A Family of Human Zinc Finger Proteins That Bind Methylated DNA and Repress Transcription

Abstract

In vertebrates, densely methylated DNA is associated with inactive transcription. Actors in this process include proteins of the MBD family that can recognize methylated CpGs and repress transcription. Kaiso, a structurally unrelated protein, has also been shown to bind methylated CGCGs through its three Krüppel-like C 2 H 2 zinc fingers. The human genome contains two uncharacterized proteins, ZBTB4 and ZBTB38, that contain Kaiso-like zinc fingers. We report that ZBTB4 and ZBTB38 bind methylated DNA in vitro and in vivo. Unlike Kaiso, they can bind single methylated CpGs. When transfected in mouse cells, the proteins colocalize with foci of heavily methylated satellite DNA and become delocalized upon loss of DNA methylation. Chromatin immunoprecipitation suggests that both of these proteins specifically bind to the methylated allele of the H19/Igf2 differentially methylated region. ZBTB4 and ZBTB38 repress the transcription of methylated templates in transfection assays. The two genes have distinct tissue-specific expression patterns, but both are highly expressed in the brain. Our results reveal the existence of a family of Kaiso-like proteins that bind methylated CpGs. Like proteins of the MBD family, they are able to repress transcription in a methyl-dependent manner, yet their tissue-specific expression pattern suggests nonoverlapping functions.

The human protein kinase HIPK2 phosphorylates and downregulates the methyl-binding transcription factor ZBTB4

“…For this, we tagged proteins with the green fluorescent protein (GFP) or the red fluorescent protein (RFP). As reported, we found GFP-HIPK2 in nuclear foci (Rinaldo et al, 2008), and ZBTB4-RFP was diffuse nuclear (Filion et al, 2006b). When GFP-HIPK2 and RFP-ZBTB4 were cotransfected, there was a strong colocalization.…”

“…ZBTB4 binds methylated DNA and represses the transcription of methylated reporter genes (Filion et al, 2006b). Very little is known about the posttranslational modifications that regulate the activity of methyl-binding transcription factors (Clouaire and Stancheva, 2008).…”

“…ZBTB4 was detected using PAD#98, the fourth bleed of a rabbit polyclonal serum raised against residues 1-125 of the human protein (Filion et al, 2006b). The dilution was 1/3000.…”

Yeast two-hybrid screening of proteins interacting with plasmin receptor subunit: C-terminal fragment of annexin A2

“…In preclinical tumor models, it has been shown that therapeutic targeting of RPS2 is an excellent approach for the eradication of prostate cancer [26] . ZBTB4 binds to methylated CpGs, repressing transcription of P21CIP1 and controlling the cellular response to p53 activation, thereby playing a crucial role in oncogenesis [27,28] . OGDH is a well-characterized auto-antigen in primary biliary cirrhosis.…”

Le double jeu de l’épigénétique

“…Les protéines liant spécifiquement l'ADN méthylé sont l'interface entre méthylation de l'ADN et chromatine. À ce jour 3 familles sont connues : (1) la famille des protéines à MBD (methyl-binding domain) [9] ; (2) la famille de protéines à doigts de Zinc, contenant Kaiso, ZBTB4, et ZBTB38 [10] ; et (3) un groupe de deux protéines à domaine SRA (SET and RING-finger associated), UHRF1 et UHRF2 [11]. Les protéines MBD, ainsi que celles apparentées à Kaiso, sont des répresseurs transcriptionnels.…”