Nuclear factor kappaB controls acetylcholine receptor clustering at the neuromuscular junction

• Published in: The Journal of neuroscience 2010-08, Vol.30 (33), p.11104
• Main Authors: Wang, Jia, Fu, Xiu-Qing, Lei, Wen-Liang, Wang, Tong, Sheng, Ai-Li, Luo, Zhen-Ge
• Format: Article
• Language: English
• Subjects: Agrin - metabolism; Animals; Cell Line; Cytoplasm - metabolism; Gene Expression Regulation; I-kappa B Proteins - genetics; I-kappa B Proteins - metabolism; Mice; Mice, Knockout; Mice, Transgenic; Muscle Proteins - genetics; Muscle Proteins - metabolism; Muscle, Skeletal - growth & development; Muscle, Skeletal - metabolism; Mutation; Myoblasts - metabolism; Neuromuscular Junction - growth & development; Neuromuscular Junction - metabolism; NF-kappa B - antagonists & inhibitors; NF-kappa B - genetics; NF-kappa B - metabolism; Promoter Regions, Genetic; Receptors, Cholinergic - metabolism; RNA, Messenger - metabolism; Transcription Factor RelA - genetics; Transcription Factor RelA - metabolism; Transcription, Genetic
• ISSN: 1529-2401; 1529-2401
• DOI: 10.1523/JNEUROSCI.2118-10.2010

At the vertebrate neuromuscular junction (NMJ), acetylcholine receptor (AChR) clustering is stimulated by motor neuron-derived glycoprotein Agrin and requires a number of intracellular signal or structural proteins, including AChR-associated scaffold protein Rapsyn. Here, we report a role of nuclear factor kappaB (NF-kappaB), a well known transcription factor involved in a variety of immune responses, in regulating AChR clustering at the NMJ. We found that downregulating the expression of RelA/p65 subunit of NF-kappaB or inhibiting NF-kappaB activity by overexpression of mutated form of IkappaB (inhibitor kappaB), which is resistant to proteolytic degradation and thus constitutively keeps NF-kappaB inactive in the cytoplasma, impeded the formation of AChR clusters in cultured C2C12 muscle cells stimulated by Agrin. In contrast, overexpression of RelA/p65 promoted AChR clustering. Furthermore, we investigated the mechanism by which NF-kappaB regulates AChR clustering. Interestingly, we found that downregulating the expression of RelA/p65 caused a marked reduction in the protein and mRNA level of Rapsyn and upregulation of RelA/p65 enhanced Rapsyn promoter activity. Mutation of NF-kappaB binding site on Rapsyn promoter prevented responsiveness to RelA/p65 regulation. Moreover, forced expression of Rapsyn in RelA/p65 downregulated muscle cells partially rescued AChR clusters, suggesting that NF-kappaB regulates AChR clustering, at least partially through the transcriptional regulation of Rapsyn. In line with this notion, genetic ablation of RelA/p65 selectively in the skeletal muscle caused a reduction of AChR density at the NMJ and a decrease in the level of Rapsyn. Thus, NF-kappaB signaling controls AChR clustering through transcriptional regulation of synaptic protein Rapsyn.