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.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子弹和调查员（PI）可能已经从其他NIH来源获得了主要资金，因此可以在其他清晰的条目中代表。列出的机构适用于该中心，这不一定是调查员的机构。胰岛素样生长因子I（IGF-I）是一种有效的肌源性因子，已证明在肌肉再生和肌肉肥大中起关键作用。病毒介导的IGF-I基因转移会上调肌肉大小并增加肌肉力量。目前尚不清楚IGF-I诱导的肌肉肥大是否是通过蛋白质合成的增加和/或现有肌纤维和卫星细胞中蛋白水解速率降低来介导的。目的：这项研究的目的是研究IGF-I过表达对体内肌肉蛋白合成率的影响。方法：年轻的成年C57BL6小鼠的左后肢被注入IGF-I（RAAV-1）的重组腺相关病毒载体。该构建体由整个大鼠IGF-I cDNA组成，该构造编码IGF-I，肌球蛋白轻链（MLC）1/3启动子和增强子，以及SV40多酰基化序列。将六只小鼠（年龄= 3周）注入80uul的10％甘油/PB，含有大约10个RAAV颗粒的甘油/PB，瞄准了一个后肢的前隔室的间质空间，瞄准了伸肌长龙杆（EDL）。转染三个月后，使用静脉内施用的L- [13C] Phe掺入EDL肌肉蛋白中，测量体内混合肌肉蛋白的合成速率。 [13C]使用气相色谱 - 燃烧 - 同位素比率质谱法对结构蛋白的phe丰度进行定量。配对样品t检验用于转染和对侧后肢之间的比较。结果：RAAV-IGF1转染导致肌肉湿重和横截面区域（9.9+9.1％）显着增加（12.1+8.5％）（P0.05）。与对侧对照肢相比，在RAAV-IGF1注射的肢体中，体内混合肌肉蛋白合成速率高26.9+15.6％（P0.05）。在RAAV-IGF1注射的肢体中，EDL肌肉蛋白合成率为10.5+2.8％/天，对侧肢体中的平均肌肉蛋白质合成率为8.2+1.9％/天。结论：这些结果表明，IGF-1的肌肉特异性腺相关病毒过表达增加了混合肌肉蛋白的合成率，这有助于肌肉肥大。进一步的研究将确定EDL收缩特性，以及在卫星细胞和成熟的肌纤维中激活的IGF-I信号通路的成分。