Project description:The retinoblastoma tumor suppressor gene (RB) product has been implicated in epigenetic control of gene expression owing to its ability to physically bind to many of chromatin modifiers. However, the biological and clinical significance of this activity was not well elucidated. To address this, we performed genetic and epigenetic analyses in an Rb-deficient mouse thyroid C cell tumor model. Here we report that the genetic interaction of Rb and ATM regulates DNMT1 protein stability, and hence controls the DNA methylation status in the promoter of at least Ink4a, Shc2, FoxO6 and Noggin genes. Further, we demonstrate that inactivation of pRB promotes the Tip60 (acetyltransferase)-dependent ATM activation, allows activated ATM to physically bind to DNMT1 forming a complex with Tip60 and UHRF1 (E3 ligase), and consequently accelerates DNMT1 ubiquitination driven by Tip60-dependent acetylation. Our results indicate that inactivation of pRB pathway in coordination with aberration in DNA damage response leads to abnormal DNA methylation pattern by affecting the stability of DNMT1. 163; Rb-/-;ATM-/- MEFs, D4; DNMT1 knockdown from 163 cells and analysed at day 4, WT8S; 163 cells reconstituted with ATM expression vector
Project description:The retinoblastoma tumor suppressor gene (RB) product has been implicated in epigenetic control of gene expression owing to its ability to physically bind to many of chromatin modifiers. However, the biological and clinical significance of this activity was not well elucidated. To address this, we performed genetic and epigenetic analyses in an Rb-deficient mouse thyroid C cell tumor model. Here we report that the genetic interaction of Rb and ATM regulates DNMT1 protein stability, and hence controls the DNA methylation status in the promoter of at least Ink4a, Shc2, FoxO6 and Noggin genes. Further, we demonstrate that inactivation of pRB promotes the Tip60 (acetyltransferase)-dependent ATM activation, allows activated ATM to physically bind to DNMT1 forming a complex with Tip60 and UHRF1 (E3 ligase), and consequently accelerates DNMT1 ubiquitination driven by Tip60-dependent acetylation. Our results indicate that inactivation of pRB pathway in coordination with aberration in DNA damage response leads to abnormal DNA methylation pattern by affecting the stability of DNMT1.
Project description:The DNA methyltransferase activity of DNMT1 is vital for genomic maintenance of DNA methylation. We report here that DNMT1 function is regulated by O-GlcNAcylation, a protein modification that is sensitive to glucose levels, and that elevated O-GlcNAcylation of DNMT1 from high glucose environment leads to alterations to the epigenome. Using mass spectrometry and complementary alanine mutation experiments, we identified S878 as the major residue that is O-GlcNAcylated on DNMT1. Functional studies further revealed that O-GlcNAcylation of DNMT1-S878 results in an inhibition of methyltransferase activity, resulting in a general loss of DNA methylation that is preferentially at partially methylated domains (PMDs). This loss of methylation corresponds with an increase in DNA damage and apoptosis. These results establish O-GlcNAcylation of DNMT1 as a mechanism through which the epigenome is regulated by glucose metabolism and implicates a role for glycosylation of DNMT1 in metabolic diseases characterized by hyperglycemia.
Project description:DNA methyltransferase 1 (DNMT1) is an enzyme known for DNA methylation maintenance. However, point mutations in its RFTS domain lead to late-onset neurodegeneration such as the autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN) disorder. Here we demonstrated that wild-type DNMT1 also has the capability to bind to mRNA transcripts and facilitate 5-methylcytosine (m5C) RNA methylation by recruiting NOP2/Sun RNA methyltransferase 2 (NSUN2). RNA m5C methylation, in turn, promotes RNA stability for those genes modulating mitochondrial function. When DNMT1 RFTS domain is mutated in the case of ADCA-DN disorder, it triggers aberrant DNMT1-RNA interaction and significantly elevated m5C RNA methylation and RNA stability for a portion of metabolic genes. Consequently, increased levels of metabolic RNA transcripts contribute to cumulative oxidative stress, mitochondrial dysfunction, and neurological symptoms. Collectively, our results highlight a novel role for DNMT1 in regulating both DNA and RNA methylation as well as mitochondrial function, shedding light on the pathogenic mechanism of DNMT1 mutation-induced neurodegeneration.
Project description:DNA methyltransferase 1 (DNMT1) is an enzyme known for DNA methylation maintenance. However, point mutations in its RFTS domain lead to late-onset neurodegeneration such as the autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN) disorder. Here we demonstrated that wild-type DNMT1 also has the capability to bind to mRNA transcripts and facilitate 5-methylcytosine (m5C) RNA methylation by recruiting NOP2/Sun RNA methyltransferase 2 (NSUN2). RNA m5C methylation, in turn, promotes RNA stability for those genes modulating mitochondrial function. When DNMT1 RFTS domain is mutated in the case of ADCA-DN disorder, it triggers aberrant DNMT1-RNA interaction and significantly elevated m5C RNA methylation and RNA stability for a portion of metabolic genes. Consequently, increased levels of metabolic RNA transcripts contribute to cumulative oxidative stress, mitochondrial dysfunction, and neurological symptoms. Collectively, our results highlight a novel role for DNMT1 in regulating both DNA and RNA methylation as well as mitochondrial function, shedding light on the pathogenic mechanism of DNMT1 mutation-induced neurodegeneration.
