|Application:||Gene expression microarray analysis, miRNA array analysis|
|Number of samples:||12|
|Release date:||Mar 24 2008|
|Last update date:||Oct 29 2018|
|Diseases:||Neoplasms, Carcinoma, Embryonal|
|Dataset link||The role of RIP140 in retinoid mediated signaling|
The current investigation sought to determine the global effects of RIP140 on RA-dependent and RA–independent gene expression. A dose of siRNA of 90 nM was chosen. Twelve independent hybridizations were performed from mRNA isolated from 12 independent samples. One scrambled and two independent RISC-free siRNA transfections and transfections with three distinct RIP140 siRNAs were performed in NT2/D1 cells. Each siRNA treatment was further treated with either 10 μM RA or DMSO control for 24 hours. Hence, the design consisted of four groups, the three siRNA controls treated with vehicle, Group 1; the siRNA controls treated with RA, Group 2; siRNA to RIP140 treated with vehicle, Group 3; and siRNA to RIP140 treated with RA, Group 4 . The treatments were done in the presence of normal sera, since charcoal absorption of sera removes many small hydrophobic ligands to the nuclear receptor family in addition to retinoids. This measure was taken with the aim to perhaps identify target genes of other nuclear receptors including orphan receptors that could be regulated by RIP140 in the presence of low levels of their cognate ligands. RA treatment of 10 μM for 24 hours was chosen since previous experience with NT2/D1 cells indicated that a reasonably sized set of altered genes would be obtained. In addition, NT2/D1 cells commit to RA-induced differentiation by 48 hours and RIP140 repression enhances and accelerates the effects of RA in these cells. Therefore, the 24-hour time point is well-within the range of the RA commitment “window” and a larger percentage of direct RA-target genes could be expect to be uncovered compared to later time points. Based on the current understanding of the properties of RIP140, a number of potential outcomes were anticipated: 1) RIP140 may limit RA target gene activation by negative-feedback inhibition upon RA addition, 2) RIP140 may participate in “active repression” of gene expression upon RA addition, 3) an unexpected outcome that RIP140 may participate in the activation of a subset of target genes, 4) RIP140 may regulate the transcription of target genes of other nuclear receptors or even non-nuclear receptor transcription factors. Total RNA was purified using RNeasy columns (Qiagen). Hybridizations were performed according to Affymetrix guidelines at the Dartmouth College Microarray Shared Resource using an Affymetrix GeneChip Workstation. Biotin-labeled cRNA was generated from 5 μg of total RNA and hybridized to the Human Genome (HG) U133 Plus 2.0 chip A total of 12 hybridizations were performed comprising 12-independent biologic samples organized into the four groups of three.
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