INTERACTION OF OESTROGENS, ANTIOESTROGENS AND PROGESTERONE WITH RECEPTORS AND REGULATION OF GENE EXPRESSION IN THE CHICK OVIDUCT

Publisher Summary This chapter presents the recent results concerning the receptor activation step in the chick oviduct, and discusses these in relation to later events in the control of specific gene expression influenced by oestrogens and progesterone. Experiments were carried out with oestrogen stimulated and with withdrawn chicks. Steroid hormones regulate the expression of specific genes in target tissues often switching these genes “on” and “off” in an all or non fashion. It has been well established that the first step in this process is binding of the hormone to an intracellular cytoplasmic protein called the “receptor.” The “native” receptor-ligand complex subsequently undergoes “activation,” a process by which it acquires the capacity to bind to polyanions such as phosphocellulose or DNA, and to whole nuclei. The activated receptor-ligand complex is translocated to the nucleus, where it presumably interacts with the chromatin in an as yet unknown way, probably inducing changes in the rate of transcription of the hormonally controlled genes.