DIFFERENTIAL EXPRESSION OF RAB3 ISOFORMS IN OLIGODENDROCYTES AND ASTROCYTES

The small GTP-binding protein Rab3a is involved in regulated secretory pathways and is enriched in synaptic and neuroendocrine secretory ves icles, We have reported previously the developmental regulation of Rab 3a in oligodendrocytes in culture and purified central nervous system myelin (Huber et al.: FEBS Lett 347: 273-278, 1994). Since multiple ra b3 isoforms exist in the brain and may be associated with different se cretory pathways, we have investigated the differential expression of the rab3 isoforms in oligodendrocytes, astrocytes, and Schwann cell li ne RT4-D6P2T. The expression of specific rab3 isoforms (rab3a-c) was d etected by polymerase chain reaction (PCR) amplification and confirmed by sequence analyses, These data show that in addition to the previou sly reported expression in neurons, the two macroglial populations, as trocytes and oligodendrocytes, also express rab3 isoforms, Rab3b was p referentially amplified from purified, cultured astrocytes, while rab3 a and rab3c were preferentially amplified from highly enriched populat ions of both cultured oligodendrocytes and those isolated directly fro m the brain by immunopanning. No novel rab3 isoform was detected in gl ia. These results indicate that glial cells in the brain express speci fic isoforms of the vesicular trafficking Rab3 protein family. (C) 199 6 Wiley-Liss, Inc.