Document Type
Article
Original Publication Date
2013
Journal/Book/Conference Title
PLOS ONE
Volume
8
DOI of Original Publication
10.1371/journal.pone.0072979
Date of Submission
October 2014
Abstract
Background
We previously identified a group of glucocorticoid-responsive genes, including Serum Glucocorticoid kinase 1 (Sgk1), regulated by acute ethanol in prefrontal cortex of DBA2/J mice. Acute ethanol activates the hypothalamic pituitary adrenal axis (HPA) causing release of glucocorticoids. Chronic ethanol dysregulates the HPA response in both humans and rodents, possibly contributing to important interactions between stress and alcoholism. Because Sgk1regulates ion channels and learning and memory, we hypothesized that Sgk1 contributes to HPA-dependent acute and adaptive neuronal responses to ethanol. These studies characterized acute and chronic ethanol regulation of Sgk1 mRNA and protein and their relationship with ethanol actions on the HPA axis.
Results
Acute ethanol increased Sgk1 mRNA expression in a dose and time dependent manner. Three separate results suggested that ethanol regulated Sgk1 via circulating glucocorticoids: acute ethanol increased glucocorticoid receptor binding to the Sgk1 promoter; adrenalectomy blocked ethanol induction of Sgk1 mRNA; and chronic ethanol exposure during locomotor sensitization down-regulated HPA axis activation and Sgk1 induction by acute ethanol. SGK1 protein had complex temporal responses to acute ethanol with rapid and transient increases in Ser422 phosphorylation at 15 min. following ethanol administration. This activating phosphorylation had functional consequences, as suggested by increased phosphorylation of the known SGK1 target, N-myc downstream-regulated gene 1 (NDRG1). After repeated ethanol administration during locomotor sensitization, basal SGK1 protein phosphorylation increased despite blunting of Sgk1 mRNA induction by ethanol.
Conclusions
These results suggest that HPA axis and glucocorticoid receptor signaling mediate acute ethanol induction of Sgk1 transcription in mouse prefrontal cortex. However, acute ethanol also causes complex changes in SGK1 protein expression and activity. Chronic ethanol modifies both SGK1 protein and HPA-mediated induction of Sgk1 mRNA. These adaptive molecular responses of glucocorticoid-responsive gene expression and SGK1 in prefrontal cortex may contribute to mechanisms underlying behavioral responses to chronic ethanol exposure.
Rights
Copyright: © 2013 Costin et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Is Part Of
VCU Pharmacology and Toxicology Publications
Sgk1 levels in the PFC of D2 mice basally (a 0 hour time point) and 2, 4 and 8 hours following saline injections.
Figure_S2.tif (141 kB)
Sgk1.1 levels following ethanol sensitization.
Figure_S3.tif (215 kB)
Q-rtPCR analysis of Sgk1.1.
Figure_S4.tif (280 kB)
Time Course Western blot analysis of total SGK1
Figure_S5.tif (356 kB)
Basal versus saline treated SGK1 levels.
Figure_S6.tif (2706 kB)
Time Course Western blot analysis of pSGK1 S422.
Figure_S7.tif (1523 kB)
Basal versus saline treated SGK1 pS422 levels.
Comments
Original Published at http://dx.doi.org/10.1371/journal.pone.0072979