Glial fibrillary acidic protein mRNA isotypes: expression in vitro and in vivo

• Published in: Journal of neuroscience research Vol. 41; no. 4; p. 452
• Main Authors: Galea, E, Dupouey, P, Feinstein, D L
• Format: Journal Article
• Language: English
• Published: United States 01-07-1995
• Subjects: Animals; Cells, Cultured; DNA, Complementary; Gene Expression; Glial Fibrillary Acidic Protein - genetics; In Vitro Techniques; Neuroglia - physiology; Peripheral Nervous System - physiology; Polymerase Chain Reaction; Rats; Rats, Sprague-Dawley; RNA, Messenger - biosynthesis; Schwann Cells - physiology
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490410404

Glial fibrillary acidic protein (GFAP) and its mRNA, primarily expressed in astrocytes, are also expressed in peripheral nervous system Schwann cells as well as in certain non-neural tissues. Schwann cells express 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 levels. In the cultured rat Schwannoma cell line RT4-D6, GFAP-beta was the major GFAP mRNA species, accounting for at least 75% of total GFAP (alpha + beta) mRNA. GFAP-beta was also detected in primary rat astrocyte cultures, where it constituted approximately 5% of the total GFAP mRNA, as well as in RNA samples prepared from normal rat cerebral cortex, and from hamster and human brain. In rat cortex, the temporal expression of GFAP-beta mRNA paralleled that of total GFAP mRNA, with plateau levels reached between postnatal days 15 and 20. In astrocyte cultures, the relative levels of GFAP-alpha and -beta mRNAs were differentially regulated by exposure to interferon-gamma (10 to 25 units/ml), which 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 independent regulation of these two GFAP mRNA species.