Wang E, etal., Proc Natl Acad Sci U S A. 2013 Mar 5;110(10):3901-6. doi: 10.1073/pnas.1301045110. Epub 2013 Feb 14.
Mixed-lineage leukemia (MLL) fusions are potent oncogenes that initiate aggressive forms of acute leukemia. As aberrant transcriptional regulators, MLL-fusion proteins alter gene expression in hematopoietic cells through interactions with the histone H3 lysine 79 (H3K79) methyltransferase DOT1L. Not
ably, interference with MLL-fusion cofactors like DOT1L is an emerging therapeutic strategy in this disease. Here, we identify the histone H2B E3 ubiquitin ligase ring finger protein 20 (RNF20) as an additional chromatin regulator that is necessary for MLL-fusion-mediated leukemogenesis. Suppressing the expression of Rnf20 in diverse models of MLL-rearranged leukemia leads to inhibition of cell proliferation, under tissue culture conditions as well as in vivo. Rnf20 knockdown leads to reduced expression of MLL-fusion target genes, effects resembling Dot1l inhibition. Using ChIP-seq, we found that H2B ubiquitination is enriched in the body of MLL-fusion target genes, correlating with sites of H3K79 methylation and transcription elongation. Furthermore, Rnf20 is required to maintain local levels of H3K79 methylation by Dot1l at Hoxa9 and Meis1. These findings support a model whereby cotranscriptional recruitment of Rnf20 at MLL-fusion target genes leads to amplification of Dot1l-mediated H3K79 methylation, thereby rendering leukemia cells dependent on Rnf20 to maintain their oncogenic transcriptional program.
Tarcic O, etal., Cell Rep. 2016 Feb 16;14(6):1462-76. doi: 10.1016/j.celrep.2016.01.020. Epub 2016 Feb 4.
Factors linking inflammation and cancer are of great interest. We now report that the chromatin-targeting E3 ubiquitin ligase RNF20/RNF40, driving histone H2B monoubiquitylation (H2Bub1), modulates inflammation and inflammation-associated cancer in mice and huma
ns. Downregulation of RNF20 and H2Bub1 favors recruitment of p65-containing nuclear factor ¿B (NF-¿B) dimers over repressive p50 homodimers and decreases the heterochromatin mark H3K9me3 on a subset of NF-¿B target genes to augment their transcription. Concordantly, RNF20(+/-) mice are predisposed to acute and chronic colonic inflammation and inflammation-associated colorectal cancer, with excessive myeloid-derived suppressor cells (MDSCs) that may quench antitumoral T cell activity. Notably, colons of human ulcerative colitis patients, as well as colorectal tumors, reveal downregulation of RNF20/RNF40 and H2Bub1 in both epithelium and stroma, supporting the clinical relevance of our tissue culture and mouse model findings.
Histone lysine methylation contributes to transcriptional regulation by serving as a platform for the recruitment of various cofactors. Intense studies have been conducted for elucidating the functional meaning of H3K79 methylation, and to date, the only known HMTase responsible for the modification
was DOT1L. In this study, we report that the MMSET isoform RE-IIBP has HMTase activity for H3K79. It was uncovered that RE-IIBP up-regulates MEIS1 transcription through H3K79 methylation via recruitment to the MEIS1 promoter. By means of proteomic and biochemical analysis, association of RE-IIBP with the E3 ubiquitin ligase RNF20 was demonstrated for synergistic activation of MEIS1 transcription via H3K79 HMTase activity. Furthermore, It was observed that RE-IIBP induces MEIS1-mediated apoptosis, which was dependent on H2BK120 ubiquitination by RNF20. These findings suggest RE-IIBP as another candidate for further studies to elucidate the mechanism of H3K79 methylation and its biological functions.
Shema E, etal., Genes Dev. 2008 Oct 1;22(19):2664-76. doi: 10.1101/gad.1703008.
Histone monoubiquitylation is implicated in critical regulatory processes. We explored the roles of histone H2B ubiquitylation in human cells by reducing the expression of hBRE1/RNF20, the major H2B-specific E3 ubiquitin ligase. While H2B ubiquitylation is broa
dly associated with transcribed genes, only a subset of genes was transcriptionally affected by RNF20 depletion and abrogation of H2B ubiquitylation. Gene expression dependent on RNF20 includes histones H2A and H2B and the p53 tumor suppressor. In contrast, RNF20 suppresses the expression of several proto-oncogenes, which reside preferentially in closed chromatin and are modestly transcribed despite bearing marks usually associated with high transcription rates. Remarkably, RNF20 depletion augmented the transcriptional effects of epidermal growth factor (EGF), increased cell migration, and elicited transformation and tumorigenesis. Furthermore, frequent RNF20 promoter hypermethylation was observed in tumors. RNF20 may thus be a putative tumor suppressor, acting through selective regulation of a distinct subset of genes.
Roder K, etal., J Biol Chem. 2014 Dec 5;289(49):33730-40. doi: 10.1074/jbc.M114.592295. Epub 2014 Oct 3.
