SP-transcription factors are involved in basal MVP promoter activity and its stimulation by HDAC inhibitors.
The major vault protein (MVP) has been implicated in multidrug resistance, cellular transport, and malignant transformation. In this study we aimed to identify crucial MVP promoter elements that regulate MVP expression. By mutation as well as deletion analysis a conserved proximal GC-box element was demonstrated to be essential for basal human MVP promoter transactivation. Binding of Sp-family transcription factors but not AP2 to this element in vitro and in vivo was shown by EMSA and ChIP assays, respectively. Inhibition of GC-box binding by a dominant-negative Sp1-variant and by mithramycin A distinctly attenuated MVP promoter activity. In Sp-null Drosophila cells, the silent human MVP promoter was transactivated by several human Sp-family members. In human cells the MVP promoter was potently stimulated by the histone deacetylase (HDAC) inhibitors butyrate (NaB) and trichostatin A (TSA), resulting in enhanced MVP expression. This stimulation was substantially decreased by mutation of the single GC-box and by application of mithramycin A. Treatment with HDAC inhibitors led to a distinct decrease of Sp1 but increase of Sp3 binding in vivo to the respective promoter sequence as demonstrated by ChIP assays. Summarising, this study identifies variations in Sp-transcription factor binding to a single proximal GC-box element as critical for basal MVP promoter activation and its stimulation by HDAC inhibitors.
Steiner
Elisabeth
E
Division of Applied and Experimental Oncology, Institute of Cancer Research, Medical University Vienna, Borschkegasse 8a, A-1090 Vienna, Austria.
Holzmann
Klaus
K
Pirker
Christine
C
Elbling
Leonilla
L
Micksche
Michael
M
Berger
Walter
W
D000818:Animals; D001483:Base Sequence; D002087:Butyrates / Q000494:pharmacology; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004330:Drosophila / Q000166:cytology; D029721:Drosophila Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D051379:Mice; D008926:Plicamycin / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D051381:Rats; D020218:Response Elements; D017384:Sequence Deletion; D016329:Sp1 Transcription Factor / Q000378:metabolism / Q000502:physiology*; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D020394:Vault Ribonucleoprotein Particles / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000099187:Major Vault Protein
D002087:Butyrates; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D008926:Plicamycin; D016329:Sp1 Transcription Factor; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D020394:Vault Ribonucleoprotein Particles; D000099187:Major Vault Protein; C493674:TfAP-2 protein, Drosophila; C012589:trichostatin A