ARTHRITIS & RHEUMATOLOGY
Vol. 66, No. 1, January 2014, pp 163–172
DOI 10.1002/art.38187
© 2014, American College of Rheumatology
Estrogen Receptor Regulates
Tripartite Motif–Containing Protein 21 Expression,
Contributing to Dysregulated Cytokine Production
in Systemic Lupus Erythematosus
Siobha ´n Smith,
1
Joan Nı ´ Gabhann,
1
Eoghan McCarthy,
1
Barbara Coffey,
1
Rebecca Mahony,
1
Jennifer C. Byrne,
1
Kevin Stacey,
1
Elizabeth Ball,
2
Aubrey Bell,
2
Gaye Cunnane,
3
Michele F. Doran,
3
Eamonn S. Molloy,
4
Ruth Z. Lee,
5
Brian Harvey,
6
Grainne Kearns,
5
and Caroline A. Jefferies
1
Objective. To examine the role of 17-estradiol in
the regulation of the autoantigen tripartite motif–
containing protein 21 (TRIM-21) in patients with sys-
temic lupus erythematosus (SLE).
Methods. Monocytes isolated from healthy con-
trol subjects and patients with SLE were stimulated
with 17-estradiol and/or the estrogen receptor
(ER) antagonist methyl-piperidino-pyrazole dihydro-
chloride. TRIM-21, ER, and CREM expression was
determined by real-time polymerase chain reaction
(PCR) analysis. MatInspector software was used to
identify putative binding sites within the TRIM-21
promoter. ER binding to the TRIM-21 gene promoter
region in monocytes was analyzed by chromatin immu-
noprecipitation (ChIP) assay. TRIM-21 and interferon
regulatory factor 3 protein levels were analyzed by
Western blotting.
Results. Real-time PCR analysis demonstrated a
role of estrogen in the regulation of TRIM-21 expression
in monocytes, which correlated positively with ER gene
expression in patients with SLE. Investigations into the
human TRIM-21 promoter revealed the presence of an
estrogen response element, with ChIP assays confirming
ER binding to this site. Studies into estrogen-induced
TRIM-21 expression revealed a hyperresponsiveness of
SLE patients to 17-estradiol, which led to the en-
hanced levels of TRIM-21 observed in these individuals.
Conclusion. Our results demonstrate a role of
estrogen in the regulation of TRIM-21 expression
through an ER-dependent mechanism, a pathway that
we observed to be overactive in SLE patients. Treatment
of monocytes with an ER antagonist abrogated
estrogen-induced TRIM-21 expression and, as a conse-
quence, decreased the expression of interleukin-23.
These findings identify TRIM-21 as a novel ER-
regulated gene and provide novel insights into the link
between estrogen and the molecular pathogenesis of
SLE.
Systemic lupus erythematosus (SLE) is character-
ized by a wide variety of immunologic abnormalities,
including abnormal T and B lymphocyte signaling (1),
the production of autoantibodies to self antigens (2),
and the defective clearance of immune complexes by
macrophages (3). In addition, a strong genetic predispo-
sition is associated with this condition, with a 9:1 ratio of
affected females to affected men (4). This sex imbalance
has suggested a role of sex hormones, particularly estro-
gen, as important players in the development of SLE.
Supported by the Science Foundation Ireland (grant 08/IN.1/
B2091).
1
Siobha ´n Smith, MSc, Joan Nı ´ Gabhann, PhD, Eoghan Mc-
Carthy, MB, Barbara Coffey, BSc, Rebecca Mahony, BSc, Jennifer C.
Byrne, PhD, Kevin Stacey, PhD, Caroline A. Jefferies, PhD: Royal
College of Surgeons in Ireland, Dublin, Ireland;
2
Elizabeth Ball, MB,
Aubrey Bell, MD: Belfast Health and Social Care Trust and Belfast
City Hospital, Belfast, UK;
3
Gaye Cunnane, PhD, Michele F. Doran,
MD: St. James Hospital, Dublin, Ireland;
4
Eamonn S. Molloy, MD: St.
Vincent’s University Hospital, Dublin, Ireland;
5
Ruth Z. Lee, MD,
Grainne Kearns, MD: Beaumont Hospital, Dublin, Ireland;
6
Brian
Harvey, PhD: Royal College of Surgeons in Ireland and Beaumont
Hospital, Dublin, Ireland.
Address correspondence to Caroline A. Jefferies, PhD, Mo-
lecular and Cellular Therapeutics, Royal College of Surgeons in
Ireland, 123 St. Stephen’s Green, Dublin 2, Ireland. E-mail: cjefferies
@rcsi.ie.
Submitted for publication April 22, 2013; accepted in revised
form August 29, 2013.
163