Biology subjects

Jeltsch, A.

Publications and source records attributed to Jeltsch, A..

11 recordsLinked to original sources

bioRxiv2025

TET CpG sequence context specific DNA demeth-ylation shapes progression of IDH-mutant gliomas

BackgroundTreatment decisions in IDH-mutant oligodendrogliomas are shaped by tumor aggressiveness, underscoring the need for objective grading of these malignant brain tumors. Material and MethodsWe collected 302 primary and recurrent resections from oligodendrogliomas and performed Ki-67 staining, proteomics and DNA methylation profiling. Results & conclusionDuring tumor progression, DNA methylation of oligodendrogliomas changed along a continuum. This continuum is linked to increased epigenetic aging, methylation of transcription factors and Ki-67+ cell density, and to large scale DNA demethylation. Demethylation was correlated with CpGs flanking sequences preferred by TET enzymes. We confirmed these findings in previously profiled astrocytomas, indicating IDH-mutant gliomas progress along a shared epigenetic axis. We developed an objective DNA methylation based prognostic continuous grading coefficient (CGC{psi}) that captured these changes and outperformed WHO grading for oligodendrogliomas. Our findings underscore the potential of DNA methylation-based grading to more accurately reflect tumor biology and inform clinical decision-making in IDH-mutant gliomas.

cancer biology↗

bioRxiv2025

A Population Model Reveals Surprising Role of Stochastic Cell Division in Epigenetic Memory Systems

Epigenetic memory systems can store transient environmental signals in bacteria in form of DNA methylation patterns. A synthetic zinc finger protein (ZnF4) binds to the DNA in a methylation-dependent manner and represses the expression of the DNA methyltransferase CcrM. The ON-state of these systems is characterized by high CcrM expression, high methylation levels, and low ZnF4 binding, but the mechanisms ensuring long-term ON-state stability remain unclear. Measurements showed a gradual shift of cell populations from ON to OFF starting after about four days of cultivation. We use a hybrid modeling approach integrating flow-cytometry data and bulk methylation measurements to test the hypothesis that stochastic cell division is a key factor in this transition. Interestingly, model parameters cluster into two groups with opposite effects of cell division rates on ON-state stability. Experiments under varying growth conditions show that faster cell division increases memory stability -- an initially unexpected result. Model simulations provide a potential explanation for this observation and deepen our understanding about the mechanisms and timing of the ON/OFF switch in individual cells.

systems biology↗

bioRxiv2025

Development of a BiAD sensor for locus-specific detection of cellular histone acetylation dynamics by fluorescence microscopy

Dynamic changes in histone acetylation play crucial roles during cellular differentiation and disease development. Here, we developed a Bimolecular Anchor Detector (BiAD) sensor for the detection of locus-specific changes in histone acetylation in living cells by fluorescence microscopy. For this, we used the BRD9 bromodomain cloned as tandem double-domain (2xBRD9-BD) as reader of histone acetylation. It was integrated it into a dual-color BiAD chassis that was previously described [Kohler et al., 2024, Cell Rep Methods 4(4):100739]. We identified the gene body of TTC34 as potential target for our sensor, because it contains dense histone acetylation and 392 local sequence repeats. Using a binding deficient mutant of 2xBRD9-BD as negative control, we established successful readout of histone acetylation at the TTC34 locus. A single domain reader did not function indicating the requirement for the double reader to enhance affinity and specificity of the chromatin interaction via avidity effects. With this sensor, we could detect dynamic changes of histone acetylation at the TTC34 locus after treatment of cells with the histone deacetylase inhibitor Trichostatin A for 6 hours indicating the applicability of this sensor for single-cell epigenome studies.

molecular biology↗

bioRxiv2024

SETDB1 activity is globally directed by H3K14 acetylation via its Triple Tudor Domain

SETDB1 is a major H3K9 methyltransferase involved in heterochromatin formation and silencing of repeat elements. It contains a unique Triple Tudor Domain (3TD) which specifically binds the dual modification of H3K14ac in the presence of H3K9me1/2/3. Here, we explored the role of the 3TD H3-tail interaction for the H3K9 methylation activity of SETDB1. We generated a binding reduced 3TD mutant and demonstrate in biochemical methylation assays on peptides and recombinant nucleosomes containing H3K14ac analogs, that H3K14 acetylation is crucial for the 3TD mediated recruitment of SETDB1. We also observe this effect in cells where SETDB1 binding and activity is globally correlated with H3K14ac, and KO of the H3K14 acetyltransferase HBO1 causes a drastic reduction in H3K9me3 levels at SETDB1 dependent sites. Further analyses revealed that 3TD particularly important at specific target regions like L1M repeat elements, where SETDB1 KO cannot be efficiently reconstituted by the 3TD mutant of SETDB1. In summary, our data demonstrate that the H3K9me3 and H3K14ac are not antagonistic marks but rather the presence of H3K14ac is required for SETDB1 recruitment via 3TD binding to H3K9me1/2/3-K14ac and establishment of H3K9me3.