Two recent studies (Newton-Cheh, C. et al. (2009) Common variants at ten loci influence QT interval duration in the QTGEN Study. Nat. Genet. 41, 399-406 and Pfeufer, A. et al. (2009) Common variants at ten loci modulate the QT interval duration in the QTSCD Study. Nat. Genet. 41, 407-414) identified
an association, with genome-wide significance, between a single nucleotide polymorphism within the gene encoding RING finger protein 207 (RNF207) and the QT interval. We sought to determine the role of RNF207 in cardiac electrophysiology. Morpholino knockdown of RNF207 in zebrafish embryos resulted in action potential duration prolongation, occasionally a 2:1 atrioventricular block, and slowing of conduction velocity. Conversely, neonatal rabbit cardiomyocytes infected with RNF207-expressing adenovirus exhibited shortened action potential duration. Using transfections of U-2 OS and HEK293 cells, Western blot analysis and immunocytochemistry data demonstrate that RNF207 and the human ether-a-go-go-related gene (HERG) potassium channel interact and colocalize. Furthermore, RNF207 overexpression significantly elevated total and membrane HERG protein and HERG-encoded current density by ~30-50%, which was dependent on the intact N-terminal RING domain of RNF207. Finally, coexpression of RNF207 and HSP70 increased HERG expression compared with HSP70 alone. This effect was dependent on the C terminus of RNF207. Taken together, the evidence is strong that RNF207 is an important regulator of action potential duration, likely via effects on HERG trafficking and localization in a heat shock protein-dependent manner.
Park IS, etal., Biochem Biophys Res Commun. 2016 Feb 19;470(4):881-7. doi: 10.1016/j.bbrc.2016.01.141. Epub 2016 Jan 25.
TRAIP/RNF206 plays diverse roles in cell cycle progression, DNA damage response, and DNA repair pathways. Physiological importance of TRAIP is highlighted by the identification of pathogenic mutations of TRAIP gene in patients diagnosed with primordial dwarfis
m. Although the diverse functions of TRAIP in the nucleus have been well characterized, molecular mechanism of TRAIP retention in the nucleus has not been determined. Here, we discovered that TRAIP is post-translationally modified by the small ubiquitin-like protein (SUMO). In addition, we identified five SUMOylation sites in TRAIP, and successfully generated SUMOylation deficient mutant of TRAIP. In an attempt to define the functional roles of TRAIP SUMOylation, we discovered that SUMOylation deficient TRAIP is not retained in the nucleus. In addition, protein stability of SUMOylation deficient TRAIP is lower than wild type TRAIP, demonstrating that SUMOylation is critical for both proper subcellular localization and protein stability of TRAIP. Taken together, these findings improve the understanding clinical implication of TRAIP in various diseases including primordial dwarfism and cancers.
Soo Lee N, etal., Nat Commun. 2016 Jan 19;7:10463. doi: 10.1038/ncomms10463.
RAP80 localizes to sites of DNA insults to enhance the DNA-damage responses. Here we identify TRAIP/RNF206 as a novel RAP80-interacting protein and find that TRAIP is necessary for translocation of RAP80 to DNA lesions. Depletion of TRAIP results in impaired acc
umulation of RAP80 and functional downstream partners, including BRCA1, at DNA lesions. Conversely, accumulation of TRAIP is normal in RAP80-depleted cells, implying that TRAIP acts upstream of RAP80 recruitment to DNA lesions. TRAIP localizes to sites of DNA damage and cells lacking TRAIP exhibit classical DNA-damage response-defect phenotypes. Biochemical analysis reveals that the N terminus of TRAIP is crucial for RAP80 interaction, while the C terminus of TRAIP is required for TRAIP localization to sites of DNA damage through a direct interaction with RNF20-RNF40. Taken together, our findings demonstrate that the novel RAP80-binding partner TRAIP regulates recruitment of the damage signalling machinery and promotes homologous recombination.
Yuan L, etal., Cardiovasc Res. 2022 Mar 30:cvac039. doi: 10.1093/cvr/cvac039.
AIMS: The heart undergoes pathological remodeling, featured by the hypertrophic growth of cardiomyocytes and increased cardiac fibrosis, under biomechanical stress such as hemodynamic overload. RNF207 is an E3 ubiquitin ligase that is predominantly ex
pressed in the heart, but its function remains elusive. In this study, we aimed to explore the role of RNF207 in the development of pathological cardiac hypertrophy and dysfunction. METHODS AND RESULTS: Transverse aortic constriction (TAC) surgery was performed on mice to induce cardiac hypertrophy. Cardiac function and remodeling were evaluated by echocardiography, histological assessment and molecular analyses. Our data indicated that RNF207 overexpression (OE) exacerbated cardiac hypertrophy, fibrosis and systolic dysfunction. In contrast, TAC-induced cardiac remodeling was profoundly blunted in RNF207 knockdown (KD) hearts. In line with the in vivo findings, RNF207 OE augmented, while RNF207 KD alleviated, phenylephrine-induced cardiomyocyte hypertrophy in vitro. Mechanistically, we demonstrated that RNF207 elicited detrimental effects by promoting K63-linked ubiquitination of TAB1, which triggered the autophosphorylation of TAK1 and the activation of downstream p38 and JNK1/2 signaling pathways. In the TAB1 knockdown cardiomyocytes, RNF207 OE-induced cell hypertrophy was significantly attenuated, indicating that RNF207-induced hypertrophy is, at least in part, TAB1 dependent. CONCLUSIONS: This study demonstrates that RNF207 exacerbates pressure overload-induced cardiac hypertrophy and dysfunction via post-translational modification of TAB1. TRANSLATIONAL PERSPECTIVE: There is currently a lack of treatment to effectively prevent or reverse cardiac hypertrophy and heart failure, which has brought the importance of in-depth understanding of the molecular mechanisms that drives the pathological cardiac growth and the discovery of novel therapeutic targets. Our work demonstrates for the first time that RNF207 exaggerates pressure overload-induced cardiac hypertrophy and dysfunction. This is due, at least in part, to the polyubiquitination of TAB1, which triggers the autophosphorylation of TAK1 and activation of TAK1-p38 and TAK1-JNK1/2 signaling pathways. These data suggest that RNF207 may be a potential therapeutic target in the treatment of cardiac hypertrophy and failure.
