Immunoelectron microscopic localization of the neural cell adhesion molecules L1 and N-CAM during postnatal development of the mouse cerebellum.

Abstract

Abstract. The cellular and subcellular localization of the neural cell adhesion molecules L1 and N-CAM was studied by pre-and postembedding immunoelectron microscopic labeling procedures in the developing mouse cerebellar cortex. The salient features of the study are: (a) L1 displays a previously unrecognized restricted expression by particular neuronal cell types (i.e., it is expressed by granule cells but not by stellate and basket cells) and by particular subcellular compartments (i.e., it is expressed on axons but not on dendrites or cell bodies of Purkinje cells). (b) L1 is always expressed on fasciculating axons and on postmitotic, premigratory, and migrating granule cells at sites of neuron-neuron contact, but never at contact sites between neuron and glia, thus strengthening the view that L1 is not involved in granule cell migration as a neuron-glia adhesion molecule. (c) While N-CAM antibodies reacting with the three major components of N-CAM (180, 140, and 120 kD) show a rather uniform labeling of all cell types, antibodies to the 180-kD component (N-CAM1s0) stain only the postmigratory granule cell bodies supporting the notion that N-CAMps0, the N-CAM component with the longest cytoplasmic domain, is not expressed before stable cell contacts are formed. Furthermore, N-CAMls0 is only transiently expressed on Purkinje cell dendrites. (d) N-CAM is present in synapses on both pre-and postsynaptic membranes. L1 is expressed only preterminally and not in the subsynaptic membranes.These observations indicate an exquisite degree of fine tuning in adhesion molecule expression during neural development and suggest a rich combinatorial repertoire in the specification of cell surface contacts.

EMA: A developmentally regulated cell‐surface glycoprotein of CNS neurons that is concentrated at the leading edge of growth cones

“…Two molecules thought to be involved in cell-cell and cell-substrate interactions, L1 and an integrin, are prominent on the filopodial tips of growth cones from chick dorsal root ganglia, whereas N-CAM and N-cadherin are more uniformly distributed (Letourneau and Shattuck, 1989). The 2A1 antigen also accumulates at contact sites between growth cones and neurites and between fasciculating neurites, as does L1 and the 180 kD form of N-CAM (Persohn and Schachner, 1987;Pollerberg et al, 1987).…”

5-HT6 Receptor Antagonists as Novel Cognitive Enhancing Agents for Alzheimer's Disease

“…A key mediator of interneuronal contacts is neural cell adhesion molecule (NCAM), which is expressed on the cell surface of perisynaptic neuronal processes. 62,63 Although it is necessary for the induction of long-term potentiation and some forms of cognition, 64 -66 the plastic nature is achieved by the post-translational polysialylation of NCAM through the attachment of large homopolymers of ␣2,8 polysialic acid (PSA) to form PSA-NCAM. PSA provides antiadhesive properties that reduce the binding affinity between NCAM on neuronal processes, 67,68 thus promoting structural plasticity.…”

Alternative splicing in the neural cell adhesion molecule pre-mRNA: regulation of exon 18 skipping depends on the 5'-splice site.

“…NCAM-180, the product of the mRNA, which includes El8, is essentially specific for postmitotic neurons (Persohn and Schachner 1987;Prieto et al 1989). Its accumulation at sites of cell-cell contact in culture (Pollerberg et al 1987) and at subsynaptic sites in vivo (Persohn et al 1989) suggests that this N C A M isoform plays a role in stabilizing permanent contacts such as those constituted by synapses.…”