The neuromuscular junction is a focal point of mTORC1 signaling in sarcopenia [NMJ data set].

Purpose: To investigate whether our signatures of mTORC1-driven sarcopenia originate from cells residing at the neuromuscular junction (NMJ), we followed laser-capture microdissection with RNA-seq from adult and sarcopenic tibialis anterior (TA) muscles. Methods: TA muscles were incubated in solution containing fluorescently-labeled bungarotoxin, which binds to post-synaptic AChRs and thereby marks NMJ regions. Approximately 300 synaptic regions (NMJ) and a comparable number of extra-synaptic (xNMJ) regions were collected from 30 µM thick sections using laser-capture microdissection (LCM) and processed for RNA-seq. Results: As compared to xNMJ regions, NMJ regions were highly enriched for genes known to be specifically expressed at the NMJ. The analysis demonstrated that genes associated with sarcopenia are significantly enriched at the NMJ in young (10 months) and old (30 months) mice. Furthermore, the age-related reduction in expression of genes associated with extracellular matrix (ECM) remodelling was particularly prominent in NMJ regions but not in xNMJ regions. Conclusions: Diminished expression of ECM genes at the NMJ may impact the stability of the NMJ and its ability to remodel following common age-related remodelling events such as muscle fiber degeneration/regeneration and motor unit loss. mRNA profiles of synaptic and extra-synaptic regions of skeletal muscles of 10 and 30 months old wild type mice by next-generation sequencing.研究目的：为探究我们所鉴定的雷帕霉素靶蛋白复合物1（mTORC1）驱动的肌肉减少症特征是否源自神经肌肉接头（NMJ）处的细胞，我们对成年及肌肉减少症小鼠的胫骨前肌（TA）样本开展激光捕获显微切割（LCM）并结合RNA测序（RNA-seq）进行分析。 实验方法：将胫骨前肌样本置于含有荧光标记银环蛇毒素的溶液中孵育，该毒素可与突触后乙酰胆碱受体（AChRs）结合，从而标记出神经肌肉接头区域。我们从30微米厚的肌肉切片中，通过激光捕获显微切割收集了约300个突触区域（NMJ）以及数量相当的突触外区域（xNMJ），随后对这些样本进行RNA测序处理。 实验结果：与突触外区域（xNMJ）相比，神经肌肉接头（NMJ）区域显著富集已知在神经肌肉接头处特异性表达的基因。分析表明，在10月龄年轻小鼠与30月龄老年小鼠的神经肌肉接头中，与肌肉减少症相关的基因均呈现显著富集状态。此外，与细胞外基质（ECM）重塑相关的基因的表达随年龄下调的现象，在神经肌肉接头区域尤为突出，而在突触外区域则未观察到此变化。 结论：神经肌肉接头处细胞外基质（ECM）基因表达的降低，可能会影响神经肌肉接头的稳定性，以及其在常见年龄相关重塑事件（如肌纤维变性/再生、运动单位丢失）后的重塑能力。 本数据集为10月龄与30月龄野生型小鼠骨骼肌突触区域及突触外区域的mRNA表达谱，通过下一代测序技术获取。