Chen Mengling, Cheng Chun, Yan Meijuan, Niu Shuqiong, Gao Shangfeng, Shi Shuxian, Liu Haiou, Qin Yongwei, Shen Aiguo
The Jiangsu Province Key Laboratory of Neuroregeneration, Nantong University, Nantong, China.
J Mol Neurosci. 2008;34(1):89-100. doi: 10.1007/s12031-007-9005-y. Epub 2007 Sep 15.
Carboxy-terminal PDZ ligand of nNOS (CAPON) protein, as an adaptor, binds to nNOS via the PDZ domain helping regulate neuronal nitric oxide synthase (nNOS) activity at post-synaptic sites in neurons (Jaffrey et al., Neuron, 20, 115-124, 1998). Recently, it has been reported that CAPON is present in mouse muscle and may be involved in mouse muscle growth, injury, and repair possibly by regulating the stability, activity, or position of nNOS (Segalat et al., Experimental Cell Research, 302, 170-179, 2005). The present study was to explore the expression patterns and roles of CAPON as well as NOS in rat muscle regeneration after nerve injury. Normal Sprague-Dawley rats were subjected to right sciatic nerve crush injury. Walking track analysis, real time polymerase chain reaction, Western blotting, in situ hybridization, immunocytochemistry, and co-immunoprecipitation techniques were used. It revealed that CAPON mRNA increased, which peaked on days 1 and 28, whereas nNOS mRNA underwent a downregulation in the ipsilateral gastrocnemius muscles after sciatic nerve injury. Their proteins approximately paralleled the mRNA expression. CAPON and nNOS were identified in the activated satellite cells or myotubes and their in vivo interaction was verified. However, eNOS and iNOS proteins suffered an upregulation and were detected in activated satellite cells or myotubes. These data suggest that CAPON and all these three isoforms of NOS might be involved in muscle regeneration after nerve injury. Further study is necessary for a better understanding of the potential functional link between CAPON, NOS, and muscle regeneration, with possible application to therapy for skeletal muscle repair from nerve injury.
神经元型一氧化氮合酶（nNOS）的羧基末端PDZ配体（CAPON）蛋白作为一种衔接蛋白，通过PDZ结构域与nNOS结合，有助于在神经元的突触后位点调节神经元型一氧化氮合酶（nNOS）的活性（Jaffrey等人，《神经元》，第20卷，第115 - 124页，1998年）。最近，有报道称CAPON存在于小鼠肌肉中，可能通过调节nNOS的稳定性、活性或位置参与小鼠肌肉的生长、损伤和修复（Segalat等人，《实验细胞研究》，第302卷，第170 - 179页，2005年）。本研究旨在探讨CAPON以及一氧化氮合酶（NOS）在大鼠神经损伤后肌肉再生中的表达模式和作用。对正常的Sprague - Dawley大鼠进行右侧坐骨神经挤压损伤。采用行走轨迹分析、实时聚合酶链反应、蛋白质印迹法、原位杂交、免疫细胞化学和免疫共沉淀技术。结果显示，坐骨神经损伤后，同侧腓肠肌中CAPON mRNA增加，在第1天和第28天达到峰值，而nNOS mRNA则下调。它们的蛋白质表达与mRNA表达大致平行。在活化的卫星细胞或肌管中鉴定出了CAPON和nNOS，并验证了它们在体内的相互作用。然而，内皮型一氧化氮合酶（eNOS）和诱导型一氧化氮合酶（iNOS）蛋白上调，并在活化的卫星细胞或肌管中被检测到。这些数据表明，CAPON以及NOS的这三种同工型可能都参与了神经损伤后的肌肉再生。有必要进一步研究以更好地理解CAPON、NOS和肌肉再生之间潜在的功能联系，这可能应用于神经损伤后骨骼肌修复的治疗。
