A herpes simplex virus-1 vector containing the rat tyrosine hydroxylase promoter directs cell type-specific expression of beta-galactosidase in cultured rat peripheral neurons.
A defective herpes simplex virus-1 (HSV-1) vector system was used to study cell type-specific expression of the tyrosine hydroxylase (TH) gene. HSV-1 particles containing 663 bp (pTHlac 663), 278 bp (pTHlac 278), or 181 bp (pTHlac 181) of the rat TH promoter driving E. coli LacZ were used to infect superior cervical ganglia (SCG: TH-expressing tissue) and dorsal root ganglia (DRG:non-TH-expressing tissue) cultures. One day after infection, expression of beta-galactosidase was visualized by X-gal cytochemistry. Following viral transduction with pTHlac 663 at a multiplicity of infection of 0.2, 14.4% of the SCG neurons were X-gal positive whereas only about 0.9% of DRG neurons were X-gal positive. Infection with either pTHlac278 or 181 resulted in 3-fold more X-gal-positive DRG neurons. These results suggest that (i) the defective HSV-1 vector system may be useful in defining regulatory promoter motifs; (ii) 663 bp of the rat TH promoter contains sufficient information for cell type-specific expression in peripheral nervous system neurons; and (iii) sequences between -278 and -663 contain an element(s) that represses gene expression in non-catecholamingeric neurons.