Cell type-specific expression of the mouse peripherin gene requires both upstream and intragenic sequences in...

Peripherin is a neuron-specific type III intermediate filament protein expressed in well-defined populations of neurons projecting towards peripheral targets. To investigate the molecular mechanisms by which a gene is expressed in a specific subset of neurons, we used a transgenic approach in order to define peripherin gene sequences that are necessary for cell-type specific expression. Transgenic mice carrying different various genomic regions of the mouse peripherin gene fused to the Escherichia coli lacZ reporter gene were generated. We used three different peripherin/lacZ constructs containing either 5.8 kb upstream sequences, or both 5.8 kb upstream and 1.1 kb intragenic sequences, or 1.1 kb intragenic sequences associated with an heterologous promoter. Analysis of lacZ gene expression in transgenic mouse embryos showed that cell type-specific expression of the mouse peripherin gene requires both upstream and intragenic sequences. Analysis of transgenic mouse lines expressing the construct containing both upstream and intragenic sequences showed that this transgene contains all regulatory elements essential for both spatial and temporal expression of the mouse peripherin gene during embryogenesis. Furthermore, lacZ+ positive cells isolated from these transgenic lines by fluorescence-activated cell sorting (FACS) can be stained with a peripherin antibody, demonstrating that the transgene containing both upstream and intragenic sequences is expressed in peripherin neurons. These mouse peripherin upstream and intragenic sequences can now be used to identify cis-acting regulatory elements and transcription factors involved in peripherin gene regulation.