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The I κ B α gene is a peroxisome proliferator‐activated receptor cardiac target gene
Author(s) -
Buroker Norman E.,
Barboza Julia,
Huang JieYu
Publication year - 2009
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2009.07039.x
Subject(s) - nuclear receptor , retinoid x receptor , thyroid hormone receptor , peroxisome proliferator activated receptor , biology , enhancer , thyroid hormone receptor beta , transcription factor , receptor , thyroid hormone receptor alpha , retinoid x receptor alpha , microbiology and biotechnology , gene , hormone receptor , genetics , cancer , breast cancer
The purpose of this study was to provide a better understanding of the regulatory role of the nuclear steroid receptor on the nuclear factor of kappa light polypeptide gene enhancer in B cells (NFκB) in mouse heart. NFκB regulates many nuclear genes and has been associated with many human cardiac diseases. NFκB’s protein regulator gene, nuclear factor of kappa light polypeptide gene enhancer in B cells inhibitor alpha gene ( I κ B α), was found in this study to be regulated by peroxisome proliferator‐activated receptors (PPARs). PPARs, retinoid X receptors (RXRs) and thyroid hormone receptors (THRs) are members of the nuclear receptor superfamily, which consists of a large number of transcription factors whose activities are regulated by their cognate ligands. These steroid hormone receptors are important regulators of gene expression and differentiation in the heart. These receptors form homo‐(RXR, THR) and hetero‐(PPAR–RXR, RXR–THR) dimers that bind DNA at various response elements (PPAR, RXR and THR) in the promoter regions of target genes. The PPAR/RXR response elements in the promoter of I κ B α are described in this article. A known PPAR activator ( Wy14643 ) and dimethylsulfoxide (vehicle) were introduced into control (FVB) and δ337T thyroid hormone receptor (TRβ) transgenic mice. The δ337T TRβ transgenic mouse has a resistance to the thyroid hormone (RTH) phenotype. Affymetrix 430_2 chip gene expression was examined for four study groups (control, control with Wy14643 , δ337T TRβ and δ337T TRβ with Wy14643 ), consisting of seven mice each. I κ B α mRNA expression in the Wy14643 control and in transgenic mice was upregulated significantly in microarray ( P < 0.05) and quantitative RT‐PCR ( P < 0.01) analyses. The increase in mRNA level was also accompanied by an increase in I κ B α protein in cells, as measured by Western blot analysis. Duplex oligo‐DNAs containing the putative PPAR/RXR motif (AGGTCA/TCCAGT) from the I κ B α promoter were used in gel shift assays to verify the binding of PPAR and RXR to their response elements. pGL4.0 [Luc] constructs of the I κ B α promoter, with and without the PPAR/RXR motifs, were co‐transfected with mouse PPAR α, β and γ 1 into HepG2 cells and used in luciferase assays to verify gene activation. In conclusion, our study revealed that PPAR regulates the mouse cardiac I κ B α gene in both control and transgenic mouse heart. The implications of this finding are discussed in relation to possible changes in cardiac function.