biochemistry↗

bioRxiv2023

Refined read-out: The hUHRF1 Tandem-Tudor domain prefers binding to histone H3 tails containing K4me1 in the context of H3K9me2/3

UHRF1 is an essential chromatin protein required for DNA methylation maintenance, mammalian development and gene regulation. We investigated the Tandem-Tudor domain (TTD) of human UHRF1 that is known to bind H3K9me2/3 histones and is a major driver of UHRF1 localization in cells. We verified binding to H3K9me2/3 but unexpectedly discovered stronger binding to H3 peptides and mononucleosomes containing K9me2/3 with additional K4me1. We investigated the combined binding of TTD to H3K4me1-K9me2/3 vs. H3K9me2/3, engineered mutants with specific and differential changes of binding, and discovered a novel read-out mechanism for H3K4me1 in an H3K9me2/3 context that is based on the interaction of R207 with the H3K4me1 methyl group and on counting the H-bond capacity of H3K4. Individual TTD mutants showed up to 10,000-fold preference for the double modified peptides, suggesting that after a conformational change, WT TTD could exhibit similar effects. The frequent appearance of H3K4me1-K9me2 regions demonstrated in our TTD pulldown and ChIP-western blot data suggests that it has specific biological roles. Chromatin pull-down of TTD from HepG2 cells and ChIP-seq data of full-length murine UHRF1 correlate with H3K4me1 profiles indicating that the H3K4me1-K9me2/3 interaction of TTD influences chromatin binding of full-length UHRF1. We demonstrated the H3K4me1-K9me2/3 specific binding of UHRF1-TTD to enhancers and promoters of cell-type specific genes, at the flanks of cell-type specific transcription factor binding sites, and provided evidence supporting an H3K4me1-K9me2/3 dependent and TTD mediated down-regulation of these genes by UHRF1, illustrating the physiological function of UHRF1-TTD binding to H3K4me1-K9me2/3 double marks in a cellular context.

molecular biology↗

bioRxiv2023

Non-canonical functions of UHRF1 maintain DNA methylation homeostasis in cancer cells

DNA methylation is an essential epigenetic chromatin modification, and its maintenance in mammals requires the protein UHRF1. It is yet unclear if UHRF1 functions solely by stimulating DNA methylation maintenance by DNMT1, or if it has important additional functions. Using degron alleles, we show that UHRF1 depletion causes a much greater loss of DNA methylation than DNMT1 depletion. This is not caused by passive demethylation as UHRF1-depleted cells proliferate more slowly than DNMT1-depleted cells. Instead, bioinformatics, proteomics and genetics experiments establish that UHRF1, besides activating DNMT1, interacts with DNMT3A and DNMT3B and promotes their activity. In addition, we show that UHRF1 antagonizes active DNA demethylation by TET2. Therefore, UHRF1 has non-canonical roles that contribute importantly to DNA methylation homeostasis; these findings have practical implications for epigenetics in health and disease.

molecular biology↗

bioRxiv2023

E2F1 methylation by SETD6 regulates SETD6 expression via positive feedback mechanism

The protein lysine methyltransferase SETD6 has been shown to influence different cellular activities and are critically involved in the regulation of diverse developmental and pathological processes. However, the upstream signal which regulates the mRNA expression of SETD6 is not known. Bioinformatics analysis revealed that SETD6 promoter has a binding site for the transcription factor E2F1. Using various experimental systems, we confirmed that E2F1 binds to the SETD6 promoter and regulates SETD6 mRNA expression. Our further observation that this phenomenon is SETD6 dependent, suggested that SETD6 and E2F1 are linked. We next demonstrate that SETD6 mono-methylates E2F1 specifically at K117 in-vitro and in cells. Finally, we show that E2F1 methylation at K117 positively regulates the expression level of SETD6 mRNA. Depletion of SETD6 or overexpression of E2F1 K117R mutant which canot be methylated by SETD6, reverses the effect. Taken together, our data provide evidence for a positive feedback mechanism which regulates the expression of SETD6 by E2F1 in a SETD6 methylation dependent manner and highlight the importance of protein lysine methyltransferases and lysine methylation signaling in the regulation of gene transcription.

molecular biology↗

bioRxiv2023

The T1150A cancer mutant of the protein lysine dimethyltransferase NSD2 can introduce H3K36 trimethylation

