Identification of a human glial fibrillary acidic protein cDNA: a tool for the molecular analysis of reactive gliosis in the mammalian central nervous system.

Two clones encoding human glial fibrillary acidic protein (GFAP) were isolated from a human astrocytoma cDNA library. The clones pHGFAP1 and pHGFAP2 were selected by the combined use of differential colony hybridization and hybridization-selection technique with polyclonal anti GFAP antiserum. The longer one, pHGFAP1, encompasses 3.0 kb and includes the 1.8 kb long 3' untranslated region specific to the human mRNA. Sequence data disclosed an extensive homology within the coding region of human and mouse GFAP cDNAs even in the end domains. Blot hybridization analysis of RNAs from human, rat and mouse brain revealed a single GFAP mRNA species of 3.1, 2.8 and 2.7 kb respectively and Southern blot experiments indicated that this mRNA is most probably transcribed from a unique gene. In situ hybridization performed with biotinylated probes on cultured mouse brain cells suggests both the sorting and the transport of GFAP mRNA throughout the cytoplasm and processes of the astrocytes. As a model of reactive gliosis secondary to degenerative disorders, 6-hydroxydopamine (6-OHDA) lesion of the substantia nigra in the rat was performed. GFAP mRNA increased 1.4 fold in the ipsilateral striatum on day 10 after the lesion. It then declined to the control level 4 months later contrasting with the lower and more sustained increase in preproenkephalin (PPE) mRNA. The interspecies cross-reactivity of the HGFAP probes make them useful as a tool for the molecular analysis of reactive gliosis in various experimental models.