LOW-LEVEL EXPRESSION OF CALCIUM-SENSOR PROTEIN VILIP INDUCES CAMP-DEPENDENT DIFFERENTIATION IN RAT C6 GLIOMA-CELLS

Wild-type visinin-like-protein (VILIP) and a myristoylation-deficient VILIP mutant, when stably expressed at low levels in C6 cells, enhance s or reduces the basal cAMP-level, respectively. The morphology of wil d-type VILIP-transfected cells resembles that of differentiated astroc ytes, whereas the myristoylation mutant shows a phenotype similar to p arental cells, but with reduced cell growth. In both parental and myri stoylation mutant cells a differentiated phenotype similar to that pro duced by wild-type VILIP-transfected cells is inducible with 8-bromo-c AMP. The changed morphology parallels an increase in the expression of the astrocytic differentiation marker glial fibrillary acidic protein (GFAP) in wild-type VILIP-transfected and cAMP-differentiated cells, but a decrease of GFAP in myristoylation mutant cells. These results s uggest that depending on myristoylation, low level ectopic expression of VILIP affects basal cAMP homeostasis differentially, thereby influe ncing differentiation of C6 model cells. (C) 1997 Elsevier Science Ire land Ltd.