Defining UHRF1 Domains That Support Maintenance of Human Colon Cancer DNA Methylation and Oncogenic Properties [expression]
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ABSTRACT: UHRF1 is essential for targeting DNA methyltransferases (DNMT’s) to replicating DNA to establish de novo DNA methylation and maintain it. While, UHRF1 domains are defined, including requirement for an E3 ligase region, for de novo methylation, those essential for maintenance have been difficult to outline. Herein, via a new assay, chromatin histone-binding and a hemimethylated DNA reader domains, but not the ligase domain are found essential for cancer-specific DNA methylation maintenance in human colorectal cancer (CRC) cells. Disrupting each essential domain phenocopies UHRF1 depletion for global DNA demethylation, reactivation of tumor suppressor genes (TSGs), and reduction in CRC invasion and metastatic properties. Moreover, there is strong negative correlation between high UHRF1 expression, low TSG expression, and abnormal methylation with CRC progression and overall survival. Our battery of findings suggest the value of targeting specific domains of UHRF1 for cancer therapy and adding a precision medicine approach through use of the biomarker associations we define.
Project description:UHRF1 is essential for targeting DNA methyltransferases (DNMT’s) to replicating DNA to establish de novo DNA methylation and maintain it. While, UHRF1 domains are defined, including requirement for an E3 ligase region, for de novo methylation, those essential for maintenance have been difficult to outline. Herein, via a new assay, chromatin histone-binding and a hemimethylated DNA reader domains, but not the ligase domain are found essential for cancer-specific DNA methylation maintenance in human colorectal cancer (CRC) cells. Disrupting each essential domain phenocopies UHRF1 depletion for global DNA demethylation, reactivation of tumor suppressor genes (TSGs), and reduction in CRC invasion and metastatic properties. Moreover, there is strong negative correlation between high UHRF1 expression, low TSG expression, and abnormal methylation with CRC progression and overall survival. Our battery of findings suggest the value of targeting specific domains of UHRF1 for cancer therapy and adding a precision medicine approach through use of the biomarker associations we define.
Project description:UHRF1 maintains DNA methylation by recruiting DNA methyltransferases (DNMT’s) to chromatin. These dynamics are well defined for mouse STELLA (mSTELLA) but poorly characterized for human STELLA (hSTELLA). Herein, we demonstrate that hSTELLA is defective, while mSTELLA is fully proficient in associating with UHRF1 and inhibiting the abnormal DNA methylation and oncogenic functions of UHRF1 in human cancer cells. We illustrate, in structural studies a region of low sequence homology between the above STELLA orthologs, allows mSTELLA but not hSTELLA to bind tightly to the essential histone binding domains of UHRF1, thus mediating their above functional differences. The ortholog-specific binding modes of STELLA proteins with UHRF1 prompt us to explore a rationale for designing UHRF1 inhibitors for cancer therapy. For this, we use a lipid nanoparticle (LNP)-mediated mRNA delivery approach demonstrating the short mSTELLA, but not hSTELLA regions are required to reverse cancer-specific DNA methylation abnormalities and impair CRC tumor growth.
Project description:DNA methylation is a heritable chromatin modification essential to mammalian development that functions with histone post-translational modifications to regulate chromatin structure and gene expression programs. The epigenetic inheritance of DNA methylation requires the combined actions of DNMT1 and UHRF1, a histone- and DNA-binding RING E3 ubiquitin ligase that facilitates DNMT1 recruitment to sites of newly replicated DNA through the ubiquitylation of histone H3. UHRF1 binds DNA with modest selectivity towards hemi-methylated CpG dinucleotides (HeDNA); however, the contribution of HeDNA sensing to UHRF1 function remains elusive. Here, we reveal that the interaction of UHRF1 with HeDNA is required for DNA methylation inheritance but is dispensable for chromatin interaction, which is governed by reciprocal positive cooperativity between the UHRF1 histone- and DNA-binding domains. We further show that HeDNA functions as an allosteric regulator of UHRF1 ubiquitin ligase activity, directing ubiquitylation towards multiple lysines on the H3 tail adjacent to the UHRF1 histone-binding site. Collectively, our studies define a highly orchestrated epigenetic control mechanism involving modifications both to histones and DNA that facilitate UHRF1 chromatin targeting, H3 ubiquitylation, and DNA methylation inheritance.
Project description:UHRF1 (Ubiquitin-like, containing PHD and RING finger domains, 1) recruits DNMT1 to hemimethylated DNA during replication, is essential for maintaining DNA methylation patterns during cell division and is suggested to direct additional repressive epigenetic marks. Uhrf1 mutation in zebrafish results in multiple embryonic defects including failed hepatic outgrowth, but the epigenetic basis of these phenotypes is not known. We find that DNA methylation is the only epigenetic mark that is depleted in uhrf1 mutants and make the surprising finding that despite the reduced organ size in uhrf1 mutants, genes regulating DNA replication and S-phase progression were highly upregulated. Further, there is a striking increase in BrdU incorporation in uhrf1 mutant cells, and they retained BrdU labeling over several days, indicating they are arrested in S-phase. Moreover, some of the label retaining nuclei co-localized with TUNEL positive nuclei, suggesting that arrested cells are responsible for apoptosis. Importantly, dnmt1 mutation phenocopies the S-phase arrest and hepatic outgrowth defects in uhrf1 mutants and Dnmt1 knock-down enhances the uhrf1 hepatic phenotype. Together, these data indicate that DNA hypomethylation is sufficient to generate the uhrf1 mutant phenotype by promoting an S-phase arrest. We thus propose that cell cycle arrest is a mechanism to restrict propagation of epigenetically deranged cells during embryogenesis. Genome-wide expression profiling was performed on 2 uhrf1 mutant and 2 wildtype zebrafish larvae (120 hours post fertilization) by using Zebrafish Genome Array (Affymetrix) according to manufacturer's instruction.
