Distinct molecular interactions mediate neuronal process outgrowth on non-neuronal cell surfaces and extracellular matrices.

Abstract

Abstract.We have compared neurite outgrowth on extracellular matrix (ECM) constituents to outgrowth on glial and muscle cell surfaces. Embryonic chick ciliary ganglion (CG) neurons regenerate neurites rapidly on surfaces coated with laminin (LN), fibronectin (FN), conditioned media (CM) from several non-neuronal cell types that secrete LN, and on intact extracellular matrices. Neurite outgrowth on all of these substrates is blocked by two monoclonal antibodies, CSAT and JG22, that prevent the adhesion of many cells, including neurons, to the ECM constituents LN, FN, and collagen. Neurite outgrowth is inhibited even on mixed LN/poly-D-lysine substrates where neuronal attachment is independent of LN. Therefore, neuronal process outgrowth on extracellular matrices requires the function of neuronal cell surface molecules recognized by these antibodies.The surfaces of cultured astrocytes, Schwann cells, and skeletal myotubes also promote rapid process outgrowth from CG neurons. Neurite outgrowth on these surfaces, though, is not prevented by CSAT or JG22antibodies. In addition, antibodies to a LN/proteoglycan complex that block neurite outgrowth on several LN-containing CM factors and on an ECM extract failed to inhibit cell surface-stimulated neurite outgrowth. After extraction with a nonionic detergent, Schwann cells and myotubes continue to support rapid neurite outgrowth. However, the activity associated with the detergent insoluble residue is blocked by CSAT and JG22 antibodies. Detergent extraction of astrocytes, in contrast, removes all neurite-promoting activity.These results provide evidence for at least two types of neuronal interactions with cells that promote neurite outgrowth. One involves adhesive proteins present in the ECM and ECM receptors on neurons. The second is mediated through detergent-extractable macromolecules present on non-neuronal cell surfaces and different, uncharacterized receptor(s) on neurons. Schwann cells and skeletal myotubes appear to promote neurite outgrowth by both mechanisms.

Purified N-cadherin is a potent substrate for the rapid induction of neurite outgrowth.

“…4). This is similar to what has been observed previously for LN on tissue culture plastic, using these same neurons (Tomaselli et al, 1986). The potency of N-cadherin in our experiments compares favorably with the ability of the calcium-independent adhesion molecules, L1 and N-CAM, to stimulate growth.…”

“…Previous experiments have shown that neurons of the chick CG do not grow neurites on noninducing substrates like tissue culture plastic or poly-o-lysine, at least during the first 16-20 h of culture (e.g., Tomaselli et al, 1986). This is true despite the ability of the CG neurons to adhere to these substrates and extend lamellipodia.…”

“…Because the neurons were able to attach to "blocked" nitrocellulose in the absence of N-cadherin, the effect of antibodies on neurite growth could be independently assessed. Further, N-cadherin is not merely a "permissive" substrate in the sense that it induces rapid process growth in a population of neurons (CG neurons) that extend few or no neurites on a variety of substrates to which the neurons quantitatively adhere, including blocked nitrocellulose, collagen, tissue culture plastic, and poly-D-lysine (Tomaselli et al, 1986;Bixby, 1989; present study). Therefore, N-cadherin joins a short list of proteins (LN, L1, and fibronectin) capable of inducing rapid and extensive outgrowth in vitro when used as purified substrates.…”

“…Preparation of ciliary ganglion (CG) neuron cultures has been described (Bixby and Reichardt, 1985;Tomaselli et al, 1986). Antibodies were added to the wells at 2x final concentration, and the neurons were added in an equal volume of medium.…”

Regional differences in glial-derived factors that promote dendritic outgrowth from mouse cortical neurons in vitro

“…The most well-studied examples of extrinsic factors are those derived from glial cells. Descriptive studies and both in vivo and in vitro manipulations indicate that neuron-glia interactions influence the generation and elaboration of neurites and provide a preferred substrate for neurite extension (Noble et al, 1984;Fallon, 1985;Tomaselli et al, 1986Tomaselli et al, , 1988Neugebauer et al, 1988;Smith et al, 1990;Norris and Kalil, 199 I;Baird et al, 1992).…”