Characterization of the cis ‐acting elements of the mouse myelin P 2 promoter

Myelin P 2 is a basic protein of an apparent molecular weight of 14,800. Expression of P 2 has been found largely in the cytosol of Schwann cells in the peripheral nervous system. Although the function of P 2 is unknown, its striking homology to a family of fatty acid binding proteins has led to the idea that P 2 may function as a fatty acid transport molecule. To investigate the DNA elements that control the expression of P 2 , 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 MT 4 H1 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). © 1993 Wiley‐Liss, Inc.