[Hormonal control of gene expression].

Three main aspects are presented: the current knowledge of structure, function and regulation of the genes coding for mRNAs is first examined. The central role of specific protein-DNA and protein-protein interactions is outlined. The two mechanisms of the hormonal regulation of genome expression, are then investigated. Hydrophobic hormones (steroid or thyroid hormones, 1-25-dihydroxyvitamin D3 and retinoic acid) act by triggering receptor binding in the regulatory regions of the genes. Hydrophylic hormones (peptide and glycoprotein hormones, growth factors, epinephrine) act indirectly via membrane receptors. They modify, via second messagers, the efficacy of transcription factors. Thirdly, the connection and competition between regulatory factors is studied. Interferences are known between hormones themselves or between receptors and non receptor proteins. They permit the best fit between environment and gene activity in each cell of the organism.