Project description:UHRF1 is a key regulator of DNA methylation maintenance. In this study, we investigated whether acetylation of UHRF1 affects its hemimethylated DNA binding affinity and alters genome-wide DNA methylation pattern. We show that cells with mutation in K490 of UHRF1 have distinct methylation profile versus wildtype UHRF1 expressing cells.
Project description:The multi-domain protein UHRF1 (ubiquitin-like, containing PHD and RING finger domains, 1) recruits DNMT1 for DNA methylation maintenance during DNA replication. Here, we show that MOF (Males absent On the First) is an acetyltransferase of UHRF1 to acetylate UHRF1 at Lys670 in the pre-RING linker region whereas HDAC1 is a deacetylase of UHRF1 at the same site. The MOF/HDAC1-mediated acetylation in UHRF1 is cell-cycle regulated and peaks at G1/S phase, in line with the function of UHRF1 in recruiting DNMT1 to maintain DNA methylation. In addition, UHRF1 acetylation significantly enhances its E3 ligase activity and elimination of UHRF1 acetylation at these sites attenuates UHRF1-mediated H3 ubiquitination, which in turn impairs the DNMT1 recruitment and DNA methylation. Taken together, these findings not only identify MOF as a new acetyltransferase for UHRF1 but also reveal a novel mechanism underlying the regulation of DNA methylation maintenance through MOF-mediated UHRF1 acetylation.
Project description:UHRF1 is a key regulator of DNA methylation maintenance. In this study, we investigated whether acetylation of UHRF1 affects its hemimethylated DNA binding affinity and alters genome-wide DNA methylation pattern. We observed that acetylation of UHRF1 is regulated by HDAC1 and PCAF. We investigated DNA methylation profile of HDAC1 depleted HCT116 cell with control cell.
Project description:DNA methylation is an essential epigenetic mark in mammals. It controls gene expression and genome stability. Global DNA methylation pattern is abnormal in cancers. Ubiquitin like with PHD and RING finger domains 1 (UHRF1) is a key epigenetic regulator that recruits and activates DNA methyltransferase 1 (DNMT1), the methylation maintenance enzyme. UHRF1 is a proven oncogene and its overexpression transforms cells in vitro and causes cancer in animal models. Therefore, UHRF1 provides a unique entry point into the links between epigenetics and cancer. However, it is still not fully clear how UHRF1 works in cancer cells. To understand UHRF1 functions in cancer, we employed experimental strategy to use an advanced chemical/genetic system, the auxin-inducible degron (AID) technology, whereby the degron-fused protein can be totally and rapidly degraded upon the addition of a small molecule, auxin. We chose the human CRC cell line HCT116 as our model and successfully generated UHRF1-AID and DNMT1-AID. Through this study, we made the significant discovery that UHRF1 not only regulates DNMT1, but also influences the activities of de novo methyltransferases DNMT3A and DNMT3B, as well as the active demethylase TET2.
Project description:DNA methylation is an essential epigenetic mark in mammals. It controls gene expression and genome stability. Global DNA methylation pattern is abnormal in cancers. Ubiquitin like with PHD and RING finger domains 1 (UHRF1) is a key epigenetic regulator that recruits and activates DNA methyltransferase 1 (DNMT1), the methylation maintenance enzyme. UHRF1 is a proven oncogene and its overexpression transforms cells in vitro and causes cancer in animal models. Therefore, UHRF1 provides a unique entry point into the links between epigenetics and cancer. However, it is still not fully clear how UHRF1 works in cancer cells. To understand UHRF1 functions in cancer, we employed experimental strategy to use an advanced chemical/genetic system, the auxin-inducible degron (AID) technology, whereby the degron-fused protein can be totally and rapidly degraded upon the addition of a small molecule, auxin. We chose the human CRC cell line HCT116 as our model and successfully generated UHRF1-AID and DNMT1-AID. Through this study, we made the significant discovery that UHRF1 not only regulates DNMT1, but also influences the activities of de novo methyltransferases DNMT3A and DNMT3B, as well as the active demethylase TET2.
Project description:The E3 ligase UHRF1 is an essential epigenetic cofactor for DNMT1 dependent maintenance DNA methylation, which provides a binding platform for DNMT1 by both cooperative binding of histones and hemi-methylated DNA as well as by ubiquitinating histone H3. Here, we conduct a comprehensive screen to identify novel ubiquitination targets of UHRF1 and its paralogue UHRF2 by comparing the ubiquitome of wildtype (wt), UHRF1- and UHRF2-deficient mouse embryonic stem cells. With an antibody-dependent enrichment of ubiquitin remnant motif-containing peptides followed by isobaric-labeling based quantitative mass spectrometry, we find both known and novel E3 ligase substrates of UHRF1 involved in a variety of biological processes such as RNA processing, DNA methylation and DNA damage repair.