The Sp1-like protein BTEB3 inhibits transcription via the basic transcription element box by interacting with mSin3A and HDAC-1 co-repressors and competing with Sp1.
Sp1-like proteins are characterized by three conserved C-terminal zinc finger motifs that bind GC-rich sequences found in promoters of numerous genes essential for mammalian cell homeostasis. These proteins behave as transcriptional activators or repressors. Although significant information has been reported on the molecular mechanisms by which Sp1-like activators function, relatively little is known about mechanisms for repressor proteins. Here we report the functional characterization of BTEB3, a ubiquitously expressed Sp1-like transcriptional repressor. GAL4 assays show that the N terminus of BTEB3 contains regions that can act as direct repressor domains. Immunoprecipitation assays reveal that BTEB3 interacts with the co-repressor mSin3A and the histone deacetylase protein HDAC-1. Gel shift assays demonstrate that BTEB3 specifically binds the BTE site, a well characterized GC-rich DNA element, with an affinity similar to that of Sp1. Reporter and gel shift assays in Chinese hamster ovary cells show that BTEB3 can also mediate repression by competing with Sp1 for BTE binding. Thus, the characterization of this protein expands the repertoire of BTEB-like members of the Sp1 family involved in transcriptional repression. Furthermore, our results suggest a mechanism of repression for BTEB3 involving direct repression by the N terminus via interaction with mSin3A and HDAC-1 and competition with Sp1 via the DNA-binding domain.
Kaczynski
J
J
Gastroenterology Research Unit, Mayo Clinic, Rochester, Minnesota 55901, USA.
Zhang
J S
JS
Ellenrieder
V
V
Conley
A
A
Duenes
T
T
Kester
H
H
van Der Burg
B
B
Urrutia
R
R
D020816:Amino Acid Motifs; D000818:Animals; D001667:Binding, Competitive; D015153:Blotting, Western; D016466:CHO Cells; D018797:Cell Cycle Proteins; D006224:Cricetinae; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism*; D007700:Kinetics; D051741:Kruppel-Like Transcription Factors; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism*; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D015534:Trans-Activators / Q000502:physiology*; D014158:Transcription, Genetic; D016335:Zinc Fingers
D018797:Cell Cycle Proteins; C486423:KLF13 protein, human; D051741:Kruppel-Like Transcription Factors; D012097:Repressor Proteins; C099683:SIN3A transcription factor; D016329:Sp1 Transcription Factor; D015534:Trans-Activators; D005982:Glutathione Transferase; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases; D056264:Sin3 Histone Deacetylase and Corepressor Complex