IGF 1 GENE TRANSFER TO ACCELERATE MUSCLE RECOVERY FOLLOWING DISUSE

IGF 1 基因转移可加速肌肉废用后的恢复

• 批准号: 7355186
• 负责人: KRISTA H VANDENBORNE
• 金额: $ 0.59万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7355186
• 关键词: IGF; GENE; TRANSFER; ACCELERATE; MUSCLE

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Insulin-like growth factor I (IGF-I) is a potent myogenic factor that has been shown to play a critical role in muscle regeneration and muscle hypertrophy. Viral-mediated gene transfer of IGF-I upregulates muscle size and increases muscle strength. It is not clear whether IGF-I-induced muscle hypertrophy is mediated by an increase in protein synthesis and/or a decrease in proteolysis rates in existing myofibers and satellite cells. PURPOSE: The objective of this study was to investigate the effect of IGF-I overexpression on in vivo muscle protein synthesis rate. METHODS: The left hindlimb of young adult C57BL6 mice was injected with a recombinant adeno-associated virus vector for IGF-I (rAAV-1). The construct consisted of the entire rat IGF-I cDNA which encodes for IGF-I, a Myosin Light Chain (MLC) 1/3 promoter and enhancer, and SV40 polyadenlyation sequence. Six mice (age=3 weeks) were injected with 80ul of 10% glycerol/PBS containing approximately 10 10 rAAV particles into the interstitial space of the anterior compartment of one hindlimb, targeting the extensor digitorum longus (EDL). Three months after transfection, in vivo mixed muscle protein synthesis rates were measured using the incorporation of intravenously administered L-[13C]-phe into EDL muscle proteins. [13C]-phe abundance in the structural proteins was quantitated using gas chromatography-combustion-isotope ratio mass spectrometry. Paired samples t-tests were used for comparisons between transfected and contralateral hindlimbs. RESULTS: rAAV-IGF1 transfection resulted in a significant increase (12.1+8.5%) in muscle wet weight and cross-sectional area (9.9+9.1%)(p0.05). In vivo mixed muscle protein synthesis rate was 26.9+15.6% higher in the rAAV-IGF1 injected limbs compared to the contralateral control limb (p0.05). Average EDL muscle protein synthesis rate was 10.5+2.8%/day in the rAAV-IGF1 injected limb and 8.2+1.9%/day in the contralateral limb. CONCLUSIONS: These results demonstrate that muscle specific adeno-associated virus overexpression of IGF-I increased mixed muscle protein synthesis rate and this contributed to muscle hypertrophy. Further research will determine EDL contractile properties, and the components of the IGF-I signaling pathway that are activated in satellite cells and mature myofibers.

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。胰岛素样生长因子I(IGF-I)是一种强有力的生肌因子，已被证明在肌肉再生和肌肉肥大中发挥关键作用。病毒介导的IGF-I基因转移可上调肌肉大小，增加肌肉力量。目前尚不清楚IGF-I诱导的肌肉肥大是否是通过增加现有肌纤维和卫星细胞中的蛋白质合成和/或降低蛋白质分解速率来实现的。目的：探讨胰岛素样生长因子-I(IGF-I)过表达对在体肌肉蛋白质合成速率的影响。方法：将IGF-I重组腺相关病毒载体(rAAV-1)注射于幼年C57BL6小鼠左侧后肢。该载体由大鼠胰岛素样生长因子-I(IGF-I)、肌球蛋白轻链(MLC)1/3启动子和增强子以及SV40多聚糖基化序列组成。6只小鼠(3周龄)在一侧后肢前室间隙注射80ul的10%甘油/PBS(含约10~10个rAAV颗粒)，靶向指长伸肌(EDL)。3个月后，通过静脉注射L-[13C]-Phe到EDL肌肉蛋白中，测定体内混合肌肉蛋白合成率。用气相色谱-燃烧-同位素比值质谱仪对结构蛋白中的[13C]-Phe丰度进行了定量。用配对样本t检验比较转染组和对侧后肢。结果：rAAV-IGF1转染组肌肉湿重和横截面积显著增加(12.1±8.5%)和(9.9±9.1%)(p0.05)。注射rAAV-IGF1的肢体体内混合肌肉蛋白质合成率较对侧对照肢体高26.9±15.6%(p0.05)。肌肉蛋白质合成速率，注射rAAV-IGF1的患肢为10.5±2.8%/d，对侧为8.2±1.9%/d。结论：这些结果表明，肌肉特异性腺相关病毒IGF-I的过表达增加了混合肌肉蛋白质合成的速度，从而促进了肌肉肥大。进一步的研究将确定EDL的收缩特性，以及在卫星细胞和成熟肌纤维中激活的IGF-I信号通路的成分。