Adult and embryonic mouse neural cell adhesion molecules have different binding properties

Abstract

Interactions between neural cell surfaces seem to be of prime importance during neuroontogenesis, and responsible for the guidance of migrating neuroblasts and growing axons and for the formation of synapses. Little is known about the underlying molecular mechanisms, but most hypotheses imply the existence of cell-surface molecules that mediate the formation of transient or permanent bonds between neural cells. Recently, a membrane glycoprotein called neural cell adhesion molecule (N-CAM) has been characterized in chick and rodent nervous tissue that appears to act as a ligand in adhesion among neural cell bodies or neurites. We have identified a mouse neural surface glycoprotein, named BSP-2 (ref. 7), which by criteriaof electrophoretic migration, developmental changes, amino acid and sugar composition seems to be closely related or identical to N-CAM. Both BSP-2 (refs 8, 9) and N-CAM undergo conversion from an embryonic to an adult form during brain development and it has been suggested that this transition changes the adhesive properties or the binding specificity of the molecule. Using a neuroblastoma line to study functional differences between embryonic and adult BSP-2/N-CAM molecules, we show here that liposomes bearing adult BSP-2 but not those bearing the embryonic form adhere to neuroblastoma cells, demonstrating that the two forms do indeed possess different binding properties.

Characterization of the kinetics of neural cell adhesion molecule homophilic binding

“…In these studies we show that NCAM homophilic binding can occur in the absence of heparin-sulphate proteoglycans and that heparin does not affect the amount of binding observed. The affinity constants determined for the interactions of adult and P0 NCAM are consistent with other reports which suggest that the rates of NCAM-mediated aggregation of brain vesicles or cells is inversely proportional to their sialic acid content [18][19][20]. The amount of PSA associated with NCAM decreases with postnatal development [19,21].…”

The role and potential of sialic acid in human nutrition

“…Sialic acid may be a negative modulator of the interactions mediated by the protein part of neural cell adhesion molecule (N-CAM) (Sadoul et al, 1983). Thus, sialic acid has a possible role in cell-to-cell interaction (Rosenberg, 1995) and has even been postulated to be the actual receptor for neurotransmitters in the central nervous system (von Itzstein & Thomson, 1997).…”

Cardiac expression of polysialylated NCAM in the chicken embryo: Correlation with the ventricular conduction system

“…Variability also exists in its glycosylation state (for review see Regan, 1991). The polysialylation of NCAM is of particular importance because of its effect on NCAM homophilic binding (Hoffman and Edelman 1983;Sadoul et al, 1983) and on cell-cell interactions in general . This carbohydrate moiety is composed of a-2-%linked sialic acids in long chains (Finne et al, 1983) which can represent 30% of the weight of NCAM (Hoffman and Edelman, 1983).…”