IBYME   02675
INSTITUTO DE BIOLOGIA Y MEDICINA EXPERIMENTAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
DUX4 negatively regulates the activity of the progesterone receptor while gonadal steroids protects cells from DUX4-mediated toxicity
Autor/es:
LAURA VIRGINIA GATICA, CECILIA PROIETTI, PATRICIA ELIZALDE, EDGARDO DANIEL CORONA, DANIELA JACQUELIN, CLAUDIA PELLIZAS, ALBERTO LUIS ROSA
Lugar:
Boston
Reunión:
Congreso; The 2013 FSH Society FSHD International Research Consortium Workshop; 2013
Resumen:
FSHD seemed to run a milder clinical course in females than males.
Females, however, appear to be more affected following menopause. No
explanation is available on this gender difference in severity and progression
of FSHD. In this work we present preliminary evidence suggesting a possible
connection between this clinical observation and a potential physiological role
we propose here for DUX4, the main candidate pathogenic protein in FSHD (1,2).
In previous studies on molecular determinants for nuclear import and
pathogenicity of DUX4 (3), we performed a detailed in silico analyses of
the C-terminal domain of DUX4 and DUX4c proteins. We found that DUX4, but no
DUX4c, contains a functional motif (LXXLL or NR box) previously recognized in
co-regulators of nuclear receptors (4). This domain is highly conserved among
DUX4-homologous proteins during evolution. We hypothesized and propose here that
DUX4 is a potential hormone receptor co-regulator and its cell toxicity may be
connected with its potential role at the endocrine pathway. Interestingly, DUX4
is highly expressed in gonadal tissues (4). In our first set of experiments we
used a gene reporter strategy to study if DUX4 regulates the activity of the
progesterone receptor (PR). In these studies, T47D cells (breast cancer) were
co-transfected, in culture media supplemented with physiological doses of
progesterone, with a MMTV-luciferase reporter gene, pRL-CMV Renilla (internal
control), and different amounts of a vector expressing DUX4. In these studies
we observed that ligand activated- PR transcriptional activation was inhibited in a DUX4-dose dependent manner. These preliminary results
highlight a potential novel function for DUX4 as a negative co-regulator of the
progesterone receptor. Additional studies concerning DUX4 as a potential
regulator of the androgen receptor (AR) are currently being performed. In our
second set of experiments we studied if treatment of cultured cells with
different doses of sex steroids (i.e. progesterone, estrogen and testosterone) modifies
DUX4-mediated cytotoxicity. In these studies, DUX4 toxicity was measured using
a DUX4/GFP co-transfection assay developed in our laboratory (1,3). Cells were
pre-treated with various amounts of the analyzed hormones (or vehicle) and then
co-transfected with plasmid vectors expressing GFP and DUX4 (or empty vector).
A 2-fold increase in GFP-positive cells (i.e. diminished toxicity of DUX4) was
observed when cells were pre-treated with physiologically doses of progesterone
or supra-physiological doses of estrogen or testosterone. These results
indicate that sex hormones protect cells from DUX4 toxicity. Our studies show
for the first time that DUX4 modulates the activity of a nuclear hormone
receptor and that gonadal steroids modulate DUX4-mediated cytotoxicity. These
findings may have physiological relevance concerning the normal/pathological
role of DUX4 contributing to explain the gender difference observed in FSHD
clinical manifestations.
(1)
Kowaljow,V., Marcowytz, A., Ansseau, E., Conde, C., Sauvage, S., Mattéotti, C.,
Arias, C., Corona, E.D., Nuñez, N.G., Leo, O. et al. (2007) The DUX4 gene at
FSHD1A locus encodes a pro-apoptotic protein. Neuromuscul. Disord., 17,
611-623.
(2) Lemmers,
R.J., van der Vliet, P.J., Klooster, R., Sacconi, S., Camaño, P., Dauwerse,
J.G., Snider, L., Straasheijm, K.R., van Ommen, G.J., Padberg, G.W. et al (2010)
A unifying genetic model for facioscapulohumeral muscular dystrophy. Science,
329, 1650-1653.
(3) Corona,
ED, Jacquelin, D, Gatica, L. and Rosa, A.L. (2013) Multiple protein domains contribute to nuclear import and cell toxicity
of DUX4, a candidate pathogenic protein for facioscapulohumeral muscular dystrophy.
PLoS ONE (in press)
(4) Leo, C. and
Chen, J.D. (2000) The SRC family of nuclear receptor coactivators. Gene., 245,
1-11.
(5) Snider, L.,
Geng, L.N., Lemmers, R.J., Kyba, M., Ware, C.B., Nelson, A.M., Tawil, R.,
Filippova, G.N., van der Maarel, S.M., Tapscott, S.J. et al. (2010) Facioscapulohumeral
dystrophy: incomplete suppression of a retrotransposed gene. PLoS. Genet., 6,
e1001181.