Charakterisierung der humanen und murinen I-kappa-B-Kinase-beta--Promotoren zur Analyse der gewebsspezifischen Variationen in der Zusammensetzng des I-kappa-B-Kinase-Komplexes
Gosemärker, Anna Teresa
LicenseStandard (Fassung vom 03.05.2003)
Nuclear factor kappa-b (NFkappa-b) plays an important role both in innate and adaptive immunity as well as in differentiation processes and carcinogenesis. The inhibitor of NFkappa-b-kinase(IKK)-complex with its main components IKKalpha, IKKbeta and NEMO is one of the key regulators of NFkappa-b-activation. In RT-PCR- and Western blot-studies we observed differences of expression levels of IKKalpha, IKKbeta and NEMO in different murine tissues, implicating a high grade of regulation for the components of the IKK-complex. For further investigation we cloned a putative IKKbeta-promoter into a luciferase reporter construct. Contitutively high promoter activity was observed which could not be influenced by agents like TNFalpha or Forskolin. Deletion mutants showed highest promoter activity in the region 200 base pairs upstream of the first exon. A closer look on this region revealed putative binding sites of the transcription factors CREB and Ets. Point mutations of these sites resulted in a strong decrease of promoter activity. Furthermore in Electrophoretic-Mobility-Shift-Assays protein complexes binding to these putative binding sites but not to the mutated sites were found. Most intrestingly differences in the composition of these protein complexes were observed depending on the cell-type. Therefore members of the CREB- and Ets-family could be responsible for tissue-specific expression of IKKbeta and perhaps in case of Ets for a coupling of the expression of IKKalpha and IKKbeta because of an already known activation of the IKKalpha-promoter through Ets.
Subject HeadingsPromotor [GND]