Project description:DNA methyltransferase 1 (DNMT1) is an enzyme known for DNA methylation maintenance. However, point mutations in its RFTS domain lead to late-onset neurodegeneration such as the autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN) disorder. Here we demonstrated that wild-type DNMT1 also has the capability to bind to mRNA transcripts and facilitate 5-methylcytosine (m5C) RNA methylation by recruiting NOP2/Sun RNA methyltransferase 2 (NSUN2). RNA m5C methylation, in turn, promotes RNA stability for those genes modulating mitochondrial function. When DNMT1 RFTS domain is mutated in the case of ADCA-DN disorder, it triggers aberrant DNMT1-RNA interaction and significantly elevated m5C RNA methylation and RNA stability for a portion of metabolic genes. Consequently, increased levels of metabolic RNA transcripts contribute to cumulative oxidative stress, mitochondrial dysfunction, and neurological symptoms. Collectively, our results highlight a novel role for DNMT1 in regulating both DNA and RNA methylation as well as mitochondrial function, shedding light on the pathogenic mechanism of DNMT1 mutation-induced neurodegeneration.
Project description:DNA methyltransferase 1 (DNMT1) is an enzyme known for DNA methylation maintenance. However, point mutations in its RFTS domain lead to late-onset neurodegeneration such as the autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN) disorder. Here we demonstrated that wild-type DNMT1 also has the capability to bind to mRNA transcripts and facilitate 5-methylcytosine (m5C) RNA methylation by recruiting NOP2/Sun RNA methyltransferase 2 (NSUN2). RNA m5C methylation, in turn, promotes RNA stability for those genes modulating mitochondrial function. When DNMT1 RFTS domain is mutated in the case of ADCA-DN disorder, it triggers aberrant DNMT1-RNA interaction and significantly elevated m5C RNA methylation and RNA stability for a portion of metabolic genes. Consequently, increased levels of metabolic RNA transcripts contribute to cumulative oxidative stress, mitochondrial dysfunction, and neurological symptoms. Collectively, our results highlight a novel role for DNMT1 in regulating both DNA and RNA methylation as well as mitochondrial function, shedding light on the pathogenic mechanism of DNMT1 mutation-induced neurodegeneration.
Project description:DNA methyltransferase 1 (DNMT1) is an enzyme known for DNA methylation maintenance. However, point mutations in its RFTS domain lead to late-onset neurodegeneration such as the autosomal dominant cerebellar ataxia-deafness and narcolepsy (ADCA-DN) disorder. Here we demonstrated that wild-type DNMT1 also has the capability to bind to mRNA transcripts and facilitate 5-methylcytosine (m5C) RNA methylation by recruiting NOP2/Sun RNA methyltransferase 2 (NSUN2). RNA m5C methylation, in turn, promotes RNA stability for those genes modulating mitochondrial function. When DNMT1 RFTS domain is mutated in the case of ADCA-DN disorder, it triggers aberrant DNMT1-RNA interaction and significantly elevated m5C RNA methylation and RNA stability for a portion of metabolic genes. Consequently, increased levels of metabolic RNA transcripts contribute to cumulative oxidative stress, mitochondrial dysfunction, and neurological symptoms. Collectively, our results highlight a novel role for DNMT1 in regulating both DNA and RNA methylation as well as mitochondrial function, shedding light on the pathogenic mechanism of DNMT1 mutation-induced neurodegeneration.
Project description:DNA methylation plays a critical role in development, particularly in repressing retrotransposons. The mammalian methylation landscape is dependent on the combined activities of the canonical maintenance enzyme Dnmt1 and the de novo Dnmts, 3a and 3b. Here we demonstrate that Dnmt1 displays de novo methylation activity in vitro and in vivo with specific retrotransposon targeting. We used whole-genome bisulfite and long-read Nanopore sequencing in genetically engineered methylation depleted embryonic stem cells to provide an in-depth assessment and quantification of this activity. Utilizing additional knockout lines and molecular characterization, we show that Dnmt1's de novo methylation activity depends on Uhrf1 and its genomic recruitment overlaps with targets that enrich for Trim28 and H3K9 trimethylation. Our data demonstrate that Dnmt1 can de novo add and maintain DNA methylation, especially at retrotransposons and that this mechanism may provide additional stability for long-term repression and epigenetic propagation throughout development.
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.