OVEREXPRESSION OF ALTERNATIVE HUMAN ACETYLCHOLINESTERASE FORMS MODULATES PROCESS EXTENSIONS IN CULTURED GLIOMA-CELLS

In addition to its well-known synaptic function, acetylcholinesterase was recently shown to stimulate neurite outgrowth from cultured chick neurons in a manner unrelated to its catalytic activity. It remained u nclear, however, whether each of the variant acety]cholinesterase enzy me forms can promote such process extension and whether this effect of acetylcholinesterase was limited to neurite outgrowth. Using DNA micr oinjections and stable transfections of cultured glioma cells, we expl ored the possibility that specific acetylcholinesterase isoforms affec t cellular development and morphology of CNS astrocytes. Cells microin jected with human ACHEDNA constructs that differ in their exon-intron composition displayed rapid yet stable induction of cell body enlargem ent and process extensions. Cells transfected with ACHEDNA carrying th e neuronal-characteristic 3'-E6 domain also displayed stable process e xtensions. However, stable transfections with ACHEDNAs including the 3 '-alternative I4/E5 region induced the appearance of small, round cell s in a dominant manner. This was associated with expression of I4/E5-A CHEmRNA transcripts and the production of soluble acetylcholinesterase monomers that were catalytically indistinguishable from the 3'-E6 enz yme but displayed higher electrophoretic mobility than that of the 3'- E6 form. Thus, variable expression levels and alternative splicing mod es of the ACHE gene correlated in these experiments with glial develop ment in a manner that was apparently unrelated to catalysis.