细胞外基质、黏附及发育程序。高剂量蛋白质-亮氨酸（15LEU相较于5LEU）激活了以IL1β为核心的促炎网络，以及白细胞迁移、分化与存活功能（Z评分2.0~2.6；P<0.001）。至运动后240分钟时，蛋白质-亮氨酸介导的转录组呈现抗炎与促肌生成特性（抑制IL-6、NF-κβ、SMAD、STAT3相关网络），其富集功能包括：白细胞迁移与结缔组织发育减弱（Z评分-1.8~2.4；P<0.01）、髓系细胞与肌细胞凋亡增加（Z评分2.2~3.0；P<0.002），以及细胞代谢增强（Z评分2.0~2.4；P<0.01）。本研究分析表明，耐力运动后摄入蛋白质-亮氨酸可调控骨骼肌恢复过程中的炎症-肌源性再生进程。未来需开展进一步细胞与转化研究，以验证氨基酸介导的骨骼肌功能可塑性中髓系与肌细胞机制。本研究所用总RNA取自分离的骨骼肌组织。