Distinct modulatory roles for thyroid hormone receptors TRα and TRβ in SREBP1-activated ABCD2 expression
pmid: 18834645
Distinct modulatory roles for thyroid hormone receptors TRα and TRβ in SREBP1-activated ABCD2 expression
Adrenoleukodystrophy-related protein, a peroxisomal ABC transporter encoded by ABCD2, displays functional redundancy with the disease-associated X-linked adrenoleukodystrophy protein, making pharmacological induction of ABCD2 a potentially attractive therapeutic approach. Sterol regulatory element (SRE)-binding proteins (SREBPs) induce ABCD2 through an SRE overlapping with a direct repeat (DR-4) element. Here we show that thyroid hormone (T(3)) receptor (TR)alpha and TRbeta bind this motif thereby modulating SREBP1-dependent activation of ABCD2. Unliganded TRbeta, but not TRalpha, represses ABCD2 induction independently of DNA binding. However, activation by TRalpha and derepression of TRbeta are T(3)-dependent and require intact SRE/DR-4 motifs. Electrophoretic mobility shift assays with nuclear extracts support a direct interaction of TR and SREBP1 at the SRE/DR-4. In the liver, Abcd2 expression is high in young mice (with high T(3) and TRalpha levels) but downregulated in adults (with low T(3) and TRalpha but elevated TRbeta levels). This temporal repression of Abcd2 is blunted in TRbeta-deficient mice, and the response to manipulated T(3) states is abrogated in TRalpha-deficient mice. These findings show that TRalpha and TRbeta differentially modulate SREBP1-activated ABCD2 expression at overlapping SRE/DR-4 elements, suggesting a novel mode of cross-talk between TR and SREBP in gene regulation.
- Inserm France
- Medical University of Vienna Austria
- National Research Institute for Agriculture, Food and Environment France
- Claude Bernard University Lyon 1 France
- University of Vienna Austria
Male, GENE EXPRESSION, PEROXISOME, [SDV]Life Sciences [q-bio], 610, Gene Expression, Electrophoretic Mobility Shift Assay, [INFO] Computer Science [cs], ATP Binding Cassette Transporter, Subfamily D, Mice, Chlorocebus aethiops, BIOLOGIE CELLULAIRE, Animals, Humans, Point Mutation, [INFO]Computer Science [cs], RNA, Messenger, Regulatory Elements, Transcriptional, Promoter Regions, Genetic, ADRENOLEUKODYSTROPHY-RELATED PROTEIN (ABCD2), Cells, Cultured, Mice, Knockout, PROTEINE SREBP1, STEROL REGULATORY PROTEIN (SREBP), STEROL REGULATORY ELEMENT (SRE), Reverse Transcriptase Polymerase Chain Reaction, Genes, erbA, ABC TRANSPORTER, THYROID HORMONE, HORMONES THYROÏDIENNES, [SDV] Life Sciences [q-bio], Liver, CULTURE DE CELLULE, THYROID RECEPTOR (TR) X-LINKED ADRENOLEUKODYSTROPHY(X-ALD), COS Cells, ATP-Binding Cassette Transporters, Plasmids
Male, GENE EXPRESSION, PEROXISOME, [SDV]Life Sciences [q-bio], 610, Gene Expression, Electrophoretic Mobility Shift Assay, [INFO] Computer Science [cs], ATP Binding Cassette Transporter, Subfamily D, Mice, Chlorocebus aethiops, BIOLOGIE CELLULAIRE, Animals, Humans, Point Mutation, [INFO]Computer Science [cs], RNA, Messenger, Regulatory Elements, Transcriptional, Promoter Regions, Genetic, ADRENOLEUKODYSTROPHY-RELATED PROTEIN (ABCD2), Cells, Cultured, Mice, Knockout, PROTEINE SREBP1, STEROL REGULATORY PROTEIN (SREBP), STEROL REGULATORY ELEMENT (SRE), Reverse Transcriptase Polymerase Chain Reaction, Genes, erbA, ABC TRANSPORTER, THYROID HORMONE, HORMONES THYROÏDIENNES, [SDV] Life Sciences [q-bio], Liver, CULTURE DE CELLULE, THYROID RECEPTOR (TR) X-LINKED ADRENOLEUKODYSTROPHY(X-ALD), COS Cells, ATP-Binding Cassette Transporters, Plasmids
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