Article: article from journal or magazin.
Neurite fasciculation mediated by complexes of axonin-1 and Ng cell adhesion molecule.
Journal of Cell Biology
Neural cell adhesion molecules composed of immunoglobulin and fibronectin type III-like domains have been implicated in cell adhesion, neurite outgrowth, and fasciculation. Axonin-1 and Ng cell adhesion molecule (NgCAM), two molecules with predominantly axonal expression exhibit homophilic interactions across the extracellular space (axonin- 1/axonin-1 and NgCAM/NgCAM) and a heterophilic interaction (axonin-1-NgCAM) that occurs exclusively in the plane of the same membrane (cis-interaction). Using domain deletion mutants we localized the NgCAM homophilic binding in the Ig domains 1-4 whereas heterophilic binding to axonin-1 was localized in the Ig domains 2-4 and the third FnIII domain. The NgCAM-NgCAM interaction could be established simultaneously with the axonin-1-NgCAM interaction. In contrast, the axonin-1-NgCAM interaction excluded axonin-1/axonin-1 binding. These results and the examination of the coclustering of axonin-1 and NgCAM at cell contacts, suggest that intercellular contact is mediated by a symmetric axonin-12/NgCAM2 tetramer, in which homophilic NgCAM binding across the extracellular space occurs simultaneously with a cis-heterophilic interaction of axonin-1 and NgCAM. The enhanced neurite fasciculation after overexpression of NgCAM by adenoviral vectors indicates that NgCAM is the limiting component for the formation of the axonin-12/NgCAM2 complexes and, thus, neurite fasciculation in DRG neurons.
Animals, Animals, Newborn, Binding Sites, Cell Adhesion Molecules, Neuron-Glia/chemistry, Cell Adhesion Molecules, Neuron-Glia/genetics, Cell Adhesion Molecules, Neuronal/chemistry, Cell Adhesion Molecules, Neuronal/genetics, Chickens, Contactin 2, Extracellular Space/physiology, Ganglia, Spinal/physiology, Mice, Mice, Inbred ICR, Models, Molecular, Mutagenesis, Neurites/physiology, Neurons/cytology, Neurons/physiology, Organ Culture Techniques, Point Mutation, Polymerase Chain Reaction, Protein Conformation, Recombinant Proteins/chemistry, Recombinant Proteins/metabolism, Sequence Deletion, Transfection
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