Positive- and negative-acting promoter sequences regulate cell type-specific expression of the rat synapsin I gene

Howland, D.S.; Hemmendinger, L.M.; Carroll, P.D.; Estes, P.S.; Melloni, R.H.; DeGennaro, L.J.

Brain Research. Molecular Brain Research 11(3-4): 345-353


ISSN/ISBN: 0169-328X
PMID: 1661826
DOI: 10.1016/0169-328x(91)90044-x
Accession: 007669040

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The phosphoprotein synapsin I is expressed exclusively in neuronal cells. We are interested in elucidating the promoter sequences involved in cell type-specific expression of the synapsin I gene. The PC12 cell line expresses the 3.4 kb and 4.5 kb synapsin I mRNAs and is used to analyze cell type specific gene expression. A series of deletion fragments of the rat synapsin I gene promoter were fused to the promoterless reporter gene encoding bacterial chloramphenicol acetyltransferase (CAT) for transfection analysis in PC12 cells and in HeLa cells, which do not express the gene. A -349 bp to +110 bp rat synapsin I promoter fragment contains a positive regulator, shown to be 33-times more active in PC12 cells than HeLa cells. Transfection of reporter plasmids containing up to 4.4 kb of rat synapsin I gene promoter sequences exhibit significantly reduced CAT activity in PC12 cells. The reduction in CAT expression was attributed to a negative regulator located between -349 bp and -1341 bp in the rat synapsin I promoter. Our results suggest that both positive and negative-acting sequence elements regulate cell type-specific expression of the rat synapsin I gene.