Membrane glycoproteins involved in neurite fasciculation.

Abstract

Abstract. Lectin affinity chromatography combined with mAb production was used to identify chick neural cell surface molecules related to L1 antigen, a mouse neural glycoprotein implicated in cell-cell adhesion (Rathjen, E G., and M. Schachner, 1984, EMBO (Eur. MoL Biol. Organ.)J., 3:1-10).A glycoprotein, G4 antigen, isolated by mAb G4 from adult chick brain is described which comprises a major 135-kD component, a minor doublet at 190 kD, and diffusely migrating bands at 80 and 65 kD in SDS PAGE. This molecule is structurally related to mouse L1 antigen according to NH2-terminal amino acid sequence (50% identity) as well as the behavior of its components in two-dimensional IEF/SDS PAGE gels. A second chicken glycoprotein, FU antigen, was isolated from adult chick brain using mAb Fll. This protein has also a major 135-kD component and minor components at 170 kD and 120 kD. Both immunotransfer analysis with polyclonal antibodies to mAb G4 and to mAb Fll isolate and the behavior on IEF/SDS PAGE gels indicates that the major 135-kD component of Fll antigen is distinct from G4 antigen components. However, the 135-kD component of FI1 antigen shares with G4 antigen and the neural cell adhesion molecule (NCAM) the HNK-1/L2 carbohydrate epitope.In immunofluorescence studies, I34 and Fll antigenie sites were found to be associated mainly with the surface of process-bearing cells, particularly in fiber-rich regions of embryonic brain.Although Fab fragments of polyclonal antibodies to rnAbs G4 or FU immunoaffinlty isolate only weakly inhibit the Ca2+-independent aggregation of neural cells, they strongly inhibit fasciculation of retinal axons. Together these studies extend the evidence that bundling of axons reflects the combined effects of a group of distinct cell surface glycoproteins.T un formation of specific connections in the nervous system during embryonic development is dependent on a variety of processes, including the adhesion of cells to each other and to extracellular matrices. In the last few years several neural cell surface glycoproteins have been identified which appear to be involved in adhesive interactions between neurons, glial cells, and matrices. Among these are the major Ca2+-independent cell-cell adhesion molecules, of which the known ones can be classified into two groups: the very closely related neural cell adhesion molecules (NCAMs) t (10, 39) and the L1 group of antigens (20,38,40).Mouse L1 antigen is biochemically and immunologically distinct from NCAM (13, 37). However, there is some functional similarity between the two molecules in that both anti-NCAM and anti-L1 Fab fragments inhibit the calciumindependent aggregation of cultured mouse cerebellar cells and neuroblastoma N2A cells (37,38). Moreover, the inhibition of aggregation of N2A cells by a combination of 1. Abbreviations used in this paper: NCAM, neural cell adhesion molecule; NgCAM, neuron-glia cell adhesion molecule; WGA, wheat germ agglutinin.anti-NCAM and anti-L1 is synergistic rather than additive (37). Anti-L1 Fab fragments ha...

p27Kip1participates in the regulation of endoreplication in differentiating chick retinal ganglion cells

“…2B), a marker that preferentially detects differentiating layered RGCs. 46 Therefore, the majority of the p27 Kip1 -positive cells present in the retina at this stage are differentiating neurons localized in the ganglion cell layer (GCL), as previously described by ref. 47 .…”

Differential expression of Csk homologous kinase (CHK) in normal brain and brain tumors

“…Among the many cues that guide the axons of embryonic neurons to their proper destinations, axon fasciculation is an important developmental mechanism. The cell adhesion molecules (CAMs) involved in neurite fasciculation 43,44 include neural cell adhesion molecule (N-CAM) and NGF-inducible large external glycoprotein in the rat, neuron-glial cell adhesion molecule, G4, and 8D9 in the chicken, and L1 in the mouse. The role of CAMs on a given axon is to promote the extension of other neurites along this axon that, in turn, produces fasciculated axons.…”

Molecular mechanisms separating two axonal pathways during embryonic development of the avian optic tectum

“…We next investigated growth of tectobulbar axons on affinity-purified G4 protein (Rathjen et al, 1987), since previous investigations have shown that G4 is expressed on tectobulbar axons in vivo and in vitro (Kröger and Schwarz, 1990). Retinal axons, whose ability to extend on G4 has already been described (Lagenaur and Lemmon, 1987), were used as controls.…”

“…The nitrocellulose was coated for 2 hr with 40 111 of laminin (1 mg/mi in PBS; LY. labs, San Mateo, CA) or affinity-purified G4 (0.3 mg/mi in carbonate buffer; Rathjen et al, 1987). The drops were spread until they covered a surface of approximately 0.5 cm'.…”

“…-Only single growth cones that contacted single neurites or very small axon bundles were selected. Since tectobulbar axons in vitro grow in faseicles, F(abh fragments of anti-G4 polyclonal antibodies (Rathjen et al, 1987) were included in the culture medium (final concentration 0.25 mg/mi). This had no effect on the growth cone behavior and the speed ofaxonal elongation, but defaseiculated tectobulbar axons (Kröger and Schwarz, 1990).…”