Induction of cholinergic differentiation with neurite sprouting by de novo biosynthesis and expression of GD3 and b-series gangliosides in Neuro2a cells.

The expression of a single glycosyltransferase, GD3 synthase, caused cholinergic differentiation with neurite sprouting. The cells that expressed GD3 were established from Neuro2a cells by transfection of a mammalian expression vector into which were carried a cDNA encoding GD3 synthase and the blasticidin-S-deaminase gene with a SV40 promoter, followed by selection with blasticidin-S-hydrochloride. The blasticidin-S-hydrochloride-resistant colonies derived from the cells transfected with the cDNA encoding GD3 synthase and the clonal cells (N2a-GD3) were spontaneously sprouting neurites but not those derived from cells transfected with only the vector without the cDNA encoding GD3 synthase (N2a-bsr). GD3 expression by N2a-GD3 was confirmed by immunostaining of the cells using the anti-GD3 monoclonal antibody, KM643. N2a-GD3 expressed not only GD3 but also GQ1b, one of the b-series gangliosides, whereas N2a-bsr did not express these gangliosides. Cell proliferation of N2a-GD3 was greatly reduced, as compared with that of N2a-bsr, and, after several passages, it completely stopped. In addition, N2a-GD3 expressed acetylcholine esterase, indicating that the differentiation of Neuro2a cells was induced by expression of GD3 synthase and subsequent modification of the biosynthesis and expression of gangliosides. These results strongly suggest that the de novo synthesis and expression of GD3 and/or b-series gangliosides induce neurite outgrowth and differentiation of Neuro2a cells. Exogenous GM1 stimulated the neuritogenesis of N2a-bsr but not differentiated N2a-GD3, indicating that the mechanism of neurite sprouting in this system may be overlapped en route with that of exogenous GM1.