A BEN-domain-containing protein associates with heterochromatin and represses transcription

Abstract

SummaryIn eukaryotes, higher order chromatin structure governs crucial cellular processes including DNA replication, transcription and posttranscriptional gene regulation. Specific chromatin-interacting proteins play vital roles in the maintenance of chromatin structure. We have identified BEND3, a quadruple BEN domain-containing protein that is highly conserved amongst vertebrates. BEND3 colocalizes with HP1 and H3 trimethylated at K9 at heterochromatic regions in mammalian cells. Using an in vivo gene locus, we have been able to demonstrate that BEND3 associates with the locus only when it is heterochromatic and dissociates upon activation of transcription. Furthermore, tethering BEND3 inhibits transcription from the locus, indicating that BEND3 is involved in transcriptional repression through its interaction with histone deacetylases and Sall4, a transcription repressor. We further demonstrate that BEND3 is SUMOylated and that such modifications are essential for its role in transcriptional repression. Finally, overexpression of BEND3 causes premature chromatin condensation and extensive heterochromatinization, resulting in cell cycle arrest. Taken together, our data demonstrate the role of a novel heterochromatin-associated protein in transcriptional repression.

BEND6 is a nuclear antagonist of Notch signaling during self-renewal of neural stem cells

“…NAC1 and Mod(mdg4) proteins also contain a BTB/POZ domain, a protein interaction motif that in certain cases recruits histone deacetylase co-repressor complexes (Huynh and Bardwell, 1998;Wong and Privalsky, 1998;Rampalli et al, 2005). In addition, some BEN proteins that lack other recognizable domains, including BANP (which contains a single BEN domain) and BEND3 (which contains four BEN domains), also recruit histone deacetylases (Rampalli et al, 2005;Sathyan et al, 2011). Collectively, these findings indicate general attributes of BEN superfamily proteins in transcriptional repression.…”

“…Nevertheless, its presence in several chromatin factors suggested a role in nuclear gene regulation (Abhiman et al, 2008). Notably, several BEN-containing proteins have been characterized as transcriptional repressors, including Drosophila Mod(mdg4) (Cai and Levine, 1997) and Insensitive (Duan et al, 2011), and vertebrate BANP (also known as SMAR1) (Rampalli et al, 2005;Pavithra et al, 2009;Sreenath et al, 2010), NAC1 (also known as NACC1) (Korutla et al, 2005;Korutla et al, 2007) and BEND3 (Sathyan et al, 2011). NAC1 and Mod(mdg4) proteins also contain a BTB/POZ domain, a protein interaction motif that in certain cases recruits histone deacetylase co-repressor complexes (Huynh and Bardwell, 1998;Wong and Privalsky, 1998;Rampalli et al, 2005).…”

Orc2 protects ORCA from ubiquitin-mediated degradation

“…84 The YFP-ORCA-expressing cell line was either fixed in 2% paraformaldehyde for 15 min at room temperature and then permeabilized by PBS + 0.5% Triton X-100 for 7 min on ice, or pre-extracted in CSK buffer (10 mM PIPES pH 7.0, 100 mM NaCl, 300 mM sucrose, 3 mM MgCl 2 ) + 0.5% Triton X-100 for 5 min on ice and then fixed with 2% paraformaldehyde. Cells were then blocked in PBS + 1% normal goat serum (NGS) and incubated with primary antibodies for 1 h and secondary antibodies for 45 min.…”

The BEN domain is a novel sequence-specific DNA-binding domain conserved in neural transcriptional repressors

“…Given that Insv and BEND5 are fairly unrelated in primary sequence, these findings suggest that some of the other >100 BEN proteins are likely to be transcription factors. Curiously, some other BEN proteins, including the BTB/POZ-BEN factor NAC-1 and the quadruple BEN protein BEND3, have previously been linked to transcriptional repression (Korutla et al 2009;Sathyan et al 2011). Potentially, their BEN domains are involved in recruiting these factors to their appropriate chromatin targets.…”