METABOLIC LABELING OF A SUBSET OF GLIAL-CELLS BY UDP-GALACTOSE - IMPLICATION FOR ASTROCYTE LINEAGE DIVERSITY

Astrocytes are implicated in many aspects of brain function; however, it remains unclear whether astrocytes arise from a single cell lineage . It is therefore important to obtain new markers for the astrocyte ce ll lineage. We show that exogenously added UDP-galactose (UDP-Gal) can be used to metabolically label a subset of glial fibrillary acidic pr otein-positive (GFAP(+)) cells. UDP-Gal was incorporated into the cult ured embryonic mouse brain slices in a time-dependent manner. Surprisi ngly, the transferred sugar moiety was no longer Gal but was mainly gl ucose. Most of the radioactivity was transferred to a polymer of gluco se, most likely to be glycogen, and also to glucosyl ceramide, In the slice culture, the reaction products were distributed densely in the v entricular zone and also on process-like structures extending to the p ial surface, In dissociation culture, UDP-Gal labeled some of the GFAP (+) cells and some of the vimentin(+) cells, Because radial glial cell s (RGCs) contain glycogen and change from vimentin(+) to GFAP(+), it i s strongly suggested that UDP-Gal labeled RGCs and their descendants. Only 27% of the GFAP(+) cells were labeled with UDP-Gal, which suggest s that only a subset of astrocytes are derived from RGCs and that ther e is a discrete group of GFAP(+) cells that is not generated from RGCs . (C) 1998 Wiley-Liss, Inc.