Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Identification of LMX1B target genes in a tet-off inducible HeLa cell line and in the mouse kidney

ABSTRACT: LMX1B is a LIM-homeodomain transcription factor essential for development. Putative LMX1B target genes have been identified through mouse gene targeting studies; however, in the absence of in vivo molecular characterization of their regulation, their identity as direct LMX1B targets remains hypothetical. We describe here the first molecular characterization of LMX1B target gene regulation. A tetracycline-inducible expression system and microarray analysis showed that a subset of NF-kappa B target genes, including IL-6 and IL-8 are upregulated in LMX1B-expressing HeLa cells. Chromatin immunoprecipitation assays revealed that LMX1B binds to the proximal promoter region of IL-6 and IL-8 in vivo, in the vicinity of the characterized kappa B site, and that LMX1B recruitment correlates with an increased NF-kappa B DNA association. Inhibition of NF-kappa B activity by short interfering RNA-mediated knock-down of p65 impairs LMX1B-dependent induction of NF-kappa B target genes, while activation of NF-kappa B activity by TNF-alpha results in a synergistic induction of these genes by LMX1B. IL-6 promoter-driven reporter assays showed that the kappa B site and an adjacent putative LMX1B binding motif are both involved in LMX1B-mediated transcription. Expression of a number of NF-kappa B target genes is affected in the kidney of Lmx1b-/- knock-out mice, thus supporting the biological relevance of the data obtained in the human cell line. Together, these data demonstrate for the first time that LMX1B directly regulates transcription of a subset of NF-kappa B target genes in cooperation with nuclear p50/p65 NF-kappa B. Human subset (GSM303547-GSM303550): Two biological replicates of non-expressing HtTA-LMX1B cells (grown in doxycycline-containing medium) and of LMX1B-expressing HtTA-LMX1B cells (grown for 4 days in doxycycline-free medium) were processed for gene expression array analyses using an Affymetrix platform. Mouse subset (GSM304379-GSM304384): Three kidney samples from newborn wild-type mice and from newborn Lmx1b-/- knock-out mice were processed for gene expression array analyses using an Agilent platform.

ORGANISM(S): Homo sapiens

SUBMITTER: Anne Rascle

PROVIDER: E-GEOD-12008 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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The LIM-homeodomain transcription factor LMX1B regulates expression of NF-kappa B target genes.

Rascle Anne A Neumann Tanja T Raschta Anne-Sarah AS Neumann Astrid A Heining Eva E Kastner Juergen J Witzgall Ralph R

Experimental cell research 20081028 1

LMX1B is a LIM-homeodomain transcription factor essential for development. Putative LMX1B target genes have been identified through mouse gene targeting studies, but their identity as direct LMX1B targets remains hypothetical. We describe here the first molecular characterization of LMX1B target gene regulation. Microarray analysis using a tetracycline-inducible LMX1B expression system in HeLa cells revealed that a subset of NF-kappaB target genes, including IL-6 and IL-8, are upregulated in LMX ...[more]

