Directing gene expression to cerebellar granule cells using gamma-aminobutyric acid type A receptor alpha6 subunit transgenes.

Expression of the gamma-aminobutyric acid type A receptor alpha6 subunit gene is restricted to differentiated granule cells of the cerebellum and cochlear nucleus. The mechanisms underlying this limited expression are unknown. Here we have characterized the expression of a series of alpha6-based transgenes in adult mouse brain. A DNA fragment containing a 1-kb portion upstream of the start site(s), together with exons 1-8, can direct high-level cerebellar granule cell-specific reporter gene expression. Thus powerful granule cell-specific determinants reside within the 5' half of the alpha6 subunit gene body. This intron-containing transgene appears to lack the cochlear nucleus regulatory elements. It therefore provides a cassette to deliver gene products solely to adult cerebellar granule cells.