The role of dietary protein in skeletal muscle regeneration post-injury

我的研究计划的长期目标是阐明膳食蛋白质发挥其生物学效应的作用和机制，但本建议的主要重点是基于鳕鱼蛋白质的氨基酸含量。我们之前的研究表明鳕鱼蛋白对血浆脂质、胰岛素敏感性和骨骼肌恢复有有益影响。此外，我们观察到鳕鱼蛋白对肌肉再生的有益作用部分依赖于其高精氨酸、赖氨酸、甘氨酸和牛磺酸（ALGT）含量的抗炎和生肌作用。因此，在这次更新申请中，我建议进一步探索这些新的发现，并研究鳕鱼蛋白中大量存在的氨基酸影响骨骼肌损伤后再生的潜在机制。我建议研究含硫氨基酸和丙氨酸提供了大量的鳕鱼蛋白，可以补充ALGT对骨骼肌损伤后再生的有益作用。使用体内方法，将在损伤之前和之后用丙氨酸和甲硫氨酸+胱氨酸单独、组合在一起以及与ALGT一起处理大鼠，并且将在一系列实验中测量以下内容：（a）通过测量肌肉质量、肌纤维横截面积（µm2）和间质面积，通过炎症和转录因子与骨骼肌修复相关的机制，所述转录因子协调成肌诱导和分化，炎性细胞积累的时程，转录因子MyoD和肌细胞生成素的表达水平，（B）通过测量IGF-1、p-Akt、p-70 S6激酶、Pax-7、Ki-67的骨骼肌蛋白合成机制，（c）通过测量GSK-3和p-GSK-3、Atrogin-1和MURF-1的骨骼肌蛋白降解机制，和（d）大鼠骨骼肌中参与肌肉蛋白降解的基因表达的变化。这些新的研究将产生关于氨基酸对炎症和肌肉损伤后再生的重要性的新知识，并将为鳕鱼蛋白及其生物活性成分作为功能性食品的使用提供指导。

The long term goal of my research program is to elucidate the effects and mechanisms whereby dietary proteins exert their biological effects but the main focus of this proposal is based on the amino acid content of cod protein. Our previous studies have shown a beneficial impact of cod protein on plasma lipids, insulin sensitivity and skeletal muscle recovery. Further, we observed that the beneficial effect of cod protein on muscle regeneration relies partly on the anti-inflammatory and myogenic action of its high arginine, lysine, glycine and taurine (ALGT) content. In this renewal application, I therefore propose to further explore these novel findings and to study the underlying mechanism by which amino acids found in high amounts in cod protein influence skeletal muscle regeneration following an injury. I propose to study sulfur amino acids and alanine provided in high quantities by cod protein that could complement the beneficial effect of ALGT on regeneration of skeletal muscle following an injury. Using in vivo methods, rats will be treated with alanine and methionine+cystine alone, combined together and with ALGT prior and following an injury and the following will be measured in a series of experiments: (a) mechanisms related to skeletal muscle repair through inflammation and transcription factors which coordinate myogenic induction and differentiation by measuring muscle mass, muscle fiber cross-sectional area (µm2) and interstitial area, time course of inflammatory cell accumulation, expression level of transcription factors, MyoD and myogenin, (b) mechanisms of skeletal muscle protein synthesis by measuring IGF-1, p-Akt, p-70S6kinase, Pax-7, Ki-67, (c) mechanisms of skeletal muscle protein degradation by measuring GSK-3 & p-GSK-3, Atrogin-1 and MURF-1, and (d) changes in expression of genes involved in muscle protein degradation in rat skeletal muscle. These novel studies will generate new knowledge on the importance of amino acids on inflammation and muscle regeneration following an injury and will also provide guidance regarding the use of cod protein and its bioactive components as functional foods.