Isolation of cDNAs from a mouse astroglial cell line by a subtracted cDNA library

Astrocytes belong to the glial cell population and represent a major subclass of the CNS. Although different subtypes of astrocytes have been described according to their morphological characteristics, biochemical markers of each subtype of astrocytes are not yet available. We have thus undertaken to compare gene expression pattern of different astroglial subtypes. In this study we have taken advantage of two astroglial cell clones derived from 8 day postnatal mouse cerebellar explants and which might be the in vitro equivalents of the velate protoplasmic (D19) and of the Golgi-Bergmann (C8S) astrocytes (Alliot and Pessac, Brain Res., 306: 283-291, 1984). We have constructed a subtracted cDNA library derived from cytoplasmic poly(A)+ RNAs of the D19 cell line. This library was enriched 12-fold for D19 specific sequences by subtractive hybridization with an excess of cytoplasmic poly(A)+ RNAs purified from the C8S astroglial clone. This subtracted library was differentially screened with cDNA probes derived from D19 and C8S cell lines; both probes were subtracted with C8S poly(A)+ RNAs. Eight cDNA clones corresponding to transcripts overexpressed in D19 were selected. Three cDNAs encode for smooth muscle actin, one for fibronectin and one for polyadenylate binding protein. The three other gene products have not been previously reported. The in vivo distribution pattern of these sequences in various mouse adult tissues shows that all these transcripts are expressed in the cerebellum and/or in the brain.