Full Description
1.1 Mechanism of Action of Glucocorticoid Hormones The current model of glucocorticoid hormone action is summarized in Fig. 1. After synthesis, glucocorticoids are secreted into the blood stream and trans- ported to target cells where they bind with high affinity (K-1O-9M) and d specificity to the intracellular glucocorticoid receptor (GR) protein. The sub- cellular localization of hormone-free GR is still a controversial issue. However, most data support the idea that unliganded GR is in the cytoplasmic compartment or loosely associated with the nucleus (Picard and Yamamoto 1987; Gustafsson et al. 1987 and references therein; LaFond et al. 1988; Gasc et al. 1989). Upon ligand binding, GR is activated into a form capable of interacting with DNA. The mechanism of GR activation probably involves a conformational change and dis- sociation from nonreceptor components, e.g., the 90-kDA heat shock protein (hsp90: Pratt et al. 1988; Bresnick et al. 1989; Denis and Gustafsson 1989). The subcellular location of activated GR has been firmly established to be inside the nucleus. In vivo, the hormone-receptor complex interacts with specific DNA Activation r:::.. ‾ qc [!3-GC ...&.GC‾ j ‾ ?
, BIOLOGICAL EFFECTS " t , Active Protein , , ‾Vl\lent.
Contents
Axonal Messenger RNA Transport: Fact or Fiction?.- Molecular Mechanisms of Regulation of Gene Expression by Glucocorticoids.- Regulation of Neuropeptide Gene Expression.- Opioid Peptide Genes: Sructure and Regulation.- Regulation of Gene Expression of Pituitary Hormones by Hypophysiotropic Hormones.- Use of Transgenic Animals in the Study of Neuropeptide Genes.- Molecular Alterations in Nerve Cells: Direct Manipulation and Physiological Mediation.- Electrophysiological Methods for Studying Endocrine Cells and Neuronal Activity from the Hypothalamo-hypophyseal System.
