DHEA modulates the effect of cortisol on RACK1 expression via interference with the splicing of the glucocorticoid receptor

• Published in: British journal of pharmacology Vol. 172; no. 11; pp. 2918 - 2927
• Main Authors: Pinto, Antonella, Malacrida, Beatrice, Oieni, Jacopo, Serafini, Melania Maria, Davin, Annalisa, Galbiati, Valentina, Corsini, Emanuela, Racchi, Marco
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-06-2015; BlackWell Publishing Ltd
• Subjects: Adrenal Cortex Hormones - pharmacology; Alternative Splicing - drug effects; Cell Line; Cytokines; Dehydroepiandrosterone - pharmacology; Gene Knockdown Techniques; Glucocorticoids - pharmacology; GTP-Binding Proteins - drug effects; GTP-Binding Proteins - genetics; GTP-Binding Proteins - metabolism; Humans; Hydrocortisone - pharmacology; Interleukin-8 - drug effects; Interleukin-8 - metabolism; Monocytes - drug effects; Monocytes - metabolism; Neoplasm Proteins - drug effects; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Receptors for Activated C Kinase; Receptors, Cell Surface - drug effects; Receptors, Cell Surface - genetics; Receptors, Cell Surface - metabolism; Receptors, Glucocorticoid - drug effects; Receptors, Glucocorticoid - genetics; Receptors, Glucocorticoid - metabolism; Research Papers; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Up-Regulation - drug effects
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/bph.13097

Background and Purpose
Dehydroepiandrosterone (DHEA) is thought to be an anti‐glucocorticoid hormone known to be fully functional in young people but deficient in aged humans. Our previous data suggest that DHEA not only counteracts the effect of cortisol on RACK1 expression, a protein required both for the correct functioning of immune cells and for PKC‐dependent pathway activation, but also modulates the inhibitory effect of cortisol on LPS‐induced cytokine production. The purpose of this study was to investigate the effect of DHEA on the splicing mechanism of the human glucocorticoid receptor (GR).
Experimental Approach
The THP1 monocytic cell line was used as a cellular model. Cytokine production was measured by specific elisa. Western blot and real‐time RT‐PCR were used, where appropriate, to determine the effect of DHEA on GRs, serine/arginine‐rich proteins (SRp), and RACK1 protein and mRNA. Small‐interfering RNA was used to down‐regulate GRβ.
Key Results
DHEA induced a dose‐related up‐regulation of GRβ and GRβ knockdown completely prevented DHEA‐induced RACK1 expression and modulation of cytokine release. Moreover, we showed that DHEA influenced the expression of some components of the SRps found within the spliceosome, the main regulators of the alternative splicing of the GR gene.
Conclusions and Implications
These data contribute to our understanding of the mechanism of action of DHEA and its effect on the immune system and as an anti‐glucocorticoid agent.