PMID: 18996370

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Project description:NIPP1, an established interactor of protein phosphatase 1 (PP1), is implicated in PRC2-mediated regulation of gene expression. Here, we explore whether PP1 associated with NIPP1 is involved in NIPP1-mediated regulation of genes. Therefore, we generated Hela Tet-off (HTO) cell lines that stably and inducibly express a Flag-tagged version of wild-type NIPP1 (HTO-NIPP1wt) or mutant NIPP1 (HTO_NIPP1m). The latter mutant lacks the major PP1 binding site by two point mutations in the RVXF-motif, an established PP1 - binding motif. All cell lines were derived from the same parental HeLa Tet-Off (HTO-PT) cell line which expresses only tTA transactivator and is used as a control. The Flag fusions were only expressed in the absence of doxycyline and at levels that were up to twofold higher than that of endogenous NIPP1. We performed a gene expression profiling of the HTO cell lines, using Whole Human Genome Oligo microarrays from Agilent. A Paired SAM analysis identified 1365 genes with an altered expression (P < 0.01) between the Flag-NIPP1 and parental cell lines. Importantly, only 185 genes were differentially expressed (P<0.01) between the Flag-NIPP1m and parental cell lines. Even more strikingly, only 5% of the genes that were affected by the expression of Flag-NIPP1 also showed a significantly different expression in the Flag-NIPP1m cells. A similar small overlap was noted when the analysis was restricted to the 50 genes that were most upregulated or downregulated by the expression of Flag-NIPP1. Finally, scatter plot analysis revealed no significant correlation between the genes that were affected by the expression of Flag-NIPP1 or Flag-NIPP1m. Collectively, these data demonstrate that a moderate increase in the concentration of NIPP1 affects the expression of numerous genes by a mechanism that depends on associated PP1. In total 12 samples were processed. Three different cell lines were analysed: HTO_parental, HTO_NIPP1wt and HTO_NIPP1m. For each cell line 4 replicates were obtained. The HTO_parental cell line is the control cell line. For the HTO_NIPP1wt the 4 replicates were obtained from two replicates of two different transgenic cell lines expressing FlagNIPP1wt (cell line wt n°1 and 2). Each cell line derived from the same parental control cell line.

Project description:Abstract. Deregulated c-MYC is found in a variety of cancers where it promotes proliferation as well as apoptosis. In many hematological malignancies enhanced NF-kB exerts prosurvival functions. Here we investigated the role of NF-kB in mouse and human c-MYC-transformed lymphomas. The NF-kB-pathway is extinguished in murine lymphoma cells and extrinsic stimuli typically inducing NF-kB activity fail to activate this pathway. Genetic activation of the NF-kB pathway induces apoptosis in these cells, while inhibition of NF-kB by an IkBa superrepressor provides a selective advantage in vivo. Furthermore, in human BurkittÂ´s lymphoma cells we find that NF-kB activation induces apoptosis. NF-kB upregulates Fas and predisposes to Fas-induced cell death, which is caspase 8 mediated and can be prevented by CFLAR overexpression. We conclude that c-MYC overexpression sensitizes cells to NF-kB-induced apoptosis and persistent inacvtivity of NF-kB signaling is a prerequisite for MYC-mediated tumorigenesis. We could also show that low immunogenicity and Fas insensitivity of MYC driven lymphoma cells is reversed by activation of NF-kB. Our observations provide a molecular explanation for the described absence of the NF-kB signaling in BurkittÂ´s lymphoma and question the applicability of NF-kB inhibitors as candidates for treatment of this cancer. Experiment Overall Design: Ramos cells were transfected in triplicates with pRTS-GFP (A+,C+,D+) or pRTS-CA-IKK2 (E+,F+,H+), selected with hygromycin and transgene expression was induced with doxycycline (0,5mg/ml) for 48hrs. RNA was isolated with RNeasy mini kit (Qiagen, Venlo, Netherlands) and Gene expression profiling (GEP) was performed using Affymetrix Human Genome U133 Plus 2.0 Array (Affymetrix, Santa Clara, CA, USA). 2 Âµg of total RNA were labeled using the GeneChipÂ® One-Cycle Target Labeling assay kit (Affymetrix). After hybridization arrays were stained and washed in a FS 450 Fluidics station (Affymetrix) before imaging on an Affymetrix GeneChip (3000) scanner. Raw data were generated using the GCOS 1.4 software (Affymetrix). Probe level data were obtained using the Robust Multichip Average (RMA) normalization algorithm and CEL files were loaded into Genesifter (GeneSifter.Net, VizX Laboratories, Seattle, WA, USA). Genes were identified as differentially expressed among the two classes if a two-sample T-test revealed a nominal significance level of 0.05 and the ratio between the two classes was at least 2 fold. Calculation of false discovery rate was done according to the method of Benjamini and Hochberg. Biological significance was determined using Gene Ontolgy reports.

Dataset Information

Identification of LMX1B target genes in a tet-off inducible HeLa cell line and in the mouse kidney

Publications

The LIM-homeodomain transcription factor LMX1B regulates expression of NF-kappa B target genes.

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