DIRECT EVIDENCE THAT THE POU FAMILY TRANSCRIPTION FACTOR OCT-2 REPRESSES THE CELLULAR TYROSINE-HYDROXYLASE GENE IN NEURONAL CELLS

The POU family transcription factor Oct-2 was originally identified in B lymphocytes but has been shown to be expressed in neuronal cells, a lthough it is absent in most other cell types. Cotransfection of Oct-2 expression vectors into nonneuronal cells with a tyrosine hydroxylase promoter/reporter plasmid suggests that Oct-2 can repress this promot er in this artificial situation. Here we report that reduction of endo genous Oct-2 levels in a neuronal cell line by an antisense approach r esults in an increase in endogenous tyrosine hydroxylase levels. In co ntrast, the level of the neuronal marker protein PGP9.5 remains unchan ged in the antisense lines whereas that of the neuronal nitric oxide s ynthase decreases. Hence, the tyrosine hydroxylase gene is a natural t arget for repression by Oct-2 in neuronal cells. The significance of t his effect is discussed in terms of the processes that regulate tyrosi ne hydroxylase gene expression and the role of Oct-2 in neuronal cells .