Shared sequences of the aromatase transcript in neurons and glia of the zebra finch brain.
In many vertebrates, the P450 enzyme aromatase (CYP19a; E-synthase) is expressed in multiple tissues including the brain and gonad. In the zebra finch (Taeniopygia guttata), the aromatase gene is alternatively spliced in the 5 untranslated region (UTR) resulting in two known transcripts expressed preferentially in the brain (Exon 1a) and ovary (Exon 1b). These transcripts share identical sequences from the beginning of their protein translational start sites (Exon 2), the coding region (Exons 3-9) and through the 3 UTR (Exons 9-10). In addition to these constitutively expressed transcripts, an inducible aromatase is expressed in reactive glia following damage to the zebra finch neuropil. Inducible aromatase is detectable 6 hours following mechanical injury and persists for at least 6 weeks. Towards understanding the regulation and expression of glial aromatase, we hypothesized that inducible (glial) aromatase represents a novel transcript in the zebra finch. To test this hypothesis, we: (i) examined the upregulation of specific amplicons within the aromatase transcript following mechanical injury using quantitative PCR (qPCR), (ii) performed 5 and 3 rapid amplification of cDNA ends (RACE) from RNA extracted from injured and non-injured brain, (iii) ran northern blot analysis on injured and non-injured telencephalic RNA and (iv) isolated the transcript in glial enriched cultures of the developing zebra finch telencephalon.