Abstract：
Ribosomal DNA (rDNA) copies exist across multiple chromosomes, and interindividual variation in copy number is speculated to influence the hypertrophic response to resistance training. Thus, we examined if rDNA copy number was associated with resistance training-induced skeletal muscle hypertrophy. Participants (n = 53 male, 21 ± 1 yr old; n = 29 female, 21 ± 2 yr old) performed 10-12 wk of full-body resistance training. Hypertrophy outcomes were determined, as was relative rDNA copy number from preintervention vastus lateralis (VL) biopsies. Pre- and postintervention VL biopsy total RNA was assayed in all participants, and mRNA/rRNA markers of ribosome content and biogenesis were also assayed in the 29 female participants before training, 24 h following training bout 1, and in the basal state after 10 wk of training. Across all participants, no significant associations were evident between relative rDNA copy number and training-induced changes in whole body lean mass (r = -0.034, P = 0.764), vastus lateralis thickness (r = 0.093, P = 0.408), mean myofiber cross-sectional area (r = -0.128, P = 0.259), or changes in muscle RNA concentrations (r = 0.026, P = 0.818), and these trends were similar when examining each gender. However, all Pol-I regulon mRNAs as well as 45S pre-rRNA, 28S rRNA, and 18S rRNA increased 24 h following the first training bout in female participants. Follow-up studies using LHCN-M2 myotubes demonstrated that a reduction in relative rDNA copy number induced by bisphenol A did not significantly affect insulin-like-growth factor-induced myotube hypertrophy. These findings suggest that relative rDNA copy number is not associated with myofiber hypertrophy.NEW & NOTEWORTHY We examined ribosomal DNA (rDNA) copy numbers in men and women who resistance trained for 10-12 wk and found no significant associations with skeletal muscle hypertrophy outcomes. These data, along with in vitro data in immortalized human myotubes whereby rDNA copy number was reduced, provide strong evidence that relative rDNA copy number is not associated with anabolism.
摘要：
核糖体DNA（rDNA）拷贝存在于多个染色体中，并且推测拷贝数的个体间差异会影响对抵抗训练的肥大反应。因此，我们检测了rDNA拷贝数是否与抗阻训练诱导的骨骼肌肥大相关.参与者(n=53名男性，21±1岁；n=29名女性，21±2岁）进行了10-12周的全身阻力训练。确定肥大结果，干预前的股外侧肌（VL）活检的相对rDNA拷贝数也是如此。在所有参与者中检测干预前后VL活检总RNA，和核糖体含量和生物发生的mRNA/rRNA标记也在训练前的29名女性中进行了测定，训练1周后24小时，训练10周后处于基础状态。在所有参与者中，相对rDNA拷贝数与训练诱导的全身瘦体重变化之间无明显关联（r=-0.034，p=0.764），股外侧肌厚度（r=0.093，p=0.408），平均肌纤维横截面积（r=-0.128，p=0.259），或肌肉RNA浓度的变化（r=0.026，p=0.818），在检查每个性别时，这些趋势是相似的。然而,所有Pol-I调节子mRNA以及45S前rRNA，28SrRNA和18SrRNA在雌性第一次训练后24小时增加。使用LHCN-M2肌管的后续研究表明，双酚A（BPA）诱导的相对rDNA拷贝数减少并未显着影响胰岛素样生长因子诱导的肌管肥大。这些发现表明相对rDNA拷贝数与肌纤维肥大无关。
