Martínez-Martínez Pilar, Phernambucq Marko, Steinbusch Laura, Schaeffer Laurent, Berrih-Aknin Sonia, Duimel Hans, Frederik Peter, Molenaar Peter, De Baets Marc H, Losen Mario
Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands, Maastricht, The Netherlands.
Neurobiol Dis. 2009 Jul;35(1):14-23. doi: 10.1016/j.nbd.2009.03.008. Epub 2009 Apr 1.
The receptor-associated protein of the synapse (rapsyn) is required for anchoring and stabilizing the nicotinic acetylcholine receptor (AChR) in the postsynaptic membrane of the neuromuscular junction (NMJ) during development. Here we studied the role of rapsyn in the maintenance of the adult NMJ by reducing rapsyn expression levels with short hairpin RNA (shRNA). Silencing rapsyn led to the average reduction of the protein levels of rapsyn (31% loss) and AChR (36% loss) at the NMJ within 2 weeks, corresponding to previously reported half life of these proteins. On the other hand, the sodium channel protein expression was augmented (66%) in rapsyn-silenced muscles. Unexpectedly, at the ultrastructural level a significant increase in the amount of secondary folds of the postsynaptic membrane in silenced muscles was observed. The neuromuscular transmission in rapsyn-silenced muscles was mildly impaired. The results suggest that the adult NMJ can rapidly produce postsynaptic folds to compensate for AChR and rapsyn loss.
在发育过程中，突触相关蛋白（rapsyn）对于将烟碱型乙酰胆碱受体（AChR）锚定并稳定在神经肌肉接头（NMJ）的突触后膜上是必需的。在此，我们通过短发夹RNA（shRNA）降低rapsyn表达水平，研究了rapsyn在成年NMJ维持中的作用。沉默rapsyn导致在2周内NMJ处rapsyn蛋白水平平均降低（损失31%）以及AChR蛋白水平平均降低（损失36%），这与先前报道的这些蛋白质的半衰期一致。另一方面，在rapsyn沉默的肌肉中，钠通道蛋白表达增加（66%）。出乎意料的是，在超微结构水平上，观察到沉默肌肉中突触后膜二次褶皱的数量显著增加。rapsyn沉默肌肉中的神经肌肉传递受到轻度损害。结果表明，成年NMJ能够快速产生突触后褶皱以补偿AChR和rapsyn的损失。
