Interleukin-1 receptor accessory protein organizes neuronal synaptogenesis as a cell adhesion molecule.

Interleukin-1 receptor accessory protein (IL-1RAcP) is the essential component of receptor complexes mediating immune responses to interleukin-1 family cytokines. IL-1RAcP in the brain exists in two isoforms, IL-1RAcP and IL-1RAcPb, differing only in the C-terminal region. Here, we found robust synaptogenic activities of IL-1RAcP in cultured cortical neurons. Knockdown of ...
IL-1RAcP isoforms in cultured cortical neurons suppressed synapse formation as indicated by decreases of active zone protein Bassoon puncta and dendritic protrusions. IL-1RAcP recovered the accumulation of presynaptic Bassoon puncta, while IL-1RAcPb rescued both Bassoon puncta and dendritic protrusions. Consistently, the expression of IL-1RAcP in cortical neurons enhances the accumulation of Bassoon puncta and that of IL-1RAcPb stimulated both Bassoon puncta accumulation and spinogenesis. IL-1RAcP interacted with protein tyrosine phosphatase (PTP) δ through the extracellular domain. Mini-exon peptides in the Ig-like domains of PTPδ splice variants were critical for their efficient binding to IL-1RAcP. The synaptogenic activities of IL-1RAcP isoforms were diminished in cortical neurons from PTPδ knock-out mice. Correspondingly, PTPδ required IL-1RAcPb to induce postsynaptic differentiation. Thus, IL-1RAcPb bidirectionally regulated synapse formation of cortical neurons. Furthermore, the spine densities of cortical and hippocampal pyramidal neurons were reduced in IL-1RAcP knock-out mice lacking both isoforms. These results suggest that IL-1RAcP isoforms function as trans-synaptic cell adhesion molecules in the brain and organize synapse formation. Thus, IL-1RAcP represents an interesting molecular link between immune systems and synapse formation in the brain.
Mesh Terms:
Amino Acids, Animals, Animals, Newborn, Cell Adhesion Molecules, Cells, Cultured, Cerebral Cortex, Coculture Techniques, Fibroblasts, Green Fluorescent Proteins, Humans, Interleukin-1 Receptor Accessory Protein, Mice, Mice, Knockout, Neural Cell Adhesion Molecules, Neurons, Presynaptic Terminals, Protein Binding, Protein Isoforms, Protein Structure, Tertiary, RNA, Small Interfering, Receptor-Like Protein Tyrosine Phosphatases, Class 4, Signal Transduction, Surface Plasmon Resonance, Synapses, Transfection, Vesicular Glutamate Transport Protein 1, Vesicular Inhibitory Amino Acid Transport Proteins
J. Neurosci.
Date: Feb. 22, 2012
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