S phase-dependent interaction with DNMT1 dictates the role of UHRF1 but not UHRF2 in DNA methylation maintenance

Abstract

Recent studies demonstrate that UHRF1 is required for DNA methylation maintenance by targeting DNMT1 to DNA replication foci, presumably through its unique hemi-methylated DNA-binding activity and interaction with DNMT1. UHRF2, another member of the UHRF family proteins, is highly similar to UHRF1 in both sequence and structure, raising questions about its role in DNA methylation. In this study, we demonstrate that, like UHRF1, UHRF2 also binds preferentially to methylated histone H3 lysine 9 (H3K9) through its conserved tudor domain and hemi-methylated DNA through the SET and Ring associated domain. Like UHRF1, UHRF2 is enriched in pericentric heterochromatin. The heterochromatin localization depends to large extent on its methylated H3K9-binding activity and to less extent on its methylated DNA-binding activity. Coimmunoprecipitation experiments demonstrate that both UHRF1 and UHRF2 interact with DNMT1, DNMT3a, DNMT3b and G9a. Despite all these conserved functions, we find that UHRF2 is not able to rescue the DNA methylation defect in Uhrf1 null mouse embryonic stem cells. This can be attributed to the inability for UHRF2 to recruit DNMT1 to replication foci during S phase of the cell cycle. Indeed, we find that while UHRF1 interacts with DNMT1 in an S phase-dependent manner in cells, UHRF2 does not. Thus, our study demonstrates that UHRF2 and UHRF1 are not functionally redundant in DNA methylation maintenance and reveals the cell-cycle-dependent interaction between UHRF1 and DNMT1 as a key regulatory mechanism targeting DNMT1 for DNA methylation.

UHRF2 mRNA Expression is Low in Malignant Glioma but Silencing Inhibits the Growth of U251 Glioma Cells in vitro

“…The UHRF2 protein can bind methylated DNA through its SRA domain and H3K9me3 through its TTD-PHD region (Fournier et al, 2011;Parry et al, 2011;Pichler et al, 2011). These processes are important for UHRF2 to be involved in controlling the expression of multiple genes through chromatin and transcriptional regulation (Zhang et al, 2011). In our study, the down-regulation of UHRF2 induced the apoptosis of U251 glioma cells.…”

Post-transcriptional gene silencing, transcriptional gene silencing and human immunodeficiency virus

“…Transcritional silencing, heterochromatin SUV39H1/2 [143] , G9a [248] , SETDB1 [249] JMJD1A/KDM3A [250] , JMJD1B/KDM3B [251] , JMJD1C/TRIP8, JMJD2A/KDM4A (B/C/D) [252] HP1 [253] , EED 17406994), TDRD7 [254] , MPP8 [255] , UHRF1/2 [256] , GLP [248] , CDY FAMILY [257] H3K27 me1/me2/me3, heterochromatin and facultative heterochromatin Transcritional silencing, heterochromatin, poised genes EZH2, EZH1 [258] JMJD1A/KDM3A, JMJD1B/KDM3B, KDM6A/UTX, JMJD3/KDM68, JMJD3/KDM6B [259] Cbx proteins [165] , EED [260] [ 166,261] H3K36 Ac Transcription activation GCN5, PCAF [244] [262]…”

The Nuclear Protein UHRF2 Is a Direct Target of the Transcription Factor E2F1 in the Induction of Apoptosis

“…UHRF1 null mouse embryos display a severe DNA methylation defect, similar to DNMT1 nulls (42,43). Intriguingly, ectopic expression of UHRF2 does not rescue this UHRF1 null defect, nor does UHRF2 display preferential binding to hemi-methylated DNA over unmethylated DNA as UHRF1, suggesting distinct functions between these proteins (18,19).…”

“…UHRF2 contains a ubiquitin-like domain, PHD finger domain, a set-and ringassociated (SRA) domain, and a RING finger domain (17). UHRF2 is functionally distinct from the structurally similar UHRF1, as ectopic UHRF2 expression does not rescue the DNA methylation defect in UHRF1 null mouse embryonic stem cells (18,19). Intriguingly, both UHRF2 and UHRF1 physically associate with the Rb tumor suppressor protein and appear to recognize DNA and histone methylation to control cell cycle progression and gene expression (20,21).…”