Genomic Response to Growth Factors

Excerpt

Polypeptide growth factors, acting through receptor-mediated pathways, have been shown to induce the sequential expression of specific genes (Cochran et al. 1983; Kelly et al. 1983; Linzer and Nathans 1983; Greenberg and Ziff 1984; Hirschhorn et al. 1984; Lau and Nathans 1985). In quiescent mammalian cells in culture, the first set of genes expressed following addition of growth factor (or serum) are transcriptionally activated even in the presence of an inhibitor of protein synthesis and are therefore thought to be activated directly by second messengers resulting from the growth factor-receptor interaction. These genes have been called “immediate early” genes or “competence” genes. Prior to DNA replication, other genes become active, but, unlike immediate early genes, activation requires new protein synthesis (Katz and Kahana 1987; Linzer and Mordacq 1987), suggesting that one or more proteins encoded by immediate early genes may act as transcriptional regulators in the activation of the “delayed...