Molecular mechanisms of axo-axonic innervation. (August 2021)

• Record Type: Journal Article
• Authors: Ango, Fabrice; Gallo, Nicholas Biron; Van Aelst, Linda
• Is Part Of: Current opinion in neurobiology. Volume 69(2021)
• Page Start: 105
• Page End: 112
• Publication Date: 2021-08
• Subjects: Neurobiology -- Periodicals; 573.8
• DOI: 10.1016/j.conb.2021.03.002
• Languages: English
• ISSNs: 0959-4388

Abstract

Abstract: One of the most intriguing features of inhibitory synapses is the precision by which they innervate their target, not only at the cellular level but also at the subcellular level (i.e. axo-dendritic, axo-somatic, or axo-axonic innervation). In particular, in the cerebellum, cortex, and spinal cord, distinct and highly specialized GABAergic interneurons, such as basket cells, chandelier cells, and GABApre interneurons, form precise axo-axonic synapses, allowing them to directly regulate neuronal output and circuit function. In this article, we summarize our latest knowledge of the cellular and molecular mechanisms that regulate the establishment and maintenance of axo-axonic synapses in these regions of the CNS. We also detail the key roles of the L1CAM family of cell adhesion molecules in such GABAergic subcellular target recognition. Highlights: Axo-axonic synapse formation is a prime example of subcellular GABAergic inhibitory synapse specificity. Axonally expressed L1CAM family is crucial for the establishment and maintenance of axo-axonic synapses. Axo-axonic synapse formation uses chemotactic- and chemoaffinity-based molecular mechanisms in the cerebellar cortex. Innervation of the axon initial segment of pyramidal neurons by chandelier cells is dependent on the L1CAM–Ankyrin-G–complex. A molecular code dependent on CAM-based trans-synaptic adhesion regulates GABApre-axo-axonic synapse in the spinal cord.