Animals, Ankyrins, Aspirin, Axon Initial Segment, Calbindins, Cerebral Cortex, Dose-Response Relationship, Drug, Embryo, Mammalian, Enzyme Inhibitors, Flow Cytometry, Green Fluorescent Proteins, I-kappa B Kinase, I-kappa B Proteins, Ligation, Mice, Mice, Inbred C57BL, Neurons, Phosphorylation, RNA, Small Interfering, Rats, Serine, Signal Transduction, Time Factors, Transfection
This work was supported by Science Foundation Ireland [08/IN.1/B1949; 14/IA/2582] and the European Union [EU FP7-EpiMiRNA under agreement Nr. 602130]. The authors declare that they have no conflict of interest.
BACKGROUND: Previous studies provided evidence for an accumulation of IκB-kinase (IKK) α/β at the axon initial segment (AIS), a neuronal compartment defined by ankyrin-G expression. Here we explored whether the presence of the IKK-complex at the AIS was associated with the activation of IKK signaling at this site.
METHODS AND RESULTS: Proximity-ligation assays (PLAs) using pan-IKKα/β, phospho-IKKα/β-specific as well as ankyrin-G specific antibodies validated their binding to proximal epitopes in the AIS, while antibodies to other phosphorylated signaling proteins showed no preference for the AIS. Small-hairpin mediated silencing of IKKβ significantly reduced anti-phospho-IKKα/β-immunoreactivities in the AIS. ank3 gene-deficient cerebellar Purkinje cells also exhibited no phosphorylated IKKα/β at the proximal region of their axons. Transient ankyrin-G overexpression in PC12 cells augmented NF-κB transactivation in an ankyrin-G death-domain dependent manner. Finally, small molecule inhibitors of IKK-activity, including Aspirin, inhibited the accumulation of activated IKK proteins in the AIS.
CONCLUSION: Our data suggest the existence of a constitutively-active IKK signaling complex in the AIS.
Physics | Physiology
König HG, Watters O, Kinsella S, Ameen M, Fenner BJ, Prehn JHM. A constitutively-active IKK-complex at the axon initial segment.Brain Research. 2018;1678:356-366
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