Two polymorphisms in the glucocorticoid receptor gene directly affect glucocorticoid-regulated gene expression.
BACKGROUND
Interindividual variation in glucocorticoid (GC)-sensitivity can be partly explained by polymorphisms in the GC receptor (GR) gene. The ER22/23EK and N363S polymorphisms have been described to be associated with lower and higher GC sensitivity, respectively.


OBJECTIVE
We examined the basis of this altered GC sensitivity by expressing GR(N363S) and GR(ER22/23EK) in COS-1 cells and investigating their transactivating and transrepressing capacities using a GC response element-luciferase reporter and a p65-activated nuclear factor kappaB-luciferase reporter, respectively. Furthermore, we evaluated the transactivating and transrepressing capacities of the GR in peripheral blood mononuclear lymphocytes of homozygous and heterozygous carriers of these polymorphisms by determining the maximum effect of dexamethasone on transactivation of the GC-induced leucine-zipper and transinhibition of the IL-2 gene by means of real-time RT-PCR.


RESULTS
The effects of the polymorphisms in the GR gene previously observed in population studies were also detected at the level of gene expression. The ER22/23EK polymorphism resulted in a significant reduction of transactivating capacity, in both transfection experiments (-14 +/- 5%, P < 0.05) and peripheral blood mononuclear lymphocytes of carriers of this polymorphism (homozygous: -48 +/- 6%, P < 0.01, n = 1; heterozygous: -21 +/- 4%, P = 0.08, n = 3). The N363S polymorphism, associated with increased GC sensitivity, resulted in a significantly increased transactivating capacity, both in vitro (8 +/- 3%; P < 0.02) and ex vivo (homozygous: 204 +/- 19%, P < 0.0001, n = 1; heterozygous: 124 +/- 8%, P = 0.05, n = 3). Neither the ER22/23EK nor the N363S polymorphism seemed to influence the transrepressing capacity of the GR.


CONCLUSIONS
The presence of these and other GC sensitivity-modulating polymorphisms may have consequences for the use of GCs in a clinical setting.
Russcher
Henk
H
Erasmus Medical Center, Department of Internal Medicine, Room Ee593, Dr. Molewaterplein 40, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands. h.russcher@erasmusmc.nl
Smit
Pauline
P
van den Akker
Erica L T
EL
van Rossum
Elisabeth F C
EF
Brinkmann
Albert O
AO
de Jong
Frank H
FH
Lamberts
Steven W J
SW
Koper
Jan W
JW
D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D017931:DNA Primers / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology*; D014644:Genetic Variation; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics; D008156:Luciferases / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D011110:Polymorphism, Genetic / Q000235:genetics*; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D011965:Receptors, Glucocorticoid / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection
D017931:DNA Primers; D007376:Interleukin-2; D011965:Receptors, Glucocorticoid; D014157:Transcription Factors; D012313:RNA; D003907:Dexamethasone; D008156:Luciferases