Retinoids are a class of lipid molecules that have dramatic effects on the growth and differentiation of both normal and neoplastic cells. These properties form the rationale for their potential use as chemopreventitive and chemotherapeutic agents. However, the moleculkar events by which retinoids, particularly retinoic-acid, alter cellular funcitons are poorly understood. We have recently demonstrated that retinoic acid acts as a direct and acute regulator of the expession of a specific enzyme, tissue transglutaminase, in mouse and human myeloid cells. Retinoic acid also induces the expression of a second, as yet unidentified, mouse mcarophage protein of 38,000 MW. We propose to take advantage of the effects of retinoic acid on these two specific murine genes in order to investigate the molecular mechanisms by which retinoids control gene expression. In order to accomplish this goal, we have prepared and cloned a partially purified mRNA from retinoic acid-induced mouse peritoneal macrophages. A tissue transglutaminase cDNA clone isolated from this library will be used to isolate and characterize the mouse tissue ITAse gene. In a similar manner, the gene coding for the 38 KD retinoid-induced protein (RIP) will be isolated and characterized. Then the 5- flanking regions of these two genes will be sequenced and compared, in order to identify the regulatory sequences that may be involved in controlling these retinoid-activated mammalian genes. Ultimately, we will link these flanking sequences to a reporter gene coding sequence, and use these chimeric genes in transcription studies to identify the critical control regions that mediate retinoid control of gene expression. THe accomplishment of these goals will form the basis for subsequent studies into retinoid acid activation of specific macrophage genes, and yield knowledge fundamental to our understanding of the molecular mechanisms by which retinoids control cellular growth and differentiation.
