Characterization of the cis-acting elements of the mouse myelin P2 promoter

Myelin P2 is a basic protein of an apparent molecular weight of 14,800. Expression of P2 has been found largely in the cytosol of Schwann cells in the peripheral nervous system. Although the function of P2 is unknown, its striking homology to a family of fatty acid binding proteins has led to the idea that P2 may function as a fatty acid transport molecule. To investigate the DNA elements that control the expression of P2, sequences 5' to the coding region were cloned upstream of the cat reporter gene. A series of 3' and 5' promoter mutants was constructed and their activity determined following transfection into secondary Schwann cells and the MT4H1 Schwann cell line. Using this strategy, we have identified a 217 bp silencer region and a 142 bp positive regulatory region. In addition, we have localized the 5' flanking sequences in the promoter that are responsive to cAMP induction and to the transcription factor CCAAT/enhancer binding protein (C/EBP).