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.

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE12008 | GEO | 2008/12/04

SECONDARY ACCESSION(S): PRJNA113281

REPOSITORIES: GEO