E. Galea et al., GLIAL FIBRILLARY ACIDIC PROTEIN MESSENGER-RNA ISOTYPES - EXPRESSION IN-VITRO AND IN-VIVO, Journal of neuroscience research, 41(4), 1995, pp. 452-461
Glial fibrillary acidic protein (GFAP) and its mRNA, primarily express
ed in astrocytes, are also expressed in peripheral nervous system Schw
ann cells as well as in certain non-neural tissues, Schwann cells expr
ess a GFAP mRNA (GFAP-beta) which differs from the CNS-type mRNA (GFAP
-alpha) by the presence of an extended 5' untranslated region, We have
developed a polymerase chain reaction assay which allows distinction
of these two GFAP mRNAs, as well as quantitative analysis of their lev
els, In the cultured rat Schwannoma cell line RT4-D6, GFAP-beta was th
e major GFAP mRNA species, accounting for at least 75% of total GFAP (
alpha + beta) mRNA, GFAP-beta was also detected in primary rat astrocy
te cultures, where it constituted approximately 5% of the total GFAP m
RNA, as well as in RNA samples prepared from normal rat cerebral corte
x, and from hamster and human brain, In rat cortex, the temporal expre
ssion of GFAP-beta mRNA paralleled that of total GFAP mRNA, with plate
au levels reached between postnatal days 15 and 20. In astrocyte cultu
res, the relative levels of GFAP-alpha and -beta mRNAs were differenti
ally regulated by exposure to interferorm-gamma (10 to 25 units/ml), w
hich caused an increase in GFAP-beta levels while at the same time no
change or a small decrease in total GFAP levels. In rat brain cortical
slices, 4 hr exposure to 25 units/ml interferon-gamma decreased total
GFAP mRNA levels over tenfold, while GFAP-beta levels were unaffected
. These data indicate that a second form of the GFAP mRNA is expressed
in astrocytes both in vivo and in vitro and provide evidence for inde
pendent regulation of these two GFAP mRNA species. (C) 1995 Wiley-Liss
, Inc.