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Sequence-specific transcriptional repression by KS1, a multiple-zinc-finger-Kruppel-associated box protein.

ABSTRACT: The vertebrate genome contains a large number of Krüppel-associated box-zinc finger genes that encode 10 or more C(2)-H(2) zinc finger motifs. Members of this gene family have been proposed to function as transcription factors by binding DNA through their zinc finger region and repressing gene expression via the KRAB domain. To date, however, no Krüppel-associated box-zinc finger protein (KRAB-ZFP) and few proteins with 10 or more zinc finger motifs have been shown to bind DNA in a sequence-specific manner. Our laboratory has recently identified KS1, a member of the KRAB-ZFP family that contains 10 different C(2)-H(2) zinc finger motifs, 9 clustered at the C terminus with an additional zinc finger separated by a short linker region. In this study, we used a random oligonucleotide binding assay to identify a 27-bp KS1 binding element (KBE). Reporter assays demonstrate that KS1 represses the expression of promoters containing this DNA sequence. Deletion and site-directed mutagenesis reveal that KS1 requires nine C-terminal zinc fingers and the KRAB domain for transcriptional repression through the KBE site, whereas the isolated zinc finger and linker region are dispensable for this function. Additional biochemical assays demonstrate that the KS1 KRAB domain interacts with the KAP-1 corepressor, and mutations that abolish this interaction alleviate KS1-mediated transcriptional repression. Thus, this study provides the first direct evidence that a KRAB-ZFP binds DNA to regulate gene expression and provides insight into the mechanisms used by multiple-zinc-finger proteins to recognize DNA sequences.

SUBMITTER: Gebelein B

PROVIDER: S-EPMC86683 | biostudies-literature | 2001 Feb

REPOSITORIES: biostudies-literature

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Sequence-specific transcriptional repression by KS1, a multiple-zinc-finger-Krüppel-associated box protein.

Gebelein B B Urrutia R R

Molecular and cellular biology 20010201 3

The vertebrate genome contains a large number of Krüppel-associated box-zinc finger genes that encode 10 or more C(2)-H(2) zinc finger motifs. Members of this gene family have been proposed to function as transcription factors by binding DNA through their zinc finger region and repressing gene expression via the KRAB domain. To date, however, no Krüppel-associated box-zinc finger protein (KRAB-ZFP) and few proteins with 10 or more zinc finger motifs have been shown to bind DNA in a sequence-spec ...[more]

PMID: 11154279

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Project description:Type XI collagen is composed of three chains, alpha 1(XI), alpha 2(XI), and alpha 3(XI), and plays a critical role in the formation of cartilage collagen fibrils and in skeletal morphogenesis. It was previously reported that the -530-bp promoter segment of the alpha 2(XI) collagen gene (Col11a2) was sufficient for cartilage-specific expression and that a 24-bp sequence from this segment was able to switch promoter activity from neural tissues to cartilage in transgenic mice when this sequence was placed in the heterologous neurofilament light gene (NFL) promoter. To identify a protein factor that bound to the 24-bp sequence of the Col11a2 promoter, we screened a mouse limb bud cDNA expression library in the yeast one-hybrid screening system and obtained the cDNA clone NT2. Sequence analysis revealed that NT2 is a zinc finger protein consisting of a Krüppel-associated box (KRAB) and is a homologue of human FPM315, which was previously isolated by random cloning and sequencing. The KRAB domain has been found in a number of zinc finger proteins and implicated as a transcriptional repression domain, although few target genes for KRAB-containing zinc finger proteins has been identified. Here, we demonstrate that NT2 functions as a negative regulator of Col11a2. In situ hybridization analysis of developing mouse cartilage showed that NT2 mRNA is highly expressed by hypertrophic chondrocytes but is minimally expressed by resting and proliferating chondrocytes, in an inverse correlation with the expression patterns of Col11a2. Gel shift assays showed that NT2 bound a specific sequence within the 24-bp site of the Col11a2 promoter. We found that Col11a2 promoter activity was inhibited by transfection of the NT2 expression vector in RSC cells, a chondrosarcoma cell line. The expression vector for mutant NT2 lacking the KRAB domain failed to inhibit Col11a2 promoter activity. These results demonstrate that KRAB-zinc finger protein NT2 inhibits transcription of its physiological target gene, suggesting a novel regulatory mechanism of cartilage-specific expression of Col11a2.

Dataset Information

Sequence-specific transcriptional repression by KS1, a multiple-zinc-finger-Kruppel-associated box protein.

Publications

Sequence-specific transcriptional repression by KS1, a multiple-zinc-finger-Krüppel-associated box protein.

Similar Datasets

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