RETINOIC ACID REGULATES SELECTIVELY THE EXPRESSION OF IMMEDIATE-EARLYRESPONSE GENES IN PC12 CELLS

Nerve growth factor (NGF) induces neuronal differentiation and growth arrest in PC12 cells. One of the initial effects of SGF in these tells is the induction of the expression of immediate early genes (IEGs), I n this study ne have analyzed the influence of retinoic acid (RA), whi ch exerts important effects on PC12 cell proliferation and function, o n the expression of IEGs, Incubation with RA did not alter nGFI-A mRNA levels, but significantly reduced the NGFI-B and c-fos response to SG F and serum. The response to NGF was maximal in the presence of cycloh eximide, and RA also reduced the superinduction of NGFI-B and c-fos mR NA levels, Sequences contained within the 5' flanking region of the c- fos gene confer responsiveness to NGF and mediate the inhibitory effec t of RA. The differential regulation by RA suggests that NGF induces e xpression of the three IEGs by different mechanisms. (C) 1998 Federati on of European Biochemical Societies.