Somatic mutations in protein lysine methyltransferases are frequently observed in cancer cells. We show here that the NSD1 mutations Y1971C, R2017Q and R2017L observed mostly in solid cancers are catalytically inactive suggesting that NSD1 acts as tumor suppressor gene in these tumors. In contrast, the frequent T1150A in NSD2 and its T2029A counterpart in NSD1, both observed in leukemia, are hyperactive and introduce up to H3K36me3 in biochemical and cellular assays, while wildtype NSD2 and NSD1 only generate up to H3K36me2. MD simulations with NSD2 revealed that H3K36me3 formation is possible due to an enlarged active site pocket of T1150A and loss of direct contacts of T1150 to critical residues which regulate the product specificity of NSD2. Bioinformatic analyses of published data suggest that the NSD2 T1150A mutation in lymphocytic leukemia could alter gene regulation by antagonizing H3K27me3 finally leading to the upregulation of oncogenes.

molecular biology↗

bioRxiv2020

Comprehensive structure-function characterization of DNMT3B and DNMT3A reveals distinctive de novo DNA methylation mechanisms

Mammalian DNA methylation patterns are established by two de novo DNA methyltransferases DNMT3A and DNMT3B, which exhibit both redundant and distinctive methylation activities. However, the related molecular basis remains undetermined. Through comprehensive structural, enzymology and cellular characterization of DNMT3A and DNMT3B, we here report a multi-layered substrate-recognition mechanism underpinning their divergent genomic methylation activities. A hydrogen bond in the catalytic loop of DNMT3B causes a lower CpG specificity than DNMT3A, while the interplay of target recognition domain and homodimeric interface fine-tunes the distinct target selection between the two enzymes, with Lysine 777 of DNMT3B acting as a unique sensor of the +1 flanking base. The divergent substrate preference between DNMT3A and DNMT3B provides an explanation for site-specific epigenomic alterations seen in ICF syndrome with DNMT3B mutations. Together, this study reveals crucial and distinctive substrate-readout mechanisms of the two DNMT3 enzymes, implicative of their differential roles during development and pathogenesis.

genetics↗

bioRxiv2019

Mutations of R882 in DNMT3A change flanking sequence preferences and cellular methylation patterns in AML

DNMT3A R882 mutations are frequently observed in AML including the abundant R882H and the rare R882C, R882P and R882S. Using deep enzymology we show here that the DNMT3A-R882H has more than 70-fold altered flanking sequence preferences when compared with wildtype DNMT3A. The R882H flanking sequence preferences mainly differ on the 3 side of the CpG site, where they resemble DNMT3B, while 5 flanking sequence preferences of R882H resemble wildtype DNMT3A, indicating that R882H behaves like a DNMT3A/DNMT3B chimera. Activities and flanking sequence preferences of R882C, R882P and R882S were determined as well. Genomic methylation patterns after expression of wildtype DNMT3A and R882H in human cells reflect the flanking sequence preferences. R882H specific hypermethylation in AML patients are correlated with R882H flanking sequence preferences. The hypermethylation events are accompanied by R882H specific misregulation of several genes with strong cancer connection in AML patients, which are potential downstream targets of R882H.

biochemistry↗

bioRxiv2017

PWO1 interacts with PcG proteins and histones to regulate Arabidopsis flowering and development.

Polycomb-group (PcG) proteins mediate epigenetic gene regulation by setting H3K27me3 via Polycomb Repressive Complex 2 (PRC2). In plants, it is largely unclear how PcG proteins are recruited to their target genes.\n\nHere, we identified the PWWP-DOMAIN INTERACTOR OF POLYCOMBS1 (PWO1) protein which interacts with all three Arabidopsis PRC2 histone methyltransferases and is required for keeping full H3 occupancy at several Arabidopsis genes. PWO1 localizes and recruits CLF to nuclear speckles in tobacco nuclei, suggesting a role in spatial organization of PcG regulation. PWO1 belongs to a gene family with three members acting redundantly: pwo1 pwo2 pwo3 triple mutants are seedling lethal and show shoot and root meristem arrest, while pwo1 single mutants are early flowering. Interestingly, PWO1s PWWP domain confers binding to histones, which is reduced by a point mutation in a highly conserved residue of this domain and blocked by phosphorylation of H3S28. PWO1 carrying this mutation is not able to fully complement the pwo1 pwo2 pwo3 triple mutant, indicating the requirement of this domain for PWO1 in vivo activity. Thus, the PWO family may present a novel class of histone readers which are involved in recruiting PcG proteins to subnuclear domains and in promoting Arabidopsis development.

plant biology↗