Recent studies on enzymes and reader proteins for histone crotonylation support a function of histone crotonyla- tion in transcription. However, the enzyme（s） responsible for histone decrotonylation ...（HDCR） remains poorly de- fined. Moreover, it remains to be determined if histone crotonylation is physiologically significant and functionally distinct from or redundant to histone acetylation. Here we present evidence that class I histone deacetylases （HDACs） rather than sirtuin family deacetylases （SIRTs） are the major histone decrotonylases, and that histone erotonylation is as dynamic as bistone acetylation in mammalian cells. Notably, we have generated novel HDAC1 and HDAC3 mutants with impaired HDAC but intact HDCR activity. Using these mutants we demonstrate that selective HDCR in mammalian cells correlates with a broad transcriptional repression and diminished promoter association of cro- tonylation but not acetylation reader proteins. Furthermore, we show that histone erotonylation is enriched in and required for self-renewal of mouse embryonic stem cells.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
As a transcription factor critical for embryonic and adult stem cell self-renewal and function, SOX2 gene amplification has been recognized as a driving factor for various cancers including ...esophageal cancer. SOX2 overexpression occurs more broadly in cancer than gene amplification, but the mechanism is poorly understood. Here we showed that in esophageal cancer cell lines the levels of SOX2 proteins are not directly correlated to the copy numbers of SOX2 genes and are strongly influenced by proteostasis. We showed that AKT is a major determinant for SOX2 overexpression and does so by protecting SOX2 from ubiquitin-dependent protein degradation. We identified UBR5 as a major ubiquitin E3 ligase that induces SOX2 degradation through ubiquitinating SOX2 at lysine 115. Phosphorylation of SOX2 at threonine 116 by AKT inhibits the interaction of UBR5 with SOX2 and thus stabilizes SOX2. We provided evidence that AKT inhibitor can effectively downregulate SOX2 and suppress esopheageal cancer cell proliferation and stemness. Taken together, our study provides new insight into the mechanism of SOX2 overexpression in cancer and evidence for targeting AKT as a potential therapeutic strategy for SOX2-positive cancers.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Epigenetic inheritance of DNA methylation in mammals requires a multifunctional protein UHRF1, which is believed to recruit DNMT1 to DNA replication forks through a unique hemi-methylated CpG-binding ...activity. Here we demonstrate that the UHRF1 mutants deficient in binding either hemi-methylated CpG or H3K9me2/3, but not both, are able to associate with pericentric heterochromatin, recruit Dnmt1 and partially rescue DNA methylation defects in mouse Uhrf1 null ES cells. Furthermore, we present evidence that the flip out of the methylated cytosine induced by UHRF1 binding is unlikely essential for subsequent DNA methylation by DNMT1. Together, our study demonstrates that UHRF1 can target DNMT1 for DNA maintenance methylation through binding either H3K9me2/3 or hemi-methylated CpG, and that the presence of both binding activities ensures high fidelity DNA maintenance methylation. In addition, our study indicates that UHRF1 mediates cross-talk between H3K9 methylation and DNA methylation at the level of DNA methylation maintenance.
Postnatal growth of mammalian oocytes is accompanied by a progressive gain of DNA methylation, which is predominantly mediated by DNMT3A, a de novo DNA methyltransferase
. Unlike the genome of sperm ...and most somatic cells, the oocyte genome is hypomethylated in transcriptionally inert regions
. However, how such a unique feature of the oocyte methylome is determined and its contribution to the developmental competence of the early embryo remains largely unknown. Here we demonstrate the importance of Stella, a factor essential for female fertility
, in shaping the oocyte methylome in mice. Oocytes that lack Stella acquire excessive DNA methylation at the genome-wide level, including in the promoters of inactive genes. Such aberrant hypermethylation is partially inherited by two-cell-stage embryos and impairs zygotic genome activation. Mechanistically, the loss of Stella leads to ectopic nuclear accumulation of the DNA methylation regulator UHRF1
, which results in the mislocalization of maintenance DNA methyltransferase DNMT1 in the nucleus. Genetic analysis confirmed the primary role of UHRF1 and DNMT1 in generating the aberrant DNA methylome in Stella-deficient oocytes. Stella therefore safeguards the unique oocyte epigenome by preventing aberrant de novo DNA methylation mediated by DNMT1 and UHRF1.
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KISLJ, NUK, SBMB, UL, UM, UPUK
Proper telomere length is essential for embryonic stem cell (ESC) self-renewal and pluripotency. Mouse ESCs (mESCs) sporadically convert to a transient totipotent state similar to that of two-cell ...(2C) embryos to recover shortened telomeres. Zscan4, which exhibits a burst of expression in 2C-like mESCs, is required for telomere extension in these cells. However, the mechanism by which Zscan4 extends telomeres remains elusive. Here, we show that Zscan4 facilitates telomere elongation by inducing global DNA demethylation through downregulation of Uhrf1 and Dnmt1, major components of the maintenance DNA methylation machinery. Mechanistically, Zscan4 recruits Uhrf1 and Dnmt1 and promotes their degradation, which depends on the E3 ubiquitin ligase activity of Uhrf1. Blocking DNA demethylation prevents telomere elongation associated with Zscan4 expression, suggesting that DNA demethylation mediates the effect of Zscan4. Our results define a molecular pathway that contributes to the maintenance of telomere length homeostasis in mESCs.
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•2C-like mESCs show global DNA hypomethylation•Zscan4 is responsible for DNA demethylation in 2C-like mESCs•Zscan4 induces Uhrf1-dependent ubiquitination and degradation of Uhrf1 and Dnmt1•Blocking DNA demethylation prevents Zscan4-mediated telomere elongation
Mouse embryonic stem cells sporadically convert to a transient totipotent (2C-like) state in which shortened telomeres are extended dependent on Zscan4. Dan et al. demonstrate that Zscan4 facilitates telomere elongation by inducing Uhrf1-dependent Uhrf1 and Dnmt1 degradation, leading to global DNA demethylation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
The UHRF1-DNMT1 axis plays a key role in DNA maintenance methylation in mammals. Accumulative studies demonstrate that UHRF1 is broadly overexpressed in cancers, which contributes to cancer cell ...proliferation and tumorigenesis. Interestingly, a proteasome-dependent downregulation of UHRF1 has been observed in pluripotent ground state mouse embryonic stem cells (mESCs) cultured in the presence of two kinase (MEK1/MEK2 and GSK3β) inhibitors (termed 2i), raising the question whether UHRF1 is similarly regulated in cancer cells. Here we present evidence that while addition of 2i broadly downregulates UHRF1 and DNMT1 in various cancer cells, distinct underlying mechanisms are involved. In contrast to mESCs, 2i-induced downregulation of UHRF1 and DNMT1 in cancer cells cannot be rescued by proteasome inhibitor and occurs primarily at the level of transcription. Furthermore, downregulation of UHRF1 and DNMT1 by 2i is due to inhibition of MEK1/MEK2, but not GSK3β activity. Data mining reveals a marked co-expression of UHRF1 and DNMT1 in normal tissues as well as cancers. We provide evidence that multiple transcription factors including E2F1 and SP1 mediate the transcriptional activation of UHRF1 and DNMT1 by the activated MEK/ERK pathway. Together our study reveals distinct regulation of UHRF1/DNMT1 in mESCs and cancer cells and identifies activated MEK/ERK pathway as a driving force for coordinated and aberrant over-expression of UHRF1 and DNMT1 in cancers.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Lysine L-lactylation K(L-la) is a newly discovered histone mark stimulated under conditions of high glycolysis, such as the Warburg effect. K(L-la) is associated with functions that are different ...from the widely studied histone acetylation. While K(L-la) can be introduced by the acetyltransferase p300, histone delactylases enzymes remained unknown. Here, we report the systematic evaluation of zinc- and nicotinamide adenine dinucleotide–dependent histone deacetylases (HDACs) for their ability to cleave ε-
-L-lactyllysine marks. Our screens identified HDAC1–3 and SIRT1–3 as delactylases in vitro. HDAC1–3 show robust activity toward not only K(L-la) but also K(D-la) and diverse short-chain acyl modifications. We further confirmed the de-L-lactylase activity of HDACs 1 and 3 in cells. Together, these data suggest that histone lactylation is installed and removed by regulatory enzymes as opposed to spontaneous chemical reactivity. Our results therefore represent an important step toward full characterization of this pathway’s regulatory elements.
The epithelial-mesenchymal transition （EMT） converts epithelial tumor cells into invasive and metastatic cancer cells, leading to mortality in cancer patients. Although TWIST is a master regulator of ...EMT and metastasis for breast and other cancers, the mechanisms responsible for TWIST-mediated gene transcription remain unknown. In this study, purification and characterization of the TWIST protein complex revealed that TWIST interacts with several components of the Mi2/nucleosome remodeling and deacetylase （Mi2/NuRD） complex, MTA2, RbAp46, Mi2 and HDAC2, and recruits them to the proximal regions of the E-cadherin promoter for transcriptional repression. Depletion of these TWIST complex components from cancer cell lines that depend on TWIST for metastasis efficiently suppresses cell migration and invasion in culture and lung metastasis in mice. These findings not only provide novel mechanistic and functional links between TWIST and the Mi2/NuRD complex but also establish new essential roles for the components of Mi2/NuRD complex in cancer metastasis.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Sox2 is a key factor for maintaining embryonic stem cell (ESS) pluripotency, but little is known about its posttranslational regulation. Here we present evidence that the precise level of Sox2 ...proteins in ESCs is regulated by a balanced methylation and phosphorylation switch. Set7 monomethylates Sox2 at K119, which inhibits Sox2 transcriptional activity and induces Sox2 ubiquitination and degradation. The E3 ligase WWP2 specifically interacts with K119-methylated Sox2 through its HECT domain to promote Sox2 ubiquitination. In contrast, AKT1 phosphorylates Sox2 at T118 and stabilizes Sox2 by antagonizing K119me by Set7 and vice versa. In mouse ESCs, AKT1 activity toward Sox2 is greater than that of Set7, leading to Sox2 stabilization and ESC maintenance. In early development, increased Set7 expression correlates with Sox2 downregulation and appropriate differentiation. Our study highlights the importance of a Sox2 methylation-phosphorylation switch in determining ESC fate.
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•Set7 methylates Sox2 at K119 and induces Sox2 ubiquitination and degradation•The E3 ligase WWP2 mediates K119me-dependent Sox2 ubiquitination•AKT1 phosphorylates Sox2 at T118, which blocks K119me by Set7 and stabilizes Sox2•A key role for Sox2 methylation-phosphorylation switch in regulating ESC fate
Fang et al. show that Set7 monomethylates Sox2 at K119 and induces Sox2 degradation. AKT1 phosphorylates Sox2 at T118 and stabilizes Sox2 by blocking K119me. This methyl-phospho switch controls Sox2 stability and ESC fate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
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