骨骼肌蛋白质合成是一个高度复杂的过程,受营养状况的影响,机械刺激,修复程序,荷尔蒙,和增长因素。蛋白质合成的分子方面集中在mTORC1复合物周围。然而,mTORC1调节的复杂性,上游和下游,扩大了加班时间。此外,骨骼肌的可塑性使其成为一种独特的组织,必须在具有相当蛋白质含量的组织内的肌纤维代谢的时间变化与肥大/萎缩刺激之间进行协调。骨骼肌通过关键调节蛋白管理合成代谢和分解代谢途径之间的推拉,以在营养剥夺时促进能量产生或在营养可用性和合成代谢刺激时激活合成代谢途径。支链氨基酸(BCAAs)可用于能量产生和信号传导以诱导蛋白质合成。BCAAs的代谢与能量和合成代谢过程串联发生,沿着它们各自的路径在几个点上汇聚。肌内BCAA的命运增加了另一层调节,具有促进或抑制肌纤维蛋白合成代谢的作用。这篇综述将概述肌肉蛋白质合成的一般机制,并描述代谢途径如何调节这一过程。最后,我们将讨论BCAA的可用性和需求如何与合成机制协调,并确定参与肌内BCAA贩运的关键因素。
Skeletal muscle protein synthesis is a highly complex process, influenced by nutritional status, mechanical stimuli, repair programs, hormones, and growth factors. The molecular aspects of protein synthesis are centered around the mTORC1 complex. However, the intricacies of mTORC1 regulation, both up and downstream, have expanded overtime. Moreover, the plastic nature of skeletal muscle makes it a unique tissue, having to coordinate between temporal changes in myofiber metabolism and hypertrophy/atrophy stimuli within a tissue with considerable protein content. Skeletal muscle manages the push and pull between anabolic and catabolic pathways through key regulatory proteins to promote energy production in times of nutrient deprivation or activate anabolic pathways in times of nutrient availability and anabolic stimuli. Branched-chain amino acids (BCAAs) can be used for both energy production and signaling to induce protein synthesis. The metabolism of BCAAs occur in tandem with energetic and anabolic processes, converging at several points along their respective pathways. The fate of intramuscular BCAAs adds another layer of regulation, which has consequences to promote or inhibit muscle fiber protein anabolism. This review will outline the general mechanisms of muscle protein synthesis and describe how metabolic pathways can regulate this process. Lastly, we will discuss how BCAA availability and demand coordinate with synthesis mechanisms and identify key factors involved in intramuscular BCAA